TRF7970A Datasheet, PDF (15/83 Pages) Texas Instruments – MULTI-PROTOCOL FULLY INTEGRATED 13.56-MHz RFID/NEAR FIELD COMMUNICATION

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5 Detailed System Description
5.1 System Block Diagram
Figure 5-1 shows a block diagram of the TRF7970A.
TRF7970A
SLOS743 – AUGUST 2011
RX_IN1
RX_IN2
VDD_PA
TX_OUT
VSS_PA
EN
EN2
ASK/OOK
MOD
OSC_IN
OSC_OUT
MUX
PHASE &
AMPLITUDE
DETECTOR
RF Level
Detector
RSSI
(EXTERNAL)
PHASE &
AMPLITUDE
DETECTOR
TRANSMITTER ANALOG
FRONT END
GAIN
RSSI
(AUX)
GAIN
RSSI
(MAIN)
FILTER
& AGC
ISO
PROTOCOL
HANDLING
FRAMING
DIGITIZER
DECODER
BIT
FRAMING
SERIAL
CONVERSION
CRC & PARITY
LOGIC
STATE
CONTROL
LOGIC
[CONTROL
REGISTERS &
COMMAND
LOGIC]
MCU
INTERFACE
128 BYTE
FIFO
DIGITAL CONTROL
STATE MACHINE
CRYSTAL / OSCILLATOR
TIMING SYSTEM
VOLTAGE SUPPLY REGULATOR SYSTEMS
[SUPPLY REGULATORS , REFERENCE VOLTAGES ]
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
VIN
VDD_A
BAND_GAP
VSS_A
VDD_RF
VSS_RF
VDD_X
VSS
VSS_D
Figure 5-1. System Block Diagram
5.2 Power Supplies
The TRF7970A 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 via 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.
5.2.1 Supply Arrangements
Regulator Supply Input: V_IN
The positive supply at V_IN (pin 2) has an input voltage range of 2.7 V to 5.5 V. V_IN provides the supply
input sources for three internal regulators with the output voltages V_{DD_RF}, V_{DD_A} and V_{DD_X}. External
bypass capacitors for supply noise filtering must be used (per reference schematics).
NOTE
V_IN must be the highest voltage supplied to the TRF7970A.
Copyright © 2011, Texas Instruments Incorporated
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Detailed System Description
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