TPS27081A: Adding shutdown feature to MC33063A, MC34063A switching regulators

Cemilhan Sunar

Part Number: TPS27081A
Other Parts Discussed in Thread: MC33063A

I saw such a circuit in the MC33063A datasheet for on/off operations, but do we need to do any pull-up or pull-down for ON/OFF?

Can I ON/OFF directly from the processor with 3.3V-0V without doing anything?

Can give me information about how to do it?

over 1 year ago

+1 Timothy Logan over 1 year ago

TI__Mastermind 29455 points

Cemilhan,

You are correct. There is no internal pull-up/pull-down on the device and as per the datasheet you need an external pull-down resistor:

0 Cemilhan Sunar over 1 year ago in reply to Timothy Logan

Prodigy 10 points

But in the application made here, for example, there is no pull down.

0 Timothy Logan over 1 year ago in reply to Cemilhan Sunar

TI__Mastermind 29455 points

In the figure you are referring to it is connected to an MCU- in which case the state can be ensured to be a known state via the MCU's software or configured as a pull-down on the MCU. In the case where you always want the switch on you will need the external pull-down.

0 Cemilhan Sunar over 1 year ago in reply to Timothy Logan

Prodigy 10 points

Now I'm thinking of controlling it by sending 1 or 0 with the MCU. So do I need to connect it? If I am going to connect, how many k a pull-down is enough?

+1 Timothy Logan over 1 year ago in reply to Cemilhan Sunar

TI__Mastermind 29455 points

10k pull-down would be sufficient.

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TPS27081A: Adding shutdown feature to MC33063A, MC34063A switching regulators