ETC EV0021 High efficiency white led driver Datasheet

MP1521
High Efficiency
White LED Driver
Monolithic Power Systems
General Description
Features
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.
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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.
Applications
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Ordering Information
Part Number ∗
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Package
Temperature
MP1521EK
MSOP10
-20° to +85°C
MP1521EQ
QFN16 (3x3)
-20° to +85°C
EV0005
MP1521EK Evaluation Board
EV0021
MP1521EQ Evaluation Board
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
Handheld Computers, Cell phones, PDAs,
Digital and Video Cameras, Small LCD
Displays
Li Ion and NiMH Battery Applications
∗ 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)
IN
OFF
SW
10
EN
BRT/
PWM
2
EN
GND
9
OLS
8
3
REF
4
BRT/PWM
FB1
7
FB3
FB2
6
5
CIN
100
GND
COUT
MP1521
White LEDs
Efficiency (%)
1
ON
Efficiency vs LED current, 1 string of 6
Using Toko D62CB 47µH Inductor
VIN
L1
D1
90
VIN = 5V
80
VIN = 4V
70
VIN = 3V
60
50
5
10
15
20
25
LED Current (mA)
MP1521 Rev 2.7 10/06/04
www.monolithicpower.com
1
MP1521
High Efficiency
White LED Driver
Monolithic Power Systems
Absolute Maximum Ratings
Supply Voltage (VIN)
Switch Voltage to GND
VEN, VREF, VBRT, VFB1, VFB2, VFB3
Storage Temperature
Recommended Operating Conditions
28V
-0.5V to 28V
–0.3V to 6V
-55°C to +150°C
Supply Voltage (VIN)
Operating Temperature
Switch Voltage to GND
2.7V to 25V
-20°C to +85°C
-0.5V to 25V
Package Thermal Characteristics
Thermal Resistance, ΘJA (MSOP10)
Thermal Resistance, ΘJA (QFN16)
150°C/W
60°C/W
Electrical Characteristics (VIN = 5.0V, TA = 25°C unless specified otherwise)
Parameters
Supply Current (shutdown)
Supply Current (quiescent)
Minimum Off Time, normal
operation
Minimum Off Time, start-up
(Note 1)
UVLO
Symbol
IIN (OFF)
IIN (ON)
tOFF (NORMAL)
tOFF (START)
Under Voltage Lockout
Enable
Threshold
Hysterisis
Leakage Current
Open Load Shutdown
Threshold
Leakage Current
Reference
Output Voltage
Load Regulation
Line Regulation
Feedback Comparator
Threshold
Hysterisis (Note 2)
FB Input Bias Current
PWM Mode
Output-Off Threshold
BRT Input Bias
BRT Full Scale Threshold
(Note 3)
Output Switch
Switch On Resistance (Note 2) RON
Switch Current Limit
Leakage Current
Thermal Shutdown (Note 2)
Condition
Min
VEN<0.4V
VEN >1.5V, VBRT=0V, VFB=0V
VEN >1.5V, VBRT =0.6V
400
VFB =0
VEN >1.5V, VBRT =0.6V,
1.5
VFB =0V
VIN RISING
VIN FALLING
Typ
1
550
Max
3
700
Units
µA
µA
500
700
nS
2.4
µS
2.6
2.4
V
V
2.0
1
V
mV
µA
45
29
1
70
V
µA
µA
2.1
1.9
0.8
1.0
60
VEN=3V
Measured at OLS Pin
VOLS=15V
VOLS=25V
26
IREF=0A
IREF=0 to 100µA
VIN =3 to 15V, IREF=0A
1.20
1.235
2.5
2.5
1.27
5
5
V
mV
mV
VBRT =1.2V
VBRT =1.2V
VFB=0.2V
380
420
-150
400
30
-50
0
mV
mV
nA
VBRT=0.6V
0.18
-100
-30
0.26
0
V
nA
1.2
V
0.6
Ω
mA
µA
°C
VIN=5.0V
300
0.5
400
VSW=25V
5
160
Notes:
1) First 64 pulses after EN switches high.
2) Guaranteed by design.
3) The output current is off when BRT is driven below the output-off threshold and full-scale when driven above the full-scale
threshold. To PWM the output drive BRT above and below these thresholds.
MP1521 Rev 2.7 10/06/04
www.monolithicpower.com
2
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