MIC2291

MIC2291 Micrel MIC2291 1.2A PWM Boost Regulator Photo Flash LED Driver General Description The MIC2291 is a 1.2MHz Pulse Width Modulation (PWM), boost-switching regulator that is optimized for high-current, white LED photo flash applications. With a guaranteed switch current of 1.2A, the MIC2291 easily drives a string of 3 white LEDs in series at 100mA, ensuring a high level of brightness and eliminating several ballast resistors. The MIC2291 implements a constant frequency, 1.2MHz PWM control scheme. The high frequency PWM operation saves board space by reducing external component sizes. The added benefit of the constant frequency PWM scheme, in contrast to variable frequency topologies, is much lower noise and input ripple injected back to the battery source. To optimize efficiency, the feedback voltage is set to only 95mV. This reduces the power dissipation in the current set resistor, and allows the lowest total output voltage, hence minimal current draw from the battery. The MIC2291 is available with 2 levels of over-voltage protection, 15V, and 34V. This allows designers to choose the smallest possible external components with the appropriate voltage ratings for their applications. The MIC2291 is available in low-profile, Thin SOT23 5-lead and 8-lead 2mm × 2mm MLF™ package options. The MIC2291 has a junction temperature range of –40°C to +125°C. All support documentation can be found on Micrel’s web site at www.micrel.com. Features 2.5V t...