MUX
RX_IN1
RX_IN2
PHASE &
AMPLITUDE
DETECTOR
GAIN
RSSI
(AUX)
LOGIC
L
E
V
E
L
S
H
IF
T
E
R
STATE
CONTROL
LOGIC
[CONTROL
REGISTERS &
COMMAND
LOGIC]
127-BYTE
FIFO
MCU
INTERFACE
VDD_I/O
I/O_0
I/O_1
I/O_2
I/O_3
I/O_4
I/O_5
I/O_6
I/O_7
IRQ
SYS_CLK
DATA _CLK
ISO
PROTOCOL
HANDLING
DECODER
RSSI
(EXTERNAL)
PHASE &
AMPLITUDE
DETECTOR
GAIN
RSSI
(MAIN)
FILTER
& AGC
DIGITIZER
BIT
FRAMING
FRAMING
SERIAL
CONVERSION
CRC & PARITY
TRANSMITTER ANALOG
FRONT END
TX_OUT
VDD_PA
VSS_PA
DIGITAL CONTROL
STATE MACHINE
CRYSTAL OR OSCILLATOR
TIMING SYSTEM
EN
EN2
ASK/OOK
MOD
OSC_IN
OSC_OUT
VOLTAGE SUPPLY REGULATOR SYSTEMS
(SUPPLY REGULATORS AND REFERENCE VOLTAGES)
VSS_A
VSS_RF
VDD_RF
VDD_X
VSS_D
VSS
VIN
VDD_A
BAND_GAP
RF LEVEL
DETECTOR
SLOS787H – MAY 2012 – REVISED APRIL 2014
The transmitter supports OOK and ASK modulation with selectable modulation depth. The TRF7964A also
includes a data transmission engine that comprises low-level encoding for ISO15693, ISO14443A/B and
FeliCa. Included with the transmit data coding is the automatic generation of Start Of Frame (SOF), End
Of Frame (EOF), Cyclic Redundancy Check (CRC), or parity bits.
Several integrated voltage regulators ensure a proper power-supply noise rejection for the complete
reader system. The built-in programmable auxiliary voltage regulator V
DD_X
(pin 32), is able to deliver up to
20 mA to supply a microcontroller and additional external circuits within the reader system.
6.2
System Block Diagram
shows a block diagram of the TRF7964A.
Figure 6-2. System Block Diagram
6.3
Power Supplies
The TRF7964A positive supply input V
IN
(pin 2) sources three internal regulators with output voltages
V
DD_RF
, V
DD_A
and V
DD_X
. All regulators use external bypass capacitors for supply noise filtering and must
be connected as indicated in reference schematics. These regulators provide a high power supply reject
ratio (PSRR) as required for RFID reader systems. All regulators are supplied by V
IN
(pin 2).
The regulators are not independent and have common control bits in register 0x0B for output voltage
setting. The regulators can be configured to operate in either automatic or manual mode (register 0x0B,
bit 7). The automatic regulator setting mode ensures an optimal compromise between PSRR and the
highest possible supply voltage for RF output (to ensure maximum RF power output). The manual mode
allows the user to manually configure the regulator settings.
6.3.1
Supply Arrangements
Regulator Supply Input: V
IN
Copyright © 2012–2014, Texas Instruments Incorporated
Detailed Description
13
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