MIC3202/MIC3202-1 High-Brightness LED Driver with Integrated MOSFET and High-Side Current Sense General Description Features The MIC3202 is a hysteretic, step-down, constant-current, 6V to 37V input voltage range High-Brightness LED (HB LED) driver. It provides an ideal High efficiency ( >90%) solution for interior/exterior lighting, architectural and 5% LED current accuracy ambient lighting, LED bulbs, and other general illumination MIC3202: Dither enabled for low EMI applications. MIC3202-1: Dither disabled The MIC3202 is well suited for lighting applications High-side current sense (up to 1A) requiring a wide-input voltage range. The hysteretic control gives good supply rejection and fast response during load Dedicated dimming control input transients and PWM dimming. The high-side current Hysteretic control (no compensation required) sensing and on-chip current-sense amplifier delivers LED Up to 1MHz switching frequency current with 5% accuracy. An external high-side current- Adjustable constant LED current sense resistor is used to set the output current. Over-temperature protection The MIC3202 offers a dedicated PWM input (DIM) which enables a wide range of pulsed dimming. High-frequency 40C to +125 C junction temperature range switching operation of up to 1MHz allows the use of smaller external components, minimizing space and cost. Applications The MIC3202 offers a frequency dither feature for low-EMI Architectural, industrial, and ambient lighting applications. LED bulbs The MIC3202 operates over a junction temperature from Indicators and emergency lighting 40 C to +125 C and is available in an 8-pin e-PAD SOIC Street lighting package. Channel letters A dither disabled version MIC3202-1 is also available in the same package as the MIC3202. 12V lighting systems (MR-16 bulbs, under-cabinet lighting, garden/pathway lighting) Datasheets and support documentation can be found on Micrels web site at: www.micrel.com. Typical Application Efficiency vs. Input Voltage 100 6LED 8LED 4LED 95 2LED 90 85 I = 1A LED L = 47uH 80 6 1422 3038 INPUT VOLTAGE (V) MIC3202 Step-Down LED Driver Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. MIC3202/MIC3202-1 (1) Ordering Information Part Number Marking Junction Temperature Range Package PWM MIC3202YME MIC3202YME 40C to +125C 8-Pin SOIC Dither MIC3202-1YME MIC3202-1YME 8-Pin SOIC Non-Dither 40C to +125C Note: 1. YM is a GREEN RoHS-compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free. Pin Configuration 8-Pin ePAD SOIC MIC3202/MIC3202-1 Pin Description Pin Pin Name Pin Function Number Voltage Regulator Output. The VCC pin supplies the power to the internal circuitry. The VCC is the output 1 VCC of a linear regulator which is powered from VIN. A 1F ceramic capacitor is recommended for bypassing and should be placed as close as possible to the VCC and AGND pins. Current-Sense Input. The CS pin provides the high-side current sense to set the LED current using an 2 CS external sense resistor. Input Power Supply. The VIN pin is the input supply pin to the internal circuitry and the positive input to the current sense comparator. Due to the high frequency switching noise, a 1F ceramic capacitor is 3 VIN recommended to be placed as close as possible to VIN pin and the power ground (PGND) pin for bypassing. Please refer to layout recommendations. 4 AGND Ground pin for analog circuitry. Internal signal ground for all low power sections. Enable Input. The EN pin provides a logic level control of the output. The voltage has to be 2.0V or higher to enable the current regulator. The output stage is also gated by the DIM input. When the EN pin is 5 EN pulled low, the regulator goes to off state and the supply current of the device is greatly reduced (below 1A). PWM Dimming Input. The DIM pin provides the control for brightness of the LED. A PWM input can be 6 DIM used to control the brightness of LED. DIM high enables the output and its voltage has to be at least 2.0V or higher. DIM low disables the output, regardless of EN high state. Power Ground pin for Internal Power FET. Power Ground (PGND) is the ground path for the high current. 7 PGND The current loop for the power ground should be as small as possible and separate from the Analog ground (AGND) loop. Refer to the layout considerations for more details. Drain of Internal Power MOSFET. The LX pin connects directly to the inductor and provides the switching 8 LX current necessary to operate in hysteretic mode. Due to the high frequency switching and high voltage associated with this pin, the switch node should be routed away from sensitive nodes. EP GND Connect to PGND. September 2010 2 M9999-091710-A