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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

Figure 6-1. Power Calculation Scheme

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

are also collected. After 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 the average can then be read.

6.3.1.2 Alert Pin

The INA226 has a single Alert Limit Register (07h), that allows the Alert pin to be programmed to respond to a

single user-defined event or to a Conversion Ready notification if desired. The Mask/Enable Register allows the

user to select from one of the five available functions to monitor and/or set the Conversion Ready bit to control

the response of the Alert pin. Based on the function being monitored, the user then enters a value into the Alert

Limit Register to set the corresponding threshold value that asserts the Alert pin.

The Alert pin allows for one of several available alert functions to be monitored to determine if a user-defined

threshold has been exceeded. The five alert functions that can be monitored are:

• Shunt Voltage Over-Limit (SOL)

• Shunt Voltage Under-Limit (SUL)

• Bus Voltage Over-Limit (BOL)

• Bus Voltage Under-Limit (BUL)

• Power Over-Limit (POL)

The Alert pin is an open-drain output. This pin is asserted when the alert function selected in the Mask/Enable

Register exceeds the value programmed into the Alert Limit Register. Only one of these alert functions can be

enabled and monitored at a time. If multiple alert functions are enabled, the selected function in the highest

significant bit position takes priority and responds to the Alert Limit Register value. For example, if the Shunt

Voltage Over-Limit function and the Shunt Voltage Under-Limit function are both selected, the Alert pin asserts

when the Shunt Voltage Register exceeds the value in the Alert Limit Register.

The Conversion Ready state of the device can also be monitored at the Alert pin to inform the user when the

device has completed the previous conversion and is ready to begin a new conversion. Conversion Ready can

be monitored at the Alert pin along with one of the alert functions. If an alert function and the Conversion Ready

are both enabled to be monitored at the Alert pin, after the Alert pin is asserted, the Mask/Enable Register

must be read following the alert to determine the source of the alert. By reading the Conversion Ready Flag

(CVRF, bit 3), and the Alert Function Flag (AFF, bit 4) in the Mask/Enable Register, the source of the alert can

be determined. If the Conversion Ready feature is not desired and the CNVR bit is not set, the Alert pin only

responds to an exceeded alert limit based on the alert function enabled.

If the alert function is not used, the Alert pin can be left floating without impacting the operation of the device.

Refer to Figure 6-1 to see the relative timing of when the value in the Alert Limit Register is compared to the

corresponding converted value. For example, if the alert function that is enabled is Shunt Voltage Over-Limit

(SOL), following every shunt voltage conversion the value in the Alert Limit Register is compared to the

INA226

SBOS547B – JUNE 2011 – REVISED SEPTEMBER 2024

www.ti.com

12

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