ATMEL ATA3742

Features
• IC Distinguishes the Signal Strength of Several Transmitters via RSSI (Received Signal
Strength Indicator) Output
• Minimal External Circuitry Requirements, No RF Components on the PC Board Except
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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 4.5V to 5.5V
Operating Temperature Range –40°C to +105°C
Single-ended RF Input for Easy Adaptation to λ / 4 Antenna or Printed Antenna on PCB
Low-cost Solution Due to High Integration Level
ESD Protection According to MIL-STD. 883 (4 KV HBM)
High Image Frequency Suppression Due to 1 MHz IF in Conjunction With a SAW
Front-end Filter (Up to 40 dB Achievable With Newer SAWs)
Communication to Microcontroller Possible via a Single, Bi-directional Data Line
Power Management (Polling) is also Possible by Means of a Separate Pin via the
Microcontroller
UHF ASK/FSK
Receiver
ATA3742
1. Description
The ATA3742 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 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 IC U2741B. Its main applications in the area of wireless control are
telemetering, security technology, tire-pressure monitoring 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 in this datasheet refer both to
433.92 MHz and 315 MHz applications.
4900B–RKE–11/07
Figure 1-1.
System Block Diagram
UHF ASK/FSK
Remote control transmitter
UHF ASK/FSK
Remote control receiver
1 Li cell
U2741B
ATA3742
1 to 3
Demod
Encoder
ATARx9x
Keys
Microcontroller
PLL
Antenna
XTO
Antenna
VCO
PLL
Power
amp.
Figure 1-2.
Control
LNA
XTO
VCO
Block Diagram
VS
FSK/ASK
Dem_out
Demodulator
and Data Filter
FSK/ASK
CDEM
RSSI
RSSI
50 kΩ
DATA
Limiter out
ENABLE
SENS
IF Amp
Sensitivity
reduction
Polling circuit
and
control logic
AVCC
TEST
AGND
MODE
DGND
FE
4th Order
CLK
DVCC
Standby
Logic
LPF
3 MHz
LFGND
MIXVCC
LFVCC
LNAGND
IF Amp
LPF
3 MHz
VCO
XTO
XTO
f
LNA_IN
LF
LNA
:64
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ATA3742
2. Pin Configuration
Figure 2-1.
Pinning SO20
SENS
1
20
DATA
FSK/ASK
2
19
ENABLE
CDEM
3
18
TEST
AVCC
4
17
RSSI
AGND
5
16
MODE
DGND
6
15
DVCC
MIXVCC
7
14
XTO
LNAGND
8
13
LFGND
LNA_IN
9
12
LF
10
11
LFVCC
NC
Table 2-1.
Pin Description
Pin
Symbol
Function
1
SENS
2
FSK/ASK
3
CDEM
Lower cut-off frequency of the data filter
4
AVCC
Analog power supply
5
AGND
Analog ground
6
DGND
Digital ground
Sensitivity-control resistor
Selecting FSK/ASK
Low: FSK, High: ASK
7
MIXVCC
Power supply mixer
8
LNAGND
High-frequency ground LNA and mixer
9
LNA_IN
10
NC
11
LFVCC
12
LF
13
LFGND
14
XTO
15
DVCC
Digital power supply
16
MODE
Selecting 433.92 MHz/315 MHz
Low: 4.90625 MHz (USA)
High: 6.76438 (Europe)
17
RSSI
Output of the RSSI amplifier
18
TEST
Test pin, during operation at GND
19
ENABLE
20
DATA
RF input
Not connected
Power supply VCO
Loop filter
Ground VCO
Crystal oscillator
Enables the polling mode
Low: polling mode off (sleep mode)
High: polling mode on (active mode)
Data output/configuration input
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3. 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. As seen in Figure 1-2 on page 2, the front end consists of an LNA (low noise
amplifier), LO (local oscillator), a mixer and an 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:
fXTO = fLO / 64
The XTO is a one-pin oscillator that operates at the series resonance of the quartz crystal. The
crystal should be connected to GND via the capacitor CL according to Figure 3-1. 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 the XTO must be
considered.
Figure 3-1.
PLL Peripherals
DVCC
VS
CL
XTO
LFGND
LF
LFVCC
VS
R1
820Ω
C9
C10
4.7 nF
1 nF
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 3-1 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. In that case,
self-polling will also not work.
fLO is determined by the RF input frequency f RF and the IF frequency fIF using the following
formula:
fLO = fRF – fIF
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ATA3742
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
f LO
MODE = 1 (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 f RF = 315 MHz, MODE must be set to “0”. In the case of
fRF = 433.92 MHz, 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 3-1 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
ATA3742 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 ∆PRef = 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 3-2 on page 6 shows a typical input matching network for f RF = 315 MHz and
fRF = 433.92 MHz using a SAW. Figure 3-3 on page 6 illustrates input matching to 50Ω without a
SAW. The input matching networks shown in Figure 3-3 on page 6 are the reference networks
for the parameters given in the “Electrical Characteristics” on page 26.
Table 3-1.
Calculation of LO and IF Frequency
Conditions
Local Oscillator Frequency
Intermediate Frequency
fRF = 315 MHz, MODE = 0
fLO = 314 MHz
fIF = 1 MHz
fRF = 433.92 MHz, MODE = 1
fLO = 432.92 MHz
fIF = 1 MHz
300 MHz < fRF < 365 MHz, MODE = 0
f RF
f LO = ------------------1
1 + ---------314
f LO
f IF = --------314
365 MHz < fRF < 450 MHz, MODE = 1
f RF
f LO = --------------------------1
1 + -----------------432.92
f LO
f IF = ----------------432.92
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Figure 3-2.
Input Matching Network With SAW Filter
8
8
LNAGND
LNAGND
ATA3742
C3
9
L
ATA3742
C3
LNA_IN
25 nH
22 pF
C17
100 pF
fRF = 433.92 MHz
27 nH
TOKO® LL2012
F33NJ
1
RFIN
L2
33 nH
C2
2
C16
fRF = 315 MHz
TOKO® LL2012
F27NJ
B3555
IN_GND
OUT
TOKO® LL2012
F82NJ
1
OUT_GND
5
6
L2
82 nH
C2
2
IN
Figure 3-3.
3, 4
7, 8
TOKO® LL2012
F47NJ
B3551
IN_GND
CASE_GND
8.2 pF
22 pF
L3
47 nH
RFIN
IN
C17
100 pF
8.2 pF
L3
LNA_IN
25 nH
47 pF
C16
9
L
OUT
OUT_GND
5
6
CASE_GND
10 pF
3, 4
7, 8
Input Matching Network Without SAW Filter
fRF = 433.92 MHz
8
fRF = 315 MHz
8
LNAGND
ATA3742
9
15 pF
25 nH
RFIN
LNAGND
ATA3742
9
LNA_IN
33 pF
25 nH
LNA_IN
RFIN
3.3 pF
22 nH
100 pF
TOKO® LL2012
F22NJ
3.3 pF
39 nH
100 pF
TOKO® LL2012
F39NJ
Please note that for all coupling conditions (see Figure 3-2 and Figure 3-3), 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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ATA3742
4. Analog Signal Processing
4.1
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, see Table 3-1 on page 5 to determine
the center frequency.
The receiver ATA3742-M3 employs an IF bandwidth of BIF = 600 kHz and can be used together
with the U2741B in FSK and ASK mode.
4.2
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 ∆RRSSI = 60 dB. If the RSSI amplifier is
operated within its linear range, the best signal-to-noise ratio (SNR) is maintained in ASK mode.
If the dynamic range is exceeded by the transmitter signal, the SNR 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 SNR 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 SENS 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 a lower sensitivity.
4.3
Pin RSSI
The output voltage of the RSSI amplifier (VRSSI) is available at pin RSSI. Using the RSSI output
signal, the signal strength of different transmitters can be distinguished.
The usable input-power range PRef is –100 dBm to –55 dBm. The temperature coefficient TC of
VRSSI is typically –2.2 mV/K. Due to TC and gain tolerance, it is not possible to find out the absolute level of each transmitter, but the level differences can be used to distinguish several
transmitters. As illustrated in Figure 4-2 on page 8, the RSSI output voltage is not constant over
the temperature range. Figure 4-1 illustrates an application that realizes a temperature compensation of VRSSI.
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4900B–RKE–11/07
Figure 4-1.
Temperature Compensation of VRSSI
VRSSI_temp_comp.
I ~ Ig(VLNA_IN)
180 kΩ
RSSI
50 kΩ
Bmin = 60
I
47 kΩ
VRSSI
ATA3742
Figure 4-2.
RSSI Characteristic
1.6
1.5
1.4
max
VRSSI (V)
1.3
1.2
1.1
1.0
-40°C
0.9
25°C
min
0.8
0.7
105°C
0.6
0.5
-110
-100
-90
-80
-70
-60
-50
PREF (dBm)
If RSense is connected to VS, the receiver operates at a lower sensitivity. The reduced sensitivity
is defined by the value of RSense, 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 3-3 on page 6 and exhibits the best possible sensitivity.
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ATA3742
RSense can be connected to VS or GND via a microcontroller. 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 shown in Figure 4-3 is
issued at pin DATA to indicate that the receiver is still active.
Figure 4-3.
Steady L State Limited DATA Output Pattern
DATA
tmin2
4.4
tDATA_L_max
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 mode; 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 inband noise signals or competing transmitters. If the
SNR 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 will be reduced. 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 SNR 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 SNR as its pass band 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
f cu_DF = ------------------------------------------------------------2 × π × 30 kΩ × 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 “Electrical Characteristics” on page 26. 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 20). BR_Range must be set in accordance to the used baud rate.
The ATA3742 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.
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4900B–RKE–11/07
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. They should not be exceeded to maintain full sensitivity of the receiver.
4.5
Receiving Characteristics
The RF receiver ATA3742 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 4-4 on page 10. This example relates to
ASK mode. FSK mode exhibits similar behavior. Note that the mirror frequency is reduced by
40 dB. The plots are printed relatively 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 ATA3742. Low-cost crystals are
specified to be within ±100 ppm. The XTO deviation of the ATA3742 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. Note that the receiving bandwidth and the IF-filter bandwidth are equivalent in ASK mode but not in FSK mode.
Figure 4-4.
Receiving Frequency Response
0
-10
-20
without SAW
dP (dB)
-30
-40
-50
-60
-70
-80
with SAW
-90
-100
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
df (mHz)
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ATA3742
5. 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 does the receiver remain active and
transfer 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, or it can be operated by up to three uni-directional ports.
5.1
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 5-1 on page 11, 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. As described in Section “RF Front End” on page 4, the frequency of the crystal oscillator
(fXTO) is defined by the RF input signal (fRFin), which also defines the operating frequency of the
local oscillator (fLO).
Figure 5-1.
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 the analog and digital signal processing
• Timing of the register programming
• Frequency of the reset marker
• IF filter center frequency (fIF0)
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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.
• Application USA (fXTO = 4.90625 MHz, MODE = L, TClk = 2.0383 µs)
• Application Europe (fXTO = 6.76438 MHz, MODE = H, TClk = 2.0697 µs)
• 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 =
5.2
BR_Range0:
TXClk = 8 × TClk
BR_Range1:
TXClk = 4 × TClk
BR_Range2:
TXClk = 2 × TClk
BR_Range3:
TXClk = 1 × TClk
Polling Mode
As seen in Figure 5-3 on page 15, 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 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, looking for 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 the electrical characteristics. 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 × T Sleep + I Son × ( T Startup + T Bitcheck )
I Spoll = -----------------------------------------------------------------------------------------------------------T Sleep + T Startup + T Bitcheck
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,microcontroller). 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_microcontroller
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5.2.1
Sleep Mode
The length of period TSleep is defined by the 5-bit word Sleep of the OPMODE register, the extension factor X Sleep according to Table 5-7 on page 22, and the basic clock cycle T Clk . It is
calculated to be:
TSleep = Sleep × XSleep × 1024 × TClk
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:
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 the 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.
The highest register value of Sleep sets the receiver into a permanent sleep condition (see
Table 5-6 on page 22). 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.
5.2.2
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 these edge-to-edge tests, before the receiver
switches to receiving mode, is also programmable.
5.2.3
Configuring the Bit Check
Assuming a modulation scheme that contains 2 edges per bit, two time frame checks verify 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 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 5-1 on page 11 shows an
example where 3 bits are tested successfully and the data signal is transferred to pin DATA.
According to Figure 5-2, 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 tee is smaller than TLim_min or tee exceeds
TLim_max, the bit check will be terminated and the receiver switches to sleep mode.
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Figure 5-2.
Valid Time Window for Bit Check
1/fSig
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 “10101...” sequence in Manchester or bi-phase is a good choice given this recommendation. 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.
The bit check limits are determined by means of the formula below:
TLim_min = Lim_min × TXClk
TLim_max = (Lim_max – 1) × 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 Section “Receiving Mode” on page 17. Due to this, the lower limit should be set to Lim_min ≥ 10. The maximum
value of the upper limit is Lim_max = 63.
14
ATA3742
4900B–RKE–11/07
ATA3742
Figure 5-3.
Polling Mode Flow Chart
Sleep Mode:
All circuits for signal processing are
disabled. Only XTO and Polling logic are
enabled.
Output level on pin IC_ACTIVE = > low
Sleep:
5-bit word defined by Sleep0 to
Sleep4 in OPMODE register
XSleep:
Extension factor defined by
XSleepTemp according to Table 5-7
TClk:
Basic clock cycle defined by fXTO
and pin MODE
TStartup:
Is defined by the selected baud-rate
range and TClk. The baud-rate range
is defined by Baud0 and Baud1 in
the OPMODE register.
XBit-check:
Depends on the result of the bit check.
IS = ISoff
TSleep = Sleep × XSleep × 1024 × TClk
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.
Output level on pin IC_ACTIVE = > high
IS = ISon
TStartup
Bit-check Mode:
The incoming 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.
Output level on pin IC_ACTIVE = > high
IS = ISon
TBit-check
NO
Bit Check
OK ?
If the bit check is ok, TBit-check
depends on the number of bits to be
checked (NBit-check) 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 and
on TClk. The baud-rate range is
defined by Baud0 and Baud1 in the
OPMODE register.
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
15
4900B–RKE–11/07
Figure 5-4.
Timing Diagram for Complete Successful Bit Check
Bit check ok
(Number of checked Bits: 3)
Enable IC
Bit check
1/2 Bit
1/2 Bit
1/2 Bit
1/2 Bit
1/2 Bit
1/2 Bit
Dem_out
Data
Startup mode
Figure 5-5.
Bit check mode
Receiving mode
Timing Diagram During Bit Check
Bit check ok
(Lim_min = 14, Lim_max = 24)
Enable IC
Bit check ok
TStartup
Bit check
1/2 Bit
1/2 Bit
1/2 Bit
Dem_out
Bit check
counter
0
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4
TXCLK
Figure 5-6.
Timing Diagram for Failed Bit Check (Condition: CV_Lim < Lim_min)
Bit check failed (CV_Lim_ < Lim_min)
(Lim_min = 14, Lim_max = 24)
Enable IC
Bit check
1/2 Bit
Dem_out
Bit check
counter
0
Startup mode
Figure 5-7.
1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 10 11 12
Bit check mode
0
Sleep mode
Timing Diagram for Failed Bit Check (Condition: CV_Lim ≥ Lim_max)
Bit check failed (CV_Lim_ ≥ Lim_max)
(Lim_min = 14, Lim_max = 24)
Enable IC
Bit check
1/2 Bit
Dem_out
Bit check
counter
0
Start up mode
16
1 2 3 4 5 6 7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Bit check mode
0
Sleep mode
ATA3742
4900B–RKE–11/07
ATA3742
Figure 5-5 on page 16 to Figure 5-7 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 5-5 on page 16 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 5-6 on page 16, 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 5-7.
5.2.4
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 T Bitcheck is given in the electrical characteristics. T Bitcheck
depends on the selected baud rate range and on TClk. A higher baud rate range causes a lower
value for TBitcheck resulting in a lower current consumption in polling mode.
In the presence of a valid transmitter signal, TBitcheck is dependent on the frequency of that signal, fSig, and on 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.
5.3
Receiving Mode
If the bit check is successful for all bits specified by NBitcheck, the receiver switches to receiving
mode. As shown in Figure 5-4 on page 16, 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.
5.3.1
Digital Signal Processing
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 5-8 on page 18 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 TXClk elapses. 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 5-9. 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
5-10 gives an example where Dem_out remains Low after the receiver is in receiving mode.
17
4900B–RKE–11/07
Figure 5-8.
Synchronization of the Demodulator Output
TXClk
Clock bit check
counter
Dem_out
DATA
Figure 5-9.
tee
Debouncing of the Demodulator Output
Dem_out
DATA
tmin1
Lim_min ≤ CV_Lim < Lim_max
tee
CV_Lim < Lim_min or CV_Lim ≥ Lim_max
tmin2
tee
Figure 5-10. Steady L State Limited DATA Output Pattern after Transmission
Enable IC
Bit check
Dem_out
DATA
tmin2
Start-up mode
Bit-check mode
tDATA_L_max
Receiving mode
After the end of 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.
18
ATA3742
4900B–RKE–11/07
ATA3742
5.3.2
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 5-11 illustrates the timing of the OFF command (see also Figure 5-15 on page
24). The minimum value of t1 depends on 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 Section “Configuration of the Receiver” on page 20. Setting the receiver to sleep mode via DATA is achieved by programming bit 1 of the OPMODE
register to be “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 τ together with an optional external pull-up resistor may not be exceeded
to ensure proper operation.
If the receiver is set to polling mode via pin ENABLE, an “L” pulse (TDoze) must be issued at that
pin. Figure 5-12 on page 20 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 an instantaneous response time. This command is a faster option than via pin
DATA, at the cost of an additional connection to the microcontroller.
Figure 5-11. Timing Diagram of the OFF Command via Pin DATA
t1
t2
t3
t5
t4
t10
t7
Out1
(microcontroller)
DATA (ATA3742)
X
Serial bi-directional
data line
X
Receiving
mode
Bit 1
("1")
(Start Bit)
TSleep
Startup mode
OFF command
19
4900B–RKE–11/07
Figure 5-12. Timing Diagram of the OFF Command via Pin ENABLE
TDoze
TSleep
toff
ENABLE
X
DATA (ATA3742)
X
Serial bi-directional
data line
Receiving mode
5.4
Startup mode
Configuration of the Receiver
The ATA3742 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 5-2 on page 21 shows the structure of the registers. Refering to Table 5-1, bit 1 defines if
the receiver is set back to polling mode via the OFF command (see Section “Receiving Mode”
on page 17), or if it is programmed. Bit 2 represents the register address. It selects the appropriate register to be programmed.
Table 5-1.
Effect of Bit 1 and Bit 2 in Programming the Registers
Bit 1
Bit 2
1
x
Action
The receiver is set back to polling mode (OFF command)
0
1
The OPMODE register is programmed
0
0
The LIMIT register is programmed
Table 5-3 on page 21 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 5-3 on page 21.
20
ATA3742
4900B–RKE–11/07
ATA3742
Table 5-2.
Bit 1 Bit 2
Effect of the Configuration Words Within the Registers
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Bit 8
Bit 9
Bit 10
Bit 11
Bit 12
Bit 13
Bit 14
OFF Command
1
OPMODE Register
0
1
0
1
BR_Range
VPOUT
NBitcheck
Sleep
XSleep
Baud1
Baud0
BitChk1
BitChk0
POUT
Sleep4
Sleep3
Sleep2
Sleep1
Sleep0
XSleep Std
XSleep Temp
0
0
1
0
0
0
1
0
1
1
0
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
(Default)
0
Table 5-3.
0
1
1
1
0
0
1
1
0
0
0
Effect of the Configuration Word BR_Range
BR_Range
Baud1
Baud0
0
0
BR_Range0 (application USA/Europe: BR_Range0 = 1.0 kBaud to 1.8 kBaud) (Default)
XLim = 8 (Default)
0
1
BR_Range1 (application USA/Europe: BR_Range1 = 1.8 kBaud to 3.2 kBaud)
XLim = 4
1
0
BR_Range2 (application USA/Europe: BR_Range2 = 3.2 kBaud to 5.6 kBaud)
XLim = 2
1
1
BR_Range3 (application USA/Europe: BR_Range3 = 5.6 kBaud to 10 kBaud)
XLim = 1
Table 5-4.
Baud Rate Range/Extension Factor for Bit Check Limits (XLim)
Effect of the Configuration Word NBitcheck
NBitcheck
BitChk1
BitChk0
Number of Bits to be Checked
0
0
0
0
1
3
1
0
6 (Default)
1
1
9
Table 5-5.
Effect of the Configuration Bit Reserved
Reserved Bit
No Function (Reserved for Future Use)
0
(Default)
1
-
21
4900B–RKE–11/07
Table 5-6.
Effect of the Configuration Word Sleep
Sleep
Sleep4
Sleep3
Sleep2
Sleep1
Sleep0
Start Value for Sleep Counter
(TSleep = Sleep × XSleep × 1024 × TClk)
0
0
0
0
0
0 (Receiver is continuously polling until a valid signal occurs)
0
0
0
0
1
1 (TSleep ≈ 2 ms for XSleep = 1 in US/European applications)
0
0
0
1
0
2
0
0
0
1
1
3
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
0
1
0
1
1
11 (USA: TSleep = 22.96 ms, Europe: TSleep = 23.31 ms) (Default)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1
1
1
0
1
29
1
1
1
1
0
30
1
1
1
1
1
31 (Permanent sleep mode)
Table 5-7.
Effect of the Configuration Word XSleep
XSleep
XSleepStd
XSleepTemp
Extension Factor for Sleep Time (TSleep = Sleep × XSleep × 1024 × TClk)
0
0
1 (Default)
0
1
8 (XSleep is reset to 1 if bit check fails once)
1
0
8 (XSleep is set permanently)
1
1
8 (XSleep is set permanently)
Table 5-8.
Effect of the Configuration Word Lim_min
Lim_min
Lower Limit Value for Bit Check
(TLim_min = Lim_min × XLim × TClk)
Lim_min < 10 is not applicable
22
0
0
1
0
1
0
10
0
0
1
0
1
1
11
0
0
1
1
0
0
12
0
0
1
1
0
1
13
0
0
1
1
1
0
14 (Default)
(USA: TLim_min = 228 µs, Europe: TLim_min = 232 µs)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1
1
1
1
0
1
61
1
1
1
1
1
0
62
1
1
1
1
1
1
63
ATA3742
4900B–RKE–11/07
ATA3742
Table 5-9.
Effect of the Configuration Word Lim_max
Lim_max
Upper Limit Value for Bit Check
Lim_max < 12 is not applicable
(TLim_max = (Lim_max – 1) × XLim × TClk)
0
0
1
1
0
0
12
0
0
1
1
0
1
13
0
0
1
1
1
0
14
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
0
1
1
0
0
0
24 (Default)
=
375
µs, Europe: TLim_max = 381 µs)
(USA: TLim_max
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1
1
1
1
0
1
61
1
1
1
1
1
0
62
1
1
1
1
1
1
63
5.4.1
Conservation of the Register Information
The ATA3742 has an integrated power-on reset (POR) and brown-out detection circuitry to provide a mechanism to preserve the RAM register information.
According to Figure 5-13, a power-on reset 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:
• fRM is lower than the lowest feasible frequency of a data signal. 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 cancelled by accident
if t1 is applied according to the proposal in the Section “Programming the Configuration
Register” on page 24.
By means of that mechanism, the receiver cannot lose its register information without communicating that condition via the reset marker RM.
23
4900B–RKE–11/07
Figure 5-13. Generation of the Power-on Reset
VS
VThreset
POR
tRst
X
DATA (ATA3742)
1/fRM
Figure 5-14. Timing of the Register Programming
t1
t2
t3
t5
t9
t4
TSleep
t8
t6
t7
Out1
(microcontroller)
DATA (ATA3742)
X
Serial bi-directional
data line
X
Receiving
mode
Bit 1
("0")
(Start bit)
Bit 2
("1")
(Register
select)
Bit 13
("0")
(Poll 8)
Bit 14
("1")
(Poll 8R)
Startup
mode
Programming frame
5.4.2
Programming the Configuration Register
The configuration registers are programmed serially via the bi-directional data line according to
Figure 5-14 and Figure 5-15.
Figure 5-15. One-wire Connection to a Microcontroller
Microcontroller
ATA3742
Internal pull-up
resistor
Bi-directional
data line
DATA
DATA
(ATA3742)
24
I/O
Out1 (microcontroller)
ATA3742
4900B–RKE–11/07
ATA3742
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 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 just-programmed mode word 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 FSK/ASK Manchester
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 × TClk: [t1(min) is the minimum specified value for the relevant BR_Range]
Programming (or the OFF command) is initiated if the receiver is not in reset mode. If the
receiver is in reset mode, programming (or the 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 × TClk
Programming (or the OFF command) is initiated in any case. RM is canceled 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.
25
4900B–RKE–11/07
6. 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
Symbol
Max.
Unit
Ptot
450
mW
Junction temperature
Tj
150
°C
Storage temperature
Tstg
–55
+125
°C
Tamb
–40
+105
°C
10
dBm
Power dissipation
Ambient temperature
Maximum input level, input matched to 50Ω
Min.
Pin_max
7. Thermal Resistance
Parameters
Junction ambient
Symbol
Value
Unit
RthJA
100
K/W
8. Electrical Characteristics
All parameters refer to GND, Tamb = –40°C to +105°C, VS = 4.5V to 5.5V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified.
(VS = 5V, Tamb = 25°C)
Parameter
Test Condition
Symbol
6.76438 Mhz Oscillator
(Mode 1)
4.90625 Mhz Oscillator
(Mode 0)
Min.
Min.
Typ.
Max.
Typ.
Max.
Variable Oscillator
Min.
Typ.
Max.
Unit
Basic Clock Cycle of the Digital Circuitry
Basic clock
cycle
MODE = 0 (USA)
MODE = 1 (Europe)
Extended
basic clock
cycle
BR_Range0
BR_Range1
BR_Range2
BR_Range3
2.0383
1 / (fXTO / 10)
1 / (fXTO / 14)
µs
µs
TXClk
16.6
8.3
4.1
2.1
16.3
8.2
4.1
2.0
8 × TClk
4 × TClk
2 × TClk
1 × TClk
µs
µs
µs
µs
TSleep
Sleep ×
XSleep ×
1024 ×
2.0697
Sleep ×
XSleep ×
1024 ×
2.0383
Sleep ×
XSleep ×
1024 ×
TClk
ms
1855
1061
1061
663
1827
1045
1045
653
896.5
512.5
512.5
320.5
× TClk
0.45
0.24
0.14
0.14
0.47
0.26
0.16
0.15
TClk
2.0697
Polling Mode
Sleep and XSleep
are defined in the
OPMODE register
Sleep time
Start-up time
Time for Bit
Check
26
BR_Range0
BR_Range1
BR_Range2
BR_Range3
TStartup
Average bit-check
time while polling
BR_Range0
BR_Range1
BR_Range2
BR_Range3
TBitcheck
Bit-check time for a
valid input signal fSig
NBitcheck = 0
NBitcheck = 3
NBitcheck = 6
NBitcheck = 9
TBitcheck
3 / fSig
6 / fSig
9 / fSig
3.5 / fSig 3 / fSig
6.5 / fSig 6 / fSig
9.5 / fSig 9 / fSig
µs
µs
µs
µs
ms
ms
ms
ms
3.5 / fSig
6.5 / fSig
9.5 / fSig
TXClk
3 / fSig
6 / fSig
9 / fSig
TXClk
3.5 / fSig
6.5 / fSig
9.5 / fSig
ms
ms
ms
ms
ATA3742
4900B–RKE–11/07
ATA3742
8. Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = –40°C to +105°C, VS = 4.5V to 5.5V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified.
(VS = 5V, Tamb = 25°C)
Parameter
Test Condition
Symbol
6.76438 Mhz Oscillator
(Mode 1)
4.90625 Mhz Oscillator
(Mode 0)
Min.
Min.
Typ.
Max.
Typ.
Max.
Variable Oscillator
Min.
Typ.
Max.
Unit
Receiving Mode
Intermediate
frequency
MODE=0 (USA)
MODE=1 (Europe)
Baud-rate
range
BR_Range0
BR_Range1
BR_Range2
BR_Range3
Minimum time
period
between
edges at
pin DATA
(Figure 5-9 on
page 18)
BR_Range0
Maximum low
period at DATA
(Figure 5-10
on page 18)
BR_Range0
BR_Range1
BR_Range2
BR_Range3
BR_Range1
BR_Range2
BR_Range3
OFF
command at
pin ENABLE
(Figure 5-12
on page 20)
BR_Range
1.0
1.8
3.2
5.6
10.0
1.0
1.8
3.2
5.6
TDATA_min
tmin1
tmin2
tmin1
tmin2
tmin1
tmin2
tmin1
tmin2
TDATA_L_max
tDoze
fXTO × 64 / 314
fXTO × 64 / 432.92
1.0
fIF
1.8
3.2
5.6
10.0
1.0
1.8
3.2
5.6
BR_Range0 ×
BR_Range1 ×
BR_Range2 ×
BR_Range3 ×
MHz
MHz
2 µs / TClk
2 µs / TClk
2 µs / TClk
2 µs / TClk
kBaud
kBaud
kBaud
kBaud
149
182
75
91
37.3
45.5
18.6
22.8
147
179
73
90
36.7
44.8
18.3
22.4
9 × TXClk
11 × TXClk
9 × TXClk
11 × TXClk
9 × TXClk
11 × TXClk
9 × TXClk
11 × TXClk
µs
µs
µs
µs
µs
µs
µs
µs
2169
1085
542
271
2136
1068
534
267
131 ×
131 ×
131 ×
131 ×
µs
µs
µs
µs
3.1
TXClk
TXClk
TXClk
TXClk
1.5 ×
TClk
3.05
µs
Configuration of the Receiver
Frequency of
the reset
marker
(Figure 5-13
on page 24)
fRM
117.9
1
---------------------------------4096 × T CLK
119.8
BR_Range0
2188
3176
2155
3128
Programming BR_Range1
start pulse
(Figure 5-11
BR_Range2
on page 19,
Figure 5-14 on BR_Range3
page 24)
after POR
1104
3176
1087
3128
561
3176
553
3128
290
3176
286
3128
Programming
delay period
(Figure 5-11
on page 19,
Figure 5-14 on
page 24)
t1
11656
t2
795
11479
798
783
786
Hz
1057 ×
TClk
533 ×
TClk
271 ×
TClk
140 ×
TClk
5632 ×
TClk
1535 ×
TClk
1535 ×
TClk
1535 ×
TClk
1535 ×
TClk
384.5 ×
TClk
385.5 ×
TClk
µs
µs
27
4900B–RKE–11/07
8. Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = –40°C to +105°C, VS = 4.5V to 5.5V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified.
(VS = 5V, Tamb = 25°C)
Parameter
Test Condition
Symbol
6.76438 Mhz Oscillator
(Mode 1)
4.90625 Mhz Oscillator
(Mode 0)
Min.
Min.
Typ.
Max.
Typ.
Max.
Variable Oscillator
Min.
Typ.
Max.
Unit
Synchroni-zati
on pulse
(Figure 5-11
on page 19,
Figure 5-14 on
page 24)
t3
265
261
128 × TClk
µs
Delay until the
program
window starts
(Figure 5-11
on page 19,
Figure 5-14 on
page 24)
t4
131
129
63.5 × TClk
µs
Programming
window
(Figure 5-11
on page 19,
Figure 5-14 on
page 24)
t5
530
522
256 × TClk
µs
Time frame
of a bit
(Figure 5-14
on page 24)
t6
1060
1044
512 × TClk
µs
Programming
pulse (Figure
5-11 on page
19, Figure
5-14 on page
24)
t7
Equivalent
acknowledge
pulse: E_Ack
(Figure 5-14
on page 24)
t8
265
261
128 × TClk
µs
Equivalent
time window
(Figure 5-14
on page 24)
t9
534
526
258 × TClk
µs
OFF-bit
programming
window
(Figure 5-11
on page 19)
t10
930
916
449.5 × TClk
µs
28
133
529
131
521
256 ×
TClk
64 × TClk
µs
ATA3742
4900B–RKE–11/07
ATA3742
9. Electrical Characteristics
All parameters refer to GND, Tamb = –40°C to +105°C, VS = 4.5V to 5.5V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified.
(VS = 5V, Tamb = 25°C)
Parameters
Test Conditions
Symbol
Min.
Typ.
Max.
Unit
Sleep mode
(XTO and polling logic active)
ISoff
190
350
µA
IC active
(start up, bit check, receiving mode)
pin DATA = H
ISon
7.0
8.6
mA
Third-order intercept point
LNA/mixer/IF amplifier
input matched according to Figure 3-3
on page 6
IIP3
–28
LO spurious emission at RFIn
Input matched according to Figure 3-3
on page 6, required according to
I-ETS 300220
ISLORF
–73
Noise figure LNA and mixer (DSB)
Input matching according to Figure 3-3
on page 6
NF
7
dB
LNA_IN input impedance
at 433.92 MHz
at 315 MHz
ZiLNA_IN
1.0 || 1.56
1.3 || 1.0
kΩ || pF
kΩ || pF
1 dB compression point
(LNA, mixer, IF amplifier)
Input matched according to Figure 3-3
on page 6, referred to RFin
IP1db
–40
dBm
Maximum input level
Input matched according to Figure 3-3
on page 6,
BER ≤ 10-3,
ASK mode
Pin_max
Current consumption
LNA Mixer
dBm
–57
dBm
–28
–20
dBm
dBm
449
MHz
–93
–113
–90
–110
dBC/Hz
dBC/Hz
–55
–47
dBC
Local Oscillator
Operating frequency range VCO
fVCO
Phase noise VCO/LO
fosc = 432.92 MHz
at 1 MHz
at 10 MHz
Spurious of the VCO
at ±fXTO
L (fm)
299
KVCO
190
MHz/V
Loop bandwidth of the PLL
For best LO noise
(design parameter)
R1 = 820Ω
C9 = 4.7 nF
C10 = 1 nF
BLoop
100
kHz
Capacitive load at pin LF
The capacitive load at pin LF is limited
if bit check is used. The limitation
therefore also applies to self-polling.
CLF_tot
VCO gain
XTO operating frequency
XTO crystal frequency,
appropriate load capacitance must be
connected to XTAL
6.764375 MHz
fXTO
4.90625 MHz
Series resonance resistor of the
crystal
fXTO = 6.764 MHz
4.906 MHz
RS
10
6.764375 6.764375 6.764375
–30 ppm
+30 ppm
4.90625 4.90625 4.90625
–30 ppm
+30 ppm
150
220
nF
MHz
MHz
Ω
Ω
29
4900B–RKE–11/07
9. Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = –40°C to +105°C, VS = 4.5V to 5.5V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified.
(VS = 5V, Tamb = 25°C)
Parameters
Test Conditions
Static capacitance of the crystal
Symbol
Min.
Typ.
Cxto
Max.
Unit
6.5
pF
Analog Signal Processing
Input sensitivity ASK
Input sensitivity ASK
Input matched according to Figure 3-3
on page 6
ASK (level of carrier)
BER ≤ 10-3, fIF = 1 MHz
fin = 433.92 MHz/315 MHz
T = 25°C, VS = 5V
PRef_ASK
BR_Range0
–108
–110
–112
dBm
BR_Range1
–106.5
–108.5
–110.5
dBm
BR_Range2
–106
–108
–110
dBm
BR_Range3
–104
–106
–108
dBm
+2.5
–1.5
dB
+5.5
+7.5
–1.5
–1.5
dB
dB
Sensitivity variation ASK for the full
operating range compared to
Tamb = 25°C, VS = 5V
fin = 433.92 MHz/315 MHz
fIF = 1 MHz
PASK = PRef_ASK + ∆PRef
∆PRef
Sensitivity variation ASK for full
operating range including IF filter
compared to Tamb = 25°C, VS = 5V
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
∆PRef
Input sensitivity FSK
Input matched according to Figure 3-3
on page 6,
BER ≤ 10-3, fIF = 1 MHz
fin = 433.92 MHz/315 MHz
T = 25°C, VS = 5V
Input sensitivity FSK
PRef_FSK
BR_Range0
df ≥ ±20 kHz
df ≥ ±30 kHz
–95.5
–96.5
–97.5
–98.5
–99.5
–100.5
dBm
dBm
BR_Range1
df ≥ ±20 kHz
df ≥ ±30 kHz
–94.5
–95.5
–96.5
–97.5
–98.5
–99.5
dBm
dBm
Sensitivity variation FSK for the full
operating range compared to
Tamb = 25°C, VS = 5V
fin = 433.92 MHz/315 MHz
fIF = 1 MHz
PFSK = PRef_FSK + ∆PRef
∆PRef
+2.5
–1.5
dB
Sensitivity variation FSK for full
operating range including IF filter
compared to Tamb = 25°C, VS = 5V
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
∆PRef
+5.5
+7.5
–1.5
–1.5
dB
dB
FSK frequency deviation
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
∆fFSK
20
20
50
50
kHz
kHz
SNR to suppress inband noise signals
ASK mode
FSK mode
SNRASK
SNRFSK
10
2
12
3
dB
dB
Dynamic range RSSI amplifier
30
∆RRSSI
30
30
60
dB
ATA3742
4900B–RKE–11/07
ATA3742
9. Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = –40°C to +105°C, VS = 4.5V to 5.5V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified.
(VS = 5V, Tamb = 25°C)
Parameters
Test Conditions
Lower cut-off frequency of the data
filter
1
f cu_DF = ------------------------------------------------------------2 × π × 30 kΩ × CDEM
Recommended CDEM for best
performance
ASK mode
BR_Range0 (Default)
BR_Range1
BR_Range2
BR_Range3
CDEM
Recommended CDEM for best
performance
FSK mode
BR_Range0 (Default)
BR_Range1
BR_Range2 and BR_Range3 are not
suitable for FSK operation
CDEM
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 data filter
Upper cut-off frequency programmable
in 4 ranges via a serial mode word
BR_Range0 (Default)
BR_Range1
BR_Range2
BR_Range3
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 3-3
on page 6
Symbol
Min.
Typ.
Max.
Unit
fcu_DF
0.11
0.16
0.20
kHz
Reduced sensitivity variation over full
operating range
nF
nF
nF
nF
27
15
nF
nF
tee_sig
fu
2.5
4.3
7.6
13.6
3.1
5.4
9.5
17.0
tee_sig
1000
560
320
180
µs
µs
µs
µs
3.7
6.5
11.4
20.4
kHz
kHz
kHz
kHz
270
156
89
50
µs
µs
µs
µs
dBm
(peak
level)
PRef_Red
(VS = 5V, Tamb = 25°C)
RSense = 56 kΩ, fin = 433.92 MHz,
Reduced sensitivity
39
22
12
8.2
–67
–72
–77
dBm
RSense = 100 kΩ, fin = 433.92 MHz
–76
–81
–86
dBm
RSense = 56 kΩ, fin = 315 MHz
–68
–73
–78
dBm
RSense = 100 kΩ, fin = 315 MHz
–77
–82
–87
dBm
5
6
0
0
0
0
dB
dB
RSense = 56 kΩ
RSense = 100 kΩ
PRed = PRef_Red + ∆PRed
∆PRed
Values relative to
RSense = 56 kΩ
Reduced sensitivity variation for
different values of RSense
RSense = 56 kΩ
RSense = 68 kΩ
RSense = 82 kΩ
RSense = 100 kΩ
RSense = 120 kΩ
RSense = 150 kΩ
PRed = PRef_Red + ∆PRed
∆PRed
0
–3.5
–6.0
–9.0
–11.0
–13.5
dB
dB
dB
dB
dB
dB
31
4900B–RKE–11/07
9. Electrical Characteristics (Continued)
All parameters refer to GND, Tamb = –40°C to +105°C, VS = 4.5V to 5.5V, f0 = 433.92 MHz and f0 = 315 MHz, unless otherwise specified.
(VS = 5V, Tamb = 25°C)
Parameters
Test Conditions
Threshold voltage for reset
Symbol
Min.
Typ.
Max.
Unit
VThRESET
1.95
2.8
3.75
V
39
0.08
50
0.3
61
2.5
41
540
V
kΩ
µs
pF
pF
0.2 × VS
V
V
0.2 × VS
V
V
0.2 × VS
V
V
0.2 × VS
V
Digital Ports
Iol = 1 mA
VOI
RPup
τ
CL
CL
Data output
- Saturation voltage LOW
- Internal pull-up resistor
- Maximum time constant
- Maximum capacitive load
τ = CL (Rpup//RExt)
without external pull-up resistor
Rext = 5 kΩ
FSK/ASK input
- Low-level input voltage
- High-level input voltage
FSK selected
ASK selected
VIl
VIh
0.8 × VS
ENABLE input
- Low-level input voltage
- High-level input voltage
Idle mode
Active mode
VIl
VIh
0.8 × VS
MODE input
- Low-level input voltage
- High-level input voltage
Division factor = 10
Division factor = 14
VIl
VIh
0.8 × VS
TEST input
- Low-level input voltage
32
Test input must always be set to LOW
VIl
ATA3742
4900B–RKE–11/07
ATA3742
10. Ordering Information
Extended Type Number
Package
Remarks
ATA3742P3-TGSY
SO20
Tube, Pb-free
ATA3742P3-TGQY
SO20
Taped and reeled, Pb-free
11. Package Information
9.15
8.65
Package SO20
Dimensions in mm
12.95
12.70
7.5
7.3
2.35
0.25
0.25
0.10
0.4
10.50
10.20
1.27
11.43
20
11
technical drawings
according to DIN
specifications
1
10
12. Revision History
Please note that the following page numbers referred to in this section refer to the specific revision
mentioned, not to this document.
Revision No.
History
4900B-RKE-11/07
• Put datasheet in the newest template
• Pb-free Logo on page 1 deleted
33
4900B–RKE–11/07
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4900B–RKE–11/07