Infineon Technologies IR2156S

Overview

IR2156S 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 programmable preheat frequency (49–60 kHz), run frequency (36–44 kHz), preheat time via CPH/RT/RPH, internal ignition ramp, and over-current threshold (1.1–1.44 V). Used in 2D/4-pin CFL and T5/T8 linear lamp drivers with automatic restart on lamp strike failure.

For engineers reviewing the IR2156S datasheet, IR2156S pinout, IR2156S application, or IR2156S equivalent, key selection criteria include preheat/run frequency tuning range, integrated dead-time control (2.0 µs), VCC zener clamp (15.6 V), current-sense propagation delay (160 ns), and shutdown hysteresis (450 mV) - all critical for reliable cold-start and fault recovery in commercial lighting systems.

Technical Context

The IR2156S implements a three-state control machine (PREHEAT → IGNITION RAMP → RUN) triggered by CPH voltage ramping under ICPH = 4.3 µA charge current and reset by CS > 1.3 V or SD > 5.1 V. Its oscillator uses CT capacitor and RT resistor to set fRUN (typ. 40 kHz) and RPH/CT to set fPH (typ. 55 kHz), with internal 50% duty cycle and dual CT thresholds (4.8 V / 8.3 V).

Protection architecture includes UVLO (11.5 V turn-on, 9.5 V turn-off), latch-immune fault detection on CS and SD pins, and micropower startup (120 µA in UVLO mode). The high-side driver supports VB up to 625 V with VS offset tracking, while LO/HO outputs drive external MOSFETs with 110 ns rise and 55 ns fall times into 1000 pF loads.

Key Specifications

Pinout & Package

IR2156S is housed in a 14-pin SOIC (SOICN14) package with creepage-optimized layout for high-voltage isolation between COM and VB/VS domains.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IRS2156D(S), IR2156S offers broader legacy support and lower cost but narrower oscillator tolerance; versus BD7810F, it delivers full high-voltage integration for direct AC-line operation but demands more complex PCB layout for HV isolation.

Availability

IR2156S is available at Aetrix Electronics and suitable for compact fluorescent lamp ballasts, T5/T8 linear fixture drivers, lamp failure detection systems, and DC bus-sensed emergency lighting requiring stable component supply across industrial lighting OEM programs.

Supply support for IR2156S 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 IR2156S belongs to Infineon's ballast control IC product line, designed specifically for self-oscillating electronic fluorescent lamp drivers with integrated protection and programmable timing - targeting cost-sensitive, high-reliability commercial lighting applications.

FAQ

What is the purpose of the CPH pin on the IR2156S?

The CPH pin serves as the preheat timing capacitor node, charged at a constant 4.3 µA current to ramp voltage from 0 V to ~10–13 V. When CPH reaches ~10 V, the IC transitions from PREHEAT to RUN mode; at ~13 V, it enters IGNITION RAMP mode. This eliminates need for external timers or microcontrollers in lamp-start sequencing.

How does the IR2156S handle lamp strike failure?

Upon lamp strike failure, the CS pin detects sustained over-current (>1.25 V for >135 ns), triggering FAULT mode: oscillator halts, HO/LO go low, and CPH discharges. After timeout, the IC automatically resets into PREHEAT mode if VCC remains valid and SD is low - enabling up to three retry attempts before latching off.

Can the IR2156S drive MOSFETs directly without external gate resistors?

No. While IR2156S provides 200 mA peak output drive, external gate resistors (typically 10–22 Ω) are required to damp ringing, limit dV/dt-induced Miller turn-on, and control switching speed for EMI compliance. Layout must minimize loop inductance between HO/LO, VS/COM, and external MOSFET sources.

What is the role of the VDC pin in IR2156S operation?

The VDC pin monitors DC bus voltage via an external resistor divider. If VDC falls below ~7 V (set by internal comparator), the IC forces UVLO reset - stopping oscillation and discharging CPH. This protects against operation during brownout or failing bulk capacitor conditions, ensuring safe restart only when bus voltage stabilizes.