MP1521
High Efficiency
White LED Driver
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.
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
Ordering Information
Part Number
∗
MP1521EK
MP1521EQ
EV0005
EV0021
Package
MSOP10
QFN16 (3x3)
Temperature
-20° to +85°C
-20° to +85°C
MP1521EK Evaluation Board
MP1521EQ Evaluation Board
∗
For Tape & Reel, add suffix –Z (i.e., MP1521EK–Z)
For Lead Free, add suffix –LF (i.e., MP1521EK–LF–Z)
Typical Application Circuit (One String of Six (6) LEDs)
L1
D1
1
V
IN
C
IN
Efficiency vs LED current, 1 string of 6
Using Toko D62CB 47µH Inductor
100
Efficiency (%)
90
80
70
60
50
5
10
15
20
25
LED Current (mA)
V
IN
= 5V
V
IN
= 4V
V
IN
= 3V
IN
SW
10
ON
OFF
MP1521
EN
2
C
OUT
GND
9
GND
EN
3
REF
OLS
8
BRT/
PWM
4
BRT/PWM
FB1
7
White LEDs
5
FB3
FB2
6
MP1521 Rev 2.7 10/06/04
www.monolithicpower.com
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MPS [ MONOLITHIC POWER SYSTEMS ]
