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TPS62802: TPS62802 PWM mode

Lawrence He
Genius 3280 points
Part Number: TPS62802
Other Parts Discussed in Thread: TPS62808

Dear,

We saw the TPS62802 datasheet, about  PWM Mode  IQ current need 8mA?

our application is wireless mouse, but look like not suitable for 2xAA Battery Powered Applications

also we simulation TPS62802 WEBENCH

input Vin: 1.8V~5V

Vout: 2V

Iout:0.2A

Ambient Temp:30 degress

but show Design cannot be created!

whats going on?

If any suggestion, Please advise me.

Thanks,

Best regards,

Lawrence.

  • 0
    TI__Guru*** 142750 points

    Hi Lawrence,

    Please read this app note on Iq: http://www.ti.com/lit/an/slyt412/slyt412.pdf

    The Iq is always higher in PWM mode, where the IC is constantly switching.  You would not likely use PWM mode for your application, so please use the Iq values above that row in the D/S.

    Your Webench inputs have a Vin below the target Vout.  No buck converter can support this.  Please increase the minimum Vin a little bit above your 2V output. 

    Please understand that the TPS62802 will continue to provide a Vout, in 100% mode, as Vin drops below the 2V target.  The 2V output will also drop, since you are in 100% mode.  This is how every buck converter will work.  It is likely ok for the application.  No software tool, such as Webench, will allow user inputs for a buck converter which have Vin below Vout.

    Finally, the lower current, more efficient TPS62808 may be a better fit for this application.