Other diagnostic functions that are not reported by the ALERT pin but are available by reading the DIAG_ALRT

register:

• Math overflow — Indicated by the MATHOF bit, reports when an arithmetic operation has caused an internal

register overflow.

• Memory status — Indicated by the MEMSTAT bit, monitors the health of the device non-volatile trim memory.

This bit will always read '1' when the device is operating properly.

• Energy overflow — Indicated by the ENERGYOF bit, reports when the ENERGY register has reached an

overflow state due to data accumulation.

• Charge overflow — Indicated by the CHARGEOF bit, reports when the CHARGE register has reached an

overflow state due to data accumulation.

When the ALERT pin is configured to report the ADC conversion complete event, the ALERT pin becomes a

multipurpose reporting output. Figure 7-8 shows an example where the device reports ADC conversion complete

events while the INA781 device is subject to an overcurrent event, bus undervoltage event, overtemperature

event and over power-limit event.

Current

Temperature

Bus Voltage

ALERT

(ALATCH = 0)

(APOL = 0)

(CNVR = 1)

Power

Current Over Limit Threshold

Bus Under Voltage Threshold

Over Temp Threshold

Power Over Limit Threshold

BUV

SET

COL

SET

BUV

CLEAR

COL

&

BUV

SET

COL

CLEAR

BUV

&

OT

SET

BUV

&

OT

&

OP

SET

- No diag. error -

Conversion Complete

Reported

Figure 7-8. Multi-Alert Configuration

7.4 Device Functional Modes

7.4.1 Shutdown Mode

In addition to the two conversion modes (continuous and triggered), the device also has a shutdown mode

(selected by the MODE bits in ADC_CONFIG register) that reduces the quiescent current to less than 5 µA and

turns off current into the device inputs, reducing the impact of supply drain when the device is not being used.

The registers of the device can be written to and read from while the device is in shutdown mode. The device

remains in shutdown mode until another triggered conversion command or continuous conversion command is

received.

The device can be triggered to perform conversions while in shutdown mode. When a conversion is triggered,

the ADC will start the conversion. When the conversion completes, the device will return to the shutdown state.

Note that the shutdown current is specified with an inactive communications bus. Active clock and data activity

will increase the current consumption as a function of the bus frequency.

7.4.2 Power-On Reset

Power-on reset (POR) is asserted when VS drops below 1.26 V (typical) at which all of the registers are reset to

their default values. A manual device reset can be initiated by setting the RST bit in the CONFIG register. The

INA781

SBOSAC0 – JULY 2023

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