Driver chips simplify ballast design

Integrated 600V self-oscillating full-bridge driver ICs are designed for HID ballast applications including general lighting, outdoor street lighting and projectors.

International Rectifier has launched the IRS2453D family of integrated 600V self-oscillating full-bridge driver ICs for HID ballast applications including general lighting, outdoor street lighting and projectors.

The new ICs use IR's proprietary high-voltage integrated circuit (HVIC) technology, integrating two high-side and two low-side gate drivers.

This process allows improvements in device capabilities, tighter specifications, temperature stability and the integration of previously unavailable features.

The IRS2453D features a simple RC network to program the oscillator, eliminating the need to synchronise two half-bridge drivers.

In contrast, solutions using two SO-8 driver ICs require a separate oscillator to drive each half-bridge, resulting in unsymmetrical voltages across the load due to mismatching of the on-time states caused by tolerances and temperature.

In lighting applications, this can cause mercury migration shortening lamp life.

The IRS2453D overcomes this problem by driving both half-bridge drivers with a single oscillator to guarantee accurate matching over the complete temperature and supply voltage range.

Greatly simplifying overall design, the IRS2453D integrates both a latched and nonlatched shutdown input, and eliminates up to seven components.

The latched shutdown allows for implementation of various protection features such as cycle-by-cycle over-current, open-load or short-circuit detection without additional components, while the nonlatched shutdown allows for easy interface to a microcontroller for use in a wider variety of power management applications.

Available in 14-lead DIP and SO packages, the lead-free devices provides 50% duty cycle, fixed 1us (typical) internal deadtime and integrated bootstrap circuitry.

Although the new ICs are designed to drive the required low-frequency AC voltage in HID lamps, they can also be used as a general-purpose block for other high-frequency applications such as fluorescent ballasts and power supplies.

Other key specifications for the IRS2453D include15.6V Zener diode clamp on Vcc and typical micropower startup current of 140uA.

Noise immunity is achieved by low di/dt peak of the gate drivers and with an undervoltage lockout hysteresis of greater than 1.5V.

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