UG-949
EVAL-AD7761FMCZ User Guide
Rev. 0 | Page 8 of 17
POWER SUPPLIES
The evaluation board requires that an external power supply,
either a bench top supply or a wall wart (dc plug) supply, be
applied to J1 or J3 (see Table 3 for more information). Linear
regulators generate the required power supply levels from the
applied V
IN
rail. The regulators used are the 5 V
ADP7118
(U1
and U7), which supply AVDD1, the on-board amplifiers and
reference, and the 3.3 V
ADP7118
(U16), which delivers 3.3 V
to the IOVDD pin of the
AD7761
.
SERIAL DATA INTERFACE
The
AD7761
evaluation board outputs conversion results to the
EVAL-SDP-CH1Z
via the eight data output pins, DOUT0 to
DOUT7. The serial data interface also includes signals such as
SCLK, DCLK, and DRDY (all are outputs).
SERIAL CONFIGURATION INTERFACE
The
AD7761
is configured by the
EVAL-SDP-CH1Z
via a
4-wire SPI interface. SL1 must be shorted to Position A for this
mode to be active.
POWERING DOWN THE SYSTEM DEMONSTRATION
PLATFORM
When disconnecting the SDP-H1 evaluation platform and
powering down the system, first exit the evaluation software.
Then, press the reset button on the
EVAL-SDP-CH1Z
board
before disconnecting the 12 V supply and then the USB.
Failure to follow this procedure can cause damage to the
EVAL-SDP-CH1Z
board.
Table 3.
AD7761
Power Supply
1
Power Supply
(V
IN
) Source
Voltage Range
Function
J1
7 V to 9 V
Wall wart (dc plug) supply to the evaluation board. Supplies LDOs that create 5 V and 3.3 V
rails. It also supplies the
ADR444
external reference. Ensure that both LK1 and LK2 are set to
Position B when the external power supply is applied to this connector.
J2
Apply voltage within
data sheet specified
ranges and GND (0 V)
Apply voltage within data sheet specified ranges and GND (0 V) to this connector to power
the evaluation board. J2 is the connector for supplying AVDD1, AVDD2, IOVDD, AVSS, and
AGND externally. SLP1, SLP2, and SLP4 must be adjusted accordingly. See Table 1 for details.
J3
7 V to 9 V
Bench top supply to the evaluation board. Supplies LDOs that create 5 V and 3.3 V rails. It also
supplies the
ADR444
external reference and on-board amplifiers. Ensure that LK1 is set to
Position A when the external power supply is applied to this connector and LK2 is set to
Position B.
EVAL-SDP-CH1Z
12 V
If using the
EVAL-SDP-CH1Z
, power can be taken from this board and supplied to the LDOs.
Set LK2 to Position A.
1
Only a single supply is required.
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