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Features
* Minimal External Circuitry Requirements, No RF Components on the PC Board Except * * * * * * * * * * * * * *
Matching to the Receiver Antenna High Sensitivity, Especially at Low Data Rates Sensitivity Reduction Possible Even While Receiving Fully Integrated VCO Low Power Consumption Due to Configurable Self Polling with a Programmable Time Frame Check Supply Voltage 4.5 V to 5.5 V Operating Temperature Range -40C to 105C Single-ended RF Input for Easy Adaptation to /4 Antenna or Printed Antenna on PCB Low-cost Solution Due to High Integration Level ESD Protection According to MIL-STD 883 (4KV HBM) Except Pin POUT (2KV HBM) High Image Frequency Suppression due to 1 MHz IF in Conjunction with a SAW Front-end Filter - Up to 40 dB is Thereby Achievable with Newer SAWs. Programmable Output Port for Sensitivity Selection or for Controlling External Periphery Communication to the Microcontroller Possible via a Single, Bi-directional Data Line Power Management (Polling) is also Possible by Means of a Separate Pin via the Microcontroller 2 Different IF Bandwidth Versions are Available (300 kHz and 600 kHz)
UHF ASK Receiver IC U3741BM
Description
The U3741BM is a multi-chip PLL receiver device supplied in an SO20 package. It has been specially developed for the demands of RF low-cost data transmission systems with low data rates from 1 kBaud to 10 kBaud (1 kBaud to 3.2 kBaud for FSK) in Manchester or Bi-phase code. The receiver is well suited to operate with Atmel's PLL RF transmitter U2741B. Its main applications are in the areas of telemetering, security technology and keyless-entry systems. It can be used in the frequency receiving range of f0 = 300 MHz to 450 MHz for ASK or FSK data transmission. All the statements made below refer to 433.92-MHz and 315-MHz applications.
Rev. 4662B-RKE-10/04
System Block Diagram
UHF ASK/FSK Remote control transmitter 1 Li cell U2741B U3741BM PLL Antenna Antenna XTO VCO PLL XTO Demod Control 1...3 C UHF ASK/FSK Remote control receiver
Encoder ATARx9x Keys
Power amp.
LNA
VCO
Block Diagram
VS FSK/ASK CDEM AVCC SENS IF Amp Sensitivity reduction Polling circuit and control logic FSK/ASKDemodulator and data filter RSSI DEMOD_OUT
50 k
DATA
Limiter out ENABLE TEST POUT MODE FE CLK DVCC
AGND DGND 4th Order
MIXVCC
LPF 3 MHz
Standby logic LFGND
LNAGND IF Amp
LFVCC
LPF 3 MHz
VCO
XTO
XTO
f LNA_IN LNA / 64 LF
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Pin Configuration
Figure 1. Pinning SO20
SENS FSK/ASK CDEM AVCC AGND DGND MIXVCC LNAGND LNA_IN NC 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 DATA ENABLE TEST POUT MODE DVCC XTO LFGND LF LFVCC
Pin Description
Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Symbol SENS FSK/ASK CDEM AVCC AGND DGND MIXVCC LNAGND LNA_IN NC LFVCC LF LFGND XTO DVCC MODE POUT TEST ENABLE DATA Function Sensitivity-control resistor Selecting FSK/ASK. Low: FSK, High: ASK Lower cut-off frequency data filter Analog power supply Analog ground Digital ground Power supply mixer High-frequency ground LNA and mixer RF input Not connected Power supply VCO Loop filter Ground VCO Crystal oscillator Digital power supply Selecting 433.92 MHz/315 MHz. Low: 4.90625 MHz (USA). High: 6.76438 (Europe) Programmable output port Test pin, during operation at GND Enables the polling mode Low: polling mode off (sleep mode) H: polling mode on (active mode) Data output/configuration input
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RF Front End
The RF front end of the receiver is a heterodyne configuration that converts the input signal into a 1-MHz IF signal. According to the block diagram, the front end consists of an LNA (low noise amplifier), LO (local oscillator), a mixer and RF amplifier. The LO generates the carrier frequency for the mixer via a PLL synthesizer. The XTO (crystal oscillator) generates the reference frequency fXTO. The VCO (voltage-controlled oscillator) generates the drive voltage frequency fLO for the mixer. fLO is dependent on the voltage at pin LF. fLO is divided by a factor of 64. The divided frequency is compared to fXTO by the phase frequency detector. The current output of the phase frequency detector is connected to a passive loop filter and thereby generates the control voltage VLF for the VCO. By means of that configuration, VLF is controlled in a way that fLO/64 is equal to fXTO. If fLO is determined, fXTO can be calculated using the following formula:
f LO f XTO = ------64
The XTO is a one-pin oscillator that operates at the series resonance of the quartz crystal. According to Figure 2, the crystal should be connected to GND via a capacitor CL. The value of that capacitor is recommended by the crystal supplier. The value of CL should be optimized for the individual board layout to achieve the exact value of fXTO and hereby of fLO. When designing the system in terms of receiving bandwidth, the accuracy of the crystal and XTO must be considered. Figure 2. PLL Peripherals
VS DVCC CL XTO
LFGND
LF VS R1 C9 C10
R1 = 820 C9 = 4.7 nF C10 = 1 nF
LFVCC
The passive loop filter connected to pin LF is designed for a loop bandwidth of BLoop = 100 kHz. This value for BLoop exhibits the best possible noise performance of the LO. Figure 2 shows the appropriate loop filter components to achieve the desired loop bandwidth. If the filter components are changed for any reason, please note that the maximum capacitive load at pin LF is limited. If the capacitive load is exceeded, a bit check may no longer be possible since fLO cannot settle in time before the bit check starts to evaluate the incoming data stream. Therefore, self polling also does not work in that case. fLO is determined by the RF input frequency fRF and the IF frequency fIF using the following formula:
f LO = f RF - f IF
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To determine fLO, the construction of the IF filter must be considered at this point. The nominal IF frequency is fIF = 1 MHz. To achieve a good accuracy of the filter's corner frequencies, the filter is tuned by the crystal frequency fXTO. This means that there is a fixed relation between fIF and fLO that depends on the logic level at pin mode. This is described by the following formulas:
f LO MODE = 0 (USA) f IF = --------314 fLO MODE = 0 (Europe) f IF = ----------------432.92
The relation is designed to achieve the nominal IF frequency of fIF = 1 MHz for most applications. For applications where fRF = 315 MHz, the MODE must be set to `0'. In the case of fRF = 433.92 MHz, the MODE must be set to `1'. For other RF frequencies, fIF is not equal to 1 MHz. fIF is then dependent on the logical level at pin MODE and on fRF. Table 1 summarizes the different conditions. The RF input either from an antenna or from a generator must be transformed to the RF input pin LNA_IN. The input impedance of that pin is provided in the electrical parameters. The parasitic board inductances and capacitances also influence the input matching. The RF receiver U3741BM exhibits its highest sensitivity at the best signal-to-noise ratio in the LNA. Hence, noise matching is the best choice for designing the transformation network. A good practice when designing the network is to start with power matching. From that starting point, the values of the components can be varied to some extent to achieve the best sensitivity. If a SAW is implemented into the input network, a mirror frequency suppression of P Ref = 40 dB can be achieved. There are SAWs available that exhibit a notch at f = 2 MHz. These SAWs work best for an intermediate frequency of IF = 1 MHz. The selectivity of the receiver is also improved by using a SAW. In typical automotive applications, a SAW is used. Figure 3 on page 6 shows a typical input matching network for f RF = 315 MHz and fRF = 433.92 MHz using a SAW. Figure 4 on page 6 illustrates an input matching to 50 without a SAW. The input matching networks shown in Figure 4 are the reference networks for the parameters given in the "Electrical Characteristics". Table 1. Calculation of LO and IF Frequency
Conditions fRF = 315 MHz, MODE = 0 fRF = 433.92 MHz, MODE = 1 Local Oscillator Frequency fLO = 314 MHz fLO = 432.92 MHz f RF f LO = ------------------1 1 + --------314 f RF f LO = --------------------------11 + ----------------432.92 Intermediate Frequency fIF = 1 MHz fIF = 1 MHz f LO fIF = --------314
300 MHz < fRF < 365 MHz, MODE = 0
365 MHz < fRF < 450 MHz, MODE = 1
f LO f IF = ----------------432.92
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Figure 3. Input Matching Network with SAW Filter
8 LNAGND 8 LNAGND
U3741BM
C3 22p L 25n 9 LNA_IN C3 47p L 25n 9
U3741BM
LNA_IN
C16
C17
C16 100p L3
C17 22p 47n
TOKO LL2012 F47NJ
100p
fRF = 433.92 MHz
L2 TOKO LL2012 F33NJ
L3 27n
8.2p
TOKO LL2012 27NJ
f RF = 315 MHz
L2 TOKO LL2012 F82NJ
RFIN C2 8.2p
1 33n 2
IN IN_GND
B3555
CASE_GND 3, 4 7, 8
OUT OUT_GND
5 6
RFIN C2 10p
1 82n 2
IN IN_GND
B3551
CASE_GND 3, 4 7, 8
5 OUT 6 OUT_GND
Figure 4. Input Matching Network without SAW Filter
fRF = 433.92 MHz fRF = 315 MHz
8 LNAGND 8
LNAGND
U3741BM
9 15p 25n LNA_IN 33p 25n
U3741BM
9 LNA_IN
RFIN 3.3p 22n
RF IN 3.3p 39n 100p
TOKO LL2012 F39NJ
100p
TOKO LL2012 F22NJ
Please note that for all coupling conditions (see Figure 3 and Figure 4), the bond wire inductivity of the LNA ground is compensated. C3 forms a series resonance circuit together with the bond wire. L = 25 nH is a feed inductor to establish a DC path. Its value is not critical but must be large enough not to detune the series resonance circuit. For cost reduction, this inductor can be easily printed on the PCB. This configuration improves the sensitivity of the receiver by about 1 dB to 2 dB.
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Analog Signal Processing
IF Amplifier
The signals coming from the RF front end are filtered by the fully integrated 4th-order IF filter. The IF center frequency is fIF = 1 MHz for applications where fRF = 315 MHz or fRF = 433.92 MHz is used. For other RF input frequencies, refer to Table 1 to determine the center frequency. The U3741BM is available with 2 different IF bandwidths. U3741BM-M2, the version with B IF = 300 kHz, is well suited for ASK systems where Atmel's PLL transmitter U2741B is used. The receiver U3741BM-M3 employs an IF bandwidth of BIF = 600 kHz. This version can be used together with the U2741B in FSK and ASK mode. If used in ASK applications, it allows higher tolerances for the receiver and PLL transmitter crystals. SAW transmitters exhibit much higher transmit frequency tolerances compared to PLL transmitters. Generally, it is necessary to use BIF = 600 kHz together with such transmitters.
RSSI Amplifier
The subsequent RSSI amplifier enhances the output signal of the IF amplifier before it is fed into the demodulator. The dynamic range of this amplifier is DRRSSI = 60 dB. If the RSSI amplifier is operated within its linear range, the best S/N ratio is maintained in ASK mode. If the dynamic range is exceeded by the transmitter signal, the S/N ratio is defined by the ratio of the maximum RSSI output voltage and the RSSI output voltage due to a disturber. The dynamic range of the RSSI amplifier is exceeded if the RF input signal is about 60 dB higher compared to the RF input signal at full sensitivity. In FSK mode, the S/N ratio is not affected by the dynamic range of the RSSI amplifier. The output voltage of the RSSI amplifier is internally compared to a threshold voltage VTh_red. VTh_red is determined by the value of the external resistor RSense. RSense is connected between pin Sense and GND or VS. The output of the comparator is fed into the digital control logic. By this means it is possible to operate the receiver at lower sensitivity. If RSense is connected to VS, the receiver operates at a lower sensitivity. The reduced sensitivity is defined by the value of R Sense , the maximum sensitivity by the signal-to-noise ratio of the LNA input. The reduced sensitivity is dependent on the signal strength at the output of the RSSI amplifier. Since different RF input networks may exhibit slightly different values for the LNA gain, the sensitivity values given in the electrical characteristics refer to a specific input matching. This matching is illustrated in Figure 4 on page 6 and exhibits the best possible sensitivity. RSense can be connected to VS or GND via a microcontroller or by the digital output port POUT of the U3741BM receiver IC. The receiver can be switched from full sensitivity to reduced sensitivity or vice versa at any time. In polling mode, the receiver will not wake up if the RF input signal does not exceed the selected sensitivity. If the receiver is already active, the data stream at pin DATA will disappear when the input signal is lower than defined by the reduced sensitivity. Instead of the data stream, the pattern according to Figure 5 is issued at pin DATA to indicate that the receiver is still active. Figure 5. Steady L State Limited DATA Output Pattern
DATA
tmin2
tDATA_L_max
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FSK/ASK Demodulator and Data Filter
The signal coming from the RSSI amplifier is converted into the raw data signal by the ASK/FSK demodulator. The operating mode of the demodulator is set via pin ASK/FSK. Logic 'L' sets the demodulator to FSK, Logic 'H' sets it into ASK mode. In ASK mode an automatic threshold control circuit (ATC) is employed to set the detection reference voltage to a value where a good signal-to-noise ratio is achieved. This circuit also implies the effective suppression of any kind of in-band noise signals or competing transmitters. If the S/N ratio exceeds 10 dB, the data signal can be detected properly. The FSK demodulator is intended to be used for an FSK deviation of f 20 kHz. Lower values may be used but the sensitivity of the receiver is reduced in that condition. The minimum usable deviation is dependent on the selected baud rate. In FSK mode, only BR_Range0 and BR_Range1 are available. In FSK mode, the data signal can be detected if the S/N Ratio exceeds 2 dB. The output signal of the demodulator is filtered by the data filter before it is fed into the digital signal processing circuit. The data filter improves the S/N ratio as its bandpass can be adopted to the characteristics of the data signal. The data filter consists of a 1st-order high-pass and a 1st-order low-pass filter. The high-pass filter cut-off frequency is defined by an external capacitor connected to pin CDEM. The cut-off frequency of the high-pass filter is defined by the following formula:
1 fcu_DF = -----------------------------------------------------------2 x x 30 k x CDEM
In self-polling mode, the data filter must settle very rapidly to achieve a low current consumption. Therefore, CDEM cannot be increased to very high values if self polling is used. On the other hand, CDEM must be large enough to meet the data filter requirements according to the data signal. Recommended values for CDEM are given in the "Electrical Characteristics" on page 23. The values are slightly different for ASK and FSK mode. The cut-off frequency of the low-pass filter is defined by the selected baud rate range (BR_Range). BR_Range is defined in the OPMODE register (refer to section "Configuration of the Receiver" on page 17). BR_Range must be set in accordance to the used baud rate. The U3741BM is designed to operate with data coding where the DC level of the data signal is 50%. This is valid for Manchester and Bi-phase coding. If other modulation schemes are used, the DC level should always remain within the range of VDC_min = 33% and VDC_max = 66%. The sensitivity may be reduced by up to 1.5 dB in that condition. Each BR_Range is also defined by a minimum and a maximum edge-to-edge time (tee_sig). These limits are defined in the "Electrical Characteristics" on page 23. They should not be exceeded to maintain full sensitivity of the receiver.
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Receiving Characteristics
The RF receiver U3741BM can be operated with and without a SAW front-end filter. In a typical automotive application, a SAW filter is used to achieve better selectivity. The selectivity with and without a SAW front end-filter is illustrated in Figure 6. This example relates to ASK mode and the 300-kHz bandwidth version of the U3741BM. FSK mode and the 600-kHz version of the receiver exhibit similar behavior. Note that the mirror frequency is reduced by 40 dB. The plots are printed relative to the maximum sensitivity. If a SAW filter is used, an insertion loss of about 4 dB must be considered. When designing the system in terms of receiving bandwidth, the LO deviation must be considered as it also determines the IF center frequency. The total LO deviation is calculated to be the sum of the deviation of the crystal and the XTO deviation of the U3741BM. Low-cost crystals are specified to be within 100 ppm. The XTO deviation of the U3741BM is an additional deviation due to the XTO circuit. This deviation is specified to be 30 ppm. If a crystal of 100 ppm is used, the total deviation is 130 ppm in that case. Note that the receiving bandwidth and the IF-filter bandwidth are equivalent in ASK mode but not in FSK mode. Figure 6. Receiving Frequency Response
0.0 -10.0 -20.0 -30.0 -40.0 without SAW
dP (dB)
-50.0 -60.0 -70.0 -80.0 with SAW -90.0 -100.0 -6.0
-5.0 -4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
df (MHz)
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Polling Circuit and Control Logic
The receiver is designed to consume less than 1 mA while being sensitive to signals from a corresponding transmitter. This is achieved via the polling circuit. This circuit enables the signal path periodically for a short time. During this time the bit check logic verifies the presence of a valid transmitter signal. Only if a valid signal is detected the receiver remains active and transfers the data to the connected microcontroller. If there is no valid signal present, the receiver is in sleep mode most of the time resulting in low current consumption. This condition is called polling mode. A connected microcontroller is disabled during that time. All relevant parameters of the polling logic can be configured by the connected microcontroller. This flexibility enables the user to meet the specifications in terms of current consumption, system response time, data rate etc. Regarding the number of connection wires to the microcontroller, the receiver is very flexible. It can be either operated by a single bi-directional line to save ports to the connected microcontroller, it can be operated by up to three uni-directional ports.
Basic Clock Cycle of the Digital Circuitry
The complete timing of the digital circuitry and the analog filtering is derived from one clock. According to Figure 7, this clock cycle TClk is derived from the crystal oscillator (XTO) in combination with a divider. The division factor is controlled by the logical state at pin MODE. According to section "RF Front End" on page 4, the frequency of the crystal oscillator (f XTO) is defined by the RF input signal (f RFin ) which also defines the operating frequency of the local oscillator (fLO). Figure 7. Generation of the Basic Clock Cycle
TClk MODE Divider :14/:10 fXTO 16 L : USA (:10) H: Europe (:14)
DVCC 15
XTO XTO 14
Pin MODE can now be set in accordance with the desired clock cycle TClk. TClk controls the following application-relevant parameters: * * * * * Timing of the polling circuit including bit check Timing of analog and digital signal processing Timing of register programming Frequency of the reset marker F filter center frequency (fIF0)
Most applications are dominated by two transmission frequencies: fSend = 315 MHz is mainly used in the USA, fSend = 433.92 MHz in Europe. In order to ease the usage of all TClk-dependent parameters, the electrical characteristics display three conditions for each parameter.
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* * * USA Applications (fXTO = 4.90625 MHz, MODE = L, TClk = 2.0383 s) Europe Applications (fXTO = 6.76438 MHz, MODE = H, TClk = 2.0697 s) Other applications (TClk is dependent on fXTO and on the logical state of pin MODE. The electrical characteristic is given as a function of TClk).
The clock cycle of some function blocks depends on the selected baud rate range (BR_Range) which is defined in the OPMODE register. This clock cycle TXClk is defined by the following formulas for further reference: BR_Range = BR_Range0: BR_Range1: BR_Range2: BR_Range3: TXClk = 8 x TClk TXClk = 4 x TClk TXClk = 2 x TClk TXClk = 1 x TClk
Polling Mode
According to Figure 3 on page 6, the receiver stays in polling mode in a continuous cycle of three different modes. In sleep mode, the signal processing circuitry is disabled for the time period TSleep while consuming a low current of IS = ISoff. During the start-up period, TStartup, all signal processing circuits are enabled and settled. In the following bit check mode, the incoming data stream is analyzed bit by bit against a valid transmitter signal. If no valid signal is present, the receiver is set back to sleep mode after the period TBitcheck. This period varies check by check as it is a statistical process. An average value for TBitcheck is given in "Electrical Characteristics" on page 23. During TStartup and TBitcheck the current consumption is IS = ISon. The average current consumption in polling mode is dependent on the duty cycle of the active mode and can be calculated as:
I Soff x T Sleep + I Son x ( TStartup + T Bitcheck ) I Spoll = -----------------------------------------------------------------------------------------------------------TSleep + TStartup + TBitcheck
During TSleep and TStartup, the receiver is not sensitive to a transmitter signal. To guarantee the reception of a transmitted command, the transmitter must start the telegram with an adequate preburst. The required length of the preburst is dependent on the polling parameters TSleep, TStartup, TBitcheck and the startup time of a connected microcontroller (TStart,C). TBitcheck thus depends on the actual bit rate and the number of bits (NBitcheck) to be tested. The following formula indicates how to calculate the preburst length. TPreburst TSleep + TStartup + TBitcheck + TStart_C Sleep Mode The length of period TSleep is defined by the 5-bit word Sleep of the OPMODE register, the extension factor XSleep, according to Figure 10 on page 13, and the basic clock cycle TClk. It is calculated to be:
T Sleep = Sleep x X Sleep x 1024 x T Clk
In US and European applications, the maximum value of TSleep is about 60 ms if XSleep is set to 1. The time resolution is about 2 ms in that case. The sleep time can be extended to almost half a second by setting XSleep to 8. XSleep can be set to 8 by bit XSleepStd or by bit XSleepTemp resulting in a different mode of action as described below:
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XSleepStd = 1 implies the standard extension factor. The sleep time is always extended. XSleepTemp = 1 implies the temporary extension factor. The extended sleep time is used as long as every bit check is OK. If the bit check fails once, this bit is set back to 0 automatically resulting in a regular sleep time. This functionality can be used to save current in presence of a modulated disturber similar to an expected transmitter signal. The connected microcontroller is rarely activated in that condition. If the disturber disappears, the receiver switches back to regular polling and is again sensitive to appropriate transmitter signals. According to Table 7 on page 19, the highest register value of Sleep sets the receiver to a permanent sleep condition. The receiver remains in that condition until another value for Sleep is programmed into the OPMODE register. This function is desirable where several devices share a single data line. Figure 8. Polling Mode Flow Chart
Sleep Mode: All circuits for signal processing are disabled. Only XTO and polling logic is enabled. Output level on pin IC_ACTIVE => low IS = ISON TSleep = Sleep x XSleep x 1024 x TClk
Sleep:
5-bit word defined by Sleep0 to Sleep4 in OPMODE register Extension factor defined by XSleepTemp according to Table 8 Basic clock cycle defined by fXTO and pin MODE Is defined by the selected baud rate range and TClk. The baud-rate range is defined by Baud0 and Baud1 in the OPMODE register. Depends on the result of the bit check. If the bit check is ok, TBit-check depends on the number of bits to be checked (NBit-checked) and on the utilized data rate. If the bit check fails, the average time period for that check depends on the selected baud-rate range on TClk. The baud-rate range is defined by Baud0 and Baud1 in the OPMODE register.
XSleep: TClk: TStartup:
Start-up Mode: The signal processing circuits are enabled. After the start-up time (TStartup) all circuits are in stable condition and ready to receive. IS = ISON TStartup
TBit-check: Bit-check Mode: The incomming data stream is analyzed. If the timing indicates a valid transmitter signal, the receiver is set to receiving mode. Otherwise it is set to Sleep mode. IS = ISon TBit-check
NO
Bit-check OK?
YES Receiving Mode: The receiver is turned on permanently and passes the data stream to the connected microcontroller. It can be set to Sleep mode through an OFF command via pin DATA or ENABLE IS = ISON OFF command
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Figure 9. Timing Diagram for a Completely Successful Bit Check
Number of Checked Bits: 3 Enable IC Bit check ok
Bit check Dem_out DATA Polling mode
1/2 Bit
1/2 Bit
1/2 Bit
1/2 Bit
1/2 Bit
1/2 Bit
Receiving mode
Bit Check Mode
In bit check mode, the incoming data stream is examined to distinguish between a valid signal from a corresponding transmitter and signals due to noise. This is done by subsequent time frame checks where the distances between 2 signal edges are continuously compared to a programmable time window. The maximum count of this edge-to-edge test, before the receiver switches to receiving, mode is also programmable. Assuming a modulation scheme that contains 2 edges per bit, two time frame checks are verifying one bit. This is valid for Manchester, Bi-phase and most other modulation schemes. The maximum count of bits to be checked can be set to 0, 3, 6 or 9 bits via the variable NBitcheck in the OPMODE register. This implies 0, 6, 12 and 18 edge-to-edge checks respectively. If NBitcheck is set to a higher value, the receiver is less likely to switch to the receiving mode due to noise. In the presence of a valid transmitter signal, the bit check takes less time if NBitcheck is set to a lower value. In polling mode, the bit check time is not dependent on NBitcheck. Figure 9 shows an example where 3 bits are tested successfully and the data signal is transferred to pin DATA. According to Figure 10, the time window for the bit check is defined by two separate time limits. If the edge-to-edge time tee is in between the lower bit check limit TLim_min and the upper bit check limit TLim_max , the check will be continued. If t ee is smaller than T Lim_min or t ee exceeds T Lim_max , the bit check will be terminated and the receiver switches to sleep mode. Figure 10. Valid Time Window for Bit Check
1/fSig
Configuring the Bit Check
Dem_out
tee Tlim_min Tlim_max
For best noise immunity it is recommended to use a low span between TLim_min and TLim_max. This is achieved using a fixed frequency at a 50% duty cycle for the transmitter preburst. A `11111...' or a `10101...' sequence in Manchester or Bi-phase is a good choice in this regard. A good compromise between receiver sensitivity and susceptibility to noise is a time window of 25% regarding the expected edge-to-edge time tee. Using preburst patterns that contain various edge-to-edge time periods, the bit check limits must be programmed according to the required span.
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The bit check limits are determined by means of the formula below: TLim_min = Lim_min x TXClk TLim_max = (Lim_max -1) x TXClk Lim_min and Lim_max are defined by a 5-bit word each within the LIMIT register. Using the above formulas, Lim_min and Lim_max can be determined according to the required TLim_min , TLim_max and TXClk. The time resolution when defining TLim_min and TLim_max is TXClk. The minimum edge-to-edge time tee (tDATA_L_min, tDATA_H_min) is defined according to the section "Receiving Mode" on page 15. Due to this, the lower limit should be set to Lim_min 10. The maximum value of the upper limit is Lim_max = 63. Figure 11, Figure 12 and Figure 13 on page 15 illustrate the bit check for the default bit check limits Lim_min = 14 and Lim_max = 24. When the IC is enabled, the signal processing circuits are enabled during TStartup. The output of the ASK/FSK demodulator (Dem_out) is undefined during that period. When the bit check becomes active, the bit check counter is clocked with the cycle TXClk. Figure 11 shows how the bit check proceeds if the bit-check counter value CV_Lim is within the limits defined by Lim_min and Lim_max at the occurrence of a signal edge. In Figure 12, the bit check fails as the value CV_lim is lower than the limit Lim_min. The bit check also fails if CV_Lim reaches Lim_max. This is illustrated in Figure 13 on page 15. Figure 11. Timing Diagram During Bit Check
(Lim_min = 14, Lim_max = 24) Enable IC TStartup Bit check 1/2 Bit Dem_out Bit check Counter
1 234 56 78123 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1 2 345 67 8 9 10 11 12 13 14 15 1 234
Bit check ok
Bit check ok
1/2 Bit
1/2 Bit
0
TXClk
Figure 12. Timing Diagram for Failed Bit Check (Condition: CV_Lim < Lim_min)
(Lim_min = 14, Lim_max = 24) Enable IC Bit check failed ( CV_Lim < Lim_min )
Bit check Dem_out Bit check Counter 0 Startup Mode
1/2 Bit
1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 101112 Bit check Mode
0 Sleep Mode
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Figure 13. Timing Diagram for Failed Bit Check (Condition: CV_Lim Lim_max)
(Lim_min = 14, Lim_max = 24) Bit check failed (CV_Lim = Lim_max)
Enable IC
Bit check Dem_out Bit check Counter 0 Startup Mode
1/2 Bit
1 2 3 4 5 6 7 1 2 3 4 5 6 7 8 9 10 1112 13141516171819 20 21222324 Bit check Mode
0 Sleep Mode
Duration of the Bit Check
If no transmitter signal is present during the bit check, the output of the ASK/FSK demodulator delivers random signals. The bit check is a statistical process and TBitcheck varies for each check. Therefore, an average value for TBitcheck is given in "Electrical Characteristics". TBitcheck depends on the selected baud rate range and on TClk. A higher baudrate range causes a lower value for TBitcheck resulting in lower current consumption in polling mode. In the presence of a valid transmitter signal, TBitcheck is dependant on the frequency of that signal, fSig and the count of the checked bits, NBitcheck. A higher value for NBitcheck thereby results in a longer period for TBitcheck requiring a higher value for the transmitter preburst TPreburst.
Receiving Mode
If the bit check has been successful for all bits specified by N Bitcheck , the receiver switches to receiving mode. According to Figure 9 on page 13, the internal data signal is switched to pin DATA in that case. A connected microcontroller can be woken up by the negative edge at pin DATA. The receiver stays in that condition until it is switched back to polling mode explicitly. The data from the ASK/FSK demodulator (Dem_out) is digitally processed in different ways and as a result converted into the output signal data. This processing depends on the selected baud rate range (BR_Range). Figure 14 on page 16 illustrates how Dem_out is synchronized by the extended clock cycle TXClk. This clock is also used for the bit check counter. Data can change its state only after T XClk elapsed. The edge-to-edge time period tee of the Data signal as a result is always an integral multiple of TXClk. The minimum time period between two edges of the data signal is limited to tee TDATA_min. This implies an efficient suppression of spikes at the DATA output. At the same time, it limits the maximum frequency of edges at DATA. This eases the interrupt handling of a connected microcontroller. TDATA_min is to some extent affected by the preceding edge-to-edge time interval tee as illustrated in Figure 15. If tee is in between the specified bit check limits, the following level is frozen for the time period TDATA_min = tmin1, in case of tee being outside that bit check limits TDATA_min = tmin2 is the relevant stable time period. The maximum time period for DATA to be low is limited to TDATA_L_max. This function ensures a finite response time during programming or switching off the receiver via pin DATA. TDATA_L_max is thereby longer than the maximum time period indicated by the transmitter data stream. Figure 16 gives an example where Dem_out remains low after the receiver has switched to receiving mode.
Digital Signal Processing
15
4662B-RKE-10/04
Figure 14. Synchronization of the Demodulator Output
TXClk Clock Bitcheck counter Dem_out
DATA
tee
Figure 15. Debouncing of the Demodulator Output
Dem_out
DATA Lim_min CV_Lim < Lim_max tee CV_Lim < Lim_min or CV_Lim Lim_max tee tmin2 tmin1
Figure 16. Steady L State Limited DATA Output Pattern after Transmission
Enable IC
Bit check Dem_out
DATA Sleep mode Bit check mode Receiving mode tmin2 tDATA_L_max
After the end of a data transmission, the receiver remains active and random noise pulses appear at pin DATA. The edge-to-edge time period tee of the majority of these noise pulses is equal to or slightly higher than TDATA_min. Switching the Receiver Back to Sleep Mode The receiver can be set back to polling mode via pin DATA or via pin ENABLE. When using pin DATA, this pin must be pulled to low for the period t1 by the connected microcontroller. Figure 17 illustrates the timing of the OFF command (see also Figure 21 on page 21). The minimum value of t1 depends on the BR_Range. The maximum value for t1 is not limited but it is recommended not to exceed the specified value to prevent erasing the reset marker. This item is explained in more detail in the section "Configuration of the Receiver" on page 17. Setting the receiver to sleep mode via DATA is achieved by programming bit 1 of the OPMODE register to 1. Only one sync pulse (t3) is issued. The duration of the OFF command is determined by the sum of t1, t2 and t10. After the OFF command, the sleep time TSleep elapses. Note that the capacitive load at pin DATA is limited. The resulting time constant together with an optional external pull-up resistor may not be exceeded to ensure proper operation.
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If the receiver is set to polling mode via pin ENABLE, an `L' pulse (TDoze) must be issued at that pin. Figure 18 illustrates the timing of that command. After the positive edge of this pulse, the sleep time TSleep elapses. The receiver remains in sleep mode as long as ENABLE is held to `L'. If the receiver is polled exclusively by a microcontroller, TSleep can be programmed to 0 to enable a instantaneous response time. This command is the faster option than via pin DATA at the cost of an additional connection to the microcontroller. Figure 17. Timing Diagram of the OFF Command Via Pin DATA
t1 t2 t3 t4 t5 t10 t7 Out1 (microcontroller)
DATA (U3741BM)
X
X
Serial bi-directional data line
X Bit 1 ("1") (Start bit) OFF command
X
Receiver on
TSleep
Startup mode
Figure 18. Timing Diagram of the OFF Command Via Pin ENABLE
TDoze TSleep
toff
ENABLE
DATA (U3741BM)
X
X
Serial bi-directional data line
X
X
Receiver on
Startup mode
Configuration of the Receiver
The U3741BM receiver is configured via two 12-bit RAM registers called OPMODE and LIMIT. The registers can be programmed by means of the bi-directional DATA port. If the register contents have changed due to a voltage drop, this condition is indicated by a certain output pattern called reset marker (RM). The receiver must be reprogrammed in that case. After a power-on reset (POR), the registers are set to default mode. If the receiver is operated in default mode, there is no need to program the registers. Table 3 on page 18 shows the structure of the registers. According to Table 2 on page 18, bit 1 defines if the receiver is set back to polling mode via the OFF command, (see section "Receiving Mode" on page 15) or if it is programmed. Bit 2 represents the register address. It selects the appropriate register to be programmed.
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Table 2. Effect of Bit 1 and Bit 2 in Programming the Registers
Bit 1 1 0 0 Bit 2 x 1 0 Action The receiver is set back to polling mode (OFF command) The OPMODE register is programmed The LIMIT register is programmed
Table 4 and the following illustrate the effect of the individual configuration words. The default configuration is highlighted for each word. BR_Range sets the appropriate baud rate range. At the same time it defines XLim. XLim is used to define the bit check limits TLim_min and TLim_max as shown in Table 4. POUT can be used to control the sensitivity of the receiver. In that application, POUT is set to 1 to reduce the sensitivity. This implies that the receiver operates with full sensitivity after a POR. Table 3. Effect of the Configuration Words within the Registers
Bit1 Bit2 Bit2 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9 Bit10 Bit11 Bit12 Bit13 Bit14 OFF Command 1 OPMODE Register 0 0 1 1 BR_Range Baud1 0 Baud0 0 NBitcheck BitChk1 1 BitChk0 0 VPOUT POUT 0 Sleep4 0 Sleep3 1 Sleep Sleep2 0 Sleep1 1 Sleep0 1 XSleep XSleep Std 0 XSleep Temp 0
(Default) LIMIT Register 0 0 0 0
Lim_min
Lim_max
Lim_min5 Lim_min4 Lim_min3 Lim_min2 Lim_min1 Lim_min0 Lim_max5 Lim_max4 Lim_max3 Lim_max2 Lim_max1 Lim_max0 0 0 1 1 1 0 0 1 1 0 0 0
(Default)
Table 4. Effect of the Configuration Word BR_Range
BR_Range Baud1 0 0 1 1 Baud0 0 1 0 1 Baud Rate Range/Extension Factor for Bit Check Limits (XLim) BR_Range0 (application USA/Europe: BR_Range0 = 1.0 kBaud to 1.8 kBaud) (Default) XLim = 8 (Default) BR_Range1 (application USA/Europe: BR_Range1 = 1.8 kBaud to 3.2 kBaud) XLim = 4 BR_Range2 (application USA/Europe: BR_Range2 = 3.2 kBaud to 5.6 kBaud) XLim = 2 BR_Range3 (Application USA/Europe: BR_Range3 = 5.6 kBaud to 10 kBaud) XLim = 1
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Table 5. Effect of the Configuration Word NBitcheck
NBitcheck BitChk1 0 0 1 1 BitChk0 0 1 0 1 Number of Bits to be Checked 0 3 6 (Default) 9
Table 6. Effect of the Configuration Bit VPOUT
VPOUT POUT 0 1 0 (Default) 1 Level of the Multi-purpose Output Port POUT
Table 7. Effect of the Configuration Word Sleep
Sleep Sleep4 0 0 0 0 . . . 0 . . . 1 1 1 Sleep3 0 0 0 0 . . . 1 . . . 1 1 1 Sleep2 0 0 0 0 . . . 0 . . . 1 1 1 Sleep1 0 0 1 1 . . . 1 . . . 0 1 1 Sleep0 0 1 0 1 . . . 1 . . . 1 0 1 Start Value for Sleep Counter (TSleep = Sleep x XSleep x 1024 x TClk) 0 (Receiver is continuously polling until a valid signal occurs) 1 (TSleep 2ms for XSleep = 1 in US-/European applications) 2 3 . . . 11 (USA: TSleep = 22.96 ms, Europe: TSleep = 23.31 ms) (Default) . . . 29 30 31 (Permanent sleep mode)
Table 8. Effect of the Configuration Word XSleep
XSleep XSleepStd 0 0 1 1 XSleepTemp 0 1 0 1 Extension Factor for Sleep Time (TSleep = Sleep x XSleep x 1024 x TClk) 1 (Default) 8 (XSleep is reset to 1 if bit check fails once) 8 (XSleep is set permanently) 8 (XSleep is set permanently)
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Table 9. Effect of the Configuration Word Lim_min
Lim_min Lim_min < 10 is not applicable 0 0 0 0 0 . . . 1 1 1 0 0 0 0 0 . . . 1 1 1 1 1 1 1 1 . . . 1 1 1 0 0 1 1 1 . . . 1 1 1 1 1 0 0 1 . . . 0 1 1 0 1 0 1 0 . . . 1 0 1 61 62 63 Lower Limit Value for Bit Check (TLim_min = Lim_min x XLim x TClk) 10 11 12 13 14 (Default) (USA: TLim_min = 228 s, Europe: TLim_min = 232 s)
Table 10. Effect of the Configuration Word Lim_max
Lim_max Lim_max < 12 is not applicable 0 0 0 . . . 0 . . . 1 1 1 0 0 0 . . . 1 . . . 1 1 1 1 1 1 . . . 1 . . . 1 1 1 1 1 1 . . . 0 . . . 1 1 1 0 0 1 . . . 0 . . . 0 1 1 0 1 0 . . . 0 . . . 1 0 1 61 62 63 24 (Default) (USA: TLim_max = 375 s, Europe: TLim_max = 381 s) Upper Limit Value for Bit Check (TLim_max = (Lim_max - 1) x XLim x TClk) 12 13 14
Conservation of the Register Information
The U3741BM has an integrated power-on reset and brown-out detection circuitry to provide a mechanism to preserve the RAM register information. According to Figure 19 on page 21, a power-on reset (POR) is generated if the supply voltage VS drops below the threshold voltage VThReset. The default parameters are programmed into the configuration registers in that condition. Once VS exceeds VThReset, the POR is canceled after the minimum reset period tRst. A POR is also generated when the supply voltage of the receiver is turned on. To indicate that condition, the receiver displays a reset marker (RM) at pin DATA after a reset. The RM is represented by the fixed frequency fRM at a 50% duty cycle. RM can be canceled via an `L' pulse t1 at pin DATA. The RM implies the following characteristics:
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* * fRM is lower than the lowest feasible frequency of a data signal. By this means, RM cannot be misinterpreted by the connected microcontroller. If the receiver is set back to polling mode via pin DATA, RM cannot be canceled by accident if t1 is applied according to the proposal in the section "Programming the Configuration Register" on page 21.
By means of that mechanism, the receiver cannot lose its register information without communicating that condition via the reset marker RM. Figure 19. Generation of the Power-on Reset
VS VThReset
POR tRst DATA (U3741BM) X
1/fRM
Figure 20. Timing of the Register Programming
t1 t2 t3 t4 t5 t6 t7 Out1 (microcontroller) t9 t8 TSleep
DATA (U3741BM)
X
X
Serial bi-directional data line
X Bit 1 ("0") Receiver on (Start bit) Bit 2 ("1") (Register select) Programming Frame Bit 13 ("0") (Poll8) Bit 14 ("1") (Poll8R)
X
Startup mode
Programming the Configuration Register
The configuration registers are programmed serially via the bi-directional data line according to Figure 20 and Figure 21. Figure 21. One-wire Connection to a Microcontroller
U3741BM Internal pull-up resistor Bi-directional data line DATA I/O microcontroller
Out 1 (C) DATA (U3741BM)
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To start programming, the serial data line DATA is pulled to `L' for the time period t1 by the microcontroller. When DATA has been released, the receiver becomes the master device. When the programming delay period t2 has elapsed, it emits 14 subsequent synchronization pulses with the pulse length t3. After each of these pulses, a programming window occurs. The delay until the program window starts is determined by t4, the duration is defined by t5. Within the programming window, the individual bits are set. If the microcontroller pulls down pin DATA for the time period t7 during t5, the according bit is set to `0'. If no programming pulse t7 is issued, this bit is set to `1'. All 14 bits are subsequently programmed in this way. The time frame to program a bit is defined by t6. Bit 14 is followed by the equivalent time window t9. During this window, the equivalent acknowledge pulse t8 (E_Ack) occurs if the mode word just programmed is equivalent to the mode word that was already stored in that register. E_Ack should be used to verify that the mode word was correctly transferred to the register. The register must be programmed twice in that case. Programming of a register is possible both during sleep and active mode of the receiver. During programming, the LNA, LO, low-pass filter, IF-amplifier and the demodulator are disabled. The programming start pulse t1 initiates the programming of the configuration registers. If bit 1 is set to `1', it represents the OFF command to set the receiver back to polling mode at the same time. For the length of the programming start pulse t1, the following convention should be considered: * t1(min) < t1 < 1535 x TClk: [t1(min) is the minimum specified value for the relevant BR_Range]
Programming (respectively OFF command) is initiated if the receiver is not in reset mode. If the receiver is in reset mode, programming (respectively Off command) is not initiated, and the reset marker RM is still present at pin DATA. This period is generally used to switch the receiver to polling mode. In a reset condition, RM is not canceled by accident. * t1 > 5632 x TClk Programming (respectively OFF command) is initiated in any case. RM is cancelled if present. This period is used if the connected microcontroller detected RM. If a configuration register is programmed, this time period for t1 can generally be used. Note that the capacitive load at pin DATA is limited. The resulting time constant t together with an optional external pull-up resistor may not be exceeded to ensure proper operation.
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Absolute Maximum Ratings
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Parameters Supply voltage Power dissipation Junction temperature Storage temperature Ambient temperature Maximum input level, input matched to 50 W Symbol VS Ptot Tj Tstg Tamb Pin_max -55 -40 Min. Max. 6 450 150 +125 +105 10 Unit V mW C C C dBm
Thermal Resistance
Parameters Junction ambient Symbol RthJA Value 100 Unit K/W
Electrical Characteristics
All parameters refer to GND, Tamb = -40C to +105C, VS = 4.5 V to 5.5 V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified. (VS = 5 V, Tamb = 25C)
6.76438-Mhz Osc. (Mode 1) Parameter Test Condition Symbol Min. Typ. Max. 4.90625-Mhz Osc. (Mode 0) Min. Typ. Max. Min. Variable Oscillator Typ. Max. Unit
Basic Clock Cycle of the Digital Circuitry Basic clock cycle Extended basic clock cycle Polling Mode Sleep and XSleep are defined in the OPMODE register BR_Range0 BR_Range1 BR_Range2 BR_Range3 Average bit check time while polling BR_Range0 BR_Range1 BR_Range2 BR_Range3 Bit check time for a valid input signal fSig NBitcheck = 0 NBitcheck = 3 NBitcheck = 6 NBitcheck = 9 Sleep x XSleep x 1024 x 2.0697 1855 1061 1061 663 Sleep x XSleep x 1024 x 2.0383 1827 1045 1045 653 Sleep x XSleep x 1024 x TClk 896.5 512.5 512.5 320.5 x TClk MODE = 0 (USA) MODE = 1 (Europe) BR_Range0 BR_Range1 BR_Range2 BR_Range3 TClk 2.0697 16.6 8.3 4.1 2.1 2.0383 16.3 8.2 4.1 2.0 1/(fXTO/10) 1/(fXTO/14) 8 x TClk 4 x TClk 2 x TClk 1 x TClk s s s s s s
TXClk
Sleep time
TSleep
ms
Start-up time
TStartup
s s s s
TBitcheck
Time for Bit Check
0.45 0.24 0.14 0.14
0.47 0.26 0.16 0.15
ms ms ms ms
TBitcheck
3/fSig 6/fSig 9/fSig
3.5/fSig 6.5/fSig 9.5/fSig
3/fSig 6/fSig 9/fSig
3.5/fSig 6.5/fSig 9.5/fSig
TXClk 3.5/fSig 6.5/fSig 9.5/fSig
ms ms ms ms
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Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = -40C to +105C, VS = 4.5 V to 5.5 V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified. (VS = 5 V, Tamb = 25C)
6.76438-Mhz Osc. (Mode 1) Parameter Test Condition Symbol Min. Typ. Max. 4.90625-Mhz Osc. (Mode 0) Min. Typ. Max. Min. Variable Oscillator Typ. fXTO x 64/314 fXTO x 64/432.92 1.8 3.2 5.6 10.0 BR_Range0 x BR_Range1 x BR_Range2 x BR_Range3 x 2 s/TClk 2 s/TClk 2 s/TClk 2 s/TClk Max. Unit
Receiving Mode Intermediate frequency Baud rate range MODE=0 (USA) MODE=1 (Europe) BR_Range0 BR_Range1 BR_Range2 BR_Range3 fIF 1.0 1.8 3.2 5.6 1.0 1.8 3.2 5.6 10.0 1.0 1.8 3.2 5.6 1.0 MHz MHz kBaud kBaud kBaud kBaud
BR_Range
Minimum time BR_Range0 period between BR_Range1 edges at pin DATA BR_Range2 (Figure 15) BR_Range3 BR_Range0 Maximum low BR_Range1 period at DATA BR_Range2 (Figure 16) BR_Range3 OFF command at pin ENABLE (Figure 18) Configuration of the Receiver Frequency of the reset marker (Figure 19) BR_Range0 BR_Range1 Programming start pulse (Figure 17, Figure 20) BR_Range2 BR_Range3 after POR Programming delay period (Figure 17, Figure 20) Synchronization pulse (Figure 17, Figure 20)
TDATA_min tmin1 tmin2 tmin1 tmin2 tmin1 tmin2 tmin1 tmin2
149 182 75 91 37.3 45.5 18.6 22.8 2169 1085 542 271
147 179 73 90 36.7 44.8 18.3 22.4 2136 1068 534 267 1.5 TClk
9 x TXClk 11 x TXCl 9 x TXClk 11 x TXClk 9 x TXClk 11 x TXClk 9 x TXClk 11 x TXClk 131 x 131 x 131 x 131 x TXClk TXClk TXClk TXClk
s s s s s s s s s s s s
TDATA_L_max
tDoze
3.1
3.05
s
fRM
117.9
119.8
1 -------------------------------4096 x T CLK
3128 3128 3128 3128 1057 x TClk 533 x TClk 271 x TClk 140 x TClk 5632 x TClk 384.5 x TClk 1535 x TClk 1535 x TClk 1535 x TClk 1535 x TClk
Hz
2188 1104 t1 561 290 11656
3176 3176 3176 3176
2155 1087 553 286 11479
s
t2
795
798
783
786
385.5 x TClk
s
t3
265
261
128 x TClk
s
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Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = -40C to +105C, VS = 4.5 V to 5.5 V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified. (VS = 5 V, Tamb = 25C)
6.76438-Mhz Osc. (Mode 1) Parameter Delay until the program window starts (Figure 17, Figure 20) Programming window (Figure 17, Figure 20) Time frame of a bit (Figure 20) Programming pulse (Figure 17, Figure 20) Equivalent acknowledge pulse: E_Ack (Figure 20) Equivalent time window (Figure 20) OFF-bit programming window (Figure 17) Test Condition Symbol Min. Typ. Max. 4.90625-Mhz Osc. (Mode 0) Min. Typ. Max. Min. Variable Oscillator Typ. Max. Unit
t4
131
129
63.5 x TClk
s
t5
530
522
256 x TClk
s
t6
1060
1044 64 x TClk
512 x TClk 256 x TClk
s
t7
133
529
131
521
s
t8
265
261
128 x TClk
s
t9
534
526
258 x TClk
s
t10
930
916
449.5 x TClk
s
Electrical Characteristics
All parameters refer to GND, Tamb = -40C to +105C, VS = 4.5 V to 5.5 V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified. (VS = 5 V, Tamb = 25C) Parameters Test Conditions Sleep mode (XTO and polling logic active) Current consumption IC active (startup-, bit check-, receiving mode) pin DATA = H LNA/mixer/IF amplifier input matched according to Figure 4 Input matched according to Figure 4, required according to I-ETS 300220 Input matching according to Figure 4 at 433.92 MHz at 315 MHz Symbol ISoff ISon Min. Typ. 190 Max. 350 Unit A
7.0
8.6
mA
LNA Mixer Third-order intercept point LO spurious emission at RFIn Noise figure LNA and mixer (DSB) LNA_IN input impedance IIP3 ISLORF NF ZiLNA_IN IP1db -28 -73 7 1.0 || 1.56 1.3 || 1.0 -40 -57 dBm dBm dB k || pF k || pF dBm
1 dB compression point (LNA, mixer, IF Input matched according to Figure 4, referred to RFin amplifier)
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Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = -40C to +105C, VS = 4.5 V to 5.5 V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified. (VS = 5 V, Tamb = 25C) Parameters Test Conditions Input matched according to Figure 4, BER 10-3, ASK mode Symbol Min. Typ. Max. Unit
Maximum input level
Pin_max
-28 -20 299 -93 -113 -55 190 449 -90 -110 -47
dBm dBm MHz dBC/Hz dBC/Hz dBC MHz/V
Local Oscillator Operating frequency range VCO Phase noise VCO/LO Spurious of the VCO VCO gain For best LO noise (design parameter) R1 = 820 C9 = 4.7 nF C10 = 1 nF The capacitive load at pin LF is limited if bit check is used. The limitation therefore also applies to self polling. XTO crystal frequency, appropriate load capacitance must be connected to XTAL 6.764375 MHz 4.90625 MHz fXTO = 6.764 MHz 4.906 MHz fosc = 432.92 MHz at 1 MHz at 10 MHz at fXTO KVCO fVCO L (fm)
Loop bandwidth of the PLL
BLoop
100
kHz
Capacitive load at pin LF
CLF_tot
10
nF
XTO operating frequency
fXTO
6.764375 6.764375 6.764375 -30 ppm +30 ppm 4.90625 4.90625 4.90625 -30 ppm +30 ppm 150 220 6.5
MHz MHz pF
Series resonance resistor of the crystal Static capacitance of the crystal Analog Signal Processing
RS Cxto
Input sensitivity ASK 300-kHz IF filter
Input matched according to Figure 4 ASK (level of carrier) BER 10-3, B = 300 kHz fin = 433.92 MHz/315 MHz T = 25C, VS = 5 V fIF = 1 MHz BR_Range0 BR_Range1 BR_Range2 BR_Range3 Input matched according to Figure 4 ASK (level of carrier) BER 10-3, B = 600 kHz fin = 433.92 MHz/315 MHz T = 25C, VS = 5 V fIF = 1 MHz
PRef_ASK
Input sensitivity ASK 300-kHz IF filter Input sensitivity ASK 300-kHz IF filter Input sensitivity ASK 300-kHz IF filter Input sensitivity ASK 300-kHz IF filter
-109 -107 -106 -104
-111 -109 -108 -106
-113 -111 -110 -108
dBm dBm dBm dBm
Input sensitivity ASK 600 kHz IF filter
PRef_ASK
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Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = -40C to +105C, VS = 4.5 V to 5.5 V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified. (VS = 5 V, Tamb = 25C) Parameters Input sensitivity ASK 600 kHz IF filter Input sensitivity ASK 600 kHz IF filter Input sensitivity ASK 600 kHz IF filter Input sensitivity ASK 600 kHz IF filter Sensitivity variation ASK for the full operating range compared to Tamb = 25C, VS = 5 V Sensitivity variation ASK for full operating range including IF filter compared to Tamb = 25C, VS = 5 V Test Conditions BR_Range0 BR_Range1 BR_Range2 BR_Range3 300-kHz and 600-kHz version fin = 433.92 MHz/315 MHz fIF = 1 MHz PASK = PRef_ASK + PRef 300-kHz version fin = 433.92 MHz/315 MHz fIF = 0.88 MHz to 1.12 MHz fIF = 0.85 MHz to 1.15 MHz PASK = PRef_ASK + PRef 600-kHz version fin = 433.92 MHz/315 MHz fIF = 0.79 MHz to 1.21 MHz fIF = 0.73 MHz to 1.27 MHz PASK = PRef_ASK + PRef Input matched according to Figure 4, BER 10-3, B = 600 kHz fin = 433.92 MHz/315 MHz T = 25C, VS = 5 V fIF = 1 MHz BR_Range0 df 20 kHz df 30 kHz BR_Range1 df 20 kHz df 30 kHz 600-kHz version fin = 433.92 MHz/315 MHz fIF = 1 MHz PFSK = PRef_FSK + PRef 600-kHz version fin = 433.92 MHz/315 MHz fIF = 0.86 MHz to 1.14 MHz fIF = 0.82 MHz to 1.18 MHz PFSK = PRef_FSK + PRef The sensitivity of the receiver is higher for higher values of fFSK BR_Range0 BR_Range1 BR_Range2 and BR_Range3 are not suitable for FSK operation ASK mode FSK mode PRef PRef Symbol Min. -108 -106.5 -106 -104 Typ. -110 -108.5 -108 -106 Max. -112 -110.5 -110 -108 Unit dBm dBm dBm dBm
+2.5
-1.5
dB
PRef
+5.5 +7.5
-1.5 -1.5
dB dB
Sensitivity variation ASK for full operating range including IF filter compared to Tamb = 25C, VS = 5 V
PRef
+5.5 +7.5
-1.5 -1.5
dB dB
Input sensitivity FSK 600 kHz IF filter
PRef_FSK
Input sensitivity FSK 600 kHz IF filter
-95.5 -96.5 -94.5 -95.5
-97.5 -98.5 -96.5 -97.5
-99.5 -100.5 -98.5 -99.5
dBm dBm dBm dBm
Input sensitivity FSK 600 kHz IF filter
Sensitivity variation FSK for the full operating range compared to Tamb = 25C, VS = 5 V Sensitivity variation FSK for full operating range including IF filter compared to Tamb = 25C, VS = 5 V
+2.5
-1.5
dB
PRef
+5.5 +7.5
-1.5 -1.5
dB dB
FSK frequency deviation
fFSK
20 20
30 30
50 50
kHz kHz
S/N ratio to suppress inband noise signals Dynamic range RSSI ampl.
SNRASK SNRFSK RRSSI
10 2 60
12 3
dB dB dB
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Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = -40C to +105C, VS = 4.5 V to 5.5 V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified. (VS = 5 V, Tamb = 25C) Parameters Lower cut-off frequency of the data filter Test Conditions 1 f cu_DF = ----------------------------------------------------------2 x x 30k x CDEM ASK mode BR_Range0 (Default) BR_Range1 BR_Range2 BR_Range3 FSK mode BR_Range0 (Default) BR_Range1 BR_Range2 and BR_Range3 are not suitable for FSK operation Symbol fcu_DF Min. 0.11 Typ. 0.16 Max. 0.20 Unit kHz
Recommended CDEM for best performance
CDEM
39 22 12 8.2
nF nF nF nF
Recommended CDEM for best performance
CDEM
27 15 1000 560 320 180
nF nF s s s s
BR_Range0 (Default) Maximum edge-to-edge time period of BR_Range1 the input data signal for full sensitivity BR_Range2 BR_Range3 Upper cut-off frequency programmable in 4 ranges via a serial mode word BR_Range0 (Default) BR_Range1 BR_Range2 BR_Range3
tee_sig
Upper cut-off frequency data filter
fu
2.5 4.3 7.6 13.6
3.1 5.4 9.5 17.0
3.7 6.5 11.4 20.4 270 156 89 50
kHz kHz kHz kHz s s s s dBm (peak level)
BR_Range0 (Default) Minimum edge-to-edge time period of BR_Range1 the input data signal for full sensitivity BR_Range2 BR_Range3 Reduced sensitivity RSense connected from pin Sens to VS, input matched according to Figure 4 RSense = 56 k, fin = 433.92 MHz, (VS = 5 V, Tamb = 25C) at B = 300 kHz at B = 600 kHz RSense = 100 k, fin = 433.92 MHz at B = 300 kHz at B = 600 kHz RSense = 56 k, fin = 315 MHz at B = 300 kHz at B = 600 kHz RSense = 100 k, fin = 315 MHz at B = 300 kHz at B = 600 kHz RSense = 56 k RSense = 100 k PRed = PRef_Red + DPRed
tee_sig
PRef_Red
Reduced sensitivity
-71 -67 -80 -76 -72 -68 -81 -77 PRed 5 6
-76 -72 -85 -81 -77 -73 -86 -82 0 0
-81 -77 -90 -86 -82 -78 -91 -87 0 0
dBm dBm dBm dBm dBm dBm dBm dBm dB dB
Reduced sensitivity
Reduced sensitivity
Reduced sensitivity
Reduced sensitivity variation over full operating range
28
U3741BM
4662B-RKE-10/04
U3741BM
Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = -40C to +105C, VS = 4.5 V to 5.5 V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified. (VS = 5 V, Tamb = 25C) Parameters Test Conditions Values relative to RSense = 56 k RSense = 56 k RSense = 68 k RSense = 82 k RSense = 100 k RSense = 120 k RSense = 150 k PRed = PRef_Red + PRed 0 -3.5 -6.0 -9.0 -11.0 -13.5 1.95 2.8 0.08 50 3.75 0.3 61 2.5 41 540 0.3 dB dB dB dB dB dB V V k s pF pF V V V V V V V V V Symbol Min. Typ. Max. Unit
Reduced sensitivity variation for different values of RSense
PRed
Threshold voltage for reset Digital Ports Data output - Saturation voltage LOW - Internal pull-up resistor - Maximum time constant - Maximum capacitive load POUT output - Saturation voltage LOW - Saturation voltage HIGH FSK/ASK input - Low-level input voltage - High-level input voltage ENABLE input - Low-level input voltage - High-level input voltage MODE input - Low-level input voltage - High-level input voltage TEST input - Low-level input voltage Iol = 1 mA t = CL (Rpup//RExt) without ext. pull-up resistor Rext = 5 k IPOUT = 1 mA IPOUT = -1 mA FSK selected ASK selected Idle mode Active mode Division factor = 10 Division factor = 14 Test input must always be set to LOW
VThRESET VOI RPup CL CL VOl VOh VIl VIh VIl VIh VIl VIh VIl
39
0.08 VS - 0.3 V VS - 0.14V
0.8 x VS
0.2 x VS
0.8 x VS
0.2 x VS
0.8 x VS
0.2 x VS 0.2 x VS
29
4662B-RKE-10/04
Ordering Information
Extended Type Number U3741BM-P2FL U3741BM-P2FLG3 U3741BM-P3FL U3741BM-P3FLG3 Package SO20 SO20 SO20 SO20 Remarks 2: IF bandwidth of 300 kHz, tube 2: IF bandwidth of 300 kHz, taped and reeled 3: IF bandwidth of 600 kHz, tube 3: IF bandwidth of 600 kHz, taped and reeled
Package Information
Package SO20
Dimensions in mm
12.95 12.70 9.15 8.65 7.5 7.3
2.35 0.25 10.50 10.20 11
0.4 1.27 11.43 20
0.25 0.10
technical drawings according to DIN specifications
1
10
30
U3741BM
4662B-RKE-10/04
U3741BM
Revision History
Changes from Rev. 4662A - 06/03 to Rev. 4662B - 10/04
Please note that the following page numbers referred to in this section refer to the specific revision mentioned, not to this document. 1. Put datasheet in a new template. 2. Heading rows at Table "Absolute Maximum Ratings" added. 3. Table "Ordering Information" on page 30 changed.
31
4662B-RKE-10/04
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