CD74HCT154: 5V _OE and 3.3V VDD

TI-CSC

Part Number: CD74HCT154
Other Parts Discussed in Thread: CD74HC154

Hello E2E Experts,

Good day.

Developing a test board to test PCB panel with 16 PCB. Will use a decoder CD74HCT154 to get 5V output as _OE to decide which PCB will be tested.

1. May I use this switch with VCC=3.3, _OE (5V and 0V, 5V tolerant), all input ports are between 3.3V to 0V, and get a similar output voltage (minus Ron effect) from input?

2. Plan to decide whether the 3.3VDD 30mA can or cannot go through the tested PCB. May I use multiple input ports for 3.3VDD 30mA, and get the output to supply the PCB with 3.3VDD 30mA? The reason I plan to use multi ports is to minimize the Ron as parallel resistors, and thus the 3.3VDD voltage drop across this switch can be minimized. Plan to use 2 or 3 ports.

Thank you in advance for your help.

Regards,

CSC

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 259460 points

HCT devices work only with a 5 V supply.

This device is not a switch; its inputs and outputs are buffered.

Why are you mentioning both VCC and VDD? Do you have two different supplies? Please draw a schematic.

0 Sebastian Muriel over 2 years ago

TI__Genius 14240 points

Hi,

As Clemens stated this device is not a switch; its inputs and outputs are buffered.

The CDHCT154 only supports a supply voltage of 4.5-V to 5.5-V, the CD74HC154 will support a supply voltage of 2-V to 6-V.

These devices have clamp diodes on the I/O, the current must not exceed 20mA on any input or output for functional operation of the device.

Please see this FAQ Can the input voltage (Vi) to my logic device be higher than the supply (Vcc)?

Can you please provide a schematic?

Regards,

Sebastian

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CD74HCT154: 5V _OE and 3.3V VDD