EC4503｜White LED Set-Up Converter

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White LED Set-up Converter

EC4503

General Description

The EC4503 is a current-mode and fixed frequency

Boost converter with an integrated N-FET to drive

white LEDs.

The series connection allows the LED current to be

identical for uniform brightness. Its low on-resistance

of NFET and low feedback voltage reduce power loss

and achieve high efficiency. Fast switching frequency (1.5MHz typical) allows using small size inductor and both of input and output capacitors. An over voltage protection function, which monitors the output voltage via OVP pin,stops switching of the IC if the OVP voltage exceeds the over voltage threshold. An internal soft-start

circuit eliminates the inrush current during start-up.

The EC4503 also integrates under-voltage lockout,

Overtemperature protection, and current limit circuits to

Protect the IC in abnormal conditions.

The EC4503 is available in a SOT-23-6 packages.

Features

●Wide Input Voltage from 2.7V to 6V

●0.2V Reference Voltage

●Fixed 1.5MHz Switching Frequency

●PWM Brightness Control with Wide Frequency

Range of 100Hz to 100kHz

●Build‐In Power MOSFET : 0.2Ω

●Open‐LED Protection

●Under‐Voltage Lockout Protection

●Over‐Temperature Protection

●<1mA Quiescent Current during Shutdown

●SOT‐23‐6 Packages

● Lead Free and Green Devices Available

●(RoHS Compliant)

Applications

●White LED Display Backlighting

●Cell Phone and Smart Phone

●PDA, PMP, MP3

●Digital Camera

White LED Set-up Converter

EC4503

Pin Assignments

Pin Description

Pin Number	Pin Name	Description
1	LX	Switch pin. Connect this pin to inductor/diode here.
2	GND	Ground
3	FB	Feedback Pin. Connect this pin to cathode of the lowest LED and current‐sense resistor (R1). Calculate resistor value according to R1=VREF/ILED .
4	EN	Enable Control Input. Forcing this pin above 1.0V enables the device, or forcing this pin below 0.4V to shut it down. In shutdown, all functions are disabled to decrease the supply current below 1μA. Do not leave this pin floating.
5	OVP	Converter Output and Over‐Voltage Protection Input Pin.
6	IN	Main Supply Pin. Must be closely decoupled to GND with a 4.7μF or greater ceramic capacitor.

Ordering Information

Part Number

Package

Marking

Marking Information

EC4503NNB3R

SOT23-6

4503f

Starting with underlined 5, a bar is for production year 2012. The next bar is mark on top of 0 is for year 2013. The next bar is mark on bottom of 0 is for year 2014. The next bar is mark on top of 3 is year for 2015. The naming pattern continues with consecutive characters for later years.
f is the week of production. The big character of A~Z is for the week of 1~26, and small a~z is for the week of 27~52.

EC4503ANB3R

SOT23-6

4503A

LLLLL

LLLLL：Lot No

Functional Block Diagram

White LED Set-up Converter

EC4503

Function Block Diagram of EC4503

Absolute Maximum Ratings

Symbol	Parameter	Rating	Unit
VIN	VIN Supply Voltage (VIN to GND) ‐	-0.3 ~ 7	V
VLX	FB, EN to GND ‐	-0.3 ~ VIN	V
VLX	LX to GND Voltage ‐	-0.3 ~ 27.5	V
VOVP	OVP to GND ‐	-0.3 ~ 27.5	V
PD	Power Dissipation	Internally Limit	W
TJ	Maximum Junction Temperature	150	℃
TSTG	Storage Temperature ‐	-65 ~ 150	℃
TSDR	Maximum Lead Soldering Temperature, 10 Seconds	260	℃

Recommended Operating Conditions

Symbol	Parameter	Typical Value	Unit
θJA	Junction-to-Ambient Resistance in Free Air	220	℃/W
θJC	Junction-to-Case Resistance	120	℃/W
VIN	VIN Supply Voltage(VIN to GND)	2.7‐6	V
VOVP	VOUT to GND	VIN‐22	V
CIN	Input Capacitor	4.7~	uF
COUT	Output Capacitor	4.7~	uF
L1	Converter Output Inductor	2.2‐10	uH
TA	Ambient Temperature ‐	-40~85	℃
TJ	Junction Temperature ‐	-40~125	℃

Electrical Characteristics

The following specifications apply for VIN =3.6V TA=25 oC, unless specified otherwise.

Symbol	Parameter	Test Conditions		EC4503			Unit
Symbol	Parameter	Test Conditions		Min.	Typ.	Max.	Unit
VIN	Input Voltage Range			2.7		6	V
IDD1	Input DC Bias Current	VFB = 0.4V, no switching			300		µA
IDD2		VFB = 0V, switching -			2	5	mA
ISD		EN = GND -				1	µA
	UVLO Threshold Voltage	VIN Rising		2.0	2.2	2.4	V
	UVLO Hysteresis Voltage	VIN Failing		50	100	150	mV
VREF	Regulated Feedback Voltage	VIN=2.7V~6V,TA = 25°C		0.185	0.2	0.215	V
VREF	Regulated Feedback Voltage	VIN=2.7V~6V, TA = -40 ~ 85℃		0.18		0.22	V
IFB	FB Input Current			-50	---	50	nA
FSW	Switching Frequency			1.25	1.5	1.75	MHz
RON	Power Switch On Resistance		-		0.2		Ω
ILIM	Power Switch Current-Limit				2		A
	LX Leakage Current		VEN=0V, VLX=0V or 6V, VIN = 6V	-1		1	µA
DMAX	LX Maximum Duty Cycle			92	95	98	%
	Over-Voltage Threshold		Vout Rising,( EC4503ANB3R)	22	24	27.5	V
	Over-Voltage Threshold		Vout Rising, (EC4503NNB3R)	14.5	16	20	V
	OVP Voltage Hysteresis		Vout Failing		3		V
	OVP Leakage Current		VOVP =20V -		50		nA
	Enable Voltage Threshold	VEN Rising		1			V
	Shut-down Voltage Threshold	VEN Failing				0.4	V
	EN Leakage Current	VEN= 0~6V, VIN = 6V		-2		2	µA
	EN Minimum on pluse-width	VEN= 0~6V, VIN=6V, PWM			800		ns
TOTP	Over-Temperature Protection	TJ Rising -			150 -		℃
	Over-Temperature Protection	TJ Failing			40		℃

White LED Set-up Converter

EC4503

Typical Performance Characteristics

White LED Set-up Converter

EC4503

Typical Performance Characteristics(Cont.)

Operating Waveforms