Identify This Voltage Regulator (SiLA 8)

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Robbie Hatley 15 years ago

Greetings, group. I'm repairing some boards that have a small voltage regulator in one corner (designated "VR1"), TO-92 package (like a typical small signal transistor) which I'm having trouble identifying.

The device is marked like this:

SiLA 8 XXXX

(where XXXX is a 4-digit hexidecimal date or batch code, varying between devices, wheras "SiLA" and "8" are always the same)

First off, anyone know what manufacturer has logo "SiLA"? I can't find info on this.

Secondly, how in hell can I trace a part with part number "8"??? Come on, mfg.... "8"??? "8"??? Surely you guys can think of a more unique part number than just "8"??? Sigh. Maybe it's supposed to be an 8V regulator? Seems to be putting out about 20V, though.

Could be something like a 78LXX, but may be completely different. Pin 1 is connected to what I'll call A+ (100-300VDC). Pin 2 seems to be the output. Pin 3 is connected to the center point of a resistive voltage divider from Pin 2 to ground (Vref?). When powered up on test bench I'm getting V(pin1)=200VDC, V(pin2)=18VDC, V(pin3)=20VDC. Might be a 20V regulator.

Anyone have any clues what this is? (I need to buy some, because these seem to burn out frequently on these boards.)

Cheers, Robbie Hatley hatley [[dot]] software [[at]] gmail [[dot]] com

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Meat Plow 15 years ago

Try researching under the name Silan Microeletronics.

Live Fast, Die Young and Leave a Pretty Corpse

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Grant 15 years ago

Does the pinout match 78L08? Might be an 8V regulator.

Grant.

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Robbie Hatley 15 years ago

Regarding my query about the TO-92 voltage regulator marked "SiLA/8/XXXX", "Meat Plow" said, "Try researching under the name Silan Microeletronics". Thanks for the tip; however, I note that the Silan Microelectronics logo given by the sites I've looked at so far are all "script 'SL' in tilted ellipse", rather than "SiLA". Something tells me that "SiLA" may be the logo of some other company. An alluring match of first 4 letters though; I'll look into it further to make sure.

Cheers, Robbie Hatley

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Michael A. Terrell 15 years ago

Are any of the regulators working? They may be in shutdown mode, from another problem. If they are three pin it shouldn't be hard to find the input and ground. Unsolder the remaining terminal and read the voltage.

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who where 15 years ago

Would need to be a "special" type for that sort of input voltage capability - which may also be aprt of the frequent failures.

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Franc Zabkar 15 years ago

On Thu, 5 Aug 2010 12:24:25 -0700, "Robbie Hatley" put finger to keyboard and composed:

"Si" would suggest Vishay Siliconix. Siliconix makes a range of power semis, including regulators.

Your description of the pinout would suggest that pin 3 is the "ground" or "adjust" terminal of a 3-terminal regulator.

1 |-----| 2 Vin o-----| |-----+--o Vout |--|--| | 3 | | +-- R2 --| | R1 | _|_ =

However, I would have expected that V2 would be greater than V3. Furthermore, V2-V3 would be a fixed voltage (Vref), eg 1.25V or 2.5V.

The output voltage would then be ...

Vout = Vref (1 + R1 / R2)

What are the values of R2 and R1?

What voltage do you measure on a good VR1 when you disconnect the load?

BTW, if the output were 20V, then VR1 would be dissipating ...

P = (Vout - Vin) x Iload = 180 x Iload

This means that a 6mA load would be enough to cause the TO92 package to dissipate 1W.

- Franc Zabkar

Please remove one 'i' from my address when replying by email.

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Meat Plow 15 years ago

Well it was just a suggestion and seemed reasonable to investigate further. Why not match something up just be electrical specs? If you have a working device to get some voltage references from I don't see a problem with specing it out to another vendor. And since you are seeing high failure rate, overspec it.

Live Fast, Die Young and Leave a Pretty Corpse

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Identify This Voltage Regulator (SiLA 8)

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