NXP Semiconductors HEF4794BP,112

Overview

HEF4794BP,112 from Nexperia is an 8-stage serial-in/parallel-out shift-and-store register LED driver with open-drain outputs (QP0–QP7), dual serial outputs (QS1/QS2), and independent strobe (STR) and output enable (OE) controls. It operates from 3 V to 15 V, supports -40 °C to +125 °C ambient, and delivers up to 40 mA per output for driving LEDs in industrial signage and multiplexed display systems.

For engineers reviewing the HEF4794BP,112 datasheet, HEF4794BP,112 pinout, HEF4794BP,112 application, or HEF4794BP,112 equivalent, key selection considerations include its dual-edge cascading capability (QS1 on CP↑, QS2 on CP↓), 15 V-rated open-drain outputs, strobe-controlled latch timing, wide supply range, and SO16 package compatibility with legacy HEF4000B-series layouts.

Technical Context

The HEF4794BP,112 integrates two synchronized register stages: an 8-bit shift register clocked on CP rising edges, and a parallel storage latch triggered by STR HIGH. Data transfers from shift register to storage register only when STR is asserted, decoupling serial loading from output update - critical for glitch-free LED column updates in multiplexed displays.

Its dual serial outputs enable robust daisy-chaining: QS1 provides low-latency data forwarding on CP↑ for fast-rise-clock systems, while QS2 delivers the same bit on CP↓ to accommodate slow-rise clocks without added delay. All inputs are CMOS-compatible with rail-to-rail voltage thresholds, and outputs are open-drain with 40 mA sink capability and 15 V absolute max rating.

Key Specifications

Pinout & Package

HEF4794BP,112 is housed in a 16-lead plastic small outline package (SO16), SOT109-1, with 3.9 mm body width and 1.27 mm lead pitch - compatible with standard SOIC-16 footprints and reflow profiles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit shift-and-store LED driver applications.

Compared with SN74HC595DR and HEF4094BT,118, the HEF4794BP,112 uniquely combines 15 V open-drain outputs, dual-edge cascading, and automotive-grade temperature range - making it the sole option for high-voltage, noise-immune, multi-device LED systems operating beyond 6 V or above 85 °C.

Availability

HEF4794BP,112 is available at Aetrix Electronics and suitable for industrial HMIs, automotive interior lighting, LED signage, and programmable annunciator systems requiring stable component supply across extended temperature and voltage ranges.

Supply support for HEF4794BP,112 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Nexperia is a leading semiconductor manufacturer specializing in high-performance, high-reliability logic, analog, and discrete components for automotive, industrial, and consumer markets.

The HEF4794BP,112 belongs to Nexperia's HEF4000B logic family - designed specifically for robust, wide-supply-voltage serial interface and LED driving in harsh environments where noise immunity and temperature stability are critical.

FAQ

What is the maximum clock frequency supported by the HEF4794BP,112?

The HEF4794BP,112 supports a maximum clock frequency of 28 MHz at 15 V supply, 22 MHz at 10 V, and 10 MHz at 5 V - verified per Table 7's fclk(max) specification. These values assume CL ≤ 50 pF and tr/tf ≤ 20 ns; actual achievable rate depends on PCB trace capacitance and driver strength. The HEF4794BP,112 maintains timing integrity across its full 3–15 V range, unlike many 5 V-only shift registers.

Can the HEF4794BP,112 drive LEDs directly from a 12 V supply?

Yes, the HEF4794BP,112 can directly sink current from 12 V LED anodes via its open-drain QPn outputs, which are rated for 40 mA per pin and tolerate up to 15 V at VO. When used with 12 V, ensure the series resistor limits current to ≤40 mA (e.g., 12 V − 1.8 V LED VF ÷ 40 mA ≈ 255 Ω). The HEF4794BP,112's 15 V absolute max rating guarantees safe operation under transient overvoltage conditions.

How does the dual serial output (QS1 and QS2) improve cascading reliability?

QS1 outputs data on CP rising edges for fast-clock systems; QS2 outputs the same bit on CP falling edges to accommodate slow-rise clocks (>100 ns), eliminating setup-time violations in long daisy chains. This dual-edge capability means the HEF4794BP,112 requires no external clock inversion or delay matching - a key advantage over single-output shift registers like the SN74HC595 when cascading more than 3–4 devices.

What is the function of the STR (strobe) pin on the HEF4794BP,112?

The STR pin controls transfer of all 8 bits from the internal shift register into the parallel output storage latch. When STR is HIGH, data loaded serially into the shift register appears simultaneously at QP0–QP7 after the next CP edge. This decouples serial loading from output update - preventing partial-frame glitches during LED matrix refresh. The HEF4794BP,112 requires STR assertion only once per full byte, not per bit.

Is the HEF4794BP,112 pin-compatible with older HEF4794 variants?

Yes, the HEF4794BP,112 uses the SO16 (SOT109-1) package and matches the pinout of HEF4794BT and legacy HEF4794B variants per Table 2 and Fig. 1. All signal names (D, CP, STR, OE, QP0–QP7, QS1, QS2, VDD, VSS) occupy identical positions - enabling drop-in replacement in existing designs without PCB modification. The HEF4794BP,112 retains full functional and timing compatibility with earlier revisions.