AnsweredAssumed Answered

L6920DB - Will not fully shutdown ?

Question asked by nurquhar on Apr 22, 2013
Latest reply on Apr 24, 2013 by grimaldi.vincenzo
I have built my own evaluation circuit as below.  It seem to work ok when I hook it up to my bench PSU with 2.6v input and the output connected to a standard 5v LED.  Output measures 4.9v as expected.  The circuit is only populated with C1,C2,C4,L1 & U1.  Capacitors are all MLCC's.

However when I link the /SHDN input to ground the LED dims but still remains on.  My DVM says the /SHDN is definatly 0v but the output is still giving 2.0v and the LED current is 3mA.

The datasheet says :
"Shutdown

In shutdown mode (SHDN pulled low) all internal circuitries are turned off, minimizing the

current provided by the battery (I

 

SHDN < 100 nA, in typical case)."

 

So why does not L6920 not fully shutdown ?  It seems to be still conducting between Vbatt(7) and Vout(8) when it is in shutdown.  So how can this be correct  or useful in a battery application ?  Its just going to run the battery flat.
L6920DB-eval.JPG
L6920-eval%20-%20Schematic.jpg

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