Microchip MCP1662

Description

The MCP1662 device is a compact, space-efficient,fixed-frequency, non-synchronous step-up converter optimized to drive LED strings with constant current from two and three-cell alkaline and NiMH/NiCd or one-cell Li-Ion or Li-Polymer batteries.

The device integrates a 36V, 800 m low-side switch,which is protected by the 1.3A cycle-by-cycle inductor peak current limit operation. Low-voltage technology allows the MCP1662 to start-up without high inrush current or output overshoot. All compensation and protection circuitry is integrated to minimize the number of external components.

The internal feedback (VFB) voltage is set to 300 mV for low power dissipation when sensing and regulating the LED current. A single resistor sets the LED current.

The device features an UVLO which avoids start-up with low inputs or ischarged batteries for two cell-powered applications.

There is an open load protection (OLP) which turns off the operation in situations when the LED string is accidentally disconnected or the feedback pin is short-circuited to GND.

For standby applications (EN = GND), the device stops switching, enters in Sleep mode and consumes 20 nA typical of input current.

Features

• 36V, 800m Integrated Switch
• Up to 92% Efficiency
• Drive LED Strings in Constant Current
• 1.3A Peak Input Current Limit:
• ILED up to 200 mA @ 5.0V VIN, 4 White LEDs
• ILED up to 125 mA @ 3.3V VIN, 4 White LEDs
• ILED up to 100 mA @ 4.2V VIN, 8 White LEDs
• Input Voltage Range: 2.4V to 5.5V
• Feedback Voltage Reference: VFB = 300 mV
• Undervoltage Lockout (UVLO):
• UVLO@VIN Rising: 2.3V, typical
• UVLO@VIN Falling: 1.85V, typical
• Sleep Mode with 20 nA Typical Quiescent Current
• PWM Operation: 500 kHz Switching Frequency
• Cycle-by-Cycle Current Limiting
• Internal Compensation
• Inrush Current Limiting and Internal Soft Start
• Open Load Protection (OLP) in the Event of:
• Feedback pin shorted to GND (preventexcessive current into LEDs)
• Disconnected LED string (prevent overvoltageto the converter’s Output and SW pin)
• Overtemperature Protection
• Available Packages:
• 5-Lead SOT-23
• 8-Lead 2x3 TDFN

Typical applications

• Medical Equipment
• Camera Flash
• Two and Three-Cell Alkaline or NiMH/NiCd White LED Driver for Backlighting Products
• Portable DVD Players
• GPS Navigation Systems
• LCD Monitors
• Li-Ion Battery LED Lightning Application
• LED Flashlights and Backlight Current Source
• Handheld Gaming Devices
• Portable Devices

More information

• Datasheet
• IC product information