The SN74LVC1G125-Q1 is a single 3-state bus buffer: it drives its output (Y = A) when the active-low output-enable is asserted and presents a high-impedance output otherwise. In a vehicle, where many modules share internal buses and where boards may be serviced or hot-swapped, that 3-state ability is only half the story — the other half is behaving safely when the device is not powered.

That is the role of I_off. The partial-power-down circuit disables the I/O when V_CC is absent, so the buffer’s pins stay high-impedance and cannot back-drive current into a bus that is still live. This lets a card be inserted into or removed from a powered system — live insertion — without latch-up, glitches or damage to the running network. Combined with the AEC-Q100 automotive qualification (Temperature Grade 1, −40 °C to +125 °C), it is built for the harsh, always-connected environment of automotive and industrial buses.

Electrically it is a full LVC part: 1.65 V–5.5 V, 5.5 V-tolerant inputs for mixed-rail buses, a strong ±24 mA output at 3.3 V and only about 10 µA quiescent. The SC-70 (DCK) outline keeps it small enough to sit right at the connector or bus tap.

Note: Values are from the Texas Instruments SN74LVC1G125-Q1 data sheet (SGES002E). Confirm every parameter against the latest data sheet before committing a design.

This order option ships in the DCK 5-pin SC-70 (JEDEC MO-203, ~1.1 mm maximum height, body about 2.0 mm × 1.25 mm, 0.65 mm pitch). For a hot-pluggable bus tap, the SC-70 is a practical size — small enough to place beside the connector, but with leads that are still straightforward to inspect and rework. The same die is also available in the smaller DRY (SON) and the larger DBV (SOT-23).

The dimensioned outline below gives the SC-70-5 body and lead geometry for the land pattern and stencil.

Five pins carry the enable, input, output and supply pair (top view):

• Pin 1 – OE (Output Enable, active-low): low enables Y = A; high forces Hi-Z. Hold high during power-up/insertion.
• Pin 2 – A (Input): data input; 5.5 V-tolerant.
• Pin 3 – GND: Ground (0 V) reference.
• Pin 4 – Y (Output): 3-state output; ±24 mA at 3.3 V or Hi-Z.
• Pin 5 – V_CC: Supply, 1.65 V to 5.5 V; bring up before enabling, decouple locally.

Related single 3-state buffers. The first row is the same device in the tiny SON package; note the SN74LVC1G126 has the opposite (active-high) enable. Confirm package, family and enable polarity before substituting.

Logic Family Comparison

Texas Instruments (TI, NASDAQ: TXN), of Dallas, Texas, is a leading logic supplier; its LVC family is the wide-supply, 5 V-tolerant workhorse for bus interfacing, and the “-Q1” variants are AEC-Q100 qualified with I_off for live-insertion-capable automotive designs.

The governing document is the SN74LVC1G125-Q1 data sheet (SGES002E), which defines the 3-state behaviour, the I_off circuit and timing. InFortune Electronics supplies the device under code 1P1G125QDCKRQ1 and provides sourcing and technical support.