TPS61089: Bypass operation

tateo yamashiro

Guru 10890 points

Part Number: TPS61089
Other Parts Discussed in Thread: TPS61178

Hi,

We got a question from customer about TPS61089 and TPS61178.
Could you help us?

[Question]
They are considering to use the ICs under the following condition.

Vin=2.7 to 7V
Vout=4.5V
Iout=2A

Their requirement is bypass operation(Vin=Vout) when input voltage exceed the set output voltage. They are thinking this IC can operate bypass operation.
Is their opinion right? If their opinion is right, how is the behavior of high side FET? To keep FET ON or turn-OFF(current through the body diode)?

Best Regards,
tateo

over 8 years ago

0 Helen chen over 8 years ago

TI__Mastermind 40080 points

Hi,

Both TPS61089 and TPS61178 don't have true by-pass function.

When Vin is between (Vo) to (Vo+Vf) , where Vf is the internal body diode voltage drop, the converter will work for several cycle, then stop, then again work for several cycle, then stop again. There may exist big noise because of the low frequency <20kHz.

So seriously, these two converter don't have bypass fucntion.

Could you please share the application with us? my email address is helen-chen@ti.com

0 tateo yamashiro over 8 years ago in reply to Helen chen

Guru 10890 points

Thank you for your reply. When the input voltage is over (Vo + Vf), how is the behavior of the IC?
I will confirm thier requirement more clearly and I'll let you know.

Best Regards,
tateo

0 Helen chen over 8 years ago in reply to tateo yamashiro

TI__Mastermind 40080 points

When Vin>Vo+Vf, then IC can pass through. the output voltage will be Vin-Vf.

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TPS61089: Bypass operation