STMicroelectronics L9651-TR

Overview

L9651-TR from STMicroelectronics is a quad low-side power switch IC with integrated diagnostic serial interface, designed for automotive and industrial load control. It features four 2.2 A-rated VDMOS outputs (RDSON < 500 mΩ at 25°C), 70 V internal output clamping, wide 4.7–30 V supply range, and real-time fault detection including open-load, short-to-battery/ground, and overtemperature.

For engineers reviewing the L9651-TR datasheet, L9651-TR pinout, L9651-TR application, or L9651-TR equivalent, key selection criteria include its daisy-chainable 500 kHz SPI-compatible diagnostic interface, per-channel fault storage in an 8-bit serial register, and CMOS-compatible inputs with internal pull-ups-critical for robust body electronics and ECU-level load management.

Technical Context

The L9651-TR implements four independent low-side switches using modified VDMOS technology, each with fast turn-on/off slew rates (10/15 V/μs) and precise current-limiting thresholds that vary with junction temperature (2.2–4.3 A). Its diagnostic engine samples output voltage during off-state (open-load detection at < 2/3 VBAT) and on-state (short-to-battery detection), with 100 μs filtering to reject transients.

Communication occurs via a synchronous 4-wire serial interface (CL, SY, DI, DO) supporting daisy-chaining without external logic. Fault data is latched and readable as an 8-bit register; critical faults also assert a hardware-level DO signal without requiring full register readout-enabling immediate system-level response.

Key Specifications

Pinout & Package

Package: PowerSO-20 (JEDEC MO-166), thermally enhanced exposed slug, 1.9 g mass, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad low-side switch applications.

Compared with VNQ5E04TR-E and TPS27082LDR, the L9651-TR uniquely combines quad integration, 70 V clamping, and daisy-chain diagnostics in one PowerSO-20 package - delivering the highest functional density and diagnostic fidelity for automotive body electronics where channel count and fault visibility are critical.

Availability

L9651-TR is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC output stages, smart lighting control units, and electric power steering auxiliary load drivers requiring stable component supply and long-term lifecycle support.

Supply support for L9651-TR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, serving automotive, industrial, and consumer markets with silicon solutions since 1987.

The L9651-TR belongs to ST's Smart Power family, engineered specifically for automotive body electronics and industrial actuator control - emphasizing integrated protection, real-time diagnostics, and AEC-Q100 qualified reliability.

FAQ

What is the maximum allowable supply voltage transient for L9651-TR?

The L9651-TR supports transient supply voltages up to 40 V for durations under 400 ms, as specified in its Absolute Maximum Ratings table. This withstand capability covers standard automotive load-dump events defined in ISO 7637-2 Pulse 5a, enabling direct connection to battery rails without external transient suppressors in most 12 V systems.

Does L9651-TR require external pull-up resistors on its serial interface lines?

Yes - the DO (serial data out) pin is open-drain and requires an external pull-up resistor (typically 4.7 kΩ to VCC) to ensure valid logic-high levels. The DI (data in), CL (clock), and SY (sync) inputs have internal pull-downs and do not require external biasing, but system-level noise immunity may benefit from optional weak pull-downs in high-EMI environments.

How does the L9651-TR detect open-load faults?

The L9651-TR detects open-load faults during output-off periods by measuring output voltage: if VOUT drops below 2/3 VBAT (e.g., < 9.3 V at 14 V supply), it registers an open-load condition after 100 μs filtering. This method relies on internal diagnostic current sources (100–500 μA) that bias the output node - eliminating need for external sense resistors or comparator circuits.

Can multiple L9651-TR devices be connected in series for extended diagnostic chains?

Yes - the L9651-TR supports true daisy-chaining: DO of one device connects to DI of the next, with shared CL and SY lines. Up to eight devices can be chained using standard PCB traces (≤10 cm per segment), maintaining full 500 kHz interface speed and preserving individual 8-bit fault register integrity across the chain without additional address decoding logic.