Hi TI,
We are experiencing a functional failure with a logic level translator IC in our latest production batch. This is the first time this issue has occurred in our device history, previous units using the same design have functioned without error.
The IC is intended to shift data signals from a 3.3V Controller (VCCB) to a 1.8V Modem (VCCA). While the input signals are reaching the IC correctly, the output remains unresponsive.
Testing and Observations:
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Power Rails: Both VCCB (3.3V) and VCCA(1.8V) were verified using an oscilloscope. Both rails are stable, within the recommended operating conditions, and show no significant noise or fluctuations.
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Signal Integrity: During hard reset cycles, we monitored the controller-side inputs. The data patterns are correct and meet the VIH/VIL thresholds. However, the modem-side (VCCA) receives no data.
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Isolation Test: To rule out external PCB contention or modem-side loading issues, we lifted the output data pin from the pad.
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With the pin physically isolated from the rest of the circuit, the IC still failed to toggle.
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The isolated pin remains stuck at a constant 1.8V (HIGH).
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Impedance Check: We performed a continuity and resistance check between the isolated output pin and the VCCA rail. There is no short circuit detected, ruling out a solder bridge or internal short to the supply rail.
Could you please review the schematic and the behavior described? Specifically, we would like to know if this "stuck-high" behavior on an isolated pin points to an internal latch-up state or a specific failure mode known for this family of translators.
Thanks and regards,
Manish Dhumal
