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TPL5110-Q1: TPL5110-Q1

Allan Balgley
Prodigy 180 points

Part Number: TPL5110-Q1
Other Parts Discussed in Thread: TPL5111, TPL5110

Tool/software:

Hi, 

My engineer has sent me a revised design using the TPL5111 instead of the TPL5110. 

Below is the schematic of the original design using a lmc555ctp timer and new design using the TPL5111.

He is asking:

This has the old 555 timer diagram and the new chip TPL5111 you want to use.  The problem is triggering the new part.  This needs a high to trigger where the 555 needed a low.  I did that by charging a capacitor then when the switch moved it pulled pin 2 low to activate.  Now it is the opposite. The main issue is that the switch is normally closed and there is no room on the flex board to add any kind of bigger circuit than maybe one or two passive components.  Any ideas for this as we don't want any more current draw than what the chip draws.

  • 0
    TI__Guru** 115140 points

    Hi Allan,

    The most straight forward solution is to have the switch normally open.

    If this is not acceptable, I am afraid I don't have solution. 

  • 0 in reply to Noel Fung
    Prodigy 180 points

    1. What is the current draw if the circuit  stays the same using a 3v 220mah battery. How long would this battery last. Is it not 35nA?

    2. If space wasn't a concern how can this be resolved?

  • 0 in reply to Allan Balgley
    TI__Guru** 115140 points

    Hi Allan,

    the max. operation current as specified in the datasheet is 50nA. 

    Anything added to convert the logic will consume more current, have the switch normally open is the best solution. 

    Indeed, the switch has to be opened when Vcc power up the device, as the device needs to read the resistor value to determine the time interval. 

    One more thing, although you do not use the DONE pin, this pin should be pull-low with a shunt resistor.