Texas Instruments LM5109AMA/NOPB

Overview

LM5109AMA/NOPB from Texas Instruments is a high-voltage, 1A peak half-bridge gate driver IC designed to independently control high-side and low-side N-channel MOSFETs in synchronous buck and half-bridge power converters. It features TTL-compatible inputs, 30 ns typical propagation delay, 108 V bootstrap supply capability, and dual UVLO protection on VDD and HB–HS rails. Used in motor drives and isolated DC–DC topologies requiring robust level-shifting.

For engineers reviewing the LM5109AMA/NOPB datasheet, LM5109AMA/NOPB pinout, LM5109AMA/NOPB application, or LM5109AMA/NOPB equivalent, key selection criteria include high-side floating operation up to 90 V HS voltage, matched 2 ns typical propagation delay between channels, 15 ns rise/fall times into 1000 pF, SOIC-8 and WSON-8 package options, and independent HI/LI logic control with pull-down input resistors.

Technical Context

The LM5109AMA/NOPB integrates a robust high-speed level shifter to translate TTL-level HI signals to the floating high-side driver referenced to the HS node, enabling clean switching of N-MOSFETs with rail voltages up to 90 V. Its dual UVLO circuitry independently monitors VDD (6.7 V threshold) and HB–HS (6.6 V threshold), disabling HO during bootstrap under-voltage while allowing LO to remain functional.

Each output stage delivers ±1.0 A peak current with <0.65 V low-level output voltage at 100 mA sink, supporting fast turn-on/turn-off of power MOSFETs. The device operates across –40°C to +125°C junction temperature and supports switching frequencies up to 500 kHz with minimal timing skew (≤15 ns max delay matching).

Key Specifications

Pinout & Package

LM5109AMA/NOPB is available in SOIC-8 (4.90 mm × 3.91 mm) and thermally enhanced WSON-8 (4.00 mm × 4.00 mm) packages. Both feature exposed thermal pad (WSON) or standard leadframe (SOIC) for PCB heat dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM5109MX/NOPB, LM5109AMA/NOPB offers identical performance in tube packaging for prototyping and low-volume builds; versus UCC27201D, it trades peak current and speed for integrated bootstrap UVLO and wider HB–HS voltage tolerance-critical for reliable operation in variable-duty-cycle converters.

Availability

LM5109AMA/NOPB is available at Aetrix Electronics and suitable for motor drives, isolated DC–DC converters, current-fed push-pull topologies, and two-switch forward power supplies requiring stable component supply, long-lifecycle support, and consistent parametric performance across temperature and voltage ranges.

Supply support for LM5109AMA/NOPB 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 ICs, with decades of expertise in high-reliability power conversion solutions.

The LM5109AMA/NOPB belongs to TI's high-voltage gate driver product line, engineered specifically for cost-sensitive, high-efficiency half-bridge and synchronous buck applications where bootstrap-based high-side drive and TTL compatibility are essential.

FAQ

What is the maximum allowable HS node voltage for LM5109AMA/NOPB?

The LM5109AMA/NOPB supports HS node voltages from –1 V to +90 V relative to VSS. Transient excursions below ground must not exceed VDD – 15 V (e.g., if VDD = 10 V, HS must stay ≥ –5 V) to prevent parasitic conduction. This rating is confirmed in Section 6.1 Absolute Maximum Ratings and Figure 10 of the SNVS412C datasheet.

Does LM5109AMA/NOPB require an external bootstrap diode?

Yes, LM5109AMA/NOPB requires an external fast-recovery or Schottky bootstrap diode (e.g., 1N4148 or PMEG4010CEH) connected from VDD to HB. The diode charges the bootstrap capacitor during low-side conduction; its forward voltage drop directly impacts minimum achievable HB–HS voltage and must be factored into UVLO margin calculations per Section 8.2.2.2.

Can LM5109AMA/NOPB drive P-channel MOSFETs on the high side?

No, LM5109AMA/NOPB is designed exclusively for N-channel MOSFETs on both high-side and low-side positions. Its HO output is a source-follower configuration referenced to HS and cannot provide the gate-to-source voltage polarity required for P-MOSFET enhancement-mode operation. The datasheet explicitly states "drives both a high-side and low-side N-Channel MOSFET" in Feature 1.

What is the purpose of the internal pulldown resistors on HI and LI pins of LM5109AMA/NOPB?

The LM5109AMA/NOPB integrates ~200 kΩ internal pulldown resistors on HI and LI pins to ensure both outputs default to low when inputs are unconnected or floating. This prevents unintended MOSFET turn-on during power-up, reset, or controller fault conditions-critical for safety in motor and power supply applications per Section 5 Pin Functions.

How does LM5109AMA/NOPB handle mismatched input timing between HI and LI?

LM5109AMA/NOPB processes HI and LI independently with no internal interlock or dead-time insertion. If both inputs go high simultaneously, both HO and LO will assert, risking shoot-through. System-level dead time must be implemented in the upstream PWM controller. The device's 2 ns typical delay matching (Section 6.6) minimizes timing skew but does not prevent overlap-confirmed in Table 1 INPUT and OUTPUT Logic Table.