Infineon Technologies IRS21531DSPBF

Overview

IRS21531DSPBF from Infineon Technologies is a self-oscillating 600 V half-bridge gate driver IC with integrated bootstrap FET, 50% max duty cycle, 0.6 µs typical deadtime, and 15.4 V VCC zener clamp-designed for resonant LLC and CFL ballast control in AC-DC offline converters.

For engineers reviewing the IRS21531DSPBF datasheet, IRS21531DSPBF pinout, IRS21531DSPBF application, or IRS21531DSPBF equivalent, key selection criteria include dV/dt immunity (±50 V/ns), micropower startup current (130–170 µA), CT-based shutdown threshold (2.2–2.4 V), and SOIC-8 package compatibility with board-level thermal management.

Technical Context

The IRS21531DSPBF integrates a CMOS 555-style oscillator front-end with RT/CT programmable frequency control (88–100 kHz), dual UVLO comparators (VCCUV+ = 11.0 V, VBSUV+ = 9.0 V), and independent high-side/low-side drivers with internal deadtime logic. Its HVIC process enables direct 600 V floating operation referenced to VS.

It features non-latched shutdown triggered when CT voltage drops below 1/6 × VCC, internal bootstrap FET with 55 mA VB sourcing capability at 13.7 V, and ±50 V/ns dV/dt noise immunity on HO/LO outputs-critical for reliable switching in high-noise bridge configurations.

Key Specifications

Pinout & Package

IRS21531DSPBF is housed in an 8-lead SOIC package (SO8) with standard 1.27 mm pitch, rated for 128 °C/W junction-to-ambient thermal resistance under board-mounted conditions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IRS2153DSPBF and IR21531PBF, the IRS21531DSPBF offers optimal trade-off of compact SOIC packaging, lowest deadtime, and integrated bootstrap FET-making it ideal for space-constrained, high-efficiency resonant converters requiring fast, reliable switching.

Availability

IRS21531DSPBF is available at Aetrix Electronics and suitable for compact fluorescent lamp ballasts, LED drivers with resonant topology, and induction heating power stages requiring stable component supply and long-term industrial availability.

Supply support for IRS21531DSPBF 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 German semiconductor manufacturer specializing in power management, automotive, and industrial control ICs, with leadership in high-voltage gate driver technology.

The IRS2153x family targets cost-sensitive, self-oscillating half-bridge applications in lighting, appliance, and auxiliary power conversion-emphasizing integration, noise immunity, and ease of implementation.

FAQ

What is the purpose of the CT pin shutdown feature?

The CT pin shutdown activates when voltage drops below 2.3 V (1/6 × VCC), disabling both HO and LO outputs without latching. This provides non-destructive fault response during overcurrent or loss-of-bootstrap conditions, allowing automatic recovery once CT voltage rises above threshold-ideal for intermittent overload protection in resonant converters.

Can IRS21531DSPBF drive SiC MOSFETs directly?

No. IRS21531DSPBF's 180 mA source / 260 mA sink current and 220 ns rise time are optimized for silicon MOSFETs with ≤1 nF gate capacitance. Driving SiC devices typically requires higher peak current (>1 A) and faster edge rates; a dedicated SiC gate driver or external buffer stage is recommended.

How does the internal bootstrap FET function during startup?

At power-on, the internal bootstrap FET conducts when VB > VCC, charging the bootstrap capacitor through the internal path. It sustains ~55 mA at 13.7 V, enabling reliable high-side drive without external diode-reducing startup time and eliminating reverse recovery losses associated with discrete diodes.

Is the 15.4 V VCC clamp active during normal operation?

Yes-the internal Zener remains active whenever VCC exceeds 15.4 V. To prevent excessive power dissipation, the external supply must limit current to ≤5 mA (per datasheet Note 1). Typical designs use a resistor-fed auxiliary winding or current-limited LDO to maintain safe clamp conduction during steady-state operation.