Infineon Technologies IR2156STR

Overview

IR2156STR from Infineon Technologies is a high-voltage ballast control IC integrating a half-bridge gate driver, programmable oscillator, and state-machine logic for fluorescent lamp electronic ballasts. It delivers programmable preheat frequency (49–60 kHz), preheat time (via RPH/CPH), ignition ramp, 1.25 V over-current threshold, and 40 kHz run frequency - enabling reliable cold-start operation in commercial lighting systems.

For engineers reviewing the IR2156STR datasheet, IR2156STR pinout, IR2156STR application, or IR2156STR equivalent, key selection criteria include its integrated dead-time control (2.0 µs), VCC zener clamp (15.6 V), micropower startup (150 µA), CT/RT/CPH/RPH programmability, and fault latching behavior during lamp strike failure.

Technical Context

The IR2156STR implements a state-driven control architecture with four operational modes: UVLO, Preheat, Ignition Ramp, and Run - each triggered by CPH voltage, SD pin status, and CS threshold crossing. Its oscillator uses CT/RT to set f_PH and f_RUN, while RPH and CPH jointly determine preheat duration and ramp profile.

Protection is hardware-based: over-current detection at CS pin (1.25 V threshold, 160 ns propagation delay), shutdown pin hysteresis (5.1 V trip / 450 mV reset), and VCC undervoltage lockout (11.5 V rising / 9.5 V falling). The internal 15.6 V zener clamp on VCC limits supply rail stress during transients.

Key Specifications

Pinout & Package

IR2156STR is supplied in a 14-pin SOIC (SOICN14) package with exposed pad for thermal enhancement. Pin 1 is RT, Pin 14 is VB, and Pin 7 is COM - all pins match the standard SOICN14 footprint and thermal pad layout per Infineon's packaging specification.

Key Features

Applications

Equivalent & Alternatives

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

Compared with FAN7711MX and IRS2166DSTRPBF, the IR2156STR offers superior integration for legacy fluorescent ballast replacement - especially where micropower UVLO, single-supply VCC clamp, and deterministic state-mode sequencing are required without firmware dependency.

Availability

IR2156STR is available at Aetrix Electronics and suitable for commercial lighting ballasts, industrial T5/T8 lamp drivers, and UV-C germicidal systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for IR2156STR 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 IR2156STR belongs to Infineon's Ballast Control IC product line, designed specifically for self-oscillating, microcontroller-free fluorescent lamp drivers with integrated protection and programmable timing.

FAQ

What is the maximum allowable VBS voltage for IR2156STR?

The absolute maximum high-side floating supply voltage (VB) is 625 V referenced to COM. Sustained operation above 600 V risks accelerated degradation of the internal level-shifter and may trigger overvoltage protection. Designers must ensure VB remains within recommended operating conditions (≤600 V) under worst-case line transients and lamp arc instability.

How does the IR2156STR handle lamp filament failure during preheat?

During preheat, the IR2156STR monitors CS voltage continuously. If filament opens, CS drops below 1.25 V threshold before CPH reaches 7.5 V, causing the state machine to enter FAULT mode - disabling HO/LO outputs, discharging CPH, and holding latch until VCC falls below 9.5 V and recovers.

Can IR2156STR drive MOSFETs directly without external gate resistors?

No. Although IR2156STR provides 500 mA peak output current, external gate resistors (typically 10–22 Ω) are required to dampen ringing, limit dV/dt-induced Miller turn-on, and control rise/fall times (tr ≤150 ns, tf ≤100 ns) per datasheet test conditions.

Is the CT pin internally biased, or does it require an external pull-down?

The CT pin is actively driven by internal current sources during oscillation and floats during UVLO/FAULT modes. No external pull-down is needed - the pin is designed for direct connection to timing capacitor (470 pF typical) and RT/RPH resistors without bias network.