Datasheet

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ADS1220EVM Hardware Details

5.4.3 External Control

The header and socket connectors, JAC and JDB, provide access to the digital control and serial data

pins of the ADS1220. To use this option, connectors must be installed on the bottom-side of the

ADS1220EVM. Also, the on-board controller must have the control functions disabled. The outputs of the

on-board controller pass through 3-state buffers, U8. To disable the output of the buffers, jumper JP5 must

be shorted. This jumper is not installed by default. A wire can be soldered to the terminals of JP5, or a

standard 0.1-inch pitch header with a shorting block can be installed.

All logic levels on JAC and JDB are 3.3-V CMOS. Table 10 describes the JAC serial interface pins, and

Table 11 describes JDB. The connector footprint conforms to the Samtec connector SSW-110-22-F-D-VS-

K, which is a dual-row, 20-pin, surface-mount socket with 0.1-inch pitch spacing.

Table 10. JAC: External Interface Connector

Function Signal Name Pin Number (JAC)

ADS1220 data in DIN 15

ADS1220 device select CS 3

ADS1220 interrupt output DRDY 11

Analog power supply +5V 2

Digital power supply +3.3V 1

(1)

N/C N/C 5-10, 12-14, 16-20

Power-supply ground AGND/DGND 4

(1)

Pin 1 is bottom-side below and to the right of the reference designator.

Table 11. JDB: External Interface Connector

Function Signal Name Pin Number (JDB)

ADS1220 data out DOUT/DRDY 18

C serial clock SCL 14

C serial data SDA 12

N/C N/C 1

(1)

, 3-11, 13, 15, 17, 19, 20

Power-supply ground AGND/DGND 2

SPI serial clock SCLK 16

(1)

Pin 1 is at the bottom-side below and to the right of the reference designator.

5.5 Power-Supply Connections

The primary power supply is +5 V. The +5-V supply derives the +3.3 V with LDO regulator U5. +3.3 V is

required for powering the digital components on the EVM. The analog supply can be either +3.3 V or

+5 V, and is selectable at jumper JP3.

+5 V can be supplied via USB (default), or can be wired to the terminal block J7. If J7 is used, the USB

supply can be disconnected from the EVM by removing the shorting jumper JP7. If the external controller

option is used through JAC, both the +3.3 V and +5 V can be connected as either a source or target

supply. If +3.3 V is supplied to the EVM, jumper JP8 should be removed so that U5 does not sink current

from an external source.

SBAU203–July 2013 ADS1x20EVM

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