EV0021

MP1521 High Efficiency

White LED Driver

EVALUATION BOARD

EV0021 Rev 1.1_01/21/03

www.monolithicpower.com

3

Monolithic Power Systems

Table 1: EV0021 Bill of Materials

Parts

Package

Vendor

QTY

Components

ICs

MP1521EQ

QFN16

MPS

1

U1

Capacitors

4.7

µF

1206

Any

1

C1

1

µF, 25V

1210

Any

1

C2

Resistors

10K

Ω

0603

Any

3

R1, R2, R3

20

Ω

0603

Any

3

R4, R5, R6

Inductors

15

µH

CDRH3D16

Sumida

1

L1

Diodes

B130, 1A, 30V, Schottky

SMA

Any

1

D1

LEDS (Not Provided)

Operating Instructions

1. Connect VCC to the power source’s positive output.

2. Connect GND to supply ground.

logic low puts it into low current shutdown mode. Place a 100K

Ω resistor in series with EN if

the input is greater than 10V. For automatic start up connect EN to VCC.

4. Applying a PWM signal to the BRT will adjust the LED brightness. When used in analog

mode, apply a DC voltage of 0.3 to 1.2V. This input voltage is attenuated by 1/3 to set the

voltage across sense resistors at FB1, FB2, and FB3. Maximum brightness (20mA) occurs

with 1.2V applied. To control brightness in PWM mode, apply a PWM square wave with a

minimum voltage less the 0.18V and a maximum greater than 1.2V. When a voltage less than

0.18V is applied to this pin, the output switch is turned off.

The regulator operates at

maximum brightness when more than 1.2V is applied. The frequency of the PWM signal must

be between 100 to 400 Hz.

5. The FB1, FB2 and FB3 pins can be used to measure the voltage across the current-sense

resistor that is in series with the LED strings. Unused feedback pins must be connected to

any used feedback pin.

6. OLS senses the regulator output voltage to protect IC during open load operation. When this

pin’s voltage exceeds 28V, the output switch is shut off. The output switch remains off until

the IC is reset by cycling the enable pin (EN) or input supply (VIN)