Datasheet

INA230
SBOS601 –FEBRUARY 2012 www.ti.com
Data transfer is then initiated and eight bits of data are sent, followed by an ACK. 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 INA230 includes a 28-ms timeout on its interface to prevent locking up the bus.
Serial Bus Address
To communicate with the INA230, 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 INA230 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.
Table 7. INA230 Address Pins and
Slave Addresses
A1 A0 SLAVE ADDRESS
GND GND 1000000
GND V
S
1000001
GND SDA 1000010
GND SCL 1000011
V
S
GND 1000100
V
S
V
S
1000101
V
S
SDA 1000110
V
S
SCL 1000111
SDA GND 1001000
SDA V
S
1001001
SDA SDA 1001010
SDA SCL 1001011
SCL GND 1001100
SCL V
S
1001101
SCL SDA 1001110
SCL SCL 1001111
Serial Interface
The INA230 operates only as a slave device on both the I
2
C bus and the SMBus. Connections to the bus are
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, 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 INA230 supports the transmission protocol for Fast (1 kHz to 400 kHz) and High-speed (1 kHz to 3.4 MHz)
modes. All data bytes are transmitted most significant byte first.
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