TPS1HTC100-Q1: Max PWM support

Frank QIN

Expert 8950 points

Part Number: TPS1HTC100-Q1

Tool/software:

Hi Team,

I found there is a thread discussed about the max PWM topic:

(2) TPS1HTC100-Q1: TPS1HTC100-Q1 - Power management forum - Power management - TI E2E support forums

I can understand the calculation in that thread and the result is 2.5kHz would be supportable.

My question is:

If I want to apply 1.5kHz, which is 667us. And the duty cycle I need is 60%, then the time period of on/off would be 400us and 267us.

The Ton and Toff time in datasheet is 200us max -- in table 5.7. So the Ton/off is 200+200=400us. I suppose it is already same as the 1.5kHz 60% duty cycle ON time. Would that be a risk?

I would like to confirm if TPS1THC100 can support 1.5kHz 60% duty cycle.

Also, I would like to learn if calculate with Ton/off time is correct. or should I calculate with VOUT rising/falling slew rate?

Thanks

Best,

Frank

10 months ago

0 Rishika Patel 10 months ago

TI__Expert 8191 points

Hi Frank,

The TPS1HTC100-Q1 should be able to support a 1.5kHz 60% duty cycle based on the calculated on and off times. However, the equation in the other thread does not account for switching loss which can cause the device to go into thermal shutdown. I will get further confirmation and get back to you tomorrow.

Thanks,

Rishika Patel

0 Rishika Patel 9 months ago in reply to Rishika Patel

TI__Expert 8191 points

Hi Frank,

How much voltage are you supplying to the device?

Thanks,

Rishika Patel

0 Frank QIN 9 months ago in reply to Rishika Patel

TI__Expert 8950 points

Hi Rishika,

It is 24V car battery, max supply 32V.

Best,

Frank

0 Rishika Patel 9 months ago in reply to Frank QIN

TI__Expert 8191 points

Hi Frank,

Sorry for the delayed response!

According to the diagram below in the datasheet, the tON = tDR + SRR time and tOFF = tDF + SRF.

However, if we wanted to calculate times using the slew rates given then:

24V car battery, max 32V supply

1.5kHz, total 667us for one period

400us on, 267us off

Note that the following calculations are done assuming max times for all and worst-case scenario.

For turn on:

Delay time tDR = 70us

Slew rate SRR = 0.7V/us

Total time for turn on = 32V / 0.7V/us + 70us = 115.7 us or worst-case tON = 200us

115.7us (or 200us) < 400us time on

For turn off:

Delay time tDF = 98us

Slew rate SRF = 0.82V/us

Total time for turn off = 32V / 0.82V/us + 98us = 137.0 us or worst-case tOFF = 200us

137.0 us (or 200us) <267us time off

Note (4/22/25): I had to modify these calculations as I made a mistake with the equation. I apologize for the confusion, but the final conclusion is still the same. Please also refer to this app note for more information - Driving PWM Loads with TI High-Side Switches.

Based on these calculations, the TPS1HTC100-Q1 should be able to support a 1.5kHz 60% duty cycle.

Thanks,

Rishika Patel