 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| MLX90313 Programmable IR Sensor Interface Features and Benefits Dual low noise, low offset, fully programmable amplifier chain 12 bit on-chip ADC Powerful signal conditioning and linearisation unit Multiple output options: 12 bit digital through SPI, 8 bit resolution analog linear signal outputs or 10 bit PWM, both for ambient and object temperature. On-chip programmable digital moving average LPF for ultimate low noise performance ISP I/O-configuration and analog settings, accessible by SPI serial interface. Wide supply voltage range from 4.5V-80V Applications Thermopile + thermistor amplification chain Digital or analog, linear, ambient-compensated IR sensor interface General purpose programmable sensor amplifier/ signal conditioner Ordering Information Part No. MLX90313 Temperature Suffix K Package DF Temperature Range -40C to 125C Automotive Functional Diagram Description The MLX90313 is a versatile in-circuit programmable interface, which performs signal conditioning, linearisation and ambient temperature compensation, particularly for infrared sensors combined with a thermistor. Other types of sensors can also be used in various configurations. Sensors that can be used include pressure sensors, strain gauges, acceleration sensors etc. The amplifier chains in MLX90313 are programmable in very broad ranges of gain. Both chains consist of high performance, chopper-stabilized amplifiers, providing excellent noise performance and low offset. The I/O configuration as well as analog settings are incircuit programmable by means of the SPI-serial interface. This serial link can also be used to read out the output signals digitally. The circuit can either provide linear analog or PWM (Pulse Width Modulated) signal outputs. Additional the circuit can perform simple control applications using on-board comparators Supply Regulator IR+ IR path pwm output option selector IRThermistor path PGA Tinn A/D 12Bit Linearisation unit PGA A/D 12Bit IRout lin non lin pwm Tempout lin non lin Tinp Digital Control Logic Configuration eeprom SPI interface SPI interface MLX90313 Programmable IR sensor Interface 3901090313 Page 1 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface MLX90313 Electrical Specifications DC Operating Parameters TA = -40 C to 125 C, VDD = 4.5V to 80V (unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Regulator and consumption Supply voltage range Supply voltage range Supply current Regulated supply voltage Regulated voltage temperature coefficient POR threshold voltage Band-gap reference Analog ground voltage Analog ground thermal coefficient Reference current mirror load drive voltage Common mode input range Common mode rejection ratio Power supply rejection ratio Available gain settings Gain tolerance Amplifier offset Input referred white noise Chopper frequency Output voltage range Output source current Output sink current DC Output impedance, drive DC Output impedance, sink Capacitive load IROUT pin Amplifier bandwidth Common mode input range Common mode rejection ratio Power supply rejection ratio TINP bias current Available gain settings Iod Ios rod ros Cmax BW CMIR CMRR PSSR Itpb Atemp Page 2 f 100kHz f 100kHz bias current enabled 0.1 75 75 1/7 1 .1 40 Agnd TCbg Vcref 1.8 2.3 2.5 15 2 2.7 50 2.2 V V/ V Vin1 Vin Idd Vreg TCvr Vpor 1.1 VDD1 VDD @ Ta=25C VDD, 10uF ext. cap 4.7 7 4.5 5 5 5 -2.35 1.3 1.5 80 5.5 5.6 5.3 V V mA V mV/ V o o IR-chain amplifier and output driver CMIR CMRR PSSR Air Gir Voff Vnir fc IROUT IROUT IROUT IROUT IROUT IROUT 500 Vdd3V 0 1 20 10 100 50 rms-value 8 Vdd0.2 f 100kHz Rsens < 60k * f 100kHz 75 55 -6.5 5500 +6.5 4 25 dB V/V % V nV/Hz KHz V mA A pF Hz V dB dB iCref* V/V Rev 1.0 21-July-2001 -0.1 75 Vdd-3 V dB Temp-chain amplifier and output driver MLX90313 Programmable IR sensor Interface 3901090313 MLX90313 Programmable IR Sensor Interface Parameter Gain tolerance Amplifier offset Input referred white noise Chopper frequency Output voltage range Output source current Output sink current DC Output impedance, drive DC Output impedance, sink Capacitive load TEMPOUT pin Amplifier bandwidth Rel1 open drain relay driver High voltage protection output impedance Comp1 comparator Potentiometer input range ADC Input stage gain External Reference voltage Internal Reference voltage Vrefp input leakage current Resolution Monotonicity Differential non-linearity Integral non-linearity Gain error Total input-referred noise DAC Resolution Monotonicity Differential non-linearity Integral non-linearity DNL INL 8 guaranteed by design 1/2 1/2 LSB LSB bit DNL INL full scale Vref=3V Vrefpex Vrefp Ilvrefp @150C 12 guaranteed by design 0.4 1/2 1 0.2 LSB LSB LSB LSB 2.95 1 2.4 2.5 3 3.05 3.3 2.6 5 V/V V V uA bit IRirout IROUT 0 100 % of Vrefp Ro 32 10 V Symbol Gtemp Voff Vntemp fc ORtemp Iod Ios rod ros Cmax BW TEMPOUT TEMPOUT TEMPOUT TEMPOUT TEMPOUT TEMPOUT 500 0 1 20 10 100 50 rms-value 8 Vdd0.2 Test Conditions bias current enabled Min -6.5 Typ Max +6.5 4 400 Unit % V nV/Hz kHz V mA uA pF Hz *Rsens is the impedance of the sensor connected between IRINP and IRINN for the IR-chain amplifier. **Icref is the current flowing out of pin CREF MLX90313 Programmable IR sensor Interface 3901090313 Page 3 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface General Description The MLX90313 is a versatile in-circuit programmable interface, which performs signal conditioning, linearisation and ambient temperature compensation, particularly for infrared sensors combined with a thermistor. Other types of sensors can also be used in various configurations. Sensors that can be used include pressure sensors, strain gauges, acceleration sensors etc. The amplifier chains in MLX90313 are programmable in very broad ranges of gain, between 50 and 12000 for the IR-chain and between 1 and 120 for the Temp-chain. Both chains consist of high performance, chopper-stabilized amplifiers, providing excellent noise performance and low offset. The I/O configuration as well as analog settings are in-circuit programmable by means of the SPI-serial interface. This serial link can also be used to read out the output signals digitally. The circuit can either provide linear analog or PWM (Pulse Width Modulated) signal outputs, relative to an analog ground, or several combinations of analog and digital comparator driven outputs. Two comparators controlled by either one of the two linearised signals are available on chip with different possibilities for the threshold level, polarity and switching hysteresis. One of the comparators drives the open drain output. The user can provide the threshold for this comparator at the IROUT I/O pin with a simple potentiometer. A bias current for the thermistor can be obtained at the TINP input by connecting an external resistor between the CREF pin and VSS. The standard package is SOIC-20. Unique Features The MLX90313 integrates dual low noise programmable gain amplifier stages. Both thermistor and IR signal path can be configured to suit a large number of components and applications. The onboard analog to digital converter (ADC) combined with the digital linearisation unit results in linear output signals. These output signals are available as analog or digital output signal. Applications requiring digital temperature information can use single wire PWM output or SPI serial communication. The complete configuration and calibration is in-system programmable through the SPI interface. Combination of all these integrated features combined with a thermopile sensor make the MLX90313 a true high accuracy automotive grade single-chip infrared thermometer. Absolute Maximum Ratings Supply Voltage, Vin1 (overvoltage) Supply Voltage, Vin (overvoltage) Supply Voltage, Vin1 (operating) Supply Voltage, Vin (operating) Reverse Voltage Protection Supply Current, IDD Output Current, IOUT Operating Temperature Range, TA Operating Temperature Range, TS ESD Susceptibility Rel1 output impedance 80V 6V 16V 5.5V -5V 5.6 mA 3 mA -40C to +125C -55C to +150C 2 kV 10 ohms MLX90313 Programmable IR sensor Interface 3901090313 Page 4 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Pin-out TINP TINN IRINP IRINN VSS REL1 IROUT SDIN TOUT1 TOUT2 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 TEMPOUT CSB SDOUT SCLK TSTCLK VDD VDD1 AGND VREFP CREF Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Symbol TINP TINN IRINP IRINN VSS REL1 IROUT SDIN TOUT1 TOUT2 CREF VREFP AGND VDD1 VDD TSTCLK SCLK SDOUT CSB TEMPOUT Description Temp-chain amplifier positive input Temp-chain amplifier negative input IR-chain amplifier positive input IR-chain amplifier negative input Supply pin Open-drain relay driver output IR-chain amplifier output SPI data input Test pin/ Oscillator output Test pin, leave open Bias current reference Reference voltage input/output Analog ground, band-gap reference voltage Automotive Ignition supply pin Regulated supply pin Clock for test mode; leave open SPI clock input SPI data output SPI chip select active low Temp-chain amplifier output MLX90313 Programmable IR sensor Interface 3901090313 Page 5 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Pin Descriptions TINP Temperature sensor positive input pin. The pin connects to the temp-chain amplifier and the on-chip biasing current source. The source is a mirrored version of the current running into CREF with programmable ratio. The current source can be switched off for use of external current biasing. TINN Temperature sensor negative input. IRINP - IRINN Thermopile sensor input pins. VSS: Supply pin REL1 Open drain relay driver output. The typical on-resistance of this driver is <10 with a supply voltage of VDD=5V. Different configurations are possible as shown below. REL1 Vrefp REL1 Tambient or Tobject Tambient or Tobject IROUT COMP External potentiometer COMP Threshold in EEPROM VSS VSS Hysteresis in EEPROM Hysteresis in EEPROM VSS The comparator is a 12 bit digital comparator. The input polarity can be inverted or not. The threshold and hysteresis registers are 16 bit registers of which the 11 MSBs are used in the comparator circuitry. The voltage on the IROUT pin is sampled with 8 bit ADC referred between VREFP and VSS pins. Note. In case of potentiometer use the linearised analog output is not available. In this case the DAC is used as 8-Bit ADC for potentiometer (or other voltage source) monitoring. IROUT IROUT/POTin analog/digital I/O pin. This pin can be configured as analog output of the IR sensor or as input for an external potentiometer. (see pin description of REL1). As analog output, this pin can either be connected to the analog amplified IR sensor signal or to the linearised object temperature by means of the DAC. The driver can source at least 1mA and sink at least 20A to/from an external load. If the capacitive load on this pin exceeds 50pF, this load should be de-coupled by means of a series resistor. This pin can be configured also as digital output to transmit the IR temperature in PWM format. The pin is protected for over-voltage and can withstand 16V. SDIN Serial data input pin for the SPI. Data is accepted on the rising edge of the serial data clock (SCLK) SDOUT MLX90313 Programmable IR sensor Interface 3901090313 Page 6 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Serial data output pin for the SPI. Data is valid on the rising edge of the serial data clock (SCLK) SCLK Serial data clock from the external master to be supplied to this pin. Maximum frequency = 125kHz. CSB Active low, chip select pin for the SPI. Communication is started on the falling edge of CS and ended on the rising edge of CS. TOUT1 - TOUT2: Test pins. In normal mode, the internal clock signal of 1Mhz is present on TOUT1 and the clock of the chopper amplifier is present on TOUT2. CREF Current reference output. CREF is the reference voltage output for the temperature independent current source. The requirements for the resistor to be connected between CREF and VSS depend on the required accuracy and range of the ambient temperature measurement. The voltage level at CREF depends directly on the internal band-gap. VREFP Voltage reference I/O pin. This level is by default dependent on the on-chip band-gap reference source and can be programmed in range 2-4.5V from eeprom . This voltage is used as reference for the DAC, external applied potentiometer and 8-bit ADC. The chip can be configured to use an external reference voltage instead of the on-chip reference. The pin is protected from over-voltage and can withstand 16V AGND Analog ground reference pin. This voltage is derived from the on-chip band-gap and has a typical level of 2.5V for maximum output range of the amplifiers. When IROUT and/or TEMPOUT are connected directly to the amplified analog signals, then these signals are referred to AGND. The regulator can be stopped from the eeprom configuration register. In this case the pin can be used for external reference for the 12bit ADC. The pin is protected from over voltage and can withstand 16V VDD1 High voltage supply pin. This supply pin can be connected directly to an automotive ignition supply voltage. The internal regulator can operate with voltages between 7V and 80V. VDD 5V regulated supply pin. The 5V regulated voltage from the on-chip regulator is available on this pin. The internal regulator can supply up to 20mA to external circuitry. VDD can also be used to supply the chip directly with an external 5V regulated supply. TEMPOUT TEMPOUT analog output/Comparator output pin. This pin can be configured as analog output of the MLX90313 Programmable IR sensor Interface 3901090313 Page 7 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface temperature sensor or as output of the internal comparator circuit. As analog output, this pin can either be connected to the analog amplified temperature sensor signal or to the linearised ambient temperature by means of the DAC. When used as comparator output, different configurations are possible as shown below. analog options Tambient or Tobject COMP Tempout Threshold in EEPROM Hysteresis in EEPROM The driver can source at least 1mA and sink at least 20A to an external load. If the capacitive load on this pin exceeds 50pF, the load should be de-coupled by means of a series resistor. The pin is also output for linearised Tambient in PWM mode. The pin is protected from over-voltage and can withstand 16V MLX90313 Programmable IR sensor Interface 3901090313 Page 8 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Analog Section Supply regulator and Power-ON Reset The on-chip supply regulator and can be powered by an automotive ignition supply line (7V-80V). The chip can withstand SAE standard ignition transients. The resulting voltage of the regulator is available on VDD (5V300mV). The VDD pin can source up to 20mA to external circuitry. The chip can also be supplied directly with a 5V regulated supply on pin VDD. The power-on reset (POR) circuitry is completely internal. The chip is fully operational 16ms from the time the supply crosses 1.3V. The POR circuit will issue another POR if the supply voltage goes below 1.3V. Band-gap, DAC and ADC references The on-chip trimmable, curvature compensated band-gap circuitry provides a stable reference level (less than 10ppm per C) for several derived reference potentials used for normal operation in MLX90313. The analog ground at the AGND pin is directly derived from this band-gap voltage. The output voltages from both amplifier chains are relative to this potential. The AGND reference can be trimmed internally to (2.5V20mV). The regulator at AGND pin can be switched off to minimize the current consumption. The pin can be also used as external input for the internal 12-bit ADC. The reference voltages for ADC and DAC are also derived from the band-gap. The DAC reference is available at pin VREFP. The MLX90313 DAC reference voltage can be programmed on chip to one of the following values: 2, 2.5, 3, 3.5, 4 and 4.5 V. Depending on the customer application Melexis can program the linearised analog outputs for object and ambient temperatures providing absolute voltage/temperature dependence. The internal regulator for the DAC reference voltage can be switched off to minimize the consumption (if linearised analog output is not in use) or to use externally supplied reference for DAC reference in range 2 to 5V The ADC reference is 2.5V typically. The chip can be also programmed to use external ADC reference connected to pin AGND. The current reference bias voltage (present at CREF pin) is also derived from the on-chip band-gap reference. IR-amplifier chain MLX90313 is available with gain settings for the IR-amplifier chain ranging from 55 to 5500. The gain can be selected by setting the appropriate bits of the `Irgain1'-register (EEPROM address 00h) according to the table below. Any gain between the abovementioned limits can be obtained within an accuracy of 6.5%. The amplifier input-referred white noise level is below 23nVrms/Hz. In the application with IRsensors, with output resistance of 50k typical, the total system noise will however depend mainly on the noise of the sensor and will rise up to 45nVrms/Hz. The offset for the chopper stabilized amplifier path can be largely calibrated out and amounts to maximum 4V. The common mode input range of the amplifier is -100mV to VDD - 3V. The output range of the amplifier is 0V to VDD-0.2V. The output of the amplifier is referred to the potential on AGND. IR chain gain settings GIR = G pr x Gb x G pa x Gl stage contr. bits G pr GCI0 Gb GCI3 0 1 1 1 1 GCI2 X 0 0 1 1 GCI1 X 0 1 0 1 5 10 15 20 25 G pa GCI4 Gl GCI7 0 0 0 0 1 1 1 1 GCI6 0 0 1 1 0 0 1 1 GCI5 0 1 0 1 0 1 0 1 1.067 1.143 1.231 1.333 1.455 1.600 1.778 2.000 0 setting 1 10 0 1 20* 1 5 MLX90313 Programmable IR sensor Interface 3901090313 Page 9 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface * This option is available only if ENLN=1 The pin ENLN controls both the noise level and distortion of the amplifier. If ENLN=1 the noise of the amplifier is 23nVrms/Hz, the gain of 20 in first stage is available but the input signal must be less than 4 mV for less than 0.05% full scale distortion. If ENLN is 0 then the span of the input signal can be 40mV with distortion less than 0.1% full scale. In this case the noise floor of the amplification chain increases 3 times. Temp-amplifier chain MLX90313 is available with gain settings for the Temp-amplifier ranging from 5 to 50. The gain can be selected by setting the appropriate bits of the `Temp gain and current control'-register (EEPROM address 02h) according to the table below. Any gain between the abovementioned limits can be obtained within an accuracy of 6.5%. It is also possible to completely bypass the temperature amplifier and force the input signal directly to the ADC. The amplifier input-referred white noise level is below 400nVrms/Hz. The common mode input range of the amplifier is -100mV to VDD-3V. The output range of the amplifier is 0V to VDD-0.2V. The output of the amplifier is referred to the potential on AGND. Temp chain gain settings GT = G pr x Gl x M stage contr. bits G pr GCT2 0 GCT1 0 GCT0 0 1 Gl GCT5 GCT4 GCT3 M IRSEL2 IRSEL1 IRSEL0 X X X 0 0 0 1.067 0 0 0 0 1 1 5 0 0 1 1.143 0 0 1 1 0 0 10 0 1 0 1.231 0 1 0 1 0 1 15 0 1 1 1.333 0 1 1 settin g 1 0 0 1.455 1 0 0 1 1 0 20 1 0 1 1.600 1 0 1 1 1 0 1.778 1 1 0 1 1 1 25 1 1 1 2.000 1 1 1 Note: When the current mirror is on (all settings except IRSEL[2:0] = 000b) the gain is defined as follows: off 1/7 2/7 3/7 4/7 5/7 6/7 1 GT = Vout Rsens Icref where Vout is the output of the analog amplifier chain, Rsens is the resistance of the sensor connected between TINP and TINN and Icref is the current out of CREF. When the current mirror is off (IRSEL[2:0]=000b), M should be replaced by 1 and the gain is defined as follows: GT = Vout Vin where Vin is the voltage difference between TINP and TINN If GCT[2:0]=0 then the temp chain will be completely off, the Timp pin will be connected directly to the ADC input, providing Gain=1 Current Reference The thermistor (or sensor) connected to TINP must be biased with a current source. This bias current is mirrored from the current through the external resistor between CREF and VSS. The voltage maintained at the CREF pin is derived from internal band-gap voltage, and thus constant. The typical value of the voltage at CREF pin is 2V. The current mirror ratio can be set between 1/7 and 1 according to the table for the Temp-chain gain settings. The setting with IRSEL[2:0]=000b switches the current mirror off. In this case the thermistor must be biased by external circuitry. MLX90313 Programmable IR sensor Interface 3901090313 Page 10 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Analog-to-Digital Converter (ADC) MLX90313 contains a 12-bit internal analog to digital converter. Real 12 bit conversion is achieved by a fully differential signal path of the converter. The input amplifier of the ADC has a fixed gain of 3. Automatic calibration is implemented in the background, which allows precise conversion in a very wide temperature range. The ADC sampling rate is 7k samples/second. The reference voltage for the ADC is normally a scaled version of the internal band-gap reference and is fixed to be 2.5V. Alternatively MLX90313 can be configured to work with an external reference potential applied to the AGND pin. In this case the appropriate bit in the configuration register (SELADREF bit in Confreg1) must be cleared. Internal ADC can work with references down to 1 V keeping the 12-bit resolution. The ADC contains an interface circuit to scale and offset the analog signals in order to make the most efficient use of the available resolution. After amplification the IR and Temp sensor signals are referred to AGND voltage level (typical value 2.5V). The additional offset is scaled version of the AGND. The ADC interface circuit is given below. The output of the Temp-chain is amplified relative to the voltage reference VrefT, which can be controlled with 2 bits (bit10 and bit9, EEPROM address 02h). The possible values for VrefT can be calculated according to the equation: VrefT = VAgnd x 1.4 x (63 + K ) , where K =0 to 3, corresponding to the value of the control bits. 70 The typical values are 3.15, 3.20, 3.25 and 3.3V. If the temp path amplifier is bypassed then VrefT will be fixed to: Agnd x 0.28 = 0.7V typical. The output of the IR-chain is amplified relative to Refir and can be calculated according to the following equation: Vrefir = VAgnd x 1.4 x (34 + K ) , Where K=0:31 depending on the selected value of Rsel[4:0] 70 The typical values (for Agnd=2.5V) are listed in the table below: ADC interface setting RSEL[4:0] Refir [V] RSEL[4:0] Refir [V] RSEL[4:0] Refir [V] RSEL[4:0] Refir [V] 11111b 11110b 11101b 11100b 11011b 11010b 11001b 11000b 3.25 3.20 3.15 3.10 3.05 3.00 2.95 2.90 10111b 10110b 10101b 10100b 10011b 10010b 10001b 10000b 2.85 2.80 2.75 2.70 2.65 2.60 2.55 2.50 01111b 01110b 01101b 01100b 01011b 01010b 01001b 01000b 2.45 2.40 2.35 2.30 2.25 2.20 2.15 2.10 00111b 00110b 00101b 00100b 00011b 00010b 00001b 00000b 2.05 2.00 1.95 1.90 1.85 1.80 1.75 1.70 MLX90313 Programmable IR sensor Interface 3901090313 Page 11 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Config register 1: BYPTEMP Vrefp TINP pin Temp-chain out TINN pin x3 ADC 12 -Vrefp VReft Vrefp Linearisation Unit IR-chain out x3 ADC 12 -Vrefp VRefir Irgain register: [RSEL4:RSEL0] ADC reference configuration Digital-to-Analog Converter (DAC) A 8 bit digital to analog converter can be used to output the data for the linearised Tobject- and Tambient signals. The DAC can work with a internal programmable reference voltage, as well as with an external one. In case the internal reference voltage is used, this voltage can be monitored on the VREFP pin. If one wants to use his own reference voltage, this can be done by applying this voltage to the VREFP pin, and setting the appropriate configuration bit. The result from D/A conversion is stored on hold capacitors and buffered. The signals are available at IROUT and TEMPOUT respectively, if the appropriate bits are set in the configuration register (EEPROM address 04h). The reference value for the D/A can be programmed with 3 bits: SELDR[2:0] (register Irgain2) according to the table below: SELDR2 0 0 0 0 1 1 SELDR1 0 0 1 1 0 0 SELDR0 0 1 0 1 0 1 ENDREFDIV 0 0 0 1 1 1 VREFP 2 2.5 3 3.5 4 4.5 For reference voltages higher than 3V the ENDREFDIV bit must be set. In this case the ASIC will divide internally the reference by 2 to provide proper input common mode for the output buffer amplifiers at pins IROUT and TEMPOUT. In this case the result of the D/A conversion result will be amplified times 2 by the output amplifiers, which will ensure the requested signal swing. Melexis can rescale the DAC reference and eeprom table for the linearisation unit to provide absolute analog output. This way, at maximum calibrated temperature, the voltage of IROUT or TEMPOUT pin will always correspond to the requested D/A reference voltage. The regulator for the VREFP voltage can be stopped and an external reference voltage can be forced and used from the D/A. The regulator for DAC reference voltage can also be stopped (bit ENDACREF=0) when DAC is not in use. This will save some supply current. MLX90313 Programmable IR sensor Interface 3901090313 Page 12 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface SELDR(2:0) AGND VREFP ENDREFDIV DACREF DAC IRout, Tout IRout Tout ENDREFDIV DAC configuration Output drivers The IROUT and TEMPOUT outputs can be connected to various signals available: The amplified analog signals (IRINP-IRINN and TINP-TINN), the linearised object respectively ambient temperature signals, or to the comparator circuitry. The IROUT and TEMPOUT pin drivers can source 1mA and sink 20A and are reverse voltage protected down to -5V relative to VSS. The available configurations are described in table below. Input/Output Setting I/O pin IROUT Control IROUTC[1:0] Bits 00b 01b Setting 10b 11b Configuration IR-chain out Linear Tobject Threshold Rel1 input PWM out TEMPOUT TOUTC[1:0] 00b 01b 10b 11b Configuration Temp-chain out Linear Tambient Comp1 out PWM out REL1 is an open drain relay driver output controlled by the on-chip comparator circuitry. The available configurations are described in the section on the comparator circuitry. MLX90313 Programmable IR sensor Interface 3901090313 Page 13 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Digital Section The digital unit on board of MLX90313 realizes all functions for control, configuration, measurements and linearisation. It contains several registers, ALU and control logic. All functions of the ASIC are hardware fixed and controlled by different state machines, which execute in sequence all procedures necessary for normal chip operation. Internal registers overview The table below contains all internal registers, their addresses for access via SPI serial interface and short functional description. Depending on their function they can be divided in 3 groups: * * * Control registers: they keep the configuration of the chip including all gain settings of the amplifiers, analog ground level, band-gap and oscillator trimming data, etc. All this data is stored in eeprom and after POR the system loads it in the corresponding peripheral registers. Data registers: they keep all data for offsets, results from measurements and linearisation of both chains. This registers can be read vis spi in normal mode and are write accessible during test mode. Computation registers. These registers support the computation unit and keep all temporary data necessary for digital low pas filtering, linearisation and comparator functions. They are not accessible via SPI in normal mode. Internal Register Table. Register IRGAIN1 IRGAIN2 TEMPGAIN CONFREG1 CONFREG2 OSCILLATOR BGCONTROL LPF ADCREG IROUT TOUT IRDATA TDATA IROS TOS MAINSTM TEST REG TEMP REG A REG B TESTCTRL 1 REG C REG E TESTCTRL 2 WP Function IR-chain settings IR-chain settings Temp-chain settings Configuration Configuration Oscillator Bandgap control Low Pass Filter ADC output data Tobject (lin) Tambient (lin) IR-chain output Temp-chain output IR-chain offset Temp-chain offset Main state machine Test mode control Temporary register for test Accumulator A Accumulator B Test control Accumulator C Accumulator E ADC test control Eeprom write protect Address Dec Hex 0 00h 1 01h 2 02h 3 03h 4 04h 5 05h 6 06h 7 07h 8 08h 9 09h 10 0Ah 11 0Bh 12 0Ch 13 0Dh 14 0Eh 15 0Fh 16 10h Access via spi Write Test mode Test mode Test mode Test mode Test mode Test mode Test mode Test mode Test mode Test mode Test mode Test mode Test mode Test mode Test mode Test mode Always Test mode Test mode Test mode Test mode Test mode Testmode Test mode Always Read No No No Always Always No No No Always Always Always Always Always Always Always No No No No No No No No No No 20 14h 23 2431 17h 18h1Fh MLX90313 Programmable IR sensor Interface 3901090313 Page 14 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Configuration and control registers overview and bit functions as they are read from the module Bit functions REGISTERH REGISTERL IRGAIN1H IRGAIN1L IRGAIN2H IRGAIN2L TEMPGAINH TEMPGAINL CONFREG1H CONFREG1L CONFREG0H CONFREG0L OSCH OSCL BGH BGL LPFH LPFL TESTH TESTL TESTCTRL1H TESTCTRL1L TESTCTRL 2H TESTCTRL 2L WPH WPL B15 B7 ENDREFDIV GCI2 AGNDC3 RSEL2 TRSEL1 GCT2 ERROR REL1V IROUTC1 TIMEOS2 B14 B6 ENDAC GCI1 AGNDC2 RSEL1 TRSEL0 GCT1 ENVR REL1P IROUTC0 TIMEOS1 B13 B5 ENLN GCI0 AGNDC1 RSEL0 IRSEL2 GCT0 HVSUP EEWREN TOUTC1 TIMEOS0 B12 B4 GCI7 AGNDC0 IRSEL1 SELADREF TESTMODE TOUTC0 B11 B3 GCI6 SELDR2 IRSEL0 POTMET SUBINC B10 B2 GCI5 SELDR1 GCT5 COMP1V SUBDEC B9 B1 GCI4 SELDR0 GCT4 COMP1P NTC B8 B0 GCI3 RSEL3 GCT3 BYPTEMP TIMEOS3 ENAGNDB RSEL4 LPFT2 1 ENOSM LPFT1 0 ENTAV LPFT0 1 IROS 1 TOS 0 LPFIR2 0 LPFIR1 1 LPFIR0 1 1 0 0 1 0 1 Register Descriptions IRGAIN1 Read access: No. The data is accessible for read via SPI only from eeprom address 00h. Write access: Directly to the register in test mode. To eeprom if WP-register is correctly set. IRGAIN1 bit functions Name POR ENDREFDIV ENDAC ENLIN GCI[7:0] X X X X val 1 1 1 0000000011111111 Function Divide the reference for the DAC and enable output amplification by 2 of the To and Ta outputs. Must be set for Vref=3.5V,4V,4.5V. Enable the DAC regulator Enable low noise. Control the gain of the IR amplifier chain (see `IR amplifier chain') IRGAIN2 Read access: No. The data is accessible for read via SPI only from eeprom address 01h. Write access: Directly to internal register in test mode. To EEprom if WP-register is correctly set. IRGAIN2 bit functions Bit POR val AGNDC [3:0] X 0000-1111 SELDR [2:0] X 000 X 001 X 010 X 011 X Function Reserved Adjustment of the DAC reference. Vref = 2V Vref =2.5V Vref = 3V Vref = 3.5V MLX90313 Programmable IR sensor Interface 3901090313 Page 15 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface IRGAIN2 bit functions Bit POR val 100 X 101 X 0000-1111 RSEL[3:0] X Function Vref = 4V Vref = 4.5V Select the value of the analog ground for IR signal path.The bits are 5, RSEL4 is in LPF register (see `ADC' part) TEMPGAIN Read access: No. The data is accessible for read via SPI only from eeprom address 02h. Write access: Directly to internal register in test mode. To EEprom if WP-register is correctly set. TEMPGAIN bit functions Bit POR val 00-11 TRSEL[1:0] X IRSEL[2:0] GCT[5:0] X X 000-111 000000111111 Function Reference voltage for Tambient measurement at ADC interface input. Current mirror ratio: See under M in table `Temp chain gain settings' in the section on the Temp-amplifier chain (analog features) Temp-gain: See table `Temp-chain gain settings' in the section on the temp-amplifier chain (analog features) CONFREG1 Read access: Directly from internal registers or EEprom. Write access: Directly to internal register in test mode. To EEprom if WP-register is correctly set. CONFREG1 bit functions Bit POR val Fatal Error 1 X Function Flags Multiple eeprom failure. Hamming coding can detect and correct only one bit per address. Bit will be cleared when going in test mode,disabling EEPROM protection and returning in normal mode.( for diagnostics only) ENVR 1 Stops the internal reference for DAC (Pin VREF). The reference voltage can be X supplied externally. If ENDAC=0 then VREF is input. HVSUP 1 1 Enable the regulator for battery supply. NOTE!!! After POR this regulator will be always on. It can be stopped from EEPROM data. SELADREF X 0 External supply of ADC reference to AGND pin. 1 Enable the internal ADC reference (connected to AGND pin). 0 Sets threshold level for Rel1 to THRel1 in EEprom (address 75h) X POTMET 1 Sets potentiometer input (pin IROUT) as threshold level 0 Sets Tobject as target voltage for comparator Comp1 X COMP1V 1 Sets Tambient as target voltage for comparator Comp1 COMP1P X 0 Sets polarity of Comp1: Inverting 1 Sets polarity of Comp1: Non-inverting 0 Output of Temp amplifier path is connected to ADC X BYPTEMP 1 Connects TINP-TINN directly to the ADC, bypassing the Temp-chain 0 Sets Tobject as target voltage for Rel1 X REL1V 1 Sets Tambient as target voltage for Rel1 0 Sets polarity of Rel1: Inverting X REL1P 1 Sets polarity of Rel1: Non-inverting EEWREN 0 1 Enables write access in EEPROM *write protect TESTMODE 0 1 Indicates chip is in test mode *write protect *control bits EEWREN and TESTMODE are write protected. Their values can be set only with writing the appropriate data in `Test' and `WP' registers. These bits are flags which indicate the system operation MLX90313 Programmable IR sensor Interface 3901090313 Page 16 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface mode. CONFREG0 CONFREG0 bit functions Bit POR val IROUTC[1:0] 00b 01b 10b 11b TOUTC[1.0] 00b 01b 10b 11b SUBINC 0 1 SUBDEC 0 1 NTC 0 1 TIMEOS[3:0] 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 Function IROUT pin function: IR-chain out IROUT pin function: Linear Tobject IROUT pin function: Threshold Rel1 input IROUT pin function: PWM out TEMPOUT pin function: Temp-chain out TEMPOUT pin function: Linear Tambient TEMPOUT pin function: Comp1 out TEMPOUT pin function: PWM out 2nd order derivative of thermistor function is positive (used if NTC=0) 2nd order derivative of thermistor function is negative (used if NTC=0) 2nd order derivative of thermistor function is positive (used if NTC=1) 2nd order derivative of thermistor function is negative (used if NTC=1) Used thermistor is PTC Used thermistor is NTC Offset calibration interval: 0'00" Offset calibration interval: 0'02" Offset calibration interval: 0'17" Offset calibration interval: 0'19" Offset calibration interval: 1'07" Offset calibration interval: 1'09" Offset calibration interval: 1'24" Offset calibration interval: 1'26" Offset calibration interval: 2'14" Offset calibration interval: 2'16" Offset calibration interval: 2'31" Offset calibration interval: 2'33" Offset calibration interval: 3'21" Offset calibration interval: 3'23" Offset calibration interval: 3'38" Offset calibration interval: 3'40" OSCCTRL Read access: No. The data is accessible for read via SPI only from eeprom address 05h. Write access: Only in test mode for both writing directly to internal registers and writing to Eeprom if WP register is correctly set. BGO: Reserved Read access: No. The data is accessible for read via SPI only from eeprom address 06h. Write access: Only in test mode for both writing directly to internal registers and writing to Eeprom if the WP register is correctly set. LPF Read access: No. The data is accessible for read via SPI only from eeprom address 07h. MLX90313 Programmable IR sensor Interface 3901090313 Page 17 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Write access: Only in test mode for both writing directly to internal registers and writing to Eeprom if the WP register is correctly set. This register keeps the calibration data for the time constants of digital low pass filters of both channels (see section Linearisation Unit). LPF bit functions Bit POR RSEL4 ENOSMB ENTAV IROS* TOS* LPFIR[2:0] LPFT[2:0] Val Function 0 Refer to ADC interface setting 0 Enable offset measurement of both IR & Temp channels. 1 Disable offset measurement of both IR &Temp channels. 0 Reserved for future development. Reset it for all applications. 1 Reserved for future development. Reset it for all applications. Number of averaged offset measurements for IR chain: 512 0 1 Number of averaged offset measurements for IR chain: 1024 0 Number of averaged offset measurements for Temp chain: 512 1 Number of averaged offset measurements for Temp chain: 1024 Number of averaged points for IR measurement 00b 64 01b 128 10b 256 11b 512 1024 100b Number of averaged points for Temp measurement 00b 64 01b 128 10b 256 11b 512 100b 1024 ADCREG Read access: Directly via SPI in all modes. Write access: Directly to internal register in test mode. This register keeps the result from last analog to digital conversion.. IROUT Read access: Directly from internal register. Write access: Directly to internal register in test mode. This register keeps the linearised object temperature. (Tobject) Register format: Bit 15 14 Name D11 D10 13 D9 12 D8 11 D7 10 D6 9 D5 8 D4 7 D3 6 D2 5 D1 4 D0 3 OVH 2 OVL 1 FE 0 Res D11..D0 : OVH: OVL: FE: Res 12 bit temperature data Overflow flag for Tambient measurement, Ta>Tamax, D[11:0] set to FFFh Underflow flag for Tambient measurement, Ta Page 18 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Note that the last 4 bits are the status register. TOUT Read access: Directly from internal register. Write access: Directly to internal register in test mode. This register keeps the linearised ambient temperature. (Tambient) Register format: Bit 15 14 Name D11 D10 13 D9 12 D8 11 D7 10 D6 9 D5 8 D4 7 D3 6 D2 5 D1 4 D0 3 OVH 2 OVL 1 FE 0 Res D11..D0 : OVH: OVL: FE: Res 12 bit temperature data Overflow flag for Tambient measurement, Ta>Tamax, D[11:0] set to FFFh Underflow flag for Tambient measurement, Ta TDATA Read access: Directly from internal register. Write access: Directly to internal register in test mode. This register keeps the measured Temp data, compensated with the current offset of the Temp amplifier (stored in Tos register). IROS Read access: Directly from internal register. Write access: Directly to internal register in test mode. This register keeps the offset of the IR amplifier. Each measurement from IR amplifier will be compensated with this offset. TOS Read access: Directly from internal register. Write access: Directly to internal register in test mode. This register keeps the offset of the Temp amplifier. Each measurement from Temp amplifier will be compensated with this offset. MLX90313 Programmable IR sensor Interface 3901090313 Page 19 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface MAINSTM: Reserved Read access: No Write access: Directly to internal register in test mode TEST Read access: No. Write access: Directly to internal register. This register determines the chip mode. It is cleared after POR which corresponds to normal mode. Writing the proper data in this register will put the chip in test mode which will be indicated with bit `Test' from confreg0. Test register Bit POR B[15:9] B[8:0] 0000000b 000000000 b val 1011001b any other X Function Forces chip in test mode Normal mode (default) WP Read access: No. Write access: Directly to internal register via SPI. The register controls the write access to the eeprom. After POR this register is cleared and the eeprom is protected, no write access available. Writing the proper data in this register will remove the write protection of the eeprom and bit EEWREN (bit 1 in Confreg1) will be set. EEprom write protect register Bit POR val B[15:9] 000000000 X b 1100101b B[6:0] 0000000b any other Function Enables write access to Eeprom* Sets EEprom write protect * The addresses 00-07h and 79-7Fh will be still protected. Write access here requires also `Test mode'. MLX90313 Programmable IR sensor Interface 3901090313 Page 20 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Eeprom Description MLX90313 contains 128 x 16 EEPROM memory. The memory can be accessed through the serial interface. The 11 most significant bits are data bits and the 5 less significant bits are control bits used for the Error Check and Correction system (ECC). After POR the ASIC reads the full eeprom contents, checks it and corrects the single errors (1 wrong bit per address). If higher order error is discovered then the bit `fatal error' will be set (see Confreg1 description in previous section). The memory has two levels of protection. After POR the write access to the eeprom will be disabled. The external unit can remove this level of protection writing proper data in WP register. In this case all addresses in range 08-77h will be available for write access. The first and last 8 addresses will still be disabled. The write access to these cells is available only if the write protection is removed and the chip is in test mode. Eeprom map overview Address list eeprom Register name IRGAIN1 IRGAIN2 TEMPGAIN CONFREG1 CONFREG2 OSCCTRL BGCTRL LPF CALIBRATION IOS-TEMP IOS-IR RESERVED THCOMP1 HSCOMP1 THREL1 HSREL1 Function IR-chain settings IR-chain settings Temp-chain settings Configuration Configuration Oscillator control Bandgap control Low Pass Filter Look up table linearisation. Initial offset Temp-chain Initial offset IR-chain Threshold for comparator Comp1 Hysteresis for comparator Comp1 Threshold for comparator of Rel1 Hysteresis for comparator of Rel1 Address Dec 0 1 2 3 4 5 6 7 8-111 112 113 114 115 116 117 118 Write access Hex 00h 01h 02h 03h 04h 05h 06h 07h 08h-6Fh 70h 71h 72h 73h 74h 75h 76h test mode** test mode test mode test mode test mode test mode test mode test mode WP* WP WP WP WP WP WP WP RESERVED 119 77h CHIP-ID Data 120-127 78h-7Fh test mode *WP: Write access to EEprom is controlled by the content of the internal register WP **Test mode: Write access controlled by the internal register WP and only available in test mode The last 8 addresses 0x78 to 0x7F are free to use for the user. They can hold some calibration data or identification number. All data programmed into the eeprom must pass the error checking. Therefore, one must add 5 hamming bits to the eeprom data, in the 5 least significant bits. MLX90313 Programmable IR sensor Interface 3901090313 Page 21 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Eeprom bit definitions Following table gives the bit definitions for all addresses that can be modified by the user. All other addresses contain specific calibration data and should be left unchanged. Note that some bits marked "RES" are reserved and should never not be changed by the user. If other bits in such an address must be changed, read original contents first to get the status of the reserved bits. EEPROM BIT DEFENITIONS ADDRESS (HEX) 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x73 0x74 0x75 0x76 0x78 - 0x7F REGISTERH REGISTERL IRGAIN1H IRGAIN1L IRGAIN2H IRGAIN2L TEMPGAINH TEMPGAINL CONFREG1H CONFREG1L CONFREG0H CONFREG0L OSCH OSCL BGH BGL LPFH LPFL THComp1 HSComp1 THRel1 HSRel1 USER1..7 B15 B7 ENDREFDIV GCI2 AGNDC3 RSEL2 TRSEL1 GCT2 ENVR REL1P IROUTC1 TIMEOS2 RES RES RES RES RSEL4 LPFT2 THR10 THR2 HST10 HST2 THR10 THR2 HST10 HST2 UDATA10 UDATA2 B14 B6 ENDAC GCI1 AGNDC2 RSEL1 TRSEL0 GCT1 HVSUP RES IROUTC0 TIMEOS1 RES RES RES RES ENOSM LPFT1 THR9 THR1 HST9 HST1 THR9 THR1 HST9 HST1 UDATA9 UDATA1 B13 B5 ENLN GCI0 AGNDC1 RSEL0 IRSEL2 GCT0 SELADREF RES TOUTC1 TIMEOS0 ENAGNDB RES RES RES ENTAV LPFT0 THR8 THR0 HST8 HST0 THR8 THR0 HST8 HST0 UDATA8 UDATA0 B12 B4 GCI7 K AGNDC0 K IRSEL1 K POTMET K TOUTC0 K RES K RES K IROS K THR7 K HST7 K THR7 K HST7 K UDATA7 K B11 B3 GCI6 H4 SELDR2 H4 IRSEL0 H4 COMP1V H4 SUBINC H4 RES H4 RES H4 TOS H4 THR6 H4 HST6 H4 THR6 H4 HST6 H4 UDATA6 H4 B10 B2 GCI5 H3 SELDR1 H3 GCT5 H3 H3 SUBDEC H3 RES H3 RES H3 LPFIR2 H3 THR5 H3 HST5 H3 THR5 H3 HST5 H3 UDATA5 H3 B9 B1 GCI4 H2 SELDR0 H2 GCT4 H2 H2 NTC H2 RES H2 RES H2 LPFIR1 H2 THR4 H2 HST4 H2 THR4 H2 HST4 H2 UDATA4 H2 B8 B0 GCI3 H1 RSEL3 H1 GCT3 H1 REL1V H1 TIMEOS3 H1 RES H1 RES H1 LPFIR0 H1 THR3 H1 HST3 H1 THR3 H1 HST3 H1 UDATA3 H1 COMP1P BYPTEMP Eeprom Hamming coding All addresses in the eeprom are coded using hamming code. Therefore, if one wants to program data into any eeprom address, the hamming bits must be calculated first. This is not done by the There are 11 bits + 4 hamming bits + 1 extra redundant bit in the eeprom. Data bits are numbered D10..D0, Hamming H4..H1, the extra bit is called K. The bit definitions in the eeprom words are: Pos name 15 D10 14 D9 13 D8 12 D7 11 D6 10 D5 9 D4 8 D3 7 D2 6 D1 5 D0 4 K 3 H4 2 H3 1 H2 0 H1 The hamming bits are calculated as follows: H1 = P(D0,D1,D3,D4,D6,D8,D10) Page 22 Rev 1.0 21-July-2001 MLX90313 Programmable IR sensor Interface 3901090313 MLX90313 Programmable IR Sensor Interface H2 = H3 = H4 = P(D0,D2,D3,D5,D6,D9,D10) P(D1,D2,D3,D7,D8,D9,D10) P(D4,D5,D6,D7,D8,D9,D10) The extra K bit is calculated as: K= P(D10,D9,D8,D7,D6,D5,D4,D3,D2,D1,D0,H4,H3,H2,H1) Note :P is parity over the noted data bits. Parity is 1 if the number of ones is odd. When reading eeprom addresses, the numerical value can be found by simply dividing the returned data by 32. MLX90313 Programmable IR sensor Interface 3901090313 Page 23 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface 90313 Algorithm The algorithm of the ASIC is divided in several operations: ECC, initialization, offset measurement, object and ambient measurement and offset cancellation, linearisation, comparator functions. Each of this operation is controlled from the main state machine. The sequence and control of all these state machines is controlled from main state machine. The normal flow of the procedure is show on the diagram below. POR ECC Initialization Offset calibration Measurement Temp. linearisation IR. linearisation Comp & Relay TRUE Recalibration FALSE Main state machine control flow MLX90313 Programmable IR sensor Interface 3901090313 Page 24 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Error Check and Correction (ECC) The ASIC starts this procedure only after Power On Reset. The state machine reads all data in the eeprom and corrects all single errors (1 wrong bit per address) if necessary. The wrong information from the eeprom will be refreshed with correct one. In case of double error (2 wrong bits per address) which can only be detected, not corrected, the system will leave the data in the address and will set the flag `Fatal error' (bit 1 in status register). This data is available through SPI or PWM. Initialization At this step the system reads its configuration from the eeprom. All data from eeprom addresses 00-07h will be filled in the corresponding peripheral registers. After this step the ASIC is ready for normal operation. Offset measurement (offset drift compensation) The offset measurement is run periodically from the main state machine. The customer can select one of 16 possible interval times for offset measurement (see `CONFREG0 bit functions'). Depending on the selected values for bits IROS and TOS in LPF register (address 07h in EEPROM) the average of 512 or 1024 measurements is stored. The time this measurement takes is about 75ms or 150ms, depending on the number of measurements taken. Note that during this time the outputs are kept on their last value before calibration started, so the current temperature is not available during offset calibration. The measured offset results will be stored in IROS (for IR amplifier chain) and TOS (for Temp amplifier chain) registers. Measurement and offset cancellation The results from analog to digital conversion for both channels will be the mean of custom defined number of measurements, controlled from the LPF register (address 07 in eeprom). This data will be compensated with corresponding offsets, stored in IROS and TOS registers and final offset free data will be stored in IRDATA (for IR amplifier chain) and TDATA (for Temp amplifier chain) registers. The number of measurements of which the averaging is taken can vary between 64 and 1024 (see `LPF register bit functions') and can be selected independently for both channels. Linearisation Linearisation proceeds in two steps and can be described by the picture below. In the first step the ambient temperature is calculated from the measured signal at TINP-TINN. The system outputs a digital value for the ambient temperature based on the calibration data. The value is stored in a dedicated register and from there available for the DAC and PWM (Tambient-register, address 0Ah). The register can also be read digitally by means of the SPI. The system is developed to support different temperature sensors. 3 bits in the configuration register (EEprom address 03h), determine the type of characteristic. NTC defines the first derivative of the temperature sensor (NTC-type is logical 1, PTC-type is logical 0). SUBDEC and INCDEC define the second derivative of the temperature sensor ( d 2VRth ). dT 2 Ta max - Ta min in K per LSB 4096 The result of the linearisation is stored as the 12 MSB's of the Tambient-register (or TOUT-register). The code 000h will correspond to Tamin, FFFh will correspond to Tamax. These two limits are determined by calibration. Accordingly the output resolution will be In the second step the value of the ambient temperature is combined with the measured signal at IRINPIRINN to obtain a calculated value for the so-called object temperature, based on the calibration data. The value is stored in a dedicated register and from there available for the DAC and PWM (Tobject-register, address 09h). The register can also be read digitally by means of the SPI. The result of the linearisation is stored as the 12 MSB's of the Tobject-register (or IROUT-register). The MLX90313 Programmable IR sensor Interface 3901090313 Page 25 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface code 000h will correspond to Tomin, FFFh will correspond to Tomax. These two limits are determined by calibration. Accordingly the output resolution will be To max - To min in K per LSB. 4096 Linearised output Irout=A.T o+B The r m opile Char acte r is tic V ir=f(To, T a) Vir Signal [V] Irout [V] Irout Ta T o [degC ] To [d e gC] T h e r m is to r ch ar acte r is tic R=f(T a) Lin. Unit L in e ar ise d o u tp u t T e m p o u t= A .T o + B R(T)/Ro R Tempout[V] Tempout T a [d eg C ] T a[d e g C ] When reading the linearised data digitally by means of the SPI, a 16-bit word is returned. The 12 MSB's contain the temperature value as described above, the 4 LSB's form a status register, which is the same for both the IROUT address and the TOUT. The meaning of the individual bits is explained in the table below. Linearisation Status Register S[3:0] Meaning 1 X X X X 1 X X X X 1 X X X X 0 Overflow flag for Tambient measurement, Ta>Tamax, TOUT[15:4] set to FFFh Underflow flag for Tambient measurement, Ta MLX90313 Programmable IR sensor Interface 3901090313 Page 26 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Comp1 circuitry setting Comp1 source signal Control Bit COMP1V Setting 0 1 Tobject Tambient Comp1 Polarity COMP1P 0 1 Inverting Non-inverting Linearised Tambient Linearised Tobject 12 12 bit 2/1 MUX 12 analog options COMP1P 12 bit digital comparator Tempout 12 COMP1V Threshold address:73h 11+1 Hysteresis address:74h Comparator1 (COMP1) Configuration diagram Note that the threshold for COMP1, is always in eeprom address 0x73. Rel1 circuitry setting Rel1 source signal Control Bit REL1V Setting 0 1 Tobject Tambient 12 Linearised T ambient 12 Linearised T object REL1P 12 bit digital comparator 12 bit 2/1 MUX REL1 REL1V 8 IROUT ADC Rel1 Threshold source POTMET 0 1 [75h] IRDATA [03h] Rel1 Polarity REL1P 0 1 Inverting Non-inverting 12 12 IRDATA register 11+1 Threshold address:75h Hysteresis address:76h 12 bit 2/1 MUX 12 4LSB 0000 POTMET Comparator2 (REL1 pin) Configuration diagram After the temperature data is updated in TOUT and IROUT registers (the current Ta&To are calculated) the main state machine will enable the comparator functions of the chip if one of them is enabled. Threshold data for both outputs is stored in addresses 73h (for Comp1) and 74h (for Rel1) in eeprom. MLX90313 Programmable IR sensor Interface 3901090313 Page 27 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface The threshold data can be calculated by the formula: Threshold value = Tthr - T min x 2048 . T max - T min where: Tthr is the target temperature for the comparator Tmin, Tmax are the minimum and maximum temperature under calibration. The hysteresis value can be calculated by following formula: Hysteresis value = Thys x 2048 T max - T min where: Thys is the desired hysteresis in deg C. Tmin, Tmax are the minimum and maximum temperature under calibration Both formulas are valid for ambient and IR temperatures. The data for hysteresis must be stored at addresses 74h (for Comp1) and 76h (for Rel1) after adding the hamming bits in the 5 least significant bit places. Refer to Hamming Coding in eeprom description section for details. Pulse Width Modulation The PWM signal has a period of 102.4ms typical consisting of 2048 clock cycles of 50s. Every frame starts with a leading buffer time, t1, during which the signal is always high, as shown in the figure below. The leading buffer time is followed by a slot for the useful data signal, t2 and t3, where the ration t2/(t2+t3) is the representation of the output value. t4 is a slot for signaling of special conditions, such as out of range measurement of the sensor temperature, Tambient and the occurrence of a fatal EEprom error, i.e. an error that can no longer be corrected automatically by the ECC circuitry of MLX90313. Error signaling band Condition Duty cycle nominal timing OVH: Tambient overflow 68.75 % 70.4 ms OVL: Tambient underflow 75 % 76.8 ms FE: Fatal Error EEprom 81.25% 83.2 ms t4:Error Signaling Band OVH output signal FE Valid Data Output Band OVL t1 t2+t3 t5 time 0 1 8 T 5 8 T 11 16 T 12 16 T 13 16 T 7 8 T T Serial Interface Protocol The digital interface implemented in MLX90313 is SPI compatible. It can be used to access the on-chip EEPROM and all internal registers. The chip will always work as a slave device. The format of any MLX90313 Programmable IR sensor Interface 3901090313 Page 28 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface command is always 32 bits: 8 bits for the operation code, 8 bits for the address and 16 bits of data. The communication protocol is presented below. CS SCLK SDI SDO C7 C6 C5 C4 C3 C2 C1 X C0 A7 C7 A6 C6 A5 C5 A4 C4 A3 C3 A2 C2 A1 C1 A0 C0 D15 A7 D14 A6 D13 A5 D12 A4 D11 A3 D10 A2 D9 A1 D8 A0 D7 D15 D6 D14 D5 D13 D4 D12 D3 D11 D2 D10 D1 D9 D0 D8 X X write command CS SCLK SDI SDO C7 C6 C5 C4 C3 C2 C1 X C0 A7 C7 A6 C6 A5 C5 A4 C4 A3 C3 A2 C2 A1 C1 A0 C0 X D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X read command Every write command starts with a high to low transition of CS and ends by a low to high transition of CS after 32 periods of the serial data clock (SCLK). MLX90313 reads the data present on SDI on the rising edge of the clock. With a delay of 8 periods of the serial clock, the SPI will repeat the opcode, address and the first 8 bits of data on pin SDO. This allows the external master to check command and address and terminate the operation in case of an error by forcing CS high before the end of the complete command cycle, i.e. before the end of the 32 clock periods. The read command is build up similarly, except that no data has to be passed of course. On SDO the opcode will be followed directly by the requested data, the address is not returned in this case. The data on SDO is valid on the rising edge of the clock. In case of a read command, the SPI output will th be valid on SDO starting on the 17 rising edge of the clock (after CS low) as indicated in the figure above. Timing/speed The bit-rate depends on the serial data clock (SCLK) supplied by the master controller and is limited to 125kb/s. The timing requirements are given in the figure and table below tcls tsclk tsch CS SCLK tsu thd SDI tdv SDO SPI timing requirements Symbol tsclk tcls tsch tsu thd Parameter Sclk period CS low to SCLK high SCLK low to CS high data in setup time data in hold time Value min 8 min 50 min 50 min 200 min 200 Page 29 Unit s ns ns ns ns Rev 1.0 21-July-2001 MLX90313 Programmable IR sensor Interface 3901090313 MLX90313 Programmable IR Sensor Interface tdv operation codes The operation code is the first series of 8bits in a command, C[7:0] in the figure on the protocol above. Below table summarizes the operations available in MLX90313. Operation Codes mnem. C[7:0] X1 0 WR X1 0 RD WEPR 0 0 0 001 ER REPR X 0 0 BLWR 1 0 0 101 BLER data out valid min 1 s 1 0 1 X 0 1 X X 1 X X 1 X X 0 0 X X X X X X X X X X X X X X X X X X X Command Write internal register Read internal register Write Eeprom Erase EEprom Read Eeprom Block Write Eeprom Block erase Eeprom MLX90313 Programmable IR sensor Interface 3901090313 Page 30 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Applications Information IR sensor IR+ IRThermisto r Rsens VSS MLX9024 7 IRINP OPA A/D D/A To 12 COMP MLX90313 IRINN TINP TINN OPA TEMPOUT Digital A/D D/A Ta 12 COMP Ta IROUT REL1 SW1 AGND CREF Rbias 100k high prec. 10u VDD VSS Control and Support Blocks SPI VREFP VDD1 SW2 Vref Micro-controller I/O-port Typical application diagram In the above application diagram, a simple thermometer with alarm function is depicted. As external components there are only a thermopile (like the MLX90247x) and a current setting resistor is used. Because the current needs to be constant over temperature and time, it is advised to use a precision resistor. The tempout pin is the output of a comparator which compares the measured object temperature with the threshold set by the external potentiometer. The second comparator operates the relay. It compares the ambient temperature with a fixed threshold programmed in eeprom. Both ambient and object temperatures can be read continously by the microprocessor using the SPI interface. For more application examples, take a look at our MLX90601 Infrared thermometer module, which incorporates a MLX90247 thermopile sensor and the MLX90313 IR sensor interface. MLX90313 Programmable IR sensor Interface 3901090313 Page 31 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Support Tools In a short time Melexis will provide a demo board which can demonstrate all MLX90313's features. This will come with software which allows easy configuration of the MLX90313. Please have a look at www.melexis.com for latest info. ESD Precautions Electronic semiconductor products are sensitive to Electro Static Discharge (ESD). Always observe Electro Static Discharge control procedures whenever handling semiconductor products. FAQ Q: When is the MLX90313 available ? A: Currently Melexis only delivers the MLX90313 as part of the MLX90601x Infrared Thermometer module. Please refer to MLX90601 datasheet for details. Samples can be obtained Q3/2001, full production starts Q4/2001. Glossary of Terms ADC Ambient Compensation Analog-to-digital converter The IR signal captured by a thermopile sensor is not only dependent on the temperature of the object (Tobject) but also on the temperature of the sensor itself. Therefore the IR signal is compensated for this effect by means of the measured sensor temperature (Tambient). This rather complex calculation is performed in the linearisation unit of MLX90313. application specific integrated circuit Circuit to generate accurate absolute voltages. Usually they are independent of temperature and supply voltage, like the one used in the MLX90313 Special amplifier configuration aimed at ultra low offset ASIC Band-gap Chopper compensated amplifier DAC Differential nonlinearity (DNL) ECC Eeprom Digital-to-analog converter The deviation of any code from an ideal 1 LSB step Error Checking and Correction non-volatile memory that can be electrically erased and rewritten. This type of memory is used to store configuration and calibration data needed by the MLX90313. By giving a message a extra number of bits (= so called hamming bits), one can not only detect, but also correct a error that occurs in the stored data or the hamming bits. The eeprom memory of the MLX90313 uses hamming coding to do a error check and correction if needed and possible. This is the maximum deviation from the ideal output curve and the actual output Infrared. Every object emits infrared radiation in relation to its temperature. This effect can be used to measure this temperature without the need for physical contact. The signal from a thermopile is not linear with the object temperature. MLX90313 is therefore equipped with a digital calculation unit that produces an output that is linear with the object temperature. Least Significant Bit, Most Significant Bit See Thermistor. Programmable gain amplifier. Page 32 Rev 1.0 21-July-2001 Hamming coding Integral nonlinearity (INL) IR Linearisation LSB,MSB NTC PGA MLX90313 Programmable IR sensor Interface 3901090313 MLX90313 Programmable IR Sensor Interface POR PSSR PTC SPI Ta, Tambient, ambient temperature Thermistor power -on reset: reset circuit that starts the digital system in a known state whenever the supply voltage is cycled Power Supply Rejection Ratio: Measure for an amplifier's immunity to disturbances on the supply connections. See Thermistor. Serial Peripheral Interface. Commonly used 4 wire serial link to connect different circuits over a short distance. The temperature of the IR sensor. Temperature dependant resistor. Basically there are 2 types. The types that increase their resistance with rising temperature are PTC (positive thermal coefficient) type. The ones that decrease their resistance with rising temperature we call NTC (negative thermal coefficient) type. The MLX90313 can work with both types. commonly used terms in infrared thermometry. It refers to the temperature of the target, at which the IR sensor is "looking" Tobject, To and Target Temperature MLX90313 Programmable IR sensor Interface 3901090313 Page 33 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Disclaimer Melexis reserves the right to periodically make modifications to product specifications. The information included herein is believed to be accurate and reliable. However, Melexis assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use. MLX90313 Programmable IR sensor Interface 3901090313 Page 34 Rev 1.0 21-July-2001 MLX90313 Programmable IR Sensor Interface Physical Characteristics 0.32 0.23 10.45 10.15 7.60 7.40 1.04 0.60 0.50 0.33 1.27 0o to 8o Notes: 12.99 12.70 1. All dimensions in millimeters. 2.66 2.45 0.290 0.127 For the latest version of this document, go to our website at: www.melexis.com Or for additional information contact Melexis Direct: Europe and Japan: Phone: +32 13 61 16 31 E-mail: sales_europe@melexis.com All other locations: Phone: +1 603 223 2362 E-mail: sales_usa@melexis.com MLX90313 Programmable IR sensor Interface 3901090313 Page 35 Rev 1.0 21-July-2001 |
Price & Availability of MLX90313
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |