MCP1662 Datasheet, PDF (1/28 Pages) Microchip Technology – High-Voltage Step-Up LED Driver with UVLO and Open Load Protection

MCP1662
High-Voltage Step-Up LED Driver with UVLO and Open Load Protection
Features
• 36V, 800 m Integrated Switch
• Up to 92% Efficiency
• Drive LED Strings in Constant Current
• 1.3A Peak Input Current Limit:
- I_LED up to 200 mA @ 5.0V V_IN, 4 White LEDs
- I_LED up to 125 mA @ 3.3V V_IN, 4 White LEDs
- I_LED up to 100 mA @ 4.2V V_IN, 8 White LEDs
• Input Voltage Range: 2.4V to 5.5V
• Feedback Voltage Reference: V_FB = 300 mV
• Undervoltage Lockout (UVLO):
- UVLO @ V_IN Rising: 2.3V, typical
- UVLO @ V_IN 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
• Open Load Protection (OLP) in the Event of:
- Feedback pin shorted to GND (prevent
excessive current into LEDs)
- Disconnected LED string (prevent overvoltage
to the converter’s Output and SW pin)
• Overtemperature Protection
• Available Packages:
- 5-Lead SOT-23
- 8-Lead 2x3 TDFN
Applications
• Two and Three-Cell Alkaline or NiMH/NiCd White
LED Driver for Backlighting Products
• Li-Ion Battery LED Lighting Application
• Camera Flash
• LED Flashlights and Backlight Current Source
• Medical Equipment
• Portable Devices:
- Handheld Gaming Devices
- GPS Navigation Systems
- LCD Monitors
- Portable DVD Players
General 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 a two- or three-cell alkaline or lithium Energizer®,
or NiMH/NiCd, or one-cell Lithium-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. All compensation and pro-
tection circuitry is integrated to minimize the number of
external components.
The internal feedback (V_FB) 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 Undervoltage Lockout (UVLO)
that avoids start-up with low inputs or discharged bat-
teries for two-cell-powered applications.
There is an open load protection (OLP) which turns off
the operation in situations when the LED string is acci-
dentally disconnected or the feedback pin is short-cir-
cuited to GND.
For standby applications (EN = GND), the device stops
switching, enters into Sleep mode and consumes
20 nA typical of input current.
Package Types
MCP1662
SOT-23
SW 1
GND 2
V_FB 3
5 V_IN
4 EN
MCP1662
2x3 TDFN*
V_{FB 1}
8 ^EN
S_GND 2 EP 7 ^P_GND
SW ³
9
6 _NC
NC ⁴
5 _VIN
* Includes Exposed Thermal Pad (EP); see
Table 3-1.
 2014-2015 Microchip Technology Inc.
DS20005316E-page 1