I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

P

P

P

P

P

P

P

P

P

P

P

P

P

P

P

P

Current Limit Detect Following

Every Shunt Voltage Conversion

Bus and Power Limit Detect

Following Every Bus Voltage Conversion

Power Average

Bus Voltage Average

Shunt Voltage Average

INA226

SBOS547

– JUNE 2011

www.ti.com

Although the INA226 can be read at any time, and the data from the last conversion remain available, the

Conversion Ready Flag bit (Mask/Enable Register, CVRF bit) is provided to help coordinate one-shot or triggered

conversions. The Conversion Ready Flag bit is set after all conversions, averaging, and multiplication operations

are complete.

The Conversion Ready Flag bit clears under these conditions:

1. Writing to the Configuration Register, except when configuring the MODE bits for power-down mode; or

2. Reading the Status Register.

Power Calculation

The Current and Power are calculated following shunt voltage and bus voltage measurements as shown in

Figure 20. Current is calculated following a shunt voltage measurement based on the value set in the Calibration

Register. If there is no value loaded into the Calibration Register, the current value stored is zero. Power is

calculated following the bus voltage measurement based on the previous current calculation and bus voltage

measurement. If there is no value loaded in the Calibration Register, the power value stored is also zero. Again,

these calculations are performed in the background and do not add to the overall conversion time. These current

and power values are considered intermediate results (unless the averaging is set to 1) and are stored in an

internal accumulation register, not the corresponding output registers. Following every measured sample, the

newly-calculated values for current and power are appended to this accumulation register until all of the samples

have been measured and averaged based on the number of averages set in the Configuration Register.

Figure 20. Power Calculation Scheme

In addition to the current and power accumulating after every sample, the shunt and bus voltage measurements

are also collected. Once all of the samples have been measured and the corresponding current and power

calculations have been made, the accumulated average for each of these parameters is then loaded to the

corresponding output registers, where they can then be read.

10

Submit Documentation Feedback

Copyright

© 2011, Texas Instruments Incorporated

Product Folder Link(s): INA226