TS5A3359: Output status is not matching with datasheet when one of the control pins is floating

Wayne Wang20

Part Number: TS5A3359

Hi team,

My customer is using TS5A3359. In customer's use case, there is a condition that IN1=H and IN2 is floating. According to our datasheet, in this case, COM should be connected to NO0 or NO2. Customer did the test on 10 boards setting IN1=3.3V and IN2=floating and VCC=3.3V.

For 4 boards, COM=NO0

For 3 boards, COM=NO2

But for 3 boards, COM=NO1

It is strange that COM=NO1 when IN1=H and IN2=floating. And this phenomenon that COM=NO1 on these 3 boards will keep stable until we recycle their power supply. For these 3 abnormal boards, after we power up the board again, COM sometimes will change to NO0 or NO2.

So do you have any advice on why this will happen? And I also want to check with you if this device has internal pull-up or pull-down on IN1 and IN2 pin. Thanks.

Best regards,

Wayne

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 243920 points

There are no internal pull-ups/-downs. The control inputs must never float; see [FAQ] How does a slow or floating input affect a CMOS device? (A floating input indeed can prevent other inputs from working correctly.)

0 Sandesh Rawool over 3 years ago

TI__Intellectual 2694 points

HI Wayne,

The recommendation for IN1 and IN2 pin is to either connect it to VCC/VIH=H or GND/VIL=L signal to prevent undesired switch positions.

In the customer case mentioned, even thought IN1 = H, leaving IN2 = Floating can impact the functional logic operation and result in undesired switch positions.

There are no internal pull-ups or pull-down resistors for the control pins (IN1, IN2) hence they cannot be left floating.

Thank you.

Switches & multiplexers

Switches & multiplexers forum

TS5A3359: Output status is not matching with datasheet when one of the control pins is floating