TPS737: TPS737DCG

Hi Ranga,

If your version of the TPS737 has access to the NR pin, you can connect a capacitor from here to GND to slow down the turn on time.
This provides the capacitor in an RC filter (with the 27k ohm inside the LDO) on the internal reference, which improves the PSRR and noise (by filtering the reference noise) as well as slowing down the turn on time.  Alternatively you can use a Cff across the high side setpoint resistor in an adjustable design to improve the PSRR and delay the startup time.

Thanks,

- Stephen

Hi Ranga,

I was able to take measurements on an EVM with the existing settings of 1.8V output, which I believe illustrates how this device will behave with 1A loading.  I would recommend obtaining a TPS73701 EVM so you can modify it for your exact load and setpoint resistors, then test across your temperature to know how the device exactly behaves in your system.  For the test I was unsure if your load would be modeled as resistive or as a constant current, so using an electronic load I captured both conditions.

The input supply is 2.5V and the EVM output is 1.8V.
Both measurements are from when the enable signal toggles from low to high.
I measured from 0V to when the output settled at 1.8V, however for your application you may want the minimum regulation (so, for 3% tolerance you can use 3*0.97 = 2.91V for startup).

A constant current load of 1A measured 935 us startup for 1.8V output.
A constant resistive load equivalent to 1A measured 499 us startup for 1.8V output.

I would expect the slope of the rise time to be consistent for a larger output voltage.
For a 3V output and similar capacitive loading, and extrapolating, I would expect around 0.8ms - 0.9ms for constant resistive loading (typical).
For constant current loading I would expect around 1.5ms - 1.6ms (typical).

Thanks,

- Stephen