Here is my attempt a lower noise power supply. I was inspired by the performance of the new TI switching regulators (TPSM33625) and I thought they would make a good pre regulator for a liner reg, It also just happens that one of the new TI linear regs(TPS7A96) has quite a good PSRR at 1M which is the switching frequency of the pre reg(TPSM33625) seemed like a match made.
This is that design prototype . schematics attached.
partial assembly from jlcpcb, manual assemby of can and the 0.1% 0402 resistors required.
finger for scale
adding the can as a bit tricky the tiny clips did not want to stay in place with the hot air.
all assembled for testing
all off (background)
on but no load Vin=13.8V Vout=4.98V In=0.008A Iout=0A
on Vin=13.8V Vout=4.98V Iin=0.513A Iout=1A
on Vin=13.8V Vout=4.98V Iin=1.045A Iout=2A
I can barely tell the difference between it being on and off on the oscilloscope, I'll need to give to bill in his "RF quite zone" to see if he can evaluate it.
Here is the intermediate node between the switching reg and the linear stages at 500mA load.
This is that design prototype . schematics attached.
partial assembly from jlcpcb, manual assemby of can and the 0.1% 0402 resistors required.
finger for scale
adding the can as a bit tricky the tiny clips did not want to stay in place with the hot air.
all assembled for testing
all off (background)
on but no load Vin=13.8V Vout=4.98V In=0.008A Iout=0A
on Vin=13.8V Vout=4.98V Iin=0.513A Iout=1A
on Vin=13.8V Vout=4.98V Iin=1.045A Iout=2A
I can barely tell the difference between it being on and off on the oscilloscope, I'll need to give to bill in his "RF quite zone" to see if he can evaluate it.
Here is the intermediate node between the switching reg and the linear stages at 500mA load.
Attachments
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