AD9874 Просмотр технического описания (PDF) - Analog Devices
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AD9874 Datasheet PDF : 40 Pages
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AD9874
SERIAL PERIPHERAL INTERFACE (SPI)
The serial peripheral interface (SPI) is a bidirectional serial port. It is used to load configuration information into the registers listed
below as well as to read back their contents. Table I provides a list of the registers that may be programmed through the SPI port.
Addresses and default values are given in hexadecimal form.
Table I. SPI Address Map
Address Bit
(Hex) Breakdown Width Default Value Name
Description
POWER CONTROL REGISTERS
0x00
(7:0)
8
0xFF
STBY
Standby Control Bits (REF, LO, CKO, CK, GC, LNAMX, Unused,
and ADC).
0x01
(7:6)
(5:4)
(3:2)
(1:0)
2
0
2
0
2
0
2
0
LNAB
MIXB
CKOB
ADCB
LNA Bias Current (0 = 0.5 mA, 1 = 1 mA, 2 = 2 mA, 3 = 3 mA).
Mixer Bias Current (0 = 0.5 mA, 1 = 1.5 mA, 2 = 2.7 mA, 3 = 4 mA).
CK Oscillator Bias (0 = 0.25 mA, 1 = 0.35 mA, 2 = 0.40 mA, 3 = 0.65 mA).
Do not use.
0x02
(7:0)
8
0x00
TEST
Factory Test Mode. Do not use.
AGC
0x03
(7)
(6:0)
1
0
7
0x00
ATTEN Apply 16 dB attenuation in the front end.
AGCG(14:8) AGC Attenuation Setting (7 MSB of a 15-Bit Unsigned Word).
0x04
(7:0)
8
0x00
AGCG(7:0) AGC Attenuation Setting (8 LSB of a 15-Bit Unsigned Word).
Default corresponds to maximum gain.
0x05
(7:4)
(3:0)
4
0
4
0
AGCA
AGCD
AGC Attack Bandwidth Setting. Default yields 50 Hz raw loop bandwidth.
AGC Decay Time Setting. Default is decay time = attack time.
0x06
(7)
(6:4)
(3)
(2:0)
1
0
3
0
1
0
3
0
AGCV
AGCO
AGCF
AGCR
Enable digital VGA to increase AGC range by 12 dB.
AGC Overload Update Setting. Default is slowest update.
Fast AGC (Minimizes resistance seen between GCP and GCN).
AGC Enable/Reference Level (Disabled, 3 dB, 6 dB, 9 dB, 12 dB, 15 dB
below Clip).
DECIMATION FACTOR
0x07
(7:5)
(4)
(3:0)
3
1
0
4
4
Unused
K
M
Decimation Factor = 60 ϫ (M + 1), if K = 0; 48 ϫ (M + 1), if K = 1.
Default is Decimate-by-300.
LO SYNTHESIZER
0x08
(5:0)
6
0x00
LOR(13:8) Reference Frequency Divisor (6 MSB of a 14-Bit Word).
0x09
(7:0)
0x0A
(7:5)
(4:0)
8
0x38
3
0x5
5
0x00
LOR(7:0)
LOA
LOB(12:8)
Reference Frequency Divisor (8 LSB of a 14-Bit Word).
Default (56) yields 300 kHz from fREF = 16.8 MHz.
“A” Counter (Prescaler Control Counter).
“B” Counter MSB (5 MSB of a 13-Bit Word).
Default LOA and LOB values yield 300 kHz from 73.35 MHz to 2.25 MHz.
0x0B (7:0)
8
0x1D
LOB(7:0) “B” Counter LSB (8 LSB of a 13-Bit Word).
0x0C
(6)
(5)
(4:2)
(1:0)
1
0
1
0
3
0
2
3
LOF
LOINV
LOI
LOTM
Enable fast acquire.
Invert charge pump (0 = source current to increase VCO frequency).
Charge Pump Current in Normal Operation. IPUMP = (LOI + 1) ϫ 0.625 mA.
Manual Control of LO Charge Pump (0 = Off, 1 = Up, 2 = Down,
3 = Normal).
0x0D (5:0)
4
0x0
LOFA(13:8) LO Fast Acquire Time Unit (6 MSB of a 14-Bit Word).
0x0E (7:0)
8
0x04
LOFA(7:0) LO Fast Acquire Time Unit (8 LSB of a 14-Bit Word).
REV. A
–13–
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