is complete. Fault conditions are compared immediately after conversions or calculations based on the ADC

conversion time and are independent of the number of averages set. Reducing the conversion times result in

faster alert responses but at lower effective resolutions due to noise. Longer conversion times slow the alert

response but are less sensitive to noise. Channels or measurements that are disabled are skipped in the round

robin cycle. The conversion ready flag is set at the end of conversions after the selected number of averages are

met.

Shunt Voltage

Channel 1

Bus Voltage

Current

Power

Energy

Shunt Voltage

Channel 2

Bus Voltage

Current

Power

Energy

Start

Number of

Averages Met?

Yes

No

Yes

No

Continuous

Conversions?

Conversions

complete

Conversion Ready Flag set.

Figure 6-1. Internal Measurement and Calculation Scheme

In Figure 6-1, the Italicized registers are calculated values that do not depend on conversion times and occur in

the background. Registers are updated independently for each channel once number of averages is met. Fault

threshold comparisons are done immediately on a per result basis. Average values do not trigger alerts.

Current is calculated from the shunt voltage measurements and the value entered in the corresponding

calibration register. Power is calculated based on the previous current calculation and the latest bus voltage

measurement. Energy is accumulated by adding the previous power calculation multiplied by the current

timebase interval. If the value loaded into the corresponding calibration register is zero, current, power, and

energy values are reported as zero also. When the averaging is enabled, register values are updated once the

number of averages are met. These calculations are performed in the background and do not add to the overall

conversion time.

6.3.3 Low Bias Current

The INA2227 features very low input bias current which provides several benefits. The low input bias current of

the INA2227 reduces the current consumed by the device in both active and shutdown state. Another benefit of

low bias current is that low bias current allows the use of input filters to reject high-frequency noise before the

signal is converted to digital data. In traditional digital current-sense monitors, the addition of input filters comes

at the cost of reduced accuracy. However, as a result of the low bias current, the reduction in accuracy due to

input filters is minimized. An additional benefit of low bias current is the ability to use a larger shunt resistor to

accurately sense smaller currents. Use of a larger value for the shunt resistor allows the device to accurately

monitor currents in the sub-mA range.

www.ti.com

INA2227

SBOSAL5 – JUNE 2025

Copyright © 2025 Texas Instruments Incorporated

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