Texas Instruments ADS1271EVM, User Manual, Page: 11 / 24

www.ti.com
ADS1271EVM Hardware Details
Table 10. Digital Interface Pinout (J2) (continued)
Pin Number Signal Description
J2.20 SDA I
2
C bus data line
5.4 Power Supplies, J3
J3 provides connection to the common power bus for the ADS1271EVM. Power is supplied on the pins
listed in
Table 11 .
Table 11. Power Supply Pinout
Signal Pin Number Signal
+VA (+15V to power buffer amplifier section) 1 2 –VA (–15V to power buffer amplifier section)
+5VA 3 4 Unused
DGND 5 6 AGND
+1.8VD 7 8 Unused
+3.3VD 9 10 +5VD
When power is supplied to J3, J6 allows for either 3.3V or 1.8V to be applied to the digital sections of the
ADS1271. J6 also provides for a method of measuring AVDD and DVDD supply currents if the shunts on
J6.1-2, J6.3-4, J6.5-6, and J6.7-8 are removed and a current meter is connected between the appropriate
pins. See the schematic and printed circuit board silkscreen for details.
5.4.1 ADC Power
Power for the ADS1271 analog supply voltage (AVDD) comes from +5VA, which is supplied through J3.3.
The shunt from J6 pins 1 to 2 applies this supply to the U7 ADS1271 device, while the shunt from J6 pins
5 to 6 applies this supply to the U8 ADS1271.
The ADS1271 digital supply voltage (DVDD) is selected using J6. When a shunt is applied from J6 pins 9
to 10, +1.8VD is selected, and this power comes from J3.7. If a shunt is placed from J6 pins 11 to 12 (the
default factory setting), +3.3VD is selected, which is provided from J3.9. J6 pins 13 and 15 provide a
means of connecting analog and digital grounds to the EVM; these grounds come from J3.6 and J3.5,
respectively. These grounds are always connected together at the EVM.
CAUTION
Verify that all power supplies are within the safe operating limits shown on the
ADS1271 data sheet before applying power to the EVM.
CAUTION
Note that a shunt should only be connected between J6 pins 9 and 10 OR pins
11 and 12, but never both; doing so would short the +3.3V supply to the +1.8V
digital supply.
5.4.2 Stand-Alone Operation
When used as a stand-alone EVM, the analog power can be applied to J6.2 and J6.6, referenced to
J6.13. DVDD can be applied to J6.4 and J6.8, referenced to J6.15.
11 SBAU107C – November 2004 – Revised November 2014 ADS1271EVM and ADS1271EVM-PDK User's Guide
Submit Documentation Feedback
Copyright © 2004–2014, Texas Instruments Incorporated