Infineon Technologies IRS27951STRPBF

Overview

IRS27951STRPBF from Infineon Technologies (formerly International Rectifier) is a self-oscillating resonant half-bridge control IC for LLC DC-DC converters, featuring programmable 44–299 kHz switching frequency, 170–250 ns dead time, and dual 300 mA/900 mA gate drivers with ±600 V floating high-side operation. It enables primary-side control in high-efficiency AC-DC power supplies for flat-panel displays.

For engineers reviewing the IRS27951STRPBF datasheet, IRS27951STRPBF pinout, IRS27951STRPBF application, or IRS27951STRPBF equivalent, key selection factors include its CT/RT-programmable oscillator, overcurrent protection via low-side R_DS(on), micropower sleep mode (150–200 µA), and SOIC-8N package compatibility with high-voltage resonant topologies.

Technical Context

The IRS27951STRPBF integrates a self-timed oscillator with external RT/CT components to set frequency and dead time, eliminating need for external clock sources or timing ICs. Its high-side driver uses bootstrap operation referenced to VS, supporting up to +600 V offset with dV/dt immunity of ±50 V/ns.

Protection includes leading-edge blanking (300 ns), under-voltage lockout on both VCC (10.1–11.9 V turn-on, 2 V hysteresis) and VBS (7.6–9.4 V turn-on, 0.6 V hysteresis), and overcurrent detection triggered at VOCP = 1.9–2.1 V on the VS node using low-side MOSFET conduction loss.

Key Specifications

Pinout & Package

IRS27951STRPBF is housed in an 8-pin SOIC-N (SOIC8N) surface-mount package with standard 1.27 mm pitch and exposed pad not present. Pin functions are validated per IRF/Infineon datasheet revision August 2015.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar resonant half-bridge control applications.

Compared with IRS27952STRPBF, the IRS27951STRPBF offers lower OCP trip voltage for enhanced sensitivity in low-R_DS(on) MOSFET designs; versus UCC256301DR, it provides full external frequency/dead-time tuning but requires discrete gate drivers and lacks integrated startup circuitry.

Availability

IRS27951STRPBF is available at Aetrix Electronics and suitable for LCD TV power supplies, telecom 48 V input SMPS, and home audio amplifier PSUs requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for IRS27951STRPBF 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

Infineon Technologies is a global semiconductor leader specializing in power management, sensor, and automotive ICs, with heritage from International Rectifier's high-voltage analog and power control portfolio.

The IRS2795x family was designed specifically for primary-side-controlled LLC resonant converters in high-efficiency, high-density AC-DC power supplies targeting consumer, telecom, and industrial markets.

FAQ

What is the minimum recommended RT resistor value for stable operation?

The datasheet specifies RT = 2 kΩ as the minimum value. Using lower resistance increases oscillator current and may cause instability or excessive power dissipation in the RT pin circuit. At 2 kΩ, the IC maintains reliable startup and frequency accuracy across temperature and supply variations.

Can IRS27951STRPBF drive GaN HEMTs directly?

Yes - its 300 mA source / 900 mA sink capability and fast rise/fall times (60 ns/16 ns into 1 nF) support direct drive of common 12–25 nC GaN devices. Layout must minimize loop inductance, and gate resistor selection should balance switching speed against ringing and EMI.

How does the overcurrent protection respond to short-circuit events?

When VS drops below VOCP (1.9–2.1 V), the IC disables both HO and LO outputs within 300 ns (t_SD). Recovery requires cycling CT/SD below VEN2 (0.6–1.1 V) followed by re-enabling above VEN1 (0.75–1.4 V), ensuring latch-off behavior until fault condition clears.

Is the SOIC-8N package thermally adequate for 299 kHz operation at full load?

At TA ≤ 25°C, the SOIC-8N package delivers 0.833 W power dissipation with R_thJA = 150°C/W. Under typical LLC operating conditions (duty cycle ≤50%, intermittent peak loading), junction temperature remains below 125°C. Forced airflow or copper pour improves margin for continuous 299 kHz use.