Is it okay using VDD18 to pull-up source of PGOOD

Hi,

Using the VDD18 pin of the LT7170 as a pull-up source for the PGOOD pin is not recommended. The VDD18 pin is an internal 1.8 V regulator bypass pin, and the datasheet explicitly states: "Do not load the VDD18 pin with external circuitry." This restriction means the VDD18 pin is not designed to supply current to external components, including pull-up resistors for the PGOOD pin. Using it for such purposes could lead to improper operation or potential damage to the device.

For the PGOOD pin, the datasheet specifies that a pull-up resistor from a 1.6 V to 5.5 V supply is required. Suitable options for this pull-up source include the INTVCC (internal 3 V LDO regulator bypass pin) or an external supply within the specified voltage range. Ensure the pull-up resistor value is appropriate for your design, typically ranging from 10 kΩ to 100 kΩ, depending on the application requirements.

Recommendation:

• Use a dedicated external supply or INTVCC (if available and within the required range) as the pull-up source for the PGOOD pin.
• Avoid using the VDD18 pin to ensure compliance with the datasheet and proper operation of the device.

Regards,

Harshal