From: David Van Horn <david.vanhorn@backcountryaccess.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Wed, 5 Feb 2020 09:47:34 -0800
Subject: RE: [EE] 78L05 (SO8) overshoot on removal of over-current event?
Thread-Topic: [EE] 78L05 (SO8) overshoot on removal of over-current event?
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I've not seen this exactly, but I have seen a lot of problems with the L ve=
rsion being defective in various ways.  I generally wouldn't trust them.=20

They (and actually most PNP based regulators) can be damaged by the input b=
eing shorted to ground, if the output capacitor is large.  This is not well=
 documented, you might have to go back to Motorola data sheets from the 198=
0's to find it documented, but the output stages are still much the same.  =
 There are more modern parts that are immune.

--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO =A080301 USA
phone:=A0303-417-1345 =A0x110
email:=A0david.vanhorn@backcountryaccess.com=A0

-----Original Message-----
From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> On Behalf Of Jason =
White
Sent: Wednesday, February 5, 2020 10:36 AM
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Subject: [EE] 78L05 (SO8) overshoot on removal of over-current event?

Hello everyone,

At a previous job I observed a failure mode where the 100mA current rating =
of a 78L05 type regulator (12->5V, SO8) was exceeded causing it to saturate=
 and then briefly overshoot to >7V when the load was removed causing damage=
 to 5V circuitry. (a micro-controller was driving a large number of opto-is=
olators, all toggled on and off at the same time)

Do anyone have any links to literature that documents this behavior?

--
Jason White
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e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis=
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