7.3.5 Diagnostic Output

As shown in Figure 7-3, the open-drain DIAG pin can be monitored to confirm the device is operational and

the output voltage is valid. During power-up, the DIAG pin is actively held low until the high-side supply is in

regulation and the device operates properly. During normal operation, the DIAG pin is in high-impedance (Hi-Z)

state and is pulled high through an external pullup resistor. The DIAG pin is actively pulled low if:

• The low-side does not receive data from the high-side (for example, because of a loss of power on the high

side). In this case, the amplifier outputs are driven to the VFAILSAFE value, see Figure 7-2.

• The high-side DC/DC output voltage (DCDC_OUT) or the high-side LDO output voltage (HLDO_OUT) drop

below their respective undervoltage detection thresholds (brown-out). In this case, the low-side may still

receive data from the high-side but the data may not be valid. The amplifier outputs are driven to VFAILSAFE

value, see Figure 7-2.

High-side supply undervoltage

DIAG

Power-up

Normal

Operation

Normal

Operation

Figure 7-3. DIAG Output Under Different Operating Conditions

During normal operation, the DIAG pin is in a high-impedance state. Connect the DIAG pin to a pullup resistor or

leave open if not used.

7.4 Device Functional Modes

The AMC3302 is operational when the power supply VDD is applied, as specified in the Recommended

Operating Conditions table.

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AMC3302

SBASA11B – AUGUST 2020 – REVISED JULY 2021

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