EMP EMD2050 Schematic [ru]

ESMT/EMP

EMD2050

PWM Step-Up DC/DC Converter for Panel Backlight

General Description

The EMD2050 designed with high efficiency step up

DC/DC converter for driving white LEDs. The device

can drive up 3 white LEDs from a single Li-Ion battery

or a DC power 2.5V to 5.5V. The EMD2050 uses

current mode and pulse-width modulated (PWM)

operation. It switches at 1.2MHz and allows using

small inductor and both of input/output capacitors.

An internal compensation can reduce external

component.

The EMD2050 include under-voltage lockout, current

limit, over voltage and thermal shutdown protection.

The EMD2050 is available in SOT-26 package.

Applications

 Mobile Phone
 Digital Still Cameras
 Portable applications
 MP3 Players
 GPS Receivers

Features

 WLEDs supports (20mA for each channel):

 Up to 3S13P at VIN=3.7V
 Up to 3S18P at VIN=5.0V

(Note: SÆ Series; PÆ Parallel)

 Low Quiescent Current: 55 μA
 Over Voltage Protection: 15V
 Inherently Matched LED Current
 Shutdown Current < 1μA
 Reference Voltage 0.235V
 Efficiency : 85% (Typ) at VIN=5.0V
 PWM Dimming Control
 Internal Soft Start and Compensation
 Low Profile SOT-26 Package

Typical Application (3S13P)

Fig.1

Elite Semiconductor Memory Technology Inc. /Elite MicroPower Inc. Publication Date: Oct. 2009

Revision: 1.0 1/12

ESMT/EMP

EMD2050

Connection Diagram

Order Information

IN

LX GND FB

OUT

65 4

1 32

55

SOT-26

EN

EMD2050-00VC06NRR

00 Output voltage

VC06 SOT-26 Package

NRR RoHS & Halogen free package

Rating: -40 to 85°C

GRR RoHS Package (By Request)

Package in Tape & Reel

Order, Mark & Packing Information

Package Vout Product ID Marking Packing

OUT

SOT-26 Adjustable EMD2050-00VC06NRR

PIN1 DOT

IN

65 4

Tracking Code

1 32

LX GND FB

55

2050

EN

Tape & Reel

3Kpcs

Pin Functions

Pin Name

LX 1

GND 2 Ground Pin.

FB 3

EN 4

OUT 5 Over Voltage Protection Pin.

IN 6 Input Voltage Pin.

SOT-26

Pin #

Switch Pin.
Connect inductor/diode here.

Feedback Pin.
Reference voltage is 0.235V, connect cathode of lowest LED
and resistor here.

Chip Enable Pin.
Connect to 1.2V or higher to enable device, 0.4V or less to
disable device.

Function

Elite Semiconductor Memory Technology Inc. /Elite MicroPower Inc. Publication Date: Oct. 2009

Revision: 1.0 2/12

ESMT/EMP

EMD2050

Absolute Maximum Ratings

Devices are subjected to failure if they stay above absolute maximum ratings

Input Voltage – 0.3V to 6V

EN, VFB Voltages – 0.3V to VIN

LX ,OUT Voltage – 0.3V to 16V

ESD Susceptibility HBM 2kV

MM 200V

Operating Temperature Range –40°C to 85°C

Storage Temperature –65°C to 150°C

Junction Temperature 150°C

Lead Temperature (Soldering, 10 sec) 260°C

Electrical Characteristics

(VCC = 3.7V, TA = 25°C, unless otherwise specified.)

PARAMETER TEST CONDITION MIN TYP MAX UNIT

Under Voltage Lock Out 1.8 2.4 V

Supply Current Continuously Switching 1 mA

Quiescent Current No Switching, VFB = 1V

Shutdown Current VEN < 0.4V 1 uA

Operation Frequency 0.9 1.2 1.5 MHz

Maximum Duty Cycle 93 95 %

Feedback Voltage 0.2115 0.235 0.2585 V

Thermal Shutdown Protection 160

Thermal Shutdown Hysteresis 20

Ron Isw = 200mA 0.5 0.8 ohm

Current Limit 1.4 A

Shutdown Voltage Low 0.4 V

Enable Voltage High 1.2 V

EN Leakage Current 1.3 μA

OVP 15 V

OVP Hysteresis 0.2 1 3 V

47 55 70 μA

℃

℃

Elite Semiconductor Memory Technology Inc. /Elite MicroPower Inc. Publication Date: Oct. 2009

Revision: 1.0 3/12

ESMT/EMP

EMD2050

Function block

EN

OUT

EN

UVLO / OTP

INTERNAL

COMPENSATION

OVP

IN

_

+

SLOPE

COMPENSATION

_

+

VERF

LX

CURRENT

SENSER

LOGIC
BUFFER

OSC

GNDFB

Fig.2

Elite Semiconductor Memory Technology Inc. /Elite MicroPower Inc. Publication Date: Oct. 2009

Revision: 1.0 4/12