INA226AIDGST Datasheet, PDF (23/33 Pages) Texas Instruments – High-or Low-Side Measurement, Bi-Directional CURRENT/POWER MONITOR with I2C Interface

INA226
www.ti.com
SBOS547 – JUNE 2011
Data transfer is then initiated and eight bits of data are sent, followed by an Acknowledge bit. During data
transfer, SDA must remain stable while SCL is high. Any change in SDA while SCL is high is interpreted as a
start or stop condition.
Once all data have been transferred, the master generates a stop condition, indicated by pulling SDA from low to
high while SCL is high. The INA226 includes a 28ms timeout on its interface to prevent locking up the bus.
Serial Bus Address
To communicate with the INA226, the master must first address slave devices via a 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 INA226 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 and should be set before any
activity on the interface occurs.
A1
GND
GND
GND
GND
V_S+
V_S+
V_S+
V_S+
SDA
SDA
SDA
SDA
SCL
SCL
SCL
SCL
Table 7. INA226 Address Pins and
Slave Addresses
A0
GND
V_S+
SDA
SCL
GND
V_S+
SDA
SCL
GND
V_S+
SDA
SCL
GND
V_S+
SDA
SCL
SLAVE ADDRESS
1000000
1000001
1000010
1000011
1000100
1000101
1000110
1000111
1001000
1001001
1001010
1001011
1001100
1001101
1001110
1001111
Serial Interface
The INA226 operates only as a slave device on both the I²C bus and the SMBus. Connections to the bus are
made via 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. While there is spike suppression
integrated into the digital I/O lines, proper layout should be used 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 INA226 supports the transmission protocol for Fast (1kHz to 400kHz) and High-speed (1kHz to 3.4MHz)
modes. All data bytes are transmitted most significant byte first.
Copyright © 2011, Texas Instruments Incorporated
Product Folder Link(s): INA226
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