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The wide dynamic input voltage of low drop-out regulator

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tsai_chin_wei

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Hi,

I am designing a LDO whoes input voltage range of 6~36V. I recently have low voltage devices(5V) and high voltage devices(40V). I wanna utilize high voltage devices to realize the PMOS and the others (BG and OP)are achieved by low voltage devices.

So I don't know if it is realizable and how to realize BG and OP using low voltage devices.

Thank you!!
 

You can use the local voltage regeration circuit to privide low voltage for BG and op.
 
you may create your local 5V reference as supply to LV devices. do you have Zener diode?


BTW, how large is your output voltage?
 
strennor said:
you may create your local 5V reference as supply to LV devices. do you have Zener diode?


BTW, how large is your output voltage?
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Dear strennor,

I do not clearly understand local 5V reference that you indicate.

I beg you to give a clean-cut example.

:D thanks!!:
 

i think it is doable it but u need some start up scenario to get things started
 

Try to design internal a low voltage regulator for bandgap circuit.

It will improve line regulation.
 

For such a wide range Vin, it is safer and more area efficient to use only HV devices to implent the LDO.
 

Usually the HV transistors are not accurate for BG circuit in my experience. So use LV transistor for BG is better.
 

pls use HV reansistor except BG
 

It's sure to use low-voltage devices in the design of BG because of good matching. But local regulator is needed for BG. To reduce the input offset voltage, it's better to use HV-LV mixed design design for the error amplifier.
 

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