Texas Instruments ADS7040, User Manual

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Table 2. Analog Input Connections
Reference Designator Signal Description
J3 INP Positive single-ended input provided at the SMA
P2 INP Alternate location to provide the positive single-ended input. Normally not populated on
the board.
3 Power Supplies
The ADS7040 supports a wide range of operation on its analog supplies. The AVDD can operate from
1.8V to 3.6V. The DVDD operates from 1.65 V to 3.6 V, independent of the AVDD supply.
The analog portion of the ADS7040EVM-PDK operates from a 5-V supply. The ADS7040EVM-PDK is
configured to use the onboard regulated analog 5-V supply that in turn generates an AVDD analog supply
using the low-noise TPS79101 LDO. This supply is nominally set to 3.3 V at the factory, but this voltage
maybe changed to any value within the valid range, by modifying the value of R46 as per
Table 3 . In case
any intermediate value needs to be set, the detailed formula to arrive at these values are available in the
TPS79101 (
SGLS160 ) datasheet.
Table 3. AVDD Voltage Settings
AVDD Voltage R46 R45 C34
1.8 V 14.2 k Ω 30.1 k Ω 33 pF
2.0 V 19.1 k Ω 30.1 k Ω 27 pF
2.5 V 31.6 k Ω 30.1 k Ω 22 pF
3.0 V 43.7 k Ω 30.1 k Ω 15 pF
3.3 V (default) 51.1 k Ω 30.1 k Ω 15 pF
3.6 V 59.0 k Ω 30.1 k Ω 15 pF
Alternatively, AVDD may be set by connecting an external power source through P3. Table 4 describes
the modifications required for on-board or external AVDD supply.
Table 4. AVDD Voltage Settings
AVDD Source Position Setting
Onboard regulated AVDD (set to 3.3 V) P3 Closed
P3 Open
External AVDD
R47 Disassembled
CAUTION
The external AVDD supply applied to external connector P3 must not exceed
3.6 V as this may damage the device. The external AVDD supply must be in
the range of 1.8 V to 3.6 V for proper operation of the ADS7040EVM.
The digital portion of the ADS7040 ADC operates from a 3.3-V supply from the Simple Capture Card. The
buffer U12 is included to ensure that the SDO can be driven to the controller with minimal distortion.
4 ADS7040EVM-PDK SBAU240 – November 2014
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