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TPS2660: TPS26602 : details about Overvoltage cut-off and clamping

Part Number: TPS2660
Other Parts Discussed in Thread: TPS2640

Team,

Could you please help with the below question?

In chap 9.3.2 it is documented:

“The TPS26602 features an internally fixed 38 V overvoltage clamp (VOVC) functionality. The OVP terminal of the

TPS26602 must be connected to the RTN terminal directly. The TPS26602 clamps the output voltage to VOVC,

when the input voltage exceeds 38 V.”

The feature cut-off with adjustable threshold is probably only reserved for the types TPS26600/1.

Technical background:
we want to protect a driver that has a max. Rating of 40V. There is not too much headroom with the clamping to 38V. In the datasheet I did not find any information about the charge variation of this clamp value. There is only a curve over temperature.
Can we assume that the clamp is between about 37V and 39V?

  • Hi AnBer,

    The devices clamps to max 39V but during fast Vin transients there can be chance to go over 39V for couple of microseconds which depends on Cout and load current.

    If the output load is very sensitive, it is better to set OV clamp at lower voltages with TPS2660 by configuring it as per Figure 9-2 in https://www.ti.com/lit/ds/symlink/tps2640.pdf

    Best Regards, Rakesh

  • Dear Rakesh,

    thanks for answer. I'm a bit confused about the second part of your answer. So far I know from datsheet the TPS26602 does not provide adjustable OVset. There is only the fixed threshold of 38V (see extract in my original post). I cannot find figure 9-2 in datasheet.

    Regards Andreas

  • Hi Andreas,

    I was mentioning Figure 9-2 in TPS2640 data sheet as shown below. 

    Sorry in that case, we need to use TPS26600 adjustable OV set variant. Please let me know if I am still not clear

    Best Regards, Rakesh