LT1389-5V ,Can I provide 5V at the Input

Hello HARI, mes Yes it is perfectly appropriate to supply 5V as input to an LT1389-5V reference IC; that is its intended function.

Utilizing a buck converter to ensure a reliable 5V input would be ideal for an electric bike throttle application.

Should you have any additional inquiries or are concerned, don't hesitate to get in touch! Feel free to ask away.

Thank you..

When I tested the buck,it's output is varying from 4.8V to 5.2V.

When I/P is 4.8V the refrence won't be able to provide 5V.Please correct me if I am wrong

Hello there! Utilizing 5V as an input to an LT1389-5V reference IC is absolutely fine; using a buck converter to ensure steady 5V for your electric bike throttle input should provide ample security against sudden voltage variations between 4.8V and 5.2V can help maintain consistent 5V output from your reference IC. Hope this information has been of assistance!

Hello Hari,

your concerns are valid: the LT1389 is a shunt reference which works only in combination with a series resistor. It needs a significant voltage drop over the series resistor as "headroom" for its voltage regulation.

If there is no voltage headroom to drop over this series resistor, the LT1389 can not regulate. So the lowest value of the input volage must always be sigificantly higher than the stabilized output voltage you want to generete.

best regards

Achim

Hi Achim,

Thank you very much.

I am thinking of solution of this problem(generating a 5V reference from a buck converter whose output varies from 4.8V and 5.2V)

May I know you have any suggestions.

Regards

HARI

Hello Hari,

my first proposal would be: work with a smaller reference voltage. A LT1389BCS8-4.096 should work fine, is there really a compelling reason why the throttle absolutely needs 5V as reference?

If that is really not possible: modify your DCDC so that it delivers a slightly increased voltage as input for your LT1389BCS8-5 (or use a different DCDC if the existing one cannot be tuned).

If that is really not possible either: use a little chargepump to increase the output voltage of the DCDC and take this increased voltage as input for the LT1389BCS8-5.

best regards

Achim