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TPS74401: Schematic Review Request - Low Dropout voltage

Part Number: TPS74401

Hi team,

Would you help me for customer schematic review? The current design is as below :

Vin = 1.15V

Vout = 1V

Iout = 1.49A

Vbias = 5V 

I was concerning about small Vin-Vout, only 150mV. But it seems the figure 6 is applicable in this case. It indicates the dropout voltage is below 60mV over the temperature range with 4V of Vbias-Vout. So 150mV of Vin-Vout would be totally okay. 

Please let me know if any misunderstanding here, and any concern on this design for a normal operation. Thanks!

  • Hello Minkyung,

    Your design should work just fine.

    There are 2 dropouts to consider here.  The first is due to Vin and the second is due to Vbias.  As shown in figure 6, Vin is not a concern as you have 5V - 1V = 4V of Vbias headroom.  From this graph you need about 50 mV of headroom on Vin.  You have 150mV so the Vin dropout requirement is being met.

    The second dropout is due to Vbias. That graph is shown in figure 7.  Even the worst case value at 1.5A load is just over 1.1V from Vbias to Vout.  As you have 4V here, this requirement is also being met.

    Thanks,

    - Stephen