EV0035
MP1523 Precision Driver for
Single String of 6 White LEDs
EVALUATION BOARD
EV0035 Rev 1.1_03/19/03 www.monolithicpower.com 1
Monolithic Power Systems
General Description
The EV0035 evaluation board uses the
MP1523 to drive up to six (6) series white
LEDs from a single cell Lithium Ion battery.
The MP1523 uses a current limited, variable
frequency architecture to regulate the LED
current, which is measured through an external
current sense resistor. It’s low 0.4V feedback
threshold reduces power loss and improves
efficiency. To prevent damage due to an open
circuit condition, the BIAS pin can measure the
output voltage and turns off the converter if an
overvoltage condition is present.
The MP1523 includes under-voltage lockout,
current limiting and thermal overload protection
preventing damage in the event of an output
overload. The MP1523 is available in a tiny 5
lead SOT23 package.
Ordering Information
Board Number MPS IC Number
EV0035 MP1523DT
Absolute Maximum Ratings
Supply Voltage VIN 28V
Switch Voltage SW to GND -0.5V to 28V
VEN, VFB –0.3V to 6V
Storage Temperature -55°C to +150°C
Recommended Operating Conditions
Supply Voltage VIN 2.7 V to 25V
Features
On board power MOSFET
Drives 6 White LEDs
Up to 90% efficiency
Over 80mA output current capacity
Open Load Shut Down
Low 0.4V Feedback Threshold
UVLO, Thermal shutdown
Soft Start
Internal Current Limit
MP1523 in Tiny SOT23 package
Applications
Cell Phones
Handheld Computers and PDAs
Digital Still and Video Cameras
Small LCD Displays
Figure 1: EV0035 Evaluation Board
Actual Size: 2”X x 1.4”Y
EV0035
MP1523 Precision Driver for
Single String of 6 White LEDs
EVALUATION BOARD
EV0035 Rev 1.1_03/19/03 www.monolithicpower.com 2
Monolithic Power Systems
Figure 2: EV0035 Schematic
EV0035
MP1523 Precision Driver for
Single String of 6 White LEDs
EVALUATION BOARD
EV0035 Rev 1.1_03/19/03 www.monolithicpower.com 3
Monolithic Power Systems
Table 1: EV0035 Bill of Materials
Designator Component Package Qty
U1 MP1523DT SOT23-5 1
C1, C2 1µF 1206 2
C3 10nF 0603 1
R1 100KΩ 0603 1
R2 20Ω 0603 1
D1 MBR0540 1810 1
L1 15µH CDRH127 1
Total 8
Operating Instructions
1. Connect VIN to the power source’s positive output.
2. Connect GND to supply ground.
3. Remove the jumper J1 to allow the MP1523 to automatically start when power is applied. Place
the shorting clip across J1 to disable the MP1523. A logic signal may be applied to EN to
enable/disable the MP1523, provided the shorting clip is not installed across J1.
4. To dim the LEDs remove the shorting clip from J1 and apply a PWM signal to the EN pin.
Adjusting the duty cycle of the PWM signal determines the brightness of the LEDs.
Figure 3: EV0035 Top Silk Layer
EV0035
MP1523 Precision Driver for
Single String of 6 White LEDs
EVALUATION BOARD
EV0035 Rev 1.1 Monolithic Power Systems, Inc. 4
03/19/03 3777 Stevens Creek Blvd, Suite 400, Santa Clara, CA 95051-7364 USA
© 2003 MPS, Inc. Tel: (408) 243-0088, Fax: (408) 243-0099, Web: www.monolithicpower.com
Monolithic Power Systems
Figure 4: EV0035 Top Layer
Figure 5: EV0035 Bottom Layer
NOTICE: MPS believes the information in this document to be accurate and reliable. However, it is subject to change
without notice. Please contact the factory for current specifications. No responsibility is assumed by MPS for its use or fit to
any application, nor for infringement of patent or other rights of third parties.
