MUX507: MUX507 HV input channel impact to adjacent channels

Eddie Chou

Part Number: MUX507
Other Parts Discussed in Thread: MUX508, TMUX7308F

Hi Team,

my customer design MUX507 for analog input channel multiplexer, however their end customer connect +22V to CH15 and find CH8 signal has 3V DC offset.

Please refer to below schematic and waveform.

The same saturation will not happen if they use x2 MUX508.

customer would like to know the reason, is this caused leakage?

Thanks & Regards

Eddie

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 285080 points

The voltage at the I/O pins must not exceed V_DD. Is that 22 V measured against AGND or A_-15V?

0 Eddie Chou over 2 years ago in reply to Clemens Ladisch

TI__Expert 5630 points

Hi Clemens,

It's measured from AGND. Customer understand it's fault connection, but their end customer would like to understand,

1. Why AI8 got DC offset but AI0 not impact.?

2. The same saturation not happen on x2 MUX508 design.

3. any risk with fault connection and how to avoid?

Thanks for your comments.

Eddie Chou

0 Clemens Ladisch over 2 years ago in reply to Eddie Chou

Guru 285080 points

That 22 V exceeds the absolute maximum rating, so the device might have been damaged. Anything could happen.

To avoid this, clamp the voltage externally (with a Zener, or a diode to V+ if that supply can sink the current).

0 Tyler McGuire over 2 years ago

TI__Expert 3515 points

Hi Eddie,

As Clemens mentioned, the absolute max rating was violated and the device was potentially damaged. It is difficult to predict how the device will operate when damaged.

We offer fault and over-voltage protected multiplexers in our portfolio that will not be damaged by over-voltage events like this and offer protection to downstream components. The TMUX7308F is a single channel, 8:1 mux that can be used in place of the MUX508. Please see our mid-voltage selection guide and TI Precision Labs video on fault protection for more information.

Thanks,
Tyler

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MUX507: MUX507 HV input channel impact to adjacent channels