INA226

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SBOS547

– JUNE 2011

Simple Current Shunt Monitor Usage

(No Programming Necessary)

The INA226 can be used without any programming if it is only necessary to read a shunt voltage drop and bus

voltage with the default power-on reset configuration and continuous conversion of shunt and bus voltage.

Without programming the INA226 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 INA226 Settings

The default power-up states of the registers are shown in the INA226 Register Descriptions 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 re-programmed at every device power-up. Detailed information on programming the Calibration

Register specifically is given in the Configure/Measure/Calculate Example section and calculated based on

Equation 1.

REGISTER INFORMATION

The INA226 uses a bank of registers for holding configuration settings, measurement results, minimum/maximum

limits, and status information. Table 2 summarizes the INA226 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

All-register reset, shunt voltage and bus

0

Configuration Register

voltage ADC conversion times and

01000001 00100111

4127

R/W

averaging, operating mode.

1

Shunt Voltage

Shunt voltage measurement data.

00000000 00000000

0000

R

2

Bus Voltage

Bus voltage measurement data.

00000000 00000000

0000

R

Contains the value of the calculated

3

00000000 00000000

0000

R

power being delivered to the load.

Contains the value of the calculated

4

current flowing through the shunt

00000000 00000000

0000

R

resistor.

Sets full-scale range and LSB of current

5

Calibration

and power measurements. Overall

00000000 00000000

0000

R/W

system calibration.

Alert configuration and conversion ready

6

Mask/Enable

00000000 00000000

0000

R/W

flag.

Contains the limit value to compare to

7

Alert Limit

00000000 00000000

0000

R/W

the selected Alert function.

Contains unique die identification

FF

Die ID

ASCII

ASCII

R

number.

(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.

Copyright

© 2011, Texas Instruments Incorporated

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Product Folder Link(s): INA226