Rainbow Electronics ATA8402 User Manual
Features
• Integrated PLL Loop Filter
• ESD Protection (4 kV HBM/200V MM; Except Pin 2: 4 kV HBM/100V MM) also at
ANT1/ANT2
• High Output Power (7.5 dBm) with Low Supply Current (9.0 mA)
• Modulation Scheme ASK/FSK
– FSK Modulation is Achieved by Connecting an Additional Capacitor Between the
XTAL Load Capacitor and the Open Drain Output of the Modulating Microcontroller
• Easy to Design-in Due to Excellent Isolation of the PLL from the PA and Power Supply
• Single Li-cell for Power Supply
• Supply Voltage 2.0V to 4.0V in the Temperature Range of –40°C to +85°C
• Package TSSOP8L
• Single-ended Antenna Output with High Efficient Power Amplifier
• CLK Output for Clocking the Microcontroller
• One-chip Solution with Minimum External Circuitry
UHF ASK/FSK
Industrial
Transmitter
Applications
• Industrial/Aftermarket Remote Keyless Entry Systems
• Alarm, Telemetering, and Energy Metering Systems
• Remote Control Systems for Consumer and Industrial Markets
• Access Control Systems
• Home Automation
• Home Entertainment
• Toy s
1. Description
The ATA8402 is a PLL transmitter IC, which has been developed for the demands of
RF low-cost transmission systems for industrial applications at data rates up to
50 kBaud ASK and 32 kBaud FSK modulation scheme. The transmitting frequency
range is 429 MHz to 439 MHz. It can be used in both FSK and ASK systems.
Figure 1-1. System Block Diagram
UHF ASK/FSK
Remote control receiver
Demod Control
PLL XTO
1 to 3
Micro-
controller
1 Li cell
Keys
Encoder
ATARx9x
UHF ASK/FSK
Remote control transmitter
ATA8402 ATA3741/
PLL
XTO
Antenna
VCO
Antenna
ATA3745/
ATA5743/
ATA5744
ATA8202
ATA8402
Power
amp.
LNA VCO
4982A–IND–02/07
2. Pin Configuration
Figure 2-1. Pinning TSSOP8L
CLK
PA_ENABLE
ANT2
ANT1
1
8
ENABLE
2
3
4
GND
7
VS
6
XTAL
5
Table 2-1. Pin Description
Pin Symbol Function Configuration
Clock output signal for microconroller
1CLK
The clock output frequency is set by the
crystal to f
XTAL
/4
100Ω
100Ω
VS
CLK
2 PA_ENABLE
3
4
ANT2
ANT1
Switches on power amplifier, which is
used for ASK modulation
Emitter of antenna output stage
Open collector antenna output
50 kΩ
20 µA
ANT1
ANT2
U
= 1.1V PA_ENABLE
REF
2
ATA8402
4982A–IND–02/07
Table 2-1. Pin Description (Continued)
Pin Symbol Function Configuration
ATA8402
VS
1.5 kΩ 1.2 kΩ
VS
5 XTAL Connection for crystal
XTAL
182 µA
6 VS Supply voltage See ESD protection circuitry (see Figure 4-5 on page 9)
7 GND Ground See ESD protection circuitry (see Figure 4-5 on page 9)
ENABLE
200 kΩ
8 ENABLE Enable input
Figure 2-2. Block Diagram
ATA8402
Power up/down
CLK
PA_ENABLE
ANT2
ANT1
f
1
2
3
4
4
PA VCO
PLL
f
PDF
CP
LF
32
XTO
8
7
6
5
ENABLE
GND
VS
XTAL
4982A–IND–02/07
3
3. General Description
This fully integrated PLL transmitter allows particularly simple, low-cost RF miniature transmitters to be assembled. The VCO is locked to 32 f
needed for a 433.92 MHz transmitter. All other PLL and VCO peripheral elements are
integrated.
The XTO is a series resonance oscillator so that only one capacitor together with a crystal connected in series to GND are needed as external elements.
The crystal oscillator together with the PLL typically needs < 1 ms until the PLL is locked and the
CLK output is stable. There is a wait time of ≥ 1 ms until the CLK is used for the microcontroller
and the PA is switched on.
The power amplifier is an open-collector output delivering a current pulse, which is nearly independent from the load impedance. The delivered output power is therefore controllable via the
connected load impedance.
This output configuration enables a simple matching to any kind of antenna or to 50Ω. A high
power efficiency of η=P
load impedance of Z
4. Functional Description
If ENABLE = L and the PA_ENABLE = L, the circuit is in standby mode, consuming only a very
small amount of current, so that a lithium cell used as power supply can work for several years.
, and therefore a 13.56 MHz crystal is
XTAL
/(I
out
S,PA VS
= (166 + j223)Ω is used at 3V supply voltage.
Load
) of 36% for the power amplifier results when an optimized
With ENABLE = H the XTO, PLL, and the CLK driver are switched on. If PA_ENABLE remains
L, only the PLL and the XTO are running, and the CLK signal is delivered to the microcontroller.
The VCO locks to 32 times the XTO frequency.
With ENABLE = H and PA_ENABLE = H the PLL, XTO, CLK driver, and the power amplifier are
on. The power amplifier can be switched on and off with PA_ENABLE. This is used to perform
the ASK modulation.
4.1 ASK Transmission
The ATA8402 is activated by ENABLE = H. PA_ENABLE must remain L for t ≥1ms, then the
CLK signal can be taken to clock the microcontroller and the output power can be modulated by
means of the PA_ENABLE pin. After transmission, PA_ENABLE is switched to L and the microcontroller switches back to internal clocking. The ATA8402 is switched back to standby mode
with ENABLE = L.
4.2 FSK Transmission
The ATA8402 is activated by ENABLE = H. PA_ENABLE must remain L for t ≥1ms, then the
CLK signal can be taken to clock the microcontroller, and the power amplifier is switched on with
PA_ENABLE = H. The chip is then ready for FSK modulation. The microcontroller starts to
switch on and off the capacitor between the XTAL load capacitor and GND with an open-drain
output port, thus changing the reference frequency of the PLL. If the switch is closed, the output
frequency is lower than if the switch is open. After transmission, PA_ENABLE is switched to L,
and the microcontroller switches back to internal clocking. The ATA8402 is switched back to
standby mode with ENABLE = L.
The accuracy of the frequency deviation with XTAL pulling method is about ±25% when the following tolerances are considered.
4
ATA8402
4982A–IND–02/07
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