AD9866BCP Analog Devices Inc, AD9866BCP Datasheet - Page 36

• Manufacturer Part Number: AD9866BCP
• Description: IC FRONT-END MIXED-SGNL 64-LFCSP
• Manufacturer: Analog Devices Inc

Specifications of AD9866BCP

• Rohs Status: RoHS non-compliant
• Rf Type: HPNA, VDSL
• Features: 12-bit ADC(s), 12-bit DAC(s)
• Package / Case: 64-VFQFN, CSP Exposed Pad
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (min): 3/3.135V
• Operating Supply Voltage (max): 3.6/3.465V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Package Type: LFCSP
• Mounting: Surface Mount
• Pin Count: 64
• Lead Free Status / RoHS Status: Not Compliant

AD9866
The ADC has an internal voltage reference and reference ampli-
fier as shown in Figure 75. The internal band gap reference
generates a stable 1 V reference level that is converted to a dif-
ferential 1 V reference centered about mid-supply (AVDD/2).
The outputs of the differential reference amplifier are available
at the REFT and REFB pins and must be properly decoupled for
optimum performance. The REFT and REFB pins are conven-
iently situated at the corners of the CSP package such that C1
(0603 type) can be placed directly across its pins. C3 and C4 can
be placed underneath C1, and C2 (10 µF tantalum) can be
placed furthest from the package.
Table 21. SPI Registers for Rx ADC
Address (Hex)
0x04
0x07
0x13
1.0V
Figure 75. ADC Reference and Decoupling
Bit
(5)
(4)
(4)
(2:0)
VIEW
TOP
ADCs
TO
REFT
REFB
C1
Description
Duty cycle restore circuit
ADC clock from PLL
ADC low power mode
ADC power bias adjust
C4
C1
0.1µF
C2
C3
C3
0.1µF
C4
0.1µF
C2
10µF
Rev. A | Page 36 of 48
AGC TIMING CONSIDERATIONS
When implementing a digital AGC timing loop, it is important
to consider the Rx path latency and settling time of the Rx path
in response to a change in gain setting. Figure 21 and Figure 24
show the RxPGA’s settling response to a 60 dB and 5 dB change
in gain setting when using the Tx[5:0] or PGA[5:0] port. While
the RxPGA settling time may also show a slight dependency on
the LPF’s cutoff frequency, the ADC’s pipeline delay along with
the ADIO bus interface presents a more significant delay. The
amount of delay or latency depends on whether a half- or full-
duplex is selected. An impulse response at the RxPGA’s input
can be observed after 10.0 ADC clock cycles (1/f
of a half-duplex interface and 10.5 ADC clock cycles in the case
of a full-duplex interface. This latency along with the RxPGA
settling time should be considered to ensure stability of the
AGC loop.
ADC
) in the case