MP1521
High Efficiency
White LED Driver
MP1521 Rev 2.7 10/06/04 www.monolithicpower.com 1
Monolithic Power Systems
General Description
The MP1521 is a constant-current Boost
Regulator. This IC has three individual
current-sensing feedbacks, which are ideal for
driving multiple strings of series connected
LEDs. The OLS pin is designed for detecting
loose or open LED connections.
The IC uses a peak current, constant minimum
off-time architecture. The feedback pins
measure voltage across sense resistors in
series with the LED strings. When supplying a
bias current of 20mA, the voltage drop across
the sense resistor is only 0.4V to minimize
power loss. Either a DC voltage or a PWM
signal at the BRT/PWM input can control the
LED brightness.
The MP1521 has an on board power MOSFET
switch that is protected by current limit, open
load shutdown, thermal shutdown, and under
voltage lockout.
Ordering Information
Part Number ∗ Package Temperature
MP1521EK MSOP10
-20° to +85°C
MP1521EQ QFN16 (3x3)
-20° to +85°C
EV0005 MP1521EK Evaluation Board
EV0021 MP1521EQ Evaluation Board
∗ For Tape & Reel, add suffix –Z (i.e., MP1521EK–Z)
For Lead Free, add suffix –LF (i.e., MP1521EK–LF–Z)
Features
On Board Power MOSFET
Drive 9 White LEDs from 2.7V Input
Drive 15 White LEDs from 5V Input
Up to 90% Efficiency
Over 80mA Output Current Capacity
Open Load Shutdown
Low Current Sensing Feedback Voltage
Up to 3 String Current Sensing Feedback
Analog and Digital PWM Brightness Control
UVLO, Thermal Shutdown
Soft Start
Internal Current Limit
Available in Compact MSOP10 and
Tiny 3 mm x 3 mm QFN16 Package
Evaluation Boards Available
Applications
Handheld Computers, Cell phones, PDAs,
Digital and Video Cameras, Small LCD
Displays
Li Ion and NiMH Battery Applications
Typical Application Circuit (One String of Six (6) LEDs)
8
7
IN
BRT/PWM
FB1
OLS
SW
10
GND
9
C
IN
C
OUT
EN
REF
4
3
2
1
D1
MP1521
L1
6 5
FB2
FB3
White LE D s
BRT/
PWM
EN
GND
OFF
ON
V
IN
Efficiency vs LED current, 1 string of 6
Using Toko D 62CB 47
µ
H Inductor
50
60
70
80
90
100
5
10
15
20
25
LED Current (mA )
Effi cien cy (%)
V
IN
= 5V
V
IN
= 4V
V
IN
= 3V
