Register 7-Readback Setup Register - Analog Devices ADF7021-V Manual

ADF7021-V
REGISTER 7—READBACK SETUP REGISTER
•
Readback of the measured RSSI value is valid only in Rx
mode. Readback of the battery voltage, temperature sensor,
or voltage at the external ADCIN pin is not valid in Rx mode.
•
To read back the battery voltage, the temperature sensor, or
the voltage at the external ADCIN pin in Tx mode, the user
should first power up the ADC using Register 8, Bit DB8
because it is turned off by default in Tx mode to save power.
READBACK_
SELECT
DB8
RB3
RB3 READBACK_SELECT
0 DISABLED
1 ENABLED
RB2
0
0
1
1
Figure 69. Register 7—Readback Setup Register Map
ADC_
MODE
DB7
DB6 DB5 DB4 DB3
RB2 RB1 AD2 AD1 C4 (0)
AD2
0
0
1
1
RB1 READBACK MODE
0 AFC WORD
1 ADC OUTPUT
0 FILTER CAL
1 SILICON REV
•
For AFC readback, use the following equations (see the
Readback Format section):
FREQ RB (Hz) = (AFC READBACK × DEMOD CLK)/2
V
BATTERY
V = ADCIN VOLTAGE READBACK/42.1
ADCIN
Temperature (°C) = −40 + [(68.4 − TEMP READBACK) × 9.32]
Rev. 0 | Page 52 of 60
CONTROL
BITS
DB1 DB0
DB2
C3 (1) C2 (1) C1 (1)
AD1 ADC_MODE
0 MEASURE RSSI
1 BATTERY VOLTAGE
0 TEMP SENSOR
1 TO EXTERNAL PIN
= BATTERY VOLTAGE READBACK/21.1
18