STMicroelectronics L9856-TR

Overview

L9856-TR from STMicroelectronics is a high-voltage high-side gate driver IC designed to control N-channel power MOSFETs in floating high-side configurations. It supports rail voltages up to 160 V, delivers ±500 mA peak source/sink current, achieves 100 ns rise/fall times with 2.5 nF load, and features CMOS/TTL Schmitt-trigger inputs with hysteresis for noise immunity-used in industrial motor drives and half-bridge inverters.

For engineers reviewing the L9856-TR datasheet, L9856-TR pinout, L9856-TR application, or L9856-TR equivalent, key selection criteria include dV/dt immunity (±50 V/ns), under-voltage lockout thresholds (VCCUV+ = 4.3 V, VBSUV+ = 4.3 V), bootstrap recharge timing (ton_rech = 3–9 µs), and SO-8 package thermal resistance (Rth(j-amb) = 150 °C/W).

Technical Context

The L9856-TR integrates dual level shifters ("ON" and "OFF"), break-before-make logic, pulse filters, and dedicated reset circuitry to ensure safe high-side switching. Its BCD "OFF-LINE" process enables robust operation at VS offsets up to 150 V and dV/dt transients of ±50 V/ns across –40 °C to +125 °C.

It implements active bootstrap capacitor recharge via an internal transistor with controlled dead time (DTHOFF = 3–9 µs, DTHON = 0.1–0.7 µs), and uses negative-logic IN− and RESET− inputs compatible with microcontroller GPIOs. Undervoltage lockout operates independently on both VCC and VBS rails.

Key Specifications

Pinout & Package

Supplied in SO-8 package (ECOPACK®, lead-free), with 1.27 mm pitch, 5.0 mm × 6.0 mm body, and thermal resistance Rth(j-amb) = 150 °C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-side gate driver applications.

Compared with IRS21844PbF and UCC27712DR, the L9856-TR uniquely combines 160 V rail support, dual-rail UVLO, and integrated bootstrap recharge in SO-8-reducing BOM count and layout complexity for industrial half-bridge designs below 200 kHz.

Availability

L9856-TR is available at Aetrix Electronics and suitable for industrial motor drives, half-bridge inverters, and induction heating systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for L9856-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, specializing in automotive, industrial, and power management ICs with vertical manufacturing capabilities.

The L9856-TR belongs to ST's high-voltage gate driver product line, engineered specifically for robust, self-contained high-side switching in industrial motor control and power conversion applications using BCD "OFF-LINE" technology.

FAQ

What is the purpose of the NC pin (Pin 6) on the L9856-TR?

Pin 6 is a no-connect terminal with no internal bondwire or circuit connection. It must remain unconnected on the PCB-neither tied to ground nor left floating-to avoid mechanical stress or unintended coupling. This pin exists for package symmetry and thermal balance in the SO-8 outline, not functional use.

How does the L9856-TR handle bootstrap capacitor recharge?

The L9856-TR integrates a dedicated recharge transistor that activates when RESET− is asserted or during low-side conduction phases. It provides controlled charging with ton_rech = 3–9 µs and VRECH ≤ 1.2 V drop at 1 mA, eliminating need for external diodes or timing circuits while ensuring reliable gate drive across duty cycles.

Can the L9856-TR drive SiC MOSFETs?

The L9856-TR can drive SiC MOSFETs with gate thresholds ≤ 4 V and Qg ≤ 50 nC, provided gate loop inductance is minimized and layout adheres to high-dV/dt best practices. Its 100 ns switching and ±500 mA drive support typical SiC gate requirements-but gate resistor selection must be validated per specific device's Miller plateau and switching loss targets.

What happens when VBS falls below its UVLO threshold?

When VBS drops below VBSUV− (2.8 V), the high-side output HO is forced low and the bootstrap recharge path is enabled. The driver remains disabled until VBS rises above VBSUV+ (4.3 V), preventing weak or undefined gate drive that could cause MOSFET linear-mode operation and thermal failure.