MCP1662 High-Voltage Step-Up LED Driver with UVLO and Open Load Protection Features General Description 36V, 800 m Integrated Switch The MCP1662 device is a compact, space-efficient, fixed-frequency, non-synchronous step-up converter Up to 92% Efficiency optimized to drive LED strings with constant current Drive LED Strings in Constant Current from a two- or three-cell alkaline or lithium Energizer, 1.3A Peak Input Current Limit: or NiMH/NiCd, or one-cell Lithium-Ion or Li-Polymer -I up to 200 mA 5.0V V , 4 White LEDs LED IN batteries. -I up to 125 mA 3.3V V , 4 White LEDs LED IN The device integrates a 36V, 800 m low-side switch, -I up to 100 mA 4.2V V , 8 White LEDs LED IN which is protected by the 1.3A cycle-by-cycle inductor Input Voltage Range: 2.4V to 5.5V peak current limit operation. All compensation and pro- tection circuitry is integrated to minimize the number of Feedback Voltage Reference: V =300 mV FB external components. Undervoltage Lockout (UVLO): The internal feedback (V ) voltage is set to 300 mV for -UVLO V Rising: 2.3V, typical FB IN low power dissipation when sensing and regulating the -UVLO V Falling: 1.85V, typical IN LED current. A single resistor sets the LED current. Sleep Mode with 20 nA Typical Quiescent Current The device features an Undervoltage Lockout (UVLO) PWM Operation: 500 kHz Switching Frequency that avoids start-up with low inputs or discharged bat- Cycle-by-Cycle Current Limiting teries for two-cell-powered applications. Internal Compensation There is an open load protection (OLP) which turns off Open Load Protection (OLP) in the Event of: the operation in situations when the LED string is acci- - Feedback pin shorted to GND (prevent dentally disconnected or the feedback pin is short-cir- excessive current into LEDs) cuited to GND. - Disconnected LED string (prevent overvoltage For standby applications (EN = GND), the device stops to the converters Output and SW pin) switching, enters into Sleep mode and consumes Overtemperature Protection 20 nA typical of input current. Available Packages: - 5-Lead SOT-23 Package Types - 8-Lead 2x3 TDFN MCP1662 Applications SOT-23 Two and Three-Cell Alkaline or NiMH/NiCd White SW 1 5 V IN LED Driver for Backlighting Products GND 2 Li-Ion Battery LED Lighting Application V 3 4 EN FB Camera Flash LED Flashlights and Backlight Current Source MCP1662 Medical Equipment 2x3 TDFN* Portable Devices: V EN - Handheld Gaming Devices FB 1 8 - GPS Navigation Systems P 2 7 S EP GND GND 9 -LCD Monitors 3 6 SW NC - Portable DVD Players 4 5 NC V IN * Includes Exposed Thermal Pad (EP) see Table 3-1. 2014-2015 Microchip Technology Inc. DS20005316E-page 1MCP1662 Typical Application D L MBR0540 4.7 10 H V OUT 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 MCP1662 LED6 EN - ON V 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 = 4.7-10 F 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 250 4 wLEDs, L = 4.7 H 200 8 wLEDs, L = 10 H 150 100 50 0 2 2.5 3 3.5 4 4.5 5 5.5 V (V) IN DS20005316E-page 2 2014-2015 Microchip Technology Inc. I (mA) I OUT LED ALAKLINE ALKALINE