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AD9866
Bit
Address
Break-
1
(Hex)
down
Description
0x08
(7:0)
Rx Filter Tuning
Cutoff Frequency
Tx/Rx PATH GAIN CONTROL
0x09
(6)
Use SPI Rx Gain
(5:0)
Rx Gain Code
0x0A
(6)
Use SPI Tx Gain
(5:0)
Tx Gain Code
Tx AND Rx PGA CONTROL
0x0B
(6)
PGA Code for Tx
(5)
PGA Code for Rx
(3)
Force GAIN strobe
(2)
Rx Gain on Tx Port
(1)
3-Bit RxPGA Port
Tx DIGITAL FILTER AND INTERFACE
0x0C
(7:6)
Interpolation
Factor
(4)
Invert
TXEN/TXSYNC
(2)
LS Nibble First*
(1)
TXCLK neg. edge
(0)
Twos complement
Rx INTERFACE AND ANALOG/DIGITAL LOOPBACK
0x0D
(7)
Analog Loopback
(6)
Digital Loopback*
(5)
Rx Port 3-State
(4)
Invert
RXEN/RXSYNC
(2)
LS Nibble First*
(1)
RXCLK neg. edge
(0)
Twos complement
DIGITAL OUTPUT DRIVE STRENGTH, TxDAC OUTPUT, AND REV ID
0x0E
(7)
Low Drive
Strength
(0)
TxDAC Output
0x0F
(3:0)
REV ID Number
Tx IAMP GAIN AND BIAS CONTROL
0x10
(7)
Select Tx Gain
(6:4)
G1
(2:0)
N
0x11
(6:4)
G2
(2:0)
G3
0x12
(6:4)
Stand_Secondary
(2:0)
Stand_Primary
Power-Up Default Value
MODE = 0 (Half-Duplex)
Width
CONFIG = 0
CONFIG = 1
8
0x80
0x61
1
0x00
0x00
6
1
0x7F
0x7F
6
1
0
0
1
1
1
1
0
0
1
0
0
1
0
1**
2
01
00
1
0
0
1
N/A
N/A
1
0
0
1
0
0
1
0
0
1
0
0
1
N/A
N/A
1
0
0
1
N/A
N/A
1
0
0
1
0
0
1
0
0
1
0
0
4
0x00
0x00
1
0x44
0x44
3
3
3
0x62
0x62
3
3
0x01
0x01
3
Rev. A | Page 20 of 48
MODE = 1 (Full-Duplex)
Comments
CONFIG = 0
CONFIG = 1
Refer to Low-Pass Filter
0x80
0x80
section.
Default setting is for hardware
0x00
0x00
Rx gain code via PGA or Tx
data port.
Default setting is for Tx gain
0x7F
0x7F
code via SPI control.
0
0
Default setting is RxPGA
control active.
1
1
*Tx port with GAIN strobe
0
0
(AD9875/AD9876
1*
1*
compatible).
0
0
**3-bit RxPGA gain map
(AD9975 compatible).
01
01
Default setting is 2× interpo-
lation with LPF response.
Data format is straight binary
0
0
for half-duplex and twos
complement for full-duplex
0
0
interface.
0
0
*Full-duplex only.
1
1
0
0
Data format is straight
binary for half-duplex and
0
0
twos complement for full-
0
0
duplex interface.
0
0
Analog loopback: ADC Rx
data fed back to TxDAC.
0
0
Digital loopback: Tx input
0
0
data to Rx output port.
*Full-duplex only.
1
1
0
0
Default setting is for high
drive strength and IAMP
enabled.
0
0
0x00
0x00
Secondary path G1 = 0, 1, 2,
3, 4.
0x44
0x44
Primary path N = 0, 1, 2, 3, 4.
Secondary path stages:
0x62
0x62
G2 = 0 to 1.50 in 0.25 steps
and G3 = 0 to 6.
Standing current of primary
0x01
0x01
and secondary path.
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