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.
describes the JAC serial interface pins, and
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
I
2
C serial clock
SCL
14
I
2
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 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.
15
SBAU203 – July 2013
ADS1x20EVM
Copyright © 2013, Texas Instruments Incorporated