AD9866 Analog Devices, AD9866 Datasheet - Page 43

• Manufacturer Part Number: AD9866
• Manufacturer: Analog Devices

Specifications of AD9866

• Resolution (bits): 12bit
• # Chan: 1
• Sample Rate: 80MSPS
• Interface: Nibble
• Analog Input Type: Diff-Uni
• Ain Range: 6.3 V p-p,8 mV p-p
• Adc Architecture: Pipelined
• Pkg Type: CSP

A hardware ( RESET pin) or software (Bit 5 of Register 0x00)
reset can be used to place the AD9866 into a known state of
operation as determined by the state of the MODE and CONFIG
pins. A dc offset calibration and filter tuning routine is also
initiated upon a hardware reset, but not with a software reset.
Neither reset method flushes the digital interpolation filters in
the Tx path. Refer to the
Mode
A hardware reset can be triggered by pulsing the RESET pin low
for a minimum of 50 ns. The SPI registers are instantly reset to
their default settings upon RESET going low, while the dc offset
calibration and filter tuning routine is initiated upon RESET
returning high. To ensure sufficient power-on time of the various
functional blocks, RESET returning high should occur no less
than 10 ms upon power-up. If a digital reset signal from a
microprocessor reset circuit (such as ADM1818) is not available, a
simple R-C network referenced to DVDD can be used to hold
RESET low for approximately 10 ms upon power-up.
ANALOG AND DIGITAL LOOPBACK TEST MODES
The AD9866 features analog and digital loopback capabilities
that can assist in system debug and final test. Analog loopback
routes the digital output of the ADC back into the Tx data path
prior to the interpolation filters such that the Rx input signal
can be monitored at the output of the TxDAC or IAMP. As a
result, the analog loopback feature can be used for a half- or
full-duplex interface to allow testing of the functionality of the
entire IC (excluding the digital data interface).
sections for information on flushing the digital filters.
Half-Duplex Mode
and
Full-Duplex
Rev. B | Page 43 of 48
For example, the user can configure the AD9866 with similar
settings as the target system, inject an input signal (sinusoidal
waveform) into the Rx input, and monitor the quality of the
reconstructed output from the TxDAC or IAMP to ensure a
minimum level of performance. In this test, the user can
exercise the RxPGA as well as validate the attenuation char-
acteristics of the RxLPF. Note that the RxPGA gain setting
should be selected such that the input does not result in clipping
of the ADC.
Digital loopback can be used to test the full-duplex digital
interface of the AD9866. In this test, data appearing on the
Tx[5:0] port is routed back to the Rx[5:0] port, thereby
confirming proper bus operation. The Rx port can also be
three-stated for half- and full-duplex interfaces.
Table 26. SPI Registers for Test Modes
Address (Hex)
0x0D
Bit
(7)
(6)
(5)
Description
Analog loopback
Digital loopback
Rx port three-state
AD9866