EVAL-ADF7021DBZ5 Datasheet, PDF (54/64 Pages) Analog Devices – High Performance Narrow-Band Transceiver IC

ADF7021
REGISTER 7—READBACK SETUP REGISTER
READBACK
SELECT
ADC
MODE
CONTROL
BITS
DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
RB3 RB2 RB1 AD2 AD1 C4 (0) C3 (1) C2 (1) C1 (1)
Data Sheet
RB3 READBACK
0 DISABLED
1 ENABLED
RB2 RB1 READBACK MODE
0 0 AFC WORD
0 1 ADC OUTPUT
1 0 FILTER CAL
1 1 SILICON REV
AD2 AD1 ADC MODE
0 0 MEASURE RSSI
0 1 BATTERY VOLTAGE
1 0 TEMP SENSOR
1 1 TO EXTERNAL PIN
Figure 69. Register 7—Readback Setup Register Map
Readback of the measured RSSI value is valid only in Rx mode.
Readback of the battery voltage, temperature sensor, or voltage
at the external pin is not valid in Rx mode.
To read back the battery voltage, the temperature sensor, or the
voltage at the external pin in Tx mode, users should first power
up the ADC using R8_DB8 because it is turned off by default in
Tx mode to save power.
For AFC readback, use the following equations (see the
Readback Format section):
FREQ RB [Hz] = (AFC_READBACK × DEMOD CLK)/2¹⁸
VBATTERY = BATTERY_VOLTAGE_READBACK/21.1
VADCIN = ADCIN_VOLTAGE_READBACK/42.1
Temperature [°C] = −40 + (68.4 − TEMP_READBACK) × 9.32
Rev. B | Page 54 of 64