INA231

SBOS644 – FEBRUARY 2013

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Simple Current Shunt Monitor Usage

(No Programming Necessary)

The INA231 does not require programming to read a shunt voltage drop and the bus voltage when using the

default power-on reset configuration and running continuous conversions of the shunt and bus voltage.

Without programming the INA231 Calibration register, the device is unable to provide either a valid current or

power value because these outputs are both derived using the values loaded into the Calibration register.

Default INA231 Settings

The default power-up states of the registers are shown in the Register Details section of this data sheet. These

registers are volatile, and if programmed to a value other than the default values shown in Table 2, they must be

reprogrammed at every device power-up. Detailed information on programming the Calibration register is given in

the Configure/Measure/Calculate Example section and calculated based on Equation 1.

REGISTER INFORMATION

The INA231 uses a bank of registers for holding configuration settings, measurement results, minimum/maximum

limits, and status information. Table 2 summarizes the INA231 registers; refer to Figure 1 for an illustration of the

registers.

Table 2. Summary of Register Set

POINTER

ADDRESS

POWER-ON RESET

HEX

REGISTER NAME

FUNCTION

BINARY

HEX

This register resets all registers and

controls shunt voltage and bus voltage,

00

Configuration

01000001 00100111

4127

R/W

ADC conversion times and averaging,

as well as the device operating mode.

01

Shunt Voltage

Shunt voltage measurement data

00000000 00000000

0000

R

02

Bus Voltage

Bus voltage measurement data

00000000 00000000

0000

R

This register contains the value of the

03

calculated power being delivered to the

00000000 00000000

0000

R

load.

This register contains the value of the

04

calculated current flowing through the

00000000 00000000

0000

R

shunt resistor.

This register sets the full-scale range

and LSB of the current and power

05

Calibration

00000000 00000000

0000

R/W

measurements. This register sets the

overall system calibration.

This register sets the alert configuration

06

Mask/Enable

00000000 00000000

0000

R/W

and conversion ready flag.

This register contains the limit value to

07

Alert Limit

00000000 00000000

0000

R/W

compare to the selected alert function.

(1)

Type: R = read-only, R/W = read/write.

(2)

The Current register defaults to '0' because the Calibration register defaults to '0', yielding a zero current and power value until the

Calibration register is programmed.

18

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