STMicroelectronics L9856

Overview

L9856 from STMicroelectronics is a high-voltage high-side gate driver IC designed to control N-channel power MOSFETs in half-bridge and high-side switching topologies. It supports up to 160 V rail voltage, delivers ±500 mA peak source/sink current, achieves 100 ns rise/fall times with 2.5 nF load, features CMOS/TTL Schmitt-trigger inputs with hysteresis, and includes under-voltage lockout (UVLO) on both VCC and VB supplies - used in industrial motor drives and DC-DC converters.

For engineers reviewing the L9856 datasheet, L9856 pinout, L9856 application, or L9856 equivalent, key selection criteria include dV/dt immunity (±50 V/ns), bootstrap capacitor recharge capability, break-before-make logic, negative-logic IN-/RESET- inputs, and SO-8 package thermal resistance (150 °C/W).

Technical Context

The L9856 integrates dual-level shifters ("ON" and "OFF") with pulse filtering and flip-flop logic to ensure robust high-side gate control under fast transient conditions. Its internal architecture includes dedicated UVLO comparators for VCC and VB rails, independent reset circuitry, and a dedicated recharge path for the external bootstrap capacitor.

It implements break-before-make timing (DTHOFF = 3–9 µs, DTHON = 0.1–0.7 µs) to prevent shoot-through in bridge configurations, and uses negative-logic inputs (IN-, RESET-) compatible with microcontroller GPIOs without level-shifting. The device operates across –40 °C to +125 °C and is fabricated in ST's BCD "OFF-LINE" process for high-voltage isolation and ruggedness.

Key Specifications

Pinout & Package

Package: SO-8, surface-mount, ECOPACK® lead-free, 150 °C/W junction-to-ambient thermal resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IR2110S and UCC27211D, the L9856 uniquely combines 160 V capability, integrated bootstrap recharge, dual UVLO, and SO-8 footprint - making it optimal for space-constrained, medium-voltage industrial half-bridge designs requiring robustness and simplicity.

Availability

L9856 is available at Aetrix Electronics and suitable for industrial motor drives, isolated DC-DC converters, and solar microinverters requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for L9856 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, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and power applications.

The L9856 belongs to ST's high-voltage power driver product line, engineered specifically for robust high-side gate driving in industrial power conversion systems where dV/dt immunity, bootstrap reliability, and wide temperature operation are essential.

FAQ

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

Pin 6 is a no-connect terminal with no internal bondwire or circuit connection. It must remain unconnected on the PCB layout. Leaving it floating or tying it to ground/VCC may cause mechanical stress or unintended coupling. ST specifies this pin solely for mechanical symmetry and package compatibility - no electrical function is assigned.

Can the L9856 drive a MOSFET with gate charge >30 nC?

Yes - with its ±500 mA peak output current and 100 ns switching time into 2.5 nF, the L9856 can effectively drive MOSFETs with Qg up to ~35 nC at 10 V (calculated via I × t ≈ Q). For higher Qg devices, increase gate resistance to limit peak current and reduce EMI, while verifying rise/fall times meet system timing requirements.

How does the L9856 handle bootstrap capacitor recharge?

The L9856 integrates a dedicated recharge transistor between VB and VS that activates during the high-side off period. With <1.2 V on-state drop at 1 mA, it efficiently replenishes the bootstrap capacitor without external components. Recharge timing is internally controlled with 3–9 µs turn-on delay (ton_rech) to ensure safe break-before-make sequencing.

Is the L9856 suitable for automotive applications?

No - ST explicitly states the L9856 is not designed or authorized for automotive, safety-critical, or aerospace applications. It lacks AEC-Q100 qualification, has no automotive-grade screening, and its datasheet disclaimer excludes use in vehicles or life-support systems. For automotive use, consider ST's AEC-Q100-qualified drivers like the STL220.