Infineon Technologies IR2156

Overview

IR2156 from Infineon Technologies is a ballast control IC integrating high-voltage half-bridge gate driver, programmable oscillator, and state-machine logic for fluorescent lamp electronic ballasts. It delivers 40 kHz run frequency (typ), 55 kHz preheat frequency (typ), 2 µs dead time, 1.25 V over-current threshold, and internal 15.6 V zener clamp - enabling single-chip control of lamp preheat, ignition, and run phases in compact CFL and T8/T5 ballast designs.

For engineers reviewing the IR2156 datasheet, IR2156 pinout, IR2156 application, or IR2156 equivalent, key selection considerations include preheat timing programmability via RPH/CT, DC bus sensing via VDC/RVDC, shutdown hysteresis (450 mV), micropower startup (150 µA), and fault latching behavior during lamp strike failure.

Technical Context

The IR2156 implements a finite-state machine with four operational modes-UVLO, PREHEAT, IGNITION RAMP, and RUN-triggered by VCC, SD, CPH voltage, and CS input. Preheat frequency (f_PH) and run frequency (f_RUN) are independently set via external RT and RPH resistors with CT capacitor, while internal current source (4.3 µA typ) charges CPH to control mode transitions.

Protection is hardware-based: over-current detection at CS pin (1.25 V threshold, 160 ns propagation delay), VCC undervoltage lockout (11.5 V rising, 9.5 V falling), SD pin hysteresis (450 mV), and automatic latch-off on lamp removal or strike failure. The HO/LO drivers support 600 V floating offset and deliver 500 mA peak output current.

Key Specifications

Pinout & Package

IR2156 is available in 14-pin SOIC (IR2156PBF) and PDIP (IR2156) packages, both with standard 1.27 mm pitch and exposed thermal pad (SOICN14). Pin functions are validated per Infineon's official datasheet revision A (2005).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ballast control applications.

Compared with IRS2166D and UCC3305, the IR2156 offers standalone half-bridge control without PFC overhead and higher run frequency headroom (40 kHz vs. 30 kHz), making it optimal for mid-power T5/T8 systems requiring minimal external components and robust filament preheat control.

Availability

IR2156 is available at Aetrix Electronics and suitable for compact fluorescent lamp ballasts, T5/T8 linear lighting systems, and industrial lighting control modules requiring stable component supply across extended production lifecycles.

Supply support for IR2156 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 drivers and lighting control solutions.

The IR2156 belongs to Infineon's legacy ballast control product line, designed specifically for self-oscillating electronic fluorescent ballasts requiring programmable preheat, ignition, and run-phase timing without microcontroller intervention.

FAQ

What is the purpose of the CPH pin on the IR2156?

The CPH pin integrates a 4.3 µA current source that charges an external capacitor to generate a voltage ramp. This ramp determines preheat duration and triggers the transition from PREHEAT to IGNITION RAMP mode when CPH exceeds 10 V. During fault conditions, CPH is discharged to 0 V to force latch-off.

How does the IR2156 handle lamp strike failure?

When the CS pin voltage exceeds 1.3 V for longer than 135 ns (indicating failed lamp ignition), the IR2156 enters FAULT Mode: HO/LO outputs disable, CPH discharges, CT resets, and quiescent current rises to ~180 µA. Recovery requires cycling VCC or pulling SD low to reset the latch.

Can the IR2156 drive MOSFETs directly without external gate resistors?

No - although the IR2156 provides 500 mA peak gate drive, external series gate resistors (typically 10–22 Ω) are required to dampen ringing, limit dV/dt-induced Miller turn-on, and control rise/fall times (110 ns tr / 55 ns tf). Layout-dependent parasitics make fixed internal resistance insufficient for robust switching.

What is the role of the VDC pin in IR2156 operation?

The VDC pin connects to the rectified DC bus through an external resistor divider. Internally, it biases a comparator that monitors bus voltage level. When VDC drops below threshold, it initiates soft-start or UVLO recovery; when high, it enables the RVDC current source for preheat timing calibration and DC bus brown-out detection.