View MAX3130_47040.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-1402; Rev 0; 11/98
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
General Description
The MAX3130/MAX3131 combine an IrDA 1.2 compatible infrared transceiver with an RS-232 interface--all in a single 3V-powered hybrid microcircuit. The infrared transceiver supports IrDA data rates of 2.4kbps to 115kbps. The infrared receive channel provides a highgain/low-noise PIN-diode amplifier with 100A of ambient photodiode current rejection at a +3V supply. A high-power LED driver capable of sinking 200mA is included in the infrared transmit path. The on-board encoder/decoder (ENDEC) compresses/stretches signals to and from the external UART, allowing IrDA communication even with non-IrDA UARTs. A 2-driver/2-receiver RS-232 transceiver supports data rates up to 120kbps. A proprietary, high-efficiency, dual charge-pump power supply and a low-dropout transmitter combine to deliver true RS-232 performance from a single +3.0V to +5.5V supply. Selectable shutdown for IR and RS-232 circuitry reduces supply current to 1A. The MAX3130 is optimized for applications using a single UART for both infrared and RS-232 communication. The infrared transmitter input and infrared receiver output are multiplexed with one RS-232 transmitter input and one RS-232 receiver output, respectively. The MAX3131's IrDA transceiver and RS-232 transceivers are separate and have their own data inputs and outputs. Both these devices require a minimum of external components: four small 0.1F capacitors, a photodiode, an infrared LED, and a current-setting resistor.
Features
o Integrated RS-232 and IrDA in Single 28-Pin SSOP Package o 370A Supply Current o IrDA 1.2 Compatible: 2.4kbps to 115kbps Data Rate o On-Board IR Encoder/Decoder Allows Use of Non-IrDA UARTs o +3.0V to +5.5V Single-Supply Operation o Meet EIA/TIA-232 Specifications Down to +3V o 200mA, High-Current Infrared LED Drive o 1A Low-Power Shutdown with RS-232 Receivers Active
MAX3130/MAX3131
Ordering Information
PART MAX3130CAI MAX3130EAI MAX3131CAI MAX3131EAI TEMP. RANGE 0C to +70C -40C to +85C 0C to +70C -40C to +85C PIN-PACKAGE 28 SSOP 28 SSOP 28 SSOP 28 SSOP
Pin Configuration
TOP VIEW
EDGEDET (RXD) 1 28 R2OUT 27 R2IN 26 T2OUT 25 RSSD 24 V-
Applications
Personal Digital Assistants (PDAs) Palmtop Computers Battery-Powered Systems Hand-Held Equipment Peripherals IrDA Applications Cellular Phones
T1IN 2 T2IN 3 IRMODE (TXD) 4 R1OUT 5 R1IN 6 T1OUT 7 BAUD16 8 GND 9 VCC 10 N.C. 11 AVCC 12 AGND 13 PINC 14
MAX3130 MAX3131
23 C222 C2+ 21 C120 C1+ 19 V+ 18 N.C. 17 LEDC 16 PGND 15 IRSD
( ) ARE FOR MAX3131
SSOP
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..............................................................-0.3V to +6V AVCC to AGND .........................................................-0.3V to +6V VCC to AVCC .......................................................................0.3V AGND, PGND to GND ........................................................0.1V V+ to GND ................................................................-0.3V to +7V V- to GND .................................................................+0.3V to -7V V+ to V- ................................................................................+13V Inputs (referenced to GND) T1IN, T2IN, TXD, RSSD, IRMODE, BAUD16, IRSD....................................................................-0.3V to +6V R1IN, R2IN .....................................................................25V Outputs (referenced to GND) T1OUT, T2OUT............................................................13.2V R1OUT, R2OUT, EDGEDET, RXD.........-0.3V to (VCC + 0.3V) LEDC...................................................................-0.3V to +6V Output Short-Circuit Duration (to VCC or GND) T1OUT, T2OUT .....................................................Continuous Output Currents LEDC Continuous ........................................................200mA LEDC 20% Duty Cycle tON < 90s..............................500mA Input Current PINC ..............................................................................10mA Continuous Power Dissipation (TA = +70C) SSOP (derate 9.52mW/C above +70C) ...................762mW Operating Temperature Ranges MAX3130/MAX3131CAI ....................................0C to +70C MAX3130/MAX3131EAI..................................-40C to +85C Storage Temperature Range .............................-65C to +160C Lead Temperature (soldering, 10sec) .............................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC = AVCC = 3.0V to 5.5V, GND = AGND = PGND, C1-C4 = 0.1F (Note 1), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C and VCC = AVCC = 3.3V.) PARAMETER DC CHARACTERISTICS Power-Supply Current Analog Power-Supply Current Shutdown Supply Current Shutdown Analog Supply Current VCC = 3.3V or 5V, TA = +25C (Note 2) TA = +25C (Note 2) RSSD = low or IRMODE = low, TA = +25C (Note 2) IRSD = low, TA = +25C (Note 2) 0.25 120 1.0 0.01 1.0 200 10 1.0 mA A A A CONDITIONS MIN TYP MAX UNITS
LOGIC INPUTS (T1IN, T2IN, TXD, IRMODE, BAUD16, IRSD, RSSD) Input Logic Threshold Low Input Logic Threshold High Input Leakage Current VCC = AVCC = 3.3V VCC = AVCC = 5V VIN = 0 to VCC ISINK = 1.6mA ISOURCE = 1.0mA VCC 0.6 2.4 10 (Note 3) AVCC = 3.3V AVCC = 5V 0.0002 100 375 6 2.0 2.4 0.01 1.0 0.8 V V A
LOGIC OUTPUTS (R1OUT, R2OUT, RXD, EDGEDET) Output Voltage Low Output Voltage High IR RECEIVER Data Rate Equivalent Input Noise Current Input Current Sensitivity Ambient Photodiode Current Rejection (Note 3) 115.2 kbps nARMS mA A A 0.1 VCC 0.05 0.4 V V
2
_______________________________________________________________________________________
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
ELECTRICAL CHARACTERISTICS (continued)
(VCC = AVCC = 3.0V to 5.5V, GND = AGND = PGND, C1-C4 = 0.1F (Note 1), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C and VCC = AVCC = 3.3V.) PARAMETER IR Receiver Disable Time IR Receiver Enable Time IR Receiver Output Pulse Width IR TRANSMITTER Transmitter Rise Time Transmitter Fall Time Transmitter Output Resistance Off-Leakage Current IrDA ENCODER/DECODER (ENDEC) Maximum Operating Frequency IR Output Pulse Width BAUD16 Operating Frequency Range RS-232 RECEIVER Input Voltage Range Input Threshold Low Input Threshold High Input Hysteresis Input Resistance Receiver Propagation Delay Receiver Skew RS-232 TRANSMITTER OUTPUTS Output Voltage Swing Output Resistance Output Short-Circuit Current Output Leakage Current Maximum Data Rate Transmitter Skew T1OUT, T2OUT, loaded with 3k to GND VCC = V+ = V- = 0, T_OUT = 2V VT_OUT = 0 VT_OUT = 12V, VCC = 0 to 5.5V, RS-232 transceiver shutdown RL = 3k, CL = 1000pF, one transmitter switching tPHL - tPLH 120 235 300 5 300 5.4 10M 35 60 25 V mA A kbps ns TA = +25C R_IN to R_OUT, CL = 150pF tPHL - tPLH, CL = 150pF tPHL tPLH 3 VCC = 3.3V VCC = 5V VCC = 3.3V VCC = 5V -25 0.6 0.8 1.2 1.5 1.5 1.8 0.3 5 300 300 300 7 2.4 2.4 25 V V V V k ns ns Maximum frequency at BAUD16 fBAUD16 = 1.8432MHz, measured at VLEDC fBAUD16 required to enable ENDEC 1.43 34.6 2 2.23 2000 MHz s kHz 10% to 90% of 200mA drive current 90% to 10% of 200mA drive current IOUT = 200mA VLEDC = 5.5V AVCC = 3.3V AVCC = 5V 20 20 1.15 0.9 0.01 600 600 2 1.6 10.0 ns ns A CONDITIONS Delay until IAVCC < 1A Delay until maximum IR receive data rate is valid BAUD16 = static (Note 3) Data rate = 2.4kbps Data rate = 115kbps 1 1 1.6 MIN TYP 10 300 90 8 MAX UNITS s s s
MAX3130/MAX3131
_______________________________________________________________________________________
3
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
ELECTRICAL CHARACTERISTICS (continued)
(VCC = AVCC = 3.0V to 5.5V, GND = AGND = PGND, C1-C4 = 0.1F (Note 1), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C and VCC = AVCC = 3.3V.) PARAMETER CONDITIONS VCC = 3.3V, RL = 3k to 7k, measured from +3V to -3V or -3V to +3V, TA = +25C CL = 150pF to 1000pF CL = 150pF to 2500pF MIN 6 4 100 TYP MAX 30 V/s 30 s UNITS
Transition-Region Slew Rate
Transmitter Enable Time
Delay until transmitter outputs are valid
Note 1: C1-C4 = 0.1F, tested at +3.3V 10%. C1 = 0.047F, C2-C4 = 0.33F, tested at +5.0V 10%. Note 2: All supply current measurements are made under no-load condition on all outputs, and all input voltages are at VCC or GND. Note 3: For a compliant IrDA input signal where the data rate is within the supported data rate for the IR receive mode: rise/fall times are less than 600ns and pulse widths are between 1.41s and 3/16 of the baud rate.
Typical Operating Characteristics
(VCC = AVCC = 3.3V, GND = AGND = PGND, C1-C4 = 0.1F, RL = 3k, TA = +25C, unless otherwise noted.)
ANALOG SUPPLY CURRENT vs. TEMPERATURE
MAX3130 toc02 MAX3130 toc01
SUPPLY CURRENT vs. TEMPERATURE
380 360 340 320 IAVCC (A) ICC (A) 300 280 260 240 220 200 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 90 -40 VCC = 3.3V or 5V 150 140 130 120 110 100
AMBIENT PHOTODIODE CURRENT REJECTION vs. SUPPLY VOLTAGE
MAX3130 toc03
500
AVCC = 5V
CURRENT REJECTION (A) 80 100
400
300
AVCC = 3.3V
200
100
0 -20 0 20 40 60 3.0 3.5 4.0 4.5 5.0 5.5 TEMPERATURE (C) SUPPLY VOLTAGE (V)
LED DRIVER ON-RESISTANCE vs. TEMPERATURE
MAX3130 toc04
LEDC VOLTAGE vs. LEDC CURRENT
MAX3130 toc05
RXD OUTPUT PULSE WIDTH vs. DISTANCE (2400bps)
TRANSMITTER POWER = 200mW/sr INPUT PULSE WIDTH = 78s TEMIC BPV22NF VCC = 3.3V
MAX3130 toc06
1.6 1.4 1.2 RLED () 1.0 0.8 0.6 0.4 0.2 ILEDC = 200mA 0 -40 -20 0 20 40 80 VCC = 5V VCC = 3.3V
600 500 LEDC VOLTAGE (mV) 400 300 200 100 0 VCC = 3.3V
100
80 RXD PULSE WIDTH (s)
60
40
VCC = 5V PULSED AT 20% DUTY CYCLE
20
0 100 150 200 250 300 350 400 0 20 40 60 80 100 LEDC CURRENT (mA) DISTANCE (cm)
100
TEMPERATURE (C)
4
_______________________________________________________________________________________
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
Typical Operating Characteristics (continued)
(VCC = AVCC = 3.3V, GND = AGND = PGND, C1-C4 = 0.1F, RL = 3k, TA = +25C, unless otherwise noted.)
RXD OUTPUT PULSE WIDTH vs. DISTANCE (115.2 kbps)
MAX3130 toc07
MAX3130/MAX3131
TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
TRANSMITTER OUTPUT VOLTAGE (V) VOUT+ 1 TRANSMITTER AT 235kbps 1 TRANSMITTER AT 15kbps
MAX3130 toc08
4.0 3.5 RXD PULSE WIDTH (s) 3.0 2.5 2.0 1.5 1.0 0 20
TRANSMITTER POWER = 200mW/sr INPUT PULSE WIDTH = 1.63s TEMIC BPV22NF VCC = 3.3V
6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 0 1000 2000 3000
VOUT-
40
60
80
100
4000
5000
DISTANCE (cm)
LOAD CAPACITANCE (pF)
RS-232 TRANSMITTER SLEW RATE vs. LOAD CAPACITANCE
MAX3130 toc09
SUPPLY CURRENT vs. LOAD CAPACITANCE (RS-232 TRANSMITTING)
1 TRANSMITTER DRIVEN ONLY 35 235kbps 30 ICC (mA) 25 120kbps 20 15 20kbps 10 5 0
MAX3130-toc10
18 16 14 SLEW RATE (V/s) 12 10 8 6 4 2 0 0 1000 2000 3000 4000 +SLEW -SLEW
40
5000
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
RXD OUTPUT vs. INFRARED INPUT
RXD OUTPUT vs. INFRARED INPUT
MAX3130 toc11
MAX3130 toc12
2V/div
RXD OUTPUT
2V/div
RXD OUTPUT
2V/div
INFRARED INPUT 2V/div
INFRARED INPUT
2s/div VCC = 3.3V, 115.2kbps AT 1cm DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
100s/div VCC = 3.3V, 2400bps AT 1cm DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
_______________________________________________________________________________________
5
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
Typical Operating Characteristics (continued)
(VCC = AVCC = 3.3V, GND = AGND = PGND, C1-C4 = 0.1F, RL = 3k, TA = +25C, unless otherwise noted.)
RXD OUTPUT vs. INFRARED INPUT RXD OUTPUT vs. INFRARED INPUT
MAX3130 toc13
MAX3130 toc14
2V/div
RXD OUTPUT
2V/div
RXD OUTPUT
2V/div
INFRARED INPUT
2V/div
INFRARED INPUT
2s/div VCC = 3.3V, 115.2kbps AT 10cm DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
100s/div VCC = 3.3V, 2400bps AT 10cm DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
RXD OUTPUT vs. INFRARED INPUT
MAX3130 toc15
RXD OUTPUT vs. INFRARED INPUT
MAX3130 toc16
2V/div
RXD OUTPUT
2V/div
RXD OUTPUT
2V/div
INFRARED INPUT
2V/div
INFRARED INPUT
2s/div VCC = 3.3V, 115.2kbps AT 1m DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
100s/div VCC = 3.3V, 2400bps AT 1m DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
Pin Description
PIN MAX3130 1 -- 2 MAX3131 -- 1 2 NAME FUNCTION Edge Detector Output. EDGEDET goes low if activity is sensed on either the RS-232 receiver or the IrDA receiver, depending on the state of IRMODE. See EDGEDET: EdgeDetection Circuitry section. IR Receiver TTL/CMOS Data Output TTL/CMOS RS-232 Transmitter Input
EDGEDET RXD T1IN
6
_______________________________________________________________________________________
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
Pin Description (continued)
PIN MAX3130 MAX3131 NAME FUNCTION TTL/CMOS RS-232 Transmitter Input. For the MAX3130, drive IRMODE low to connect T2IN to the IR transmitter input, and drive IRMODE high to connect T2IN to the RS-232 transmitter input. For the MAX3131, T2IN is always connected to the RS-232 transmitter input. IR Mode Control. Drive IRMODE low to connect R2OUT to the IR receiver output and T2IN to the IR transmitter input. Driving IRMODE low also shuts down the RS-232 charge pump and puts the RS-232 transmitter outputs in a high-impedance state. Drive IRMODE high to connect R2OUT to the RS-232 receiver output and connect T2IN to the RS-232 transmitter input. IR Transmitter TTL/CMOS Data Input TTL/CMOS RS-232 Receiver Output RS-232 Receiver Input RS-232 Transmitter Output 16-Times Baud-Rate Input. To use the ENDEC, apply a signal that is 16 times the baud rate into BAUD16. Connect BAUD16 to GND or VCC to disable the ENDEC. Ground 3.0V to 5.5V Supply Voltage No Connection. Do not make connections to these pins. Analog Supply Voltage VCC for IR Signal Processing. AVCC range is 3.0V to 5.5V. Analog Ground for IR Signal Processing. Connect to GND. Silicon PIN Photodiode Input. Connect PINC to the cathode of the PIN photodiode. Connect the anode of the PIN photodiode to GND. Shutdown Input for the IrDA Transceiver Circuitry Power Ground for IR LED Driver. Connect to GND. Open-Drain Output for Driving the IR LED. Connect LEDC to the cathode of the IR LED. +5.5V Generated by the Internal Charge Pump Positive Terminal of the Voltage-Doubling Charge-Pump Capacitor Negative Terminal of the Voltage-Doubling Charge-Pump Capacitor Positive Terminal of the Inverting Charge-Pump Capacitor Negative Terminal of the Inverting Charge-Pump Capacitor -5.5V Generated by the Internal Charge Pump Shutdown Input for the RS-232 Transmitters and Charge Pump RS-232 Transmitter Output RS-232 Receiver Input TTL/CMOS RS-232 Receiver Output. For the MAX3130, drive IRMODE low to connect R2OUT to the IR receiver output, and drive IRMODE high to connect R2OUT to the RS-232 receiver output. For the MAX3131, R2OUT is always internally connected to the RS-232 receiver output.
MAX3130/MAX3131
3
3
T2IN
4
--
IRMODE
-- 5 6 7 8 9 10 11, 18 12 13 14 15 16 17 19 20 21 22 23 24 25 26 27
4 5 6 7 8 9 10 11, 18 12 13 14 15 16 17 19 20 21 22 23 24 25 26 27
TXD R1OUT R1IN T1OUT BAUD16 GND VCC N.C. AVCC AGND PINC IRSD PGND LEDC V+ C1+ C1C2+ C2VRSSD T2OUT R2IN
28
28
R2OUT
_______________________________________________________________________________________
7
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
MAX3130 Function Table
MAX3130 CONTROL INPUTS RSSD X X 0 0 1 1 IRMODE 0 0 1 1 1 1 IRSD 0 1 0 1 0 1 LOGIC INPUTS T1IN RS-232 Input RS-232 Input T2IN IrDA Input IrDA Input T1OUT High-Z High-Z High-Z High-Z RS-232 I/O T2OUT High-Z High-Z High-Z High-Z RS-232 Output RS-232 Output R1IN RS-232 Input RS-232 Input RS-232 Input RS-232 Input RS-232 Input RS-232 Input R2IN RS-232 Input RS-232 Input RS-232 Input RS-232 Input RS-232 Input RS-232 Input LOGIC OUTPUTS R1OUT RS-232 Output RS-232 Output RS-232 Output RS-232 Output RS-232 Output RS-232 Output R2OUT IrDA Output IrDA Output RS-232 Output RS-232 Output RS-232 Output RS-232 Output IrDA OUTPUT LEDC Enabled Enabled Disabled Disabled Disabled Disabled IrDA INPUT PINC Disabled Enabled Disabled Enabled Disabled Enabled
RS-232 RS-232 Input Input RS-232 RS-232 Input Input
RS-232 RS-232 RS-232 Input Input Output RS-232 RS-232 RS-232 Input Input Output
X = Don't care
MAX3131 Operational Modes Table
RSSD 0 0 1 1 IRSD 0 1 0 1 T_OUT High-Z High-Z Enabled Enabled R_IN Enabled Enabled Enabled Enabled LEDC Enabled Enabled Enabled Enabled RXD Logic High IrDA Output Logic High IrDA Output
Detailed Description
The MAX3130/MAX3131 are IrDA 1.2 compatible, infrared transceivers with an integrated RS-232 interface. By selecting appropriate external optical components, these devices support IrDA 1.2 data rates from 2.4kbps to 115kbps at distances from 1cm to 1m. A low-noise design allows them to achieve a bit-error rate below 10-8 at maximum data rates. On-chip filtering rejects out-of-band ambient light signals that interfere with infrared communication. Both devices include a high-power LED driver capable of sinking 200mA. The MAX3130 and MAX3131 contain two RS-232 drivers and two RS-232 receivers that support data rates up to 120kbps. The RS-232 transceiver is powered by a highefficiency, dual charge-pump power supply that operates with input supply voltages from +3.0V to +5.5V. The MAX3130 is optimized for applications using a single UART for both infrared and RS-232 communication. The infrared transmitter input and infrared receiver output are multiplexed with one RS-232 transmitter input and one RS-232 receiver output, respectively. The MAX3131 IrDA and RS-232 transceivers are independent of each other for use in simultaneous multiprotocol transceiver applications.
8
IR Receivers
The receiver amplifier reverse biases the PIN diode with approximately 1.2V, and the PIN diode converts pulses of IR light into pulses of current. The input transimpedance (current-to-voltage) amplifier converts and amplifies these current pulses into voltage pulses. The MAX3130/MAX3131 incorporate filters that remove lowfrequency ambient light interference and high-frequency circuit noise from these voltage pulses. A high-speed comparator then translates these voltage pulses into CMOS output levels. Figures 1 and 2 show system functional diagrams. The RXD pin is the output of the infrared receiver for the MAX3131. The R2OUT pin is the output of the infrared receiver for the MAX3130 (IRMODE = low). With the ENDEC disabled, the infrared receiver output pulses low upon each incoming infrared pulse. The pulse width of the receiver output depends on many factors, including transmitter distance and power, PIN photodiode efficiency and area, and incoming data rate. Under all circumstances the output pulse is less than one baud period. To communicate with UARTs that are not IrDA compatible, enable the ENDEC (see the IrDA Encoder/Decoder (ENDEC) section).
_______________________________________________________________________________________
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
ON C1+ C1 C1C2+ C2 C2R1OUT RECEIVE LOGIC OUTPUTS 5k R2OUT 5k EDGE T1IN TRANSMIT LOGIC INPUTS 232 IR IRMODE BAUD16 fBAUD16 TxIN ENDEC RxIN Tx Rx EDGEDET VCC GND 1F RSET T1OUT RS-232 OUTPUTS R2IN CHARGE PUMP RSSD SHDN V+ VC4 C3 OFF
R1IN RS-232 INPUTS
T2IN
T2OUT
EDGE
MAX3130
LEDC
PGND PINC
ON OFF
IRSD
BIAS
1.2V
AVCC AGND 1F
Figure 1. MAX3130 Functional Diagram
_______________________________________________________________________________________
9
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
C1+ C1 C1C2+ C2 C2R1OUT RS-232 RECEIVE LOGIC OUTPUTS CHARGE PUMP
ON SHDN RSSD V+ VC4 C3 OFF
R1IN 5k RS-232 INPUTS R2IN 5k
R2OUT
T1IN RS-232 TRANSMIT LOGIC INPUTS IrDA TRANSMIT LOGIC INPUT IrDA RECEIVE LOGIC OUTPUT
T1OUT RS-232 OUTPUTS
T2IN TXD RXD TxIN ENDEC Tx RxIN Rx
T2OUT
MAX3131
VCC GND 1F RSET
BAUD16
fBAUD16
LEDC
PGND PINC
ON OFF
IRSD
BIAS
1.2V
AVCC AGND 1F
Figure 2. MAX3131 Functional Diagram
10
______________________________________________________________________________________
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
IR Transmitter
The infrared transmitter consists of an internal highpower, open-drain MOSFET switch. This switch has an on-resistance of less than 2 and is capable of switching 200mA of current. Internal buffering keeps the input capacitance of the TXD pin extremely low to ease user drive requirements. Connect an IR LED in series with a current-setting resistor to select the appropriate IR output power (see the Powering the IR LED section). The transmitter is not current limited so do not exceed the power dissipation of the external components during high duty-cycle transmit schemes. The TXD input controls the IR LED for the MAX3131. The T2IN input controls the IR LED for the MAX3130 (IRMODE = low). With the ENDEC disabled (see IrDA Encoder/Decoder (ENDEC) section), the IR LED is turned on by a logic-high signal at the TXD or T2IN input, for the MAX3131 and MAX3130 respectively.
EDGEDET: Edge-Detection Circuitry (MAX3130)
The MAX3130 has internal edge-detection circuitry that monitors the RS-232 R2OUT line when IRMODE is low and monitors the IrDA receive channel when IRMODE is high. EDGEDET goes low when a positive or negative edge is detected on either the RS-232 R2OUT line or the IrDA receive channel (depending on the IRMODE pin). This edge-detection feature is useful for initiating an interrupt when data is received on the deselected line. The EDGEDET signal is cleared when IRMODE is toggled. Table 1 shows EDGEDET operation.
MAX3130/MAX3131
IrDA Encoder/Decoder (ENDEC)
The MAX3130 and MAX3131 provide an on-board ENDEC to communicate with UARTs that are not IrDA compatible. The ENDEC is enabled by applying a clock with a frequency 16 times the baud rate to the BAUD16 input. This BAUD16 clock is commonly provided on UARTs that do not have IrDA ENDEC capability. Figure 3 illustrates the operation of the ENDEC. The ENDEC stretches the incoming infrared pulse (a pulse between
IRMODE: Multiplexed RS-232 Operation and IrDA Operation (MAX3130)
The MAX3130 has the capability to multiplex R2OUT and T2IN between the IrDA infrared interface and the RS-232 electrical interface. The state of the IRMODE input determines which interface (infrared or RS-232) is multiplexed to R2OUT and T2IN. When IRMODE is low, R2OUT acts as the infrared receiver output and T2IN acts as the infrared transmitter input. Also, while IRMODE is low, the RS-232 charge pumps are shut down and the RS-232 transmitters are disabled (see Shutdown section). When IRMODE is high, R2OUT and T2IN assume their functions as the RS-232 data receive output and transmit input, respectively. Also, while IRMODE is high, the IR transmitter is disabled (turned off).
Table 1. EDGEDET Operation
IRSD X X X X RSSD IRMODE X X X X 0 0 1 1 X X R2IN IrDA RxIN X X EDGEDET*
X = Don't care * EDGEDET is cleared by any transition on IRMODE.
INFRARED PHOTODIODE INPUT * 1.41s < t < 3CS 16CS
R2OUT (RXD) WITH ENDEC DISABLED
R2OUT (RXD) WITH ENDEC ENABLED 16CS CS = BAUD16 CLOCK CYCLES * HIGH = INFRARED LIGHT PULSE ( ) ARE FOR MAX3131 32CS
Figure 3a. ENDEC Operation, Receiving Infrared
______________________________________________________________________________________ 11
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
T2IN (TXD)
7CS INFRARED LED OUTPUT * 3CS CS = BAUD16 CLOCK CYCLES * HIGH = INFRARED LIGHT PULSE ( ) ARE FOR MAX3131 16CS
Figure 3b. ENDEC Operation, Transmitting Infrared
1s and three BAUD16 clock cycles) into a full baud period (Figure 3a). Signals applied to TXD are inverted and compressed to three BAUD16 clock cycles by the ENDEC before being transmitted (Figure 3b). The ENDEC is disabled by connecting the BAUD16 input to VCC or GND.
__________ Applications Information
Shutdown
The MAX3130/MAX3131 have split analog and digital supplies (V CC and AV CC ) with separate shutdown modes. When IRSD is pulled low, the IR receiver is disabled and AVCC current reduces to <1A. When RSSD or IRMODE is pulled low, the RS-232 charge pumps are disabled and the RS-232 transmitter outputs become high impedance. In this mode, the VCC current reduces to <10A.
Dual Charge-Pump Voltage Converter
The MAX3130/MAX3131's internal power supply consists of a regulated dual charge pump that provides output voltages of +5.5V (doubling charge pump) and -5.5V (inverting charge pump) for supply voltages from +3.0V to +5.5V. The charge pump operates in a discontinuous mode: if the output voltages are less than 5.5V, the charge pumps are enabled; if the output voltages exceed 5.5V, the charge pumps stop switching. Each charge pump requires a flying capacitor (C1, C2) and a reservoir capacitor (C3, C4) to generate the V+ and V- supplies (Figures 1 and 2). If RSSD (or IRMODE for MAX3130) is low, both charge pumps shut down.
IR LED Selection
The IrDA specification calls for an IR transmitter with a peak wavelength between 850nm and 900nm. Within a 15 half-cone angle, the output intensity of the IR LED must be between 40mW/sr and 500mW/sr. Outside a 30 half-cone angle, the output intensity of the IR LED must fall below 40mW/sr. Within these cases, the optical rise and fall times of the IR LED must be less than 600ns. Based on these system requirements the HP HSDL-4220, the Temic TSHF5400, or equivalent IR LEDs are appropriate choices.
RS-232 Transmitters
The RS-232 transmitters are inverting level translators that convert CMOS-logic levels to 5.0V EIA/TIA-232 levels. The MAX3130/MAX3131 transmitters are guaranteed for data rates of 120kbps, providing compatibility with PC-to-PC communication software, such as LapLinkTM. These RS-232 transmitters typically operate at data rates of 235kbps. The RS-232 transmitter outputs are high impedance when either IRMODE or RSSD are low. The MAX3130/MAX3131 RS-232 receivers translate RS232 signal levels to CMOS-level logic. The RS-232 receivers also perform a logic inversion from input to output. The receivers are always active and are not affected by the RS-232 shutdown input (RSSD).
Powering the IR LED
Set the current in the IR LED with an external resistor. Using the IR LED manufacturer's data sheet, select a forward current that meets the IrDA specifications discussed in the IR LED Selection section. Determine the forward bias voltage of the IR LED (VIRLED) and the voltage drop across the MAX3130/MAX3131 LED driver (see LEDC Voltage vs. LEDC Current graph in the Typical Operating Characteristics) and choose the current-setting resistor based on the following equation: RSET = (VCC - VIRLED - VLEDC) / ISET Using the HP HSDL-4220 IR LED as an example: VCC = 5V, ISET = 100mA, VIRLED = 1.67V VLEDC = 90mV RSET = (5V - 1.67V - 90mV) / 0.1A = 32.4
LapLink is a trademark of Traveling Software.
12
______________________________________________________________________________________
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
Power dissipation of the MAX3130/MAX3131, IR LED, and RSET are based on the maximum LED current and duty cycle. Use the following equations to calculate the power dissipation in each component: MAX3130 power dissipation = ISET * VDRV * duty cycle IR LED power dissipation = ISET * VIRLED * duty cycle RSET power dissipation = ISET2 * RSET * duty cycle For reliable operation, do not exceed maximum power dissipation of the components. When using the minimum required capacitor values, make sure the capacitor value does not degrade excessively with temperature. If in doubt, use capacitors with a larger nominal value. The capacitor's equivalent series resistance (ESR) usually rises at low temperatures and increases the amount of ripple on V+ and V-.
MAX3130/MAX3131
Power-Supply Noise Rejection
Because of the extremely sensitive nature of photodiode amplifiers, it is important to maintain a low-noise supply voltage. Use a separate analog supply voltage where possible. Place a 1F ceramic bypass capacitor as close as possible to the AVCC and V CC pins. In especially noisy systems, connect a small (10) resistor in series with VCC, in addition to the normal bypass capacitors.
PIN Photodiode Selection
PIN photodiode selection is extremely important to system performance. The PIN diode must generate at least 200nA (minimum sensitivity of the MAX3130/MAX3131) of current when aimed 15 off-axis with an incident irradiance of 4W/cm2. The following equation determines if the Temic BPV22NF meets these requirements: IPIN = (4W/cm2 ) (0.075cm2) (0.95) (0.95) (1.8) (0.6A/W) = 292nA The first term (4mW/cm2) is the minimum guaranteed irradiance in the 15 angular range. The second term (0.075cm2) is the sensitive area of the PIN diode. The first 0.95 factor normalizes the sensitivity to the 875nm wavelength and the second 0.95 factor adjusts for the decreased receiver efficiency at 15 off-axis. The 1.8 factor accounts for the round lens which increases the effective PIN diode area. The last term (0.6A/W) is the sensitivity of the PIN diode. Based on this example, the Temic BPV22NF is an appropriate selection. The final important factor in selecting a PIN diode is the effective diode capacitance. It is important to keep this capacitance below 70pF at 1.2V reverse bias. Higher input capacitance compromises the noise performance of the system by increasing the noise gain of the input transimpedance amplifier.
IrDA or RS-232 Application Circuit
Figure 4 shows how the MAX3130 is used to multiplex between RS-232 and IrDA communication while using only one UART. By using the IRMODE input, the type of communication (infrared or RS-232) is controlled by the I/O of a P. The internal MAX3130 ENDEC is used to translate between UART-type and IrDA-type bitstreams. If the UART has this capability, connect BAUD16 of the MAX3130 to GND. Figure 5 shows the MAX3131 used with two UARTs to perform simultaneous IrDA and RS-232 communication. UART1 is a software UART used to perform infrared IrDA communication. The internal ENDEC on the MAX3131 translates between UART-type and IrDA-type bit-streams. The MAX3100 is implemented as UART2 and communicates via the RS-232 interface. The MAX3100 interfaces to the P using a SPI interface.
Layout Considerations
The MAX3130/MAX3131 require careful layout techniques to minimize parasitic signals coupling to the PINC input. Keep the lead length between the photodiode and PINC as short as possible. Keep PC board traces to the PIN diode away from other noisy traces. To minimize coupling, run the AGND trace adjacent to the PINC trace on both sides. To prevent oscillation, avoid routing the RXD trace near the PINC trace. Connect the anode of the PIN diode, GND, and the ground lead of the AVCC bypass capacitor in a starconnection. Keep the output pins RXD and TXD as short as possible to minimize coupling back to the input via parasitic capacitance.
Capacitor Selection
The capacitor type used for C1-C4 is not critical for proper operation; either polarized or nonpolarized capacitors are good choices. The charge pump requires 0.1F capacitors for 3.3V operation. For other supply voltages, refer to Table 2 for suggested capacitor values. Do not use values smaller than those listed in Table 2. Increasing the capacitor values (e.g., by a factor of 2) reduces ripple on the transmitter outputs and slightly reduces power consumption. C2, C3, and C4 can be increased without changing C1's value. However, do not increase C1 without also increasing the values of C2, C3, and C4.
______________________________________________________________________________________
13
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
Table 2. Required Capacitor Values
VCC (V) 3.0 to 3.6 4.5 to 5.5 3.0 to 5.5 C1 (F) 0.1 0.047 0.1 C2, C3, C4 (F) 0.1 0.33 0.47
STANDARD NON-IrDA UART P
MAX3130
RTS CTS T1IN R1OUT T1OUT R1IN T2OUT R2IN LEDC IrDA PINC DB-9 RS-232 12345 6789
Tx Rx BAUD16 232 IrDA I/O
T2IN R2OUT BAUD16 IRMODE
Figure 4. Using the MAX3130 and a Single UART to Perform Both IrDA and RS-232 Communication
SPI P DIN DOUT SCLK CS
MAX3100 UART2 RTS
MAX3131
T1IN R1OUT T2IN R2OUT T1OUT R1IN T2OUT R2IN LEDC TXD RXD BAUD16 IrDA PINC DB-9 RS-232 12345 6789
CTS Tx Rx
NON-IrDA UART TX RX BAUD16
(UART1)
Figure 5. Using the MAX3131 and Two UARTs to Perform Simultaneous IrDA and RS-232 Communication
14
______________________________________________________________________________________
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
Chip Information
TRANSISTOR COUNT: 1039
MAX3130/MAX3131
________________________________________________________Package Information
SSOP.EPS
______________________________________________________________________________________
15
3V to 5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
NOTES
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX3130

	To Download MAX3130 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .