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TLV2370 shutdown

Bob Lee(UK)
Expert 8670 points
Other Parts Discussed in Thread: TLV2370

Hi - sorry, got some questions on TLV2370 shutdown.  I'm aware that its a older product and answers may be difficult but I have a customer asking

 

Firstly what the threshold voltage for the shutdown pin - bit basic that and one you would expect in the datasheet, but ......

 

Next, trickyer - what happens in therm of disabling the input to output path during disable ?  When the customer tested the part with the output just loaded by a scope, he found almost as much signal on the output as he applied at the input when in shutdown mode.  Loading the output with 2k as per fig 28 in nthe datasheet helps but then the 2k load impedence defeats the object of having a low quiescent current part

 

I assume I didn't miss anything when I looked for a modern, low Iq part with shutdown ??

 

The customer is Firefighting Enterprises in the UK

 

Many thanks

 

Bob

  • 0
    TI__Guru 60570 points

    Bob,

    The threshold voltage levels for TLV2370 enable/disable pin are in the PDS table (see below) - 2.0V to enable and 0.8V to disable (agree, it should be in the main spec table).

    The main reason for the op amp shutdown feature is to decrease IQ current and NOT to provide a signal isolation between input and output terminals.  This is especially true in a follower configuration with unloaded output where the differential input capacitance (usually equal to half of the common-mode input capacitance - see table below) together with a differential input resistance provides a signal path from the positive to the negative input terminal, and thus to the output terminal.  Placing a small pull-down resistor (even 100k) at the output should be able in a disable mode to pull the output to the ground, and thus provide required signal isolation, without significantly increasing IQ during normal operation.

  • 0 in reply to Marek Lis
    TI__Expert 8670 points

    Many thanks Mark

     

    I missed the shutdown threshold since that's not what it was called and I did a seacrh on 'shutdown' to look for it

     

     

     

    Bob