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 |
|
EC4503ANB3R | SOT23-6 | 4503A LLLLL |
|
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 |
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 | |||
Min. | Typ. | Max. | |||||
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 | |
VIN=2.7V~6V, TA = -40 ~ 85℃
| 0.18 | | 0.22 | ||||
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 | |
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
White LED Set-up Converter
EC4503
Operating Waveforms(Cont.)