powerdown circuitry and breakdown issue

[lilqueen04]

Hi,

I'm designing a circuit that drives an LED whose forward bias voltage may vary from 2.8V ~ 3.5V. The supply voltage varies from 2.9V to 4.5V.

Does anyone have any idea on how to design the powerdown circuit in order to avoid silicon breakdown (the breakdown voltage is around 3.6V for my process)?


Thanks a lot.

 

[scottieman]

Hi,

I'm designing a circuit that drives an LED whose forward bias voltage may vary from 2.8V ~ 3.5V. The supply voltage varies from 2.9V to 4.5V.

Does anyone have any idea on how to design the powerdown circuit in order to avoid silicon breakdown (the breakdown voltage is around 3.6V for my process)?


Thanks a lot.

Don't know you are doing in IC or discrete form
If you are in discrete, parallel a 3.x voltage zener diode with your LED.

Scottie

 

[lilqueen04]

I'm doing in IC form. I cannot clamp the supply voltage to 3.x volts in normal operation, cos i need to drive the LED whose forward voltage is as large as 3.6V (equal to the silicon breakdown voltage)

 

[sunking]

dc-dc converter + LDO

Charge Pump + LDO

 

[scottieman]

I'm doing in IC form. I cannot clamp the supply voltage to 3.x volts in normal operation, cos i need to drive the LED whose forward voltage is as large as 3.6V (equal to the silicon breakdown voltage)

My suggestion is: change to a technology can sustain a higher breakdown voltage

Scottie

 

[tsanlee]

My Suggestion is:
1. Change you process , to HV process.
2. Used external MOSFET