PMP10506：Simulation, hardware & system design tools forum

Hi Kevin, we are currently looking at this request and will reply to you as soon as possible thanks!

Hi, Kevin,

Below is the question comments. It would be better to attach your design schematic and layout if possible for us checking.

Question1:

Vout=1.24V*[1+(R24+R40)/R25]. Changing R40,R25 could change output voltage according to desired output voltage. It is better to change R25 because R25 will not influence the loop

Question2:

There is several things to check. 1. over current protection, current sense resistor value correctly? RC filter(R1, C7) increasing avoiding false trigger. 2. loop parameter: checking R16, R21, Rx1.

Question3:

Output capacitor will be key factor to influence output ripple voltage, is the output capacitor part number similar with PMP10506?

Question4:

according to switching frequency equation, you are right. 

Hi, David

1. After changing R25 to 13.7K ohm, Vout is 4.96VDC. It's fine to me.
2. The R1,R2 change to 560 ohm, and C7 change to 1000pf, It's okay for Iout=6A@Vin=9VDC.
3. I Also change R7 to 2.2 ohm and change the Snubber(Rsb1/Rs12 with 36 ohm, Csb1 with 820pf) position to T1 pin2/pin5 in parallel.
4. Replace the NMOS specifications with 200V/42A/28m ohm cause it's a good delivery date for me to order.

Please help me to verify whether the above modification is okay or not.

I will test the dynamic load(Vin=9VDC, Iout=3-6A) for one night's stability.

There is the swing of Vout when dynamic load Iout 3A to 6A.
Please refer to the attached file.
I want to decrease to 5V + - 5%.
Is there any suggestion for me to adjust some components' values?

Is there any layout guide for me?
Normally rules for layout:
1. Less Copper plane under the transformer.
2. The controller signal trace is far from the transformer.
But why PMP10506 layout is more copper plane under the transformer?

Hi, Kevin,

1. For item 3, I don't recommend below change. Reserving Rsb1/Rs12 with 36 ohm, Csb1 with 820pf is for slow Vds rising and falling ramp flexible to fine tune EMI performance.

 change the Snubber(Rsb1/Rs12 with 36 ohm, Csb1 with 820pf) position to T1 pin2/pin5 in parallel.

2. For dynamic load performance, practical way to improve the undershoot is adding more capacitance. Other way is to optimize the loop parameters.

3. layout guide. please refer to LM5122 datasheet

Hi, David

Q1: How big value of Vout Capacitors do you suggest?
　　Already put 22uF MLCC*4pcs,100uF MLCC*6pcs, 680uF EC*1pcs.
Q2: Is there any suggest valule(increase/decrease）for the Loop parameters (R16, R21, Rx1)?

Q3:

What's the difference between the snubber position, is there any different purpose?
PMP 10506 is in parallel to NMOS.
Other Vendor/Linear is in parallel to Transformer.
www.analog.com/.../DC2047A-3-A-SCH.PDF
I view the ROHM web:
techweb.rohm.com.tw/.../
返馳方式中，會在變壓器的鐵芯保留間隙，增加漏磁且產生漏電感。開關電流會經過該漏電感並蓄積能量，但因為未和其他線圈相接，無法轉移功率而產生突波電壓，並施加到MOSFET的汲極-源極之間。