UCC27523: UCC27523 OUTA to INB, looks like Shorted

Hi Chu,

Can you answer a few of these questions:

1. What is the Com bus?
2. What is the failure rate?
3. Have you done an ABA analysis?
4. When did this failure occur, and do you have the waveforms before the failure?
5. Do you have any waveforms of a good unit of start-up, steady state, shut down?

Thanks,

Suzuko

Thanks 

1. Just a inverted (idle LOW) single-wire UART

2. Just prototype to replace SN74LVC2G240DCTR that no enough drive ability

3. No ABA

4. just prototype: Even both channel are disable, the pin 7 & 4 is about 15 ohm

5. never get it working 

Understanding the Problem

UCC27523 Overview

• OUTA (pin 7) and OUTB (pin 5) are independent push-pull outputs capable of sourcing/sinking ±2.5A.

• INB (pin 4) is a logic input, not designed to sink or source current.

️ What Went Wrong

If you connected OUTA (pin 7) to INB (pin 4) or tried to "loop" the outputs for half-duplex communication:

• OUTA can source/sink large current, which can destroy INB, which is a high-impedance logic input.

• INB might now be internally damaged or shorted to GND due to this overcurrent.

 Why This Won’t Work

• UCC27523 is a gate driver, not a bus transceiver.

• It's meant to drive MOSFET gates, not signal lines with possible contention or bidirectional behavior.

• There’s no output tri-state capability — outputs are always push-pull active, which is dangerous in a shared line.