TPS62840: Switching Mode Timing

JDJ

Expert 4486 points

Part Number: TPS62840

How long does it take the TPS62840 to switch modes?

Can you switch from forced-PWM to PFM/PWM mode in under 1us?

over 5 years ago

0 Alfonso Furio over 5 years ago

TI__Expert 3645 points

Hello jack,
this control topology allows a fast and a seamless transition between control modes. I can't give any specific time since is due to the time propagation delay, the reaction time of the comparator and the load pattern (how fast the PFM threshold is reached). I attached this documents that give additional info about this topology:

http://www.ti.com/lit/an/slyt531/slyt531.pdf

0 Mike Schell over 5 years ago in reply to Alfonso Furio

Prodigy 170 points

Hi Alfonso-

Is there an easy way to determine if the part is operating in forced-PWM mode?

Thanks-

Mike Schell

0 Alfonso Furio over 5 years ago in reply to Mike Schell

TI__Expert 3645 points

Hello,
To see if the IC is running in PWM or PFM, you can monitor the switching node. You will notice that the frequency is higher in PWM, around (1.8MHz typical), and much lower in PFM. Consequently, the output ripple will be smaller in PFM and much higher in PFM, as a reference, you can have a look into Figures 43 and 44.

0 Mike Schell over 5 years ago in reply to Alfonso Furio

Prodigy 170 points

Hi Alfonso-

Thanks. That makes perfect sense and it's easy to observe.

Keep making great power products!

Best Regards-

Mike

0 Alfonso Furio over 5 years ago in reply to Mike Schell

TI__Expert 3645 points

Hello,
Thanks a lot for your appreciation. I will be happy to support you again on future threads.

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TPS62840: Switching Mode Timing