Texas Instruments LM5105SDX

Overview

LM5105SDX from Texas Instruments is a 100-V half-bridge gate driver IC designed to control high-side and low-side N-channel MOSFETs in synchronous buck and half-bridge power stages. It delivers 1.8-A peak source/sink current, supports bootstrap supply up to 118 V DC, integrates a bootstrap diode, features programmable dead time via RDT pin (75–705 ns), and operates with TTL-compatible IN/EN inputs.

For engineers reviewing the LM5105SDX datasheet, LM5105SDX pinout, LM5105SDX application, or LM5105SDX equivalent, this page provides verified technical context, confirmed pin functions, real-world dead-time tuning behavior, thermal performance data, and validated alternative options for high-voltage motor drive and DC-DC converter designs.

Technical Context

The LM5105SDX implements a robust level-shift architecture enabling high-speed floating high-side drive up to 100 V HS node voltage while maintaining <26 ns typical turnoff propagation delay. Its dual UVLO circuits independently monitor VDD (6.9 V rising threshold) and HB–HS (6.6 V rising threshold) to ensure safe startup and fault recovery.

Dead time is precisely controlled by an external resistor on RDT, generating matched turnon delays for HO and LO (±50 ns matching). The integrated bootstrap diode (0.85–1.1 V forward drop at 100 mA) eliminates need for external diode, reducing BOM count and layout complexity in compact half-bridge layouts.

Key Specifications

Pinout & Package

LM5105SDX is housed in a thermally enhanced 10-pin WSON package (4.00 mm × 4.00 mm) with an exposed pad soldered to PCB ground for optimal thermal dissipation (R_θJB = 14.9 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with IRS2004PBF and UCC27201ADRMT, LM5105SDX uniquely combines integrated bootstrap diode, single-resistor dead-time programming, and 100 V HS capability in a compact WSON package-making it optimal for cost-sensitive, space-constrained 48 V industrial and motor control designs where design simplicity and reliability are prioritized.

Availability

LM5105SDX is available at Aetrix Electronics and suitable for motor control, DC-DC conversion, solid-state relay, and industrial inverter applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM5105SDX 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 company specializing in analog, embedded processing, and power management technologies, with decades of leadership in high-reliability power ICs.

The LM5105SDX belongs to TI's high-voltage gate driver product line, engineered specifically for robust, compact half-bridge control in industrial motor drives, telecom power supplies, and energy-efficient DC-DC converters.

FAQ

What is the maximum allowable voltage on the HS pin of the LM5105SDX?

The LM5105SDX specifies a maximum HS-to-VSS voltage of 100 V under recommended operating conditions. Absolute maximum rating allows transient excursions down to –5 V (if VDD ≤ 9 V), but sustained operation must remain within –1 V to 100 V to avoid latch-up or damage. This 100 V limit defines its use case in 48 V and 60 V industrial systems, not 400 V automotive or 600 V AC applications. Always verify HS node clamping in your layout using the body diode of the low-side MOSFET.

How does the RDT pin set dead time in the LM5105SDX?

The RDT pin on the LM5105SDX accepts a resistor to VSS that programs matched turnon delays for both HO and LO outputs. With RDT = 10 kΩ, dead time is 75–150 ns; with RDT = 100 kΩ, it increases to 570–705 ns. The internal RDT bias is 3 V with 1-mA current limit, making the timing linearly proportional to resistance. Layout best practice requires placing the RDT resistor within 2 mm of the pin to avoid noise coupling that could distort timing accuracy.

Does the LM5105SDX require an external bootstrap diode?

No, the LM5105SDX integrates a bootstrap diode with 0.85–1.1 V forward voltage at 100 mA, eliminating the need for an external diode. This reduces bill-of-materials count, PCB area, and routing complexity. However, the diode's dynamic resistance (0.8–1.5 Ω) and power dissipation must be considered at high switching frequencies (>500 kHz) or large bootstrap capacitor recharge currents-TI recommends verifying thermal rise in high-duty-cycle applications.

What are the UVLO thresholds and hysteresis values for the LM5105SDX?

The LM5105SDX has two independent UVLO circuits: VDD UVLO triggers at 6.9 V (rising) with 0.5 V hysteresis, and HB–HS UVLO triggers at 6.6 V (rising) with 0.4 V hysteresis. These thresholds ensure safe startup and fault recovery-VDD UVLO disables both HO and LO, while HB–HS UVLO disables only HO to maintain low-side functionality during bootstrap capacitor discharge. Both thresholds vary <±0.1 V over –40°C to 125°C.

Can the LM5105SDX drive MOSFETs with gate charge exceeding 50 nC?

Yes, the LM5105SDX can drive MOSFETs with Q_g > 50 nC. Its 1.8-A peak source and 1.6-A peak sink current, combined with 15 ns rise/fall times into 1000 pF, enable fast switching even for high-Q_g devices. For example, driving a 60 nC MOSFET at 100 kHz requires ~6 mA average gate current-well within the LM5105SDX's 3 mA typical operating supply current (IDDO). Thermal validation is recommended for continuous high-frequency operation with Q_g > 80 nC.