AD9879BS Analog Devices Inc, AD9879BS Datasheet - Page 18

• Manufacturer Part Number: AD9879BS
• Description: IC FRONT-END MIXED-SGNL 100-MQFP
• Manufacturer: Analog Devices Inc

Specifications of AD9879BS

• Rohs Status: RoHS non-compliant
• Number Of Bits: 12
• Number Of Channels: 5
• Power (watts): 587mW
• Voltage - Supply, Analog: 3.3V
• Voltage - Supply, Digital: 3.3V
• Package / Case: 100-MQFP, 100-PQFP

AD9879
The default value for the clamp level control value is 0x20. This
results in an ADC output clamp level offset of 512 LSBs. The
valid programming range for the clamp level control value is
from 0x16 to 0x127.
REGISTER 0x08—ADC CLOCK CONFIGURATION
Bit 0: Send 10-Bit ADC Data Only
When this bit is set high, the device enters a nonmultiplexed
mode and only the data from the 10-bit ADC is sent to the IF
[11:0] digital output port.
Bit 1: Send 12-Bit ADC Data Only
When this bit is set high, the device enters a nonmultiplexed
mode and only data from the 12-bit ADC is sent to the IF [11:0]
digital output port.
Bit 3: Enable 7-Bits, IQ ADC
When this bit is active, the IQ ADC is put into 7-bit mode. In
this mode, the full-scale input range is 2 Vppd. When this bit is
set inactive, the IQ ADC is put into 6-bit mode and the full-
scale input voltage range is 1 Vppd.
Bit 4: Power-Down RXSYNC and IQ ADC Clocks
Setting this bit to 1 powers down the IQ ADC’s sampling clock
and stops the RXSYNC output pin. It can be used for additional
power saving on top of the power-down selections in Register 0x02.
Bit 5: Rx Port Fast Edge Rate
Setting this bit to 1 increases the output drive strength of all
digital output pins, except MCLK, REFCLK, Σ-Δ_OUT, and
FLAG1. These pins always have high output drive capability.
Bit 7: ADC Clocked Direct from OSCIN
When set high, the input clock at OSCIN is used directly as the
ADC sampling clock. When set low, the internally generated
master clock, MCLK, is divided by two and used as the ADC
sampling clock. Best ADC performance is achieved when the
ADCs are sampled directly from f
or low jitter crystal oscillator.
REGISTER 0x0C—DIE REVISION
Bits 0–3: Version
The die version of the chip can be read from this register.
REGISTER 0x0D—Tx FREQUENCY TUNING WORDS
LSBs
This register accommodates two LSBs for both frequency
tuning words. For more information, see the description in the
Registers 0X10–0X17—Carrier Frequency Tuning section.
OSCIN
using an external crystal
Rev. A | Page 18 of 32
REGISTER 0x0E—DAC GAIN CONTROL
Bits 0–3: DAC Fine Gain Control
This bit field sets the DAC gain if the Tx Path AD8321/AD8323
gain control select bit (Register F, Bit 3) is set to 0. The DAC
gain can be set from 0.0 dB to 7.5 dB in increments of 0.5 dB.
Table 6 details the programming.
Table 6. DAC Gain Control
Bits [3:0]
0000
0001
0010
0011
....
1110
1111
REGISTER 0x0F—Tx PATH CONFIGURATION
Bit 0: Single-Tone Tx Mode
Active high configures the AD9879 for single-tone applications
such as FSK. The AD9879 supplies a single frequency output as
determined by the frequency tuning word selected by the active
profile. In this mode, the TXIQ input data pins are ignored but
should be tied to a valid logic voltage level. The default value is
0 (inactive).
Bit 1: Spectral Inversion Tx
When set to 1, inverted modulation is performed.
The default is logic low, noninverted modulation.
Bit 2: Tx Path Bypass Sinc
Setting this bit high bypasses the digital inverse sinc filter of the
Tx path.
Bit 3: Tx Path AD8322/AD8327 Gain Control Mode
This bit changes the manner in which transmit gain control is
performed. Typically either AD8321/AD8323 (default 0) or
AD8222/AD8327 (default 1) variable gain cable drivers are
programmed over the chip’s 3-wire CA interface. The Tx gain
control select changes the interpretation of the bits in
Registers 0x13 and 0x17. See the Cable Driver Gain Control
section.
MODULATOR_OUT = [I cos(ωt) + Q sin(ωt)]
MODULATOR_OUT = [I cos(ωt) + Q sin(ωt)]
DAC Gain
0.0 dB (default)
0.5 dB
1.0 dB
1.5 dB
....
7.0 dB
7.5 dB
–1
Filter
(10)
(11)