MP1521
High Efficiency
White LED Driver
Monolithic Power Systems
Pin Description
MSOP10
QFN16
1
2
3
4
5
SW
IN
EN
10
9
12
11
10
9
1
2
3
4
NC
EN
GND
GND
OLS
FB1
GND
OLS
FB1
FB2
Top
View
REF
BRT
FB3
8
NC
7
REF
6
Part Marking: MP1521EK
Part Marking: A1xx
Table 1: MP1521 MSOP10 and QFN16 Pin Assignments
MSOP
Pin #
QFN
Pin#
Pin
Name
Pin Function
1
16
IN
Input supply pin. It can be connected to the regulator’s input supply, or to the
output for boot-strapped operation (boot-strapped operation is required for VIN of
less than 3V).
2
3
4
2
4
5
EN
Regulator On/Off control input. Logic high (VEN>1V) turns on IC, logic low puts it
into low current shutdown mode. Place a 100KΩ resistor in series with EN if it is
connected to a voltage greater than 10V.
REF
BRT
1.23V reference used for setting the analog control voltage at BRT input. This
reference can supply up to 200µA to an external load. Do not connect any
bypass capacitors to this pin. It is internally compensated.
Analog or PWM input for controlling 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
6
7
8
7
8
9
FB3
FB2
FB1
OLS
Feedback input for measuring voltage across current-sense resistor that is in
series with LED string. Unused feedback pins must be connected to any used
feedback pin.
10
Open Load Shutdown pin senses 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 (IN) pin.
9
10
-
11, 12
14
GND Signal and power ground. Connect directly to ground plane.
SW
N/C
Output switch pin, power DMOS low-side switch.
No Connect
1, 3, 6,
13, 15
MP1521 Rev 2.7 10/06/04
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MPS [ MONOLITHIC POWER SYSTEMS ]
