NC7SZ126P5X

The NC7SZ126 from onsemi’s TinyLogic UHS (Ultra-High Speed) family is a single non-inverting buffer with 3-state output. The NC7SZ126P5X is the SC-70-5 (SC-88A) tape-and-reel version with 3000 units per reel. It is also available in SOT-23-5 (M5X), MicroPak-6 (L6X), and UDFN-6 (FHX) packages.

When the output enable (OE) pin is HIGH, the buffer passes the input to the output with only 2.6 ns typical propagation delay at 5 V (4.3 ns max at 5.5 V). This makes the device essentially transparent to most timing budgets. When OE is LOW, the output enters a high-impedance state, allowing other devices to drive the same bus line.

The +/-24 mA output drive at 3 V (32 mA absolute maximum) provides substantial drive capability for a tiny SC-70 package, sufficient to drive multiple CMOS loads, LED indicators, or short PCB traces. The output can also sink/source current for active-low or active-high LED drive.

The 1.65 V to 5.5 V supply range covers all common logic voltages. Inputs tolerate voltages up to 5.5 V independently of VCC, enabling 5 V to 3.3 V voltage translation when the device is powered from 3.3 V. The output also tolerates voltages above VCC when in the 3-state condition, preventing damage when a bus is driven to a higher voltage by another device.

Power-down high-impedance on all I/O pins prevents backflow current when VCC is 0 V, critical for hot-swap and power-sequencing applications. The 2 uA typical quiescent current (10 uA max) minimizes power consumption.

The NC7SZ126 is the 3-state version of the NC7SZ125 (which has an active-low OE). Both are part of the TinyLogic UHS family, which also includes the NC7SZ126M5X (SOT-23-5) and NC7SZ126L6X (MicroPak-6) package options.

**CMOS Buffer with 3-State Output:** The NC7SZ126 uses a standard CMOS inverter chain (input stage + output stage) for the buffer function, with an additional enable/disable circuit for the 3-state output. When OE is HIGH, the output stage operates as a normal push-pull CMOS driver. When OE is LOW, both the PMOS and NMOS output transistors are turned off, creating a high-impedance state.

**Propagation Delay:** The 2.6 ns typical propagation delay at 5 V is achieved through optimized transistor sizing and advanced sub-micron CMOS technology. The delay increases at lower supply voltages due to reduced drive current. At 1.65 V, the typical delay is approximately 5-7 ns.

**Over-Voltage Tolerance:** Input protection circuitry allows input voltages up to 5.5 V regardless of VCC. When a voltage above VCC appears on an input, the internal ESD diode to VCC is reverse-biased, preventing current flow into the VCC rail. This enables 5 V signals to be received by a 3.3 V device.

**3-State Bus Operation:** Multiple NC7SZ126 devices can share a common bus line if only one device has OE HIGH at a time. The high-Z state prevents bus contention. The output in 3-state can also tolerate voltages above VCC, allowing mixed-voltage bus operation.