EVAL-ADF7025DB1 View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-ADF7025DB1' PDF : 44 Pages View PDF
SERIAL INTERFACE
The serial interface allows the user to program the eleven 32-bit
registers using a 3-wire interface (SCLK, SDATA, and SLE). It
consists of a level shifter, a 32-bit shift register, and 11 latches.
Signals should be CMOS-compatible. The serial interface is
powered by the regulator, and, therefore, is inactive when CE
is low.
Data is clocked into the register, MSB first, on the rising edge of
each clock (SCLK). Data is transferred to one of 11 latches on
the rising edge of SLE. The destination latch is determined by
the value of the four control bits (C4 to C1). These are the
bottom four LSBs, DB3 to DB0, as shown in the timing diagram
in Figure 2. Data can also be read back on the SREAD pin.
READBACK FORMAT
The readback operation is initiated by writing a valid control
word to the readback register and setting the readback-enable
bit (R7_DB8 = 1). The readback can begin after the control
word has been latched with the SLE signal. SLE must be kept
high while the data is being read out. Each active edge at the
SCLK pin clocks the readback word out successively at the
SREAD pin, as shown in Figure 38, starting with the MSB first.
The data appearing at the first clock cycle following the latch
operation must be ignored.
RSSI Readback
The RSSI readback operation yields valid results in Rx mode.
The format of the readback word is shown in Figure 38. It
comprises the RSSI level information (Bit RV1 to Bit RV7), the
current filter gain (FG1 and FG2), and the current LNA gain
(LG1 and LG2) setting. The filter and LNA gain are coded in
accordance with the definitions in Register 9—AGC Register.
The input power can be calculated from the RSSI readback
value, as outlined in the RSSI/AGC section.
ADF7025
Battery Voltage ADCIN/Temperature Sensor Readback
The battery voltage is measured at Pin VDD4. The readback
information is contained in Bit RV1 to Bit RV7. This also
applies for the readback of the voltage at the ADCIN pin and
the temperature sensor. From the readback information, the
battery or ADCIN voltage can be determined using
VBATTERY = (Battery_Voltage_Readback)/21.1
VADCIN = (ADCIN_Voltage_Readback)/42.1
Silicon Revision Readback
The silicon revision readback word is valid without setting any
other registers, especially directly after power-up. The silicon
revision word is coded with four quartets in BCD format. The
product code (PC) is coded with two quartets extending from
Bit RV9 to Bit RV16. The revision code (RV) is coded with one
quartet extending from Bit RV1 to Bit RV8. The product code
should read back as PC = 0x25. The current revision code
should read as RC = 0x08.
Filter Calibration Readback
The filter calibration readback word is contained in Bit RV1 to
Bit RV8 and is for diagnostic purposes only. Using the automatic
filter calibration function, accessible through Register 6, is
recommended. Before filter calibration is initiated, Decimal 32
should be read back.
READBACK MODE
READBACK VALUE
DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
RSSI READBACK
X
X
X
X
X LG2 LG1 FG2 FG1 RV7 RV6 RV5 RV4 RV3 RV2 RV1
BATTERY VOLTAGE/ADCIN/
TEMP. SENSOR READBACK X
X
X
X
X
X
X
X
X RV7 RV6 RV5 RV4 RV3 RV2 RV1
SILICON REVISION
RV16 RV15 RV14 RV13 RV12 RV11 RV10 RV9 RV8 RV7 RV6 RV5 RV4 RV3 RV2 RV1
FILTER CAL READBACK
0
0
0
0
0
0
0
0 RV8 RV7 RV6 RV5 RV4 RV3 RV2 RV1
Figure 38. Readback Value Table
Rev. A | Page 27 of 44
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