MIC3205YML T5 Microchip

MIC3205 High-Brightness LED Driver Controller with Fixed-Frequency Hysteretic Control General Description Features The MIC3205 is a hysteretic, step-down, high-brightness 4.5V to 40V input voltage range LED (HB LED) driver with a patent pending frequency Fixed operating frequency over input voltage range regulation scheme that maintains a constant operating High efficiency ( 90%) frequency over input voltage range. It provides an ideal 5% LED current accuracy solution for interior/exterior lighting, architectural and ambient lighting, LED bulbs, and other general illumination High-side current sense applications. Dedicated dimming control input The MIC3205 is well suited for lighting applications Hysteretic control (no compensation ) requiring a wide input voltage range. The hysteretic control Up to 1.5MHz switching frequency provides good supply rejection and fast response during Adjustable constant LED current load transients and PWM dimming. The high-side current Over-temperature protection sensing and on-chip current-sense amplifier deliver LED current with 5% accuracy. An external high-side current- 40 C to 125 C junction temperature range sense resistor is used to set the output current. Applications The MIC3205 offers a dedicated PWM input (DIM) which enables a wide range of pulsed dimming. A high-frequency Architectural, industrial, and ambient lighting switching operation up to 1.5MHz allows the use of smaller LED bulbs external components minimizing space and cost. Indicators and emergency lighting The MIC3205 operates over a junction temperature from Street lighting 40C to +125C and is available in a 10-pin 3mm x 3mm Channel letters MLF package. 12V lighting systems (MR-16 bulbs, under-cabinet Data sheets and support documentation are available on lighting, garden/pathway lighting) Micrels web site at: www.micrel.com. Typical Application Normalized Switching Frequency vs. Input Voltage 2.0 I = 1A LED R = 0.2 CS 1.5 1 LED L = 22H 1.0 4 LED 10 LED 6 LED 0.5 L = 47H L = 33H L = 68H 0.0 0 9 18 27 36 45 INPUT VOLTAGE (V) MIC3205 Buck LED Driver MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc. Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. MIC3205 Ordering Information (1) Part Number Junction Temperature Range Package MIC3205YML 40C to 125C 10-Pin 3mm x 3mm MLF Note: 1. MLF is a GREEN RoHS-compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free. Pin Configuration 10-Pin 3mm x 3mm MLF (ML) Top View Pin Description Pin Number Pin Name Pin Function Voltage Regulator Output. The VCC pin is the output of a linear regulator powered from VIN, which 1 VCC supplies power to the internal circuitry. A 4.7F ceramic capacitor is recommended for bypassing. Place it as close as possible to the VCC and AGND pins. Do not connect to an external load. Current Sense Input. Negative input to the current sense comparator. Connect an external sense 2 CS resistor to set the LED current. Connect the current sense resistor as close as possible to the chip. Input Power Supply. VIN is the input supply pin to the internal circuitry. Due to high frequency switching 3 VIN noise, a 10F ceramic capacitor is recommended for bypassing and should be placed as close as possible to the VIN and PGND pins. See PCB Layout Guidelines. VIN Sense. Positive input to the current sense comparator. Connect as close as possible to the current 4 VINS sense resistor. 5 AGND Analog Ground. Ground for all internal low-power circuitry. Enable Input. Logic high (greater than 2V) powers up the regulator. A logic low (less than 0.4V) powers 6 EN down the regulator and reduces the supply current of the device to less than 2A. A logic low pulls down the DRV pin turning off the external MOSFET. Do not drive the EN pin above VIN. Do not leave floating. PWM Dimming Input. A PWM input can be used to control the brightness of the LED. Logic high (greater 7 DIM than 2V) enables the output. Logic low (less than 0.4V) disables the output regardless of the EN state. Do not drive the DIM pin above VIN. Do not leave floating. Timer Capacitor. A capacitor is required from CTIMER to ground sets the target switching frequency 8 CTIMER -4 using the equation C =2.22*10 / F TIMER SW Power Ground. Ground for the power MOSFET gate driver. The current loop for the power ground 9 PGND should be as small as possible and separate from the analog ground loop. See PCB Layout Recommendations. Gate Drive Output. Connect to the gate of an external N-channel MOSFET. The drain of the external 10 DRV MOSFET connects directly to the inductor and provides the switching current necessary to operate in hysteretic mode. EP ePAD Exposed Pad. Must be connected to a GND plane for best thermal performance. October 2012 2 M9999-102312-A