PCA9545A: whether the device can operate the hotswap function as the datasheet describe(PCA9545A)

Frank Xiao

Genius 12055 points

Part Number: PCA9545A
Other Parts Discussed in Thread: TCA9511A

Hi team,

My customer wants to use the device PCA9545A for hotswap application. Thanks.

1. whether the device can operate the hotswap function as the datasheet describe?

2. Whether the input and output 5 channels can support the function together?

3. Whether we have some tips for the hotswap requirement?

Thanks.

over 5 years ago

0 Eric Schott1 over 5 years ago

TI__Guru 53555 points

Hi Frank,

PCA9545A supports hot-swapping on downstream channels while they are disabled. This allows new devices to be added to the bus without interfering with communication on active channels. Once the new device is inserted and detected (this can be done using the interrupt pins) its associated channel can be enabled by the master. The new device will then be added to the active idle bus.

Let me know if this makes sense and if you have any other questions about hot-swapping.

Regards,
Eric

0 Frank Xiao over 5 years ago in reply to Eric Schott1

TI__Genius 12055 points

Hi Eric,

Thanks for your reply, whether the device must be disabled when do the hot plug. Or we can keep it active and do the hot plug. Thanks.

0 BOBBY over 5 years ago in reply to Frank Xiao

TI__Guru 73181 points

Only the channel needs to be disabled (to prevent the main bus from seeing a glitch), I wrote about how to use the I2C switches for hot swap in this new app note:

http://www.ti.com/lit/pdf/SCPA058

The switch should be located on the live backplane, if you are needing hot insertion support on a secondary/daughter card then you should use TCA9511A (also highlighted in the app note)

-Bobby

0 Frank Xiao over 5 years ago in reply to BOBBY

TI__Genius 12055 points

Hi Bobby,

Thanks. it seems we need not to disable it for general requirement, correct? Thanks.

0 Eric Schott1 over 5 years ago in reply to Frank Xiao

TI__Guru 53555 points

To confirm, you do not need to disable the device for hot insertion, only the channel that is being connected.

Please let us know if this has answered your questions.
Regards,
Eric

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PCA9545A: whether the device can operate the hotswap function as the datasheet describe(PCA9545A)