• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 351 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMR14020-Q1: Pull Down Resistor EN pin

Lutz Naumann
Expert 6450 points
Part Number: LMR14020-Q1
Other Parts Discussed in Thread: LMR14020

Dear Team,

We need to safely disable LMR14020-Q1 in our application to minimize system power consumption. Therefor the LMR shall be enabled only when needed. Our supply voltage max is about 27V. Temp range -40°C to 125°C. We are planning an external pull down resistor to keep the part in sleep mode. A port pin of a 5V MCU will be used to turn on the LMR14020-Q1 EN pin when needed. 

Question: What is the maximum value of the external pull down resistor that can be used to safely keep the LMR14020 in sleep mode with the mentioned conditions above and over voltage, temp and process variation. We understand there is a internal current source but unfortunately we don't know the min max specs (eg. max current to GND out of the EN pin)

many thanks

Lutz 

  • 0
    TI__Mastermind 33765 points

    Hi,

    Seems you want to use big ohm resistor on EN pin for pull down, but this will make the design little more complicated as EN pin has hysteresis current,  for worst case condition, you can use 7uA as maximum possible sourcing out current on EN pin, the EN Low threshold minimum is 1.05V, you can use 1.0V for more margin, then the maximum value is 1v/7uA=142K ohm, an 140K 1% or lower resistor is suggested for your application.