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TPS565247: Design Review

Sam Durai
Intellectual 390 points
Part Number: TPS565247

Tool/software:

Hi Team,

Using the part TPS565247DRLR, we need to generate 3 different output voltages, by keeping a single 10k pull-down resistor and adding the respective pull-ups with the help of NPN transistors.

Below is the circuit design.

The processor controls the gate pins of the transistors. 

Input voltage for the regulator = 5V

Output current/voltage 1 = 4A @ 1.2V

Output current/voltage 2 = 4A @ 1.5V

Output current/voltage 3 = 4A @ 1.8V

Can anyone please give feedback on selecting the output voltage using these NPN transistors.

Can the selected input capacitors, output capacitors and output inductor, meet the requirements of 3 different output voltages?

P/N of output inductor (1.5uH) = XAL4020-152MEC

P/N of output capacitor (22uF) = GRM21BR61C226ME44L

P/N of output capacitor/input capacitor (0.1uF) = GCJ188R71H104KA12D

P/N of input capacitor (10uF) = CGA4J1X7S1E106K125AC

Thanks in advance!

  • 0
    TI__Genius 17140 points

    Hi Sam,

    First, I see FDN339AN is NMOS not NPN transistor you said. Please check this. Then, this solution is not good. We recommend keep same pull-up resistor and use NMOS to control pull-down resistor. In your case, You can keep 20k pull-up resistor, and one 20k pull-down resistor for 1.2V, and turn on MOS1 to parallel 60k for 1.5V, and turn on both MOS1 and MOS2  to parallel 60k and 30k for 1.8V. Thanks.

    Regards,

    Shipeng