INA231 datasheet(11/44 Pages) TI1

11 / 44 page

INA231

www.ti.com

SBOS644A – FEBRUARY 2013 – REVISED JUNE 2017

Product Folder Links: INA231

Submit Documentation Feedback

Feature Description (continued)

The INA231 has two operating modes, continuous and triggered, that determine how the ADC operates after

these conversions. When the INA231 is in the normal operating mode (that is, the MODE bits of the

Configuration register are set to '111'), it continuously converts a shunt voltage reading followed by a bus voltage

reading. After the shunt voltage reading, the current value is calculated based on Equation 3. This current value

is then used to calculate the power result using Equation 4. These values are subsequently stored in an

accumulator, and the measurement and calculation sequence repeats until the number of averages set in the

Configuration register is reached. Note that the current and power calculations are based on the value

programmed into the Calibration register. If the Calibration register is not programmed, the result of the current

and power calculations is zero. Following every sequence, the present set of measured and calculated values

are appended to the previously collected values. After all of the averaging has been completed, the final values

for shunt voltage, bus voltage, current, and power are updated in the corresponding registers and can then be

read. These values remain in the data output registers until they are replaced by the next fully completed

conversion results. Reading the data output registers does not affect a conversion in progress.

The mode control bits in the Configuration register also permit selecting specific modes to convert only the shunt

voltage or the bus voltage in order to further allow the monitoring function configuration to fit specific application

requirements.

All current and power calculations are performed in the background and do not contribute to conversion time.

In triggered mode, writing any of the triggered convert modes into the Configuration register (that is, the MODE

bits of the Configuration register are set to 001, 010, or 011) triggers a single-shot conversion. This action

produces a single set of measurements. To trigger another single-shot conversion, the Configuration register

must be written to again, even if the mode does not change.

In addition to the two operating modes (continuous and triggered), the INA231 also has a power-down mode that

reduces the quiescent current and turns off current into the INA231 inputs, which reduces the impact of supply

drain when the device is not being used. Full recovery from power-down mode requires 40 ms. The registers of

the INA231 can be written to and read from while the device is in power-down mode. The device remains in

power-down mode until one of the active modes settings are written into the Configuration register.

Although the INA231 can be read at any time, and the data from the last conversion remain available, the

conversion ready flag bit (CVRF bit, Mask/Enable register) is provided to help coordinate single-shot or triggered

conversions. The CVRF bit is set after all conversions, averaging, and multiplication operations are complete for

a single cycle.

The CVRF 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.

8.3.1.1 Power Calculation

The current and power are calculated after shunt voltage and bus voltage measurements, as shown in Figure 21.

The current is calculated after 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. 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

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.

INA231 Datasheet(PDF) 11 Page - Texas Instruments

INA231 Datasheet(HTML) 11 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

Datasheet Download

Link URL