Texas Instruments LM5109BQNGTTQ1

Overview

LM5109BQNGTTQ1 from Texas Instruments is an AEC-Q100 Grade 1 qualified high-voltage half-bridge gate driver IC designed to independently control high-side and low-side N-channel MOSFETs in automotive synchronous buck and half-bridge power converters. It delivers 1-A peak sink/source output current per channel, supports bootstrap supply voltages up to 108 V DC, and features TTL/CMOS-compatible inputs with 30 ns typical propagation delay and 2 ns typical delay matching.

For engineers reviewing the LM5109BQNGTTQ1 datasheet, LM5109BQNGTTQ1 pinout, LM5109BQNGTTQ1 application, or LM5109BQNGTTQ1 equivalent, this page provides verified technical context, validated pin functions, confirmed automotive-grade operating conditions (–40°C to +125°C), real-world bootstrap design constraints, and two rigorously cross-checked alternative gate drivers for half-bridge topologies.

Technical Context

The LM5109BQNGTTQ1 integrates a robust level-shift circuit enabling clean, high-speed logic-to-high-side translation referenced to the HS node - critical for reliable operation with 90-V rail voltage swing. Its dual independent input architecture (HI/LI) allows full control of HO and LO outputs without internal logic coupling, supporting non-overlapping, complementary, or phase-shifted drive schemes.

Under-voltage lockout (UVLO) operates separately on VDD (6.7 V rising threshold, 0.5 V hysteresis) and HB–HS (6.6 V rising threshold, 0.4 V hysteresis), ensuring safe startup and fault isolation. The WSON-8 package includes an exposed thermal pad soldered to PCB ground, delivering 8.1°C/W junction-to-case (bottom) thermal resistance for sustained 1-A switching at 125°C junction temperature.

Key Specifications

Pinout & Package

LM5109BQNGTTQ1 is housed in a thermally enhanced 4.00 mm × 4.00 mm WSON-8 package with exposed thermal pad (NGT suffix). The pad must be soldered to PCB ground plane to achieve specified RθJC(bot) = 8.1°C/W and ensure stable operation at 125°C junction temperature.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM5109BQNGTTQ1, UCC27211QDRQ1 offers higher drive strength and integrated bootstrap management but sacrifices layout flexibility and noise immunity, while LM5106QNTTQ1 reduces cost and complexity at the expense of control freedom and peak current capability - making LM5109BQNGTTQ1 the optimal choice for demanding automotive half-bridge applications requiring independent timing, 1-A drive, and proven 90-V HS robustness.

Availability

LM5109BQNGTTQ1 is available at Aetrix Electronics and suitable for automotive power conversion, electric power steering systems, and on-board charger designs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LM5109BQNGTTQ1 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with deep expertise in automotive-grade reliability and functional safety.

LM5109BQNGTTQ1 belongs to TI's automotive-qualified high-voltage gate driver product line, engineered specifically for robust, high-efficiency control of N-channel MOSFETs in safety-critical 12-V, 48-V, and high-voltage traction auxiliary systems.

FAQ

What is the maximum allowable negative transient voltage on the HS pin of the LM5109BQNGTTQ1?

The HS pin may transiently swing below VSS, but must never fall more than (VDD – 15 V) below ground. For example, with VDD = 10 V, HS must remain above –5 V. This limit prevents parasitic transistor activation and excessive HB supply current. External Schottky clamping diodes between HO–HS or LO–VSS are recommended if board layout induces significant negative HS ringing, and must be placed within 2 mm of the IC pins.

Does the LM5109BQNGTTQ1 support 3.3-V logic inputs?

Yes, the LM5109BQNGTTQ1 supports 3.3-V logic inputs: its VIH threshold is guaranteed ≥2.2 V and VIL ≤0.8 V over –40°C to +125°C, ensuring reliable recognition of standard 3.3-V CMOS high/low states. No level-shifting circuitry is required when interfacing with 3.3-V microcontrollers or digital PWM controllers.

Can the LM5109BQNGTTQ1 drive both MOSFETs in a full-bridge configuration?

Yes, two LM5109BQNGTTQ1 devices can be used to drive a full-bridge: one controls the high-side/low-side pair of one leg (HO/LO), and the second controls the other leg. Each LM5109BQNGTTQ1 provides independent HI/LI inputs, enabling precise dead-time control and phase modulation - essential for minimizing shoot-through and optimizing ZVS in full-bridge topologies.

What is the recommended bootstrap capacitor value for the LM5109BQNGTTQ1 in a 500-kHz half-bridge application?

Texas Instruments recommends a minimum 100-nF X7R ceramic bootstrap capacitor placed directly between HB and HS pins. For 500-kHz operation with 17-nC gate charge and 50% duty cycle, this value maintains sufficient VHB–HS hold-up above the 6.6-V UVLO threshold. A 1-µF local VDD bypass capacitor (10× CBoot) is also required, both rated for ≥2× the applied DC voltage.

How does the LM5109BQNGTTQ1 handle undervoltage conditions on the HB rail?

When HB–HS falls below its UVLO threshold (6.6 V nominal, with 0.4-V hysteresis), the LM5109BQNGTTQ1 disables only the HO output while keeping LO fully operational. This allows continued low-side switching and safe discharge of the high-side FET during bootstrap faults - a critical safety feature in automotive motor drives where uncontrolled high-side conduction could cause torque spikes or bus short circuits.