Texas Instruments ADS8638EVM-PDK, User Manual

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EVM Operation
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4.1 Power Options
JP3 is in place for current measurement in order to regulate the power consumption of the ADS8638.
When current measurement is not taking place, jumpers must be applied across many of the jumpers to
properly power the ADC.
Table 4 lists the power option details for JP3.
Table 4. JP3 Configuration: Power Options
Row Name Function
1-2 ADC HVDD Supply current measurement point for high
voltage positive rail. Must be connected for
operation.
3-4 ADC HVEE Supply current measurement point for high
voltage negative rail. Must be connected for
operation.
5-6 ADC +5 VA Supply current measurement point for
+5-VA voltage rail. Must be connected for
operation.
7-8 GND Ground points for EVM board
9-10 ADC +3.3 VD Supply current measurement point for 3.3-V
digital supply rail. Must be connected for
ADC use with DVDD = 3.3 V. Do not
connect if +5-VD jumper is installed.
11-12 ADC +1.8 VD Supply current measurement point for 1.8V
digital supply rail. Must be connected for
ADC use with DVDD = 1.8 V. Do not
connect if +3.3-VD jumper is installed.
The ADS8638EVM has the option to either set +1.8 VD or +3.3 VD as the ADS8638 DVDD supply. Install
a jumper across pins 9-10 to set DVDD = 3.3 V, or install a jumper across pins 11-12 to set DVDD =
1.8 V.
CAUTION
Do not install both jumpers. Doing so may cause damage to the board or ADC
device itself.
4.2 Reference Voltages
The ADS8638EVM can be configured to use the internal reference voltage found within the chip, an
onboard REF5025 reference source, or use the option to input an external reference source. Jumper JP2
is used to route the reference signal to the ADC. When placed in the 1-2 position, the onboard REF5025
is used as the reference signal. When placed in the 2-3 position, an outside external reference can be
applied to J1.20 on the analog header to feed the ADC reference. If the ADC internal reference is
enabled, the shunt on jumper JP2 must be either in the 2-3 position or left disconnected. This
configuration ensures that the REF5025 source is not driving the ADS8638 reference pin when the pin is
configured as an output.
5 EVM Operation
This section provides information on the analog input, digital control, and general operating conditions of
the ADS8638EVM.
5.1 Analog Input
Each of the analog input sources can be applied directly to J1 (top or bottom side) or through
signal-conditioning modules available for the modular EVM system.
6 ADS8638EVM-PDK SBAU192 – July 2011
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