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TPS22996: TPS22996 Inductive/Capacitive load

Yoav Benita
Prodigy 50 points

Part Number: TPS22996
Other Parts Discussed in Thread: TPS22918, TPS2561, TPS22991I, TPS22976

Hi,

I am designing an FPGA board with several power rails. In order to reduce the number of switching regulators, I would like to use load switches to split the rails.

This means that the TPS22996 outputs may drive a high capacitive load and/or an inductive load, if a PI filter is used. Should I be concerned about this? 

If this device is not suitable, could you please recommend a load switch for 1.8 V and 3.3 V rails, with 0.5 A output current? An EN pin is mandatory, and a device without VBIAS is preferred.

Thanks.

  • 0
    TI__Mastermind 23211 points

    Hi Yoav,

    Our general-purpose dual channel devices will have the VBIAS pin. The TPS22976 uses a capacitor to ground to control the slew rate instead of resistors on the enable pin if you have a system preference. Two single channel options are the TPS22991I and TPS22918. Does each channel have a different voltage? If both channels are the same, you can consider using the TPS2561 which is a load switch specifically designed for USB applications but can be used as a general-purpose switch; it does not have a VBIAS pin but it does not have adjustable slew rate control either.

    The load switches are not designed for inductive load applications especially since they do not have a VDS clamp to control how negative the output drops and the pins are not rated for such low/high voltages (high-side switches are designed for this).

    It is recommended to use a high side switch which is designed to support inductive load driving because it has an integrated VDS clamp that prevents the output from continuing to go negative when the switch is turned off. The VDS clamp will engage when VS-VOUT is equal to the clamp value in the datasheet. You would have to rely on external circuitry if it is expected that the internal clamp will not be able to safely dissipate the inductive load’s stored energy. When the VDS clamp engages, the power FET is also turned on but there are no thermal protections; so, the device is expected to heat up and which is why external circuitry is needed if those limits are exceeded.

    High-side switches | TI.com

    Thanks,

    Rishika Patel 

  • 0 in reply to Rishika Patel
    TI__Mastermind 23211 points

    Forgot to mention that the TPS2561 can only support 2.5-6.5V.