Due to the U.S. Thanksgiving holiday, please expect delayed responses during the week of 11/22.

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.

Other Parts Discussed in Thread: TPS54427, TPS54227

Our customer uses the resistance of EN
as shown in the attached figure.

Question 1.

About TPS54427, does 225~900kΩ mean to RB?

And please tell me the recommended value of RB when VEN is 5V.

About TPS54227, does 220~880kΩ mean to RB?

And please tell me the recommended value of RB when VEN is 5V.

Question 2.

When VEN is 5V, does the IC have restriction about RA?

Question 3.

When customer uses TPS54427/54227 As shown in the attached figure, Can we use 1MΩ about RA?

And customer uses 1MΩ of RA, is there anything wrong?

Best regards,

Takahiro Nishizawa

Question of TPS54427 and TPS54227.pdf

• Hi,

The Ren means the input resistance of EN pin, on cictomer circuit, you can consider that there is a resistor of 220K--900K pararreled with RB. then you can calculate the Ven based on this resistor network, make sure to use Ren-min 220K and Lowest Vin to set Ven-min > 1.6V. RA can be any value as long as the Ven>1.6V.

• 1）The 225~900K means the resistor connect to the EN pin to GND directly when the Ven=12V. For the divide resistor, you can set the RA and RB during the XXX Kohm when the Ven=5V
2) The IC is restricted by the voltage of EN pin(1.6V enable voltage), which is decided by the RA and RB.
3) We don't suggest to use such a big resistor which will introduce the resistor noise into the EN pin to false trigger the EN logic

I understood that 220~900kΩ means RB and we use resistance that voltage is over 1.6V.
In datasheet, RB is 220~900kΩ when Ven is 12V.
When Ven is 5V, must we use 220~900kΩ of RB?
and can we use 1MΩ of RB?

your answer : RA can be any value as long as the Ven>1.6V.
I understood this.

Best regards,

Takahiro Nishizawa
• the 200~900K is an internal resistor, you can't change it.
For the RA and RB, you can set them during XX Kohm to XXX Kohm ( such as Rb=10K, Ra=15K, Ven=5V). 1M is too big.
If we use 1MΩ, what kind of concerns do you have?

Best regards,

Takahiro Nishizawa
• Big resistor(1Mohm) will introduce the resistor noise into the EN pin which may false trigger the EN logic