MCP1664 High-Voltage Step-Up LED Driver with UVLO and Open Load Protection Features General Description 36V, 400 m Integrated Switch The MCP1664 is a compact, space-efficient, fixed-frequency, non-synchronous step-up converter Up to 92% Efficiency optimized to drive multiple strings of LEDs with Drive LED Strings in Constant Current constant current powered from two and three-cell 1.8A Peak Input Current Limit: alkaline or NiMH/NiCd as well as from one-cell Li-Ion or -I up to 200 mA at 3.3V V , 4 White LEDs LED IN Li-Polymer batteries. -I up to 300 mA at 5.0V V , 4 White LEDs LED IN The device integrates a 36V, 400 m low-side switch, -I up to 150 mA at 4.2V V , 8 White LEDs LED IN which is protected by the 1.8A cycle-by-cycle inductor Input Voltage Range: 2.4V to 5.5V peak current limit operation. The MCP1664 starts up without high inrush current or output overshoot. All Undervoltage Lockout (UVLO): compensation and protection circuitry is integrated to -UVLOatV Rising: 2.3V, typical IN minimize the number of external components. -UVLOatV Falling: 1.85V, typical IN The internal feedback (V ) voltage is set to 300 mV for FB Shutdown Current (EN = GND): 40 nA Typical low power dissipation when sensing and regulating the PWM Operation: 500 kHz Switching Frequency LED current. A single resistor sets the LED current. Cycle-by-Cycle Current Limiting The device features an UVLO which avoids start-up Internal Compensation with low inputs or discharged batteries for two Open Load Protection (OLP) in the event of: cell-powered applications. - Feedback Pin Shorted to GND (Prevent The MCP1664 features an open load protection (OLP) Excessive Current into LEDs) which turns off the operation in situations when the - Disconnected LED String (Prevent LED string is accidentally disconnected or the feedback Overvoltage to the Converters Output and pin is short-circuited to GND. SW Pin) While in Shutdown mode (EN = GND), the device stops Overtemperature Protection switching, and consumes 40 nA typical of input current. Available Packages: - 5-Lead SOT-23 Package Types - 8-Lead 2x3 TDFN MCP1664 SOT-23 Applications V 5 IN SW 1 Two and Three-Cell Alkaline or NiMH/NiCd White LED Driver for Backlighting Products 2 GND Li-Ion Battery LED Lightning Application Camera Flash V 3 FB 4 EN LED Flashlights and Backlight Current Source Medical Equipment Portable Devices: MCP1664 2x3 TDFN* - Hand-Held Gaming Devices V 1 8 EN FB - GPS Navigation Systems S P 2 7 GND EP GND -LCD Monitors 9 3 6 NC - Portable DVD Players SW 4 5 V NC IN * Includes Exposed Thermal Pad (EP) see Table 3-1. 2015 Microchip Technology Inc. DS20005408A-page 1MCP1664 Typical Application D L V OUT MBRM140 4.7 10 H Max. 32V LED1 C IN SW 4.7 30 F V IN LED2 V 2.4V 3.0V IN 0.3V C + I = OUT LED R 10 F SET MCP1664 LED6 EN - V ON FB V =0.3V + FB R OFF SET 12 GND I =25mA LED - L = 4.7 H for maximum 4 white LEDs L = 10 H for 5 to 10 white LEDs C = 4.7 10F for V >2.5V IN IN C = 20 30 F for V <2.5V IN IN Maximum LED Current in Regulation vs. Input Voltage, T = +25C A 350 300 4 wLEDs, L = 4.7 H 250 200 150 8 wLEDs, L = 10 H 100 50 0 2 2.5 3 3.5 4 4.5 5 5.5 V (V) IN DS20005408A-page 2 2015 Microchip Technology Inc. I (mA) OUT ALAKLINE ALKALINE