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LDO AS CURRENT SOURCE

eli
Guru 13485 points

looking  for  a LDO  with  the following characteristics:

 

 

Vin   ~  +5V

ADJUSTABLE   V  out =  ~3.2  V

I  max  150 mA

Pmax   300mW

 

With  ENABLE PIN  ( IMPORTANT)

 

LOW  NOISE

 

V dropout  < 0.4V

PACK   sot23  or similar

 

 

I am  looking to use this  as  a constant  current  to drive a laser diode.

 

                        I  = 1.24/R4

 

 

What  is the typical  speed  of the EN input 

  • 0
    TI__Guru*** 149656 points
    Eli,

    If the diode was placed in series with the VIN pin then the LDO would provide a fixed voltage to the "sense" resistor. The Diode curent would the ICC (Iq) of the LDO plus the sense resistor current.

    Most LDO like having an input capacitor for stability reasons. So I have to ask, how fast and how often does the diode tun on and off. Is it PWM?