help find correct regulator

[acuser]

this a regulator(u33) on a vizio p50 hdtv20a main board 3850-0142-0150(2a)

AMC1117
F0745F

not 100% on that last F but it sure looks like it.

would a lm1117 work if so which voltage?
I cant find any info about the F0745f meaning, maybe 5F means 5 volt

thanks

[tom66]

Re: help find correct regulator

If the regulator doesn't have anything like -33 and the GND/Adjust pin shows a positive voltage, a normal LM1117 (adjustable variant if specified) should work fine.

[acuser]

Re: help find correct regulator

Im not sure what adjustable variant means, do think this one would work?


NATIONAL SEMICONDUCTOR - LM1117MP-ADJ - IC, ADJ LDO REG, 1.25V TO 13.8V SOT223-3

[tom66]

Re: help find correct regulator

Yes, that one is fine, as it has -ADJ in the part code, meaning adjustable.

[tw2005]

Re: help find correct regulator

Here's some datasheets

[budm]

Re: help find correct regulator

This is the way to figure out if the adjustable regulator is good or not:
Notes: we are looking at the regulator with the Big tab up (the big tab is tied internally to the center pin).
Adjustable regulator will have two resistors attached to it, one resistor (Rfb) is between pin1 and pin2, another resistor (Rg) is between pin1 and ground. Pin3 is an input pin.
The voltage between the Adjust pin (left pin) and the center pin (Pin2, output) will always be 1.25V +/- 2% (this is the precision voltage reference), if it is not, it is bad.
To figure out what the output voltage should be: measure the voltage between pin 1 and ground and add 1.25V to that number, that is the output voltage on pin 2 but you have to make sure you do have 1.25 between pin 1 and 2 as noted above

1117 series LDO from DIGIKEY:

SOT-223-3 style casing:

Adjustable:
http://www.digikey.com/product-detai...SCT-ND/1967218
http://www.digikey.com/product-detai...44-1-ND/586244

1.2V Fixed:
http://www.digikey.com/product-detai...40-1-ND/725525
http://www.digikey.com/product-detai...5-1-ND/1865519 1.2A

1.5V Fixed:
http://www.digikey.com/product-detai...SCT-ND/2121241 1A
http://www.digikey.com/product-detai...8-1-ND/1883983 950Ma
http://www.digikey.com/product-detai...26-1-ND/586226 1.2A

1.8V Fixed:
http://www.digikey.com/product-detai...SCT-ND/1967216

2.5V Fixed:
http://www.digikey.com/product-detai...SCT-ND/2121243 1A
http://www.digikey.com/product-detai...9-1-ND/1883984 950mA

3.3V Fixed:
http://www.digikey.com/product-detai...OSCT-ND/660708
http://www.digikey.com/product-detai...SCT-ND/3462387 1.1A

http://www.digikey.com/product-detai...28-1-ND/586228 1.2A

5V Fixed:
http://www.digikey.com/product-detai...SCT-ND/1967217
http://www.digikey.com/product-detai...7-1-ND/1865475