ECL2401|PWM/PFM Automatic Controlled DC-DC Converters —Backlight Driver


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PWM/PFM Automatic Controlled DC-DC Converters

—Backlight Driver

ECL2401

 

 

 

General Description

ECL2401 series is a group of high efficiency synchronous-rectification type buck regulator using a constant frequency,

current ​​ mode ​​ architecture. ​​ Automatic PWM/PFM mode operation increases efficiency and decreases output voltage

ripple at light loads, further extending battery life. Switching frequency is internally set at 1.4MHz, allowing the use of

small surface mount inductors ​​ and ​​ capacitors. ​​ 100% duty cycle provides low dropout operation.

 

Features

Output Current : 800mA

Shutdown Current : <1µA

Oscillation Frequency : 1.4MHz

 

Applications

LED driver

 

Typical Application Circuit

 

 

 

 

 

 

 

 

Note: ILED=100mV/RSET

 

Functional Pin Description

Pin Number

Pin Name

Function

1

CE

Chip Enable Pin

2

GND

Common Ground

3

LX

Switching Output

4

VIN

Power Input

5

FB

Feedback Voltage Pin

 

Ordering Information

 

ECL2401 N ​​ XX ​​ N

Embossed Tape :

RStandard Feed

SReverse Feed

 ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ Package Type

 ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ B2SOT23-5L

 ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​  ​​​​ A:VFB=0.1V

For example:

ECL2401AB2R is defined as ECL2401, the feedback voltage is 0.1V, the oscillator frequency of 1.4MHz, Package

SOT23-5L, Reverse Feed.

 

 

Marking Information

Designator

Symbol

Information

product name

3

ECL2401

feedback voltage

A

VFB=0.1V

product package type

M

SOT23-5L

assembly lot No.

 

0-9,A-Z; 0-9,A-Z mirror writing,repeated(G,I,J,O,Q,W exception)

 

Pin Configuration

 

 

 

 

 

 

Function Block Diagram

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Absolute Maximum Ratings

Parameter

Symbol

Ratings

Units

Input Supply Voltage

VIN

-0.3~6.5

V

Output Voltage

VOUT

-0.3~6.5

VLX

-0.3~VIN + 0.3

CE Voltage

VCE

-0.3~VIN + 0.3

V

Peak LX Current

ILX

1200

mA

Power Dissipation

SOT23-5L

Pd

250

mW

Operating Temperature Range

Topr

-40~+85

Storage Temperature Range

Tstg

-55~+125

Note: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.

 

Electrical Characteristics VIN=5V, L=2.2uH(Ta=25℃, unless otherwise noted)

Parameter

Symbol

Conditions

Min

Type

Max

Units

Feedback Voltage

VFB

-

0.09

0.1

0.11

V

Input Voltage Range

VIN

-

2

-

6

Line regulation

VOUT

ILED=300mA

-

0.45

-

%

Efficiency

EFFI

ILED=200mA

92

%

CE ”Low” voltage

VCEL

-

-

-

0.9

V

CE ”High” voltage

VCEH

-

1.1

-

-

V

Shutdown Current

ISHDN

VCE=0V

-

-

1

µA

Quiescent Current

IDD

VFB=0.1V*0.9

300

-

µA

Switch Current Limit

ILIM

-

-

1200

-

mA

PFM switching point

IPFM

VIN=5V

 

100

 

mA

Oscillation Frequency

FOSC

ILED=500mA

-

1.4

-

MHz

Max Duty Circle

MAXDTY

-

100

-

-

%

Thermal Shutdown

TSD

-

-

150

-

Thermal Hysteresis

THYST

-

-

20

-

 

 

 

 

 

 

 

 

 

 

 

 

 

Typical Application

 

 

 

 

 

 

 

 

Figure 1 Typical application circuit

Note: ILED=100mV/RSET

 

 

 

 

 

 

 

 

 

 

Figure 2 Typical application circuits with PWM dimming signal

 

Calculate ILED using the following equations

 

 

 

Where VPWM is the amplitude of PWM signal.

For example, for 3.3V VPWM, R1=4.7K, R2=100K, R3=47K.

The value of C3 depends on the frequency of PWM dimming; an empirical suggestion is around 0.1uF for MHz and 10uF for low frequency under KHz.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Typical Performance Characteristics