INA231

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SBOS644 – FEBRUARY 2013

Serial Bus Address

In order to communicate with the INA231, the master must first address slave devices using a corresponding

slave address byte. The slave address byte consists of seven address bits and a direction bit that indicates

whether the action is to be a read or write operation.

The INA231 has two address pins: A0 and A1. Table 7 describes the pin logic levels for each of the 16 possible

addresses. The state of pins A0 and A1 is sampled on every bus communication. Set these pins before any

activity on the interface occurs.

Table 7. INA231 Address Pins and

Slave Addresses

A1

A0

SLAVE ADDRESS

GND

GND

1000000

GND

1000001

GND

SDA

1000010

GND

SCL

1000011

GND

1000100

1000101

SDA

1000110

SCL

1000111

SDA

GND

1001000

SDA

1001001

SDA

SDA

1001010

SDA

SCL

1001011

SCL

GND

1001100

SCL

1001101

SCL

SDA

1001110

SCL

SCL

1001111

Serial Interface

made through the open-drain I/O lines, SDA and SCL. The SDA and SCL pins feature integrated spike-

suppression filters and Schmitt triggers to minimize the effects of input spikes and bus noise. Although there is

spike suppression integrated into the digital I/O lines, use proper layout to minimize the amount of coupling into

the communication lines. This noise introduction could occur from capacitively coupling signal edges between the

two communication lines themselves or from other switching noise sources present in the system. Routing traces

in parallel with ground in between layers on a printed circuit board (PCB) typically reduces the effects of coupling

between the communication lines. Shielding communication lines in general is recommended to reduce to

possibility of unintended noise coupling into the digital I/O lines that could be incorrectly interpreted as start or

stop commands.

The INA231 supports the transmission protocol for Fast (1 kHz to 400 kHz) and High-speed (1 kHz to 2.5 MHz)

modes. All data bytes are transmitted most significant byte first.

Copyright © 2013, Texas Instruments Incorporated

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