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MP1528DQ-LF-Z

P1-P3P4-P6P7-P9P10-P10
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
MP1528 Rev. 1.9 www.MonolithicPower.com 4
1/25/2010 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
TYPICAL PERFORMANCE CHARACTERISTICS
Circuit on front page, V
IN
= 3.6V, 9 LEDs, I
LED
= 20mA, V
BRT
= 1.2V, T
A
= +25°C, unless otherwise
noted.
500
400
300
200
100
0
FB VOLTAGE (mV)
012345
BRT VOLTAGE (V)
MP1528_TPC02
Feedback Voltage vs
BRT Voltage
430
420
410
400
390
380
370
FB VOLTAGE (mV)
EFFICIENCY (%)
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
LED CURRENT (mA)
MP1528_TPC01
Feedback Voltage vs
Input Voltage
20
18
16
14
12
10
8
6
4
2
0
LED CURRENT (mA)
0 20406080100
BRT DUTY CYCLE (%)
MP1528_TPC03
LED Current vs
BRT Duty Cycle @ 200Hz
V
EN
5V/div.
V
SW
20V/div.
V
BIAS
20V/div.
MP1528_TPC06
Startup into an
Open Load
V
SW
10V/div.
V
BIAS AC
0.2V/div.
I
INDUCTOR
0.5A/div.
MP1528_TPC04
Steady-State Operation
V
EN
5V/div.
V
SW
10V/div.
V
BIAS
10V/div.
MP1528_TPC05
Startup
MP1528_TPC08
Efficiency vs
LED Current
(8 LEDs)
100
90
80
70
60
50
40
30
0 5 10 15 20 25
EFFICIENCY (%)
LED CURRENT (mA)
MP1528_TPC09
Efficiency vs
LED Current
(9 LEDs)
100
90
80
70
60
50
40
30
0 5 10 15 20 25
EFFICIENCY (%)
LED CURRENT (mA)
MP1528_TPC07
Efficiency vs
LED Current
(6 LEDs)
100
90
80
70
60
50
40
30
0 5 10 15 20 25
12V
7.5V
5V
4.2V
3V
12V
7.5V
5V
4.2V
3V
12V
7.5V
5V
4.2V
3V
V
IN
=
V
IN
=
V
IN
=
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
MP1528 Rev. 1.9 www.MonolithicPower.com 5
1/25/2010 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
PIN FUNCTIONS
Pin #
QFN6 MSOP8 QFN8
Name Description
1 2 2 FB
Feedback Input. The MP1528 regulates the voltage across the
current sense resistor between FB and GND. Connect a current
sense resistor from the bottom of the LED string to GND and connect
the bottom of the LED string to FB. The regulation threshold is set at
0.4V for V
BRT
1.2V.
2 3 3 GND Ground.
3 4 4 SW
Power Switch Output. SW is the drain of the internal MOSFET
switch. Connect the power inductor and output rectifier to SW, which
can swing between GND and 42V.
4 5 5 BIAS
Internal Power Input. BIAS powers the internal circuitry and
measures the output voltage for open circuit protection. Connect
BIAS to the output at the top of the LED string. If open circuit
protection is not required, BIAS may be connected to the input
source to reduce power consumption of the MP1528.
5 6 6 EN
Regulator On/Off Control Input. A high voltage applied to EN turns on
the converter; a low voltage turns it off. When not used, connect EN
to the input source for automatic startup. If EN is driven over 6V,
place a 100k resistor in series with EN. Never leave EN floating.
6 7 7 BRT
Analog or PWM Input for Controlling LED Brightness. When used in
analog mode, apply a DC voltage of 0.27V to 1.2V. This input voltage
is attenuated by 1/3 to set the voltage across the sense resistor at
FB. Maximum brightness (20mA) occurs with an application of 1.2V.
To control the brightness in PWM mode, apply a PWM signal with a
minimum voltage less than 0.18V and a maximum voltage 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 100Hz to 400Hz.
1, 8 1, 8 NC No Connect
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
MP1528 Rev. 1.9 www.MonolithicPower.com 6
1/25/2010 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
OPERATION
INTERNAL
REGULATOR
& ENABLE
CIRCUIT
UVLO &
THERMAL
SHUTDOWN
330ns
ONE-SHOT
TIMER
FEEDBACK
COMPARATOR
OPEN LOAD
SHUTDOWN
COMPARATOR
CURRENT LIMIT
COMPARATOR
CONTROL
LOGIC &
OUTPUT
DRIVER
--
+
1.2V
FB
MP1528_F01_BD01
GND
SW
0.6V
1.23V
29V
--
+
--
+
--
+
--
+
BIAS
EN
BRT
1
2
3
4
5
6
Figure 1—Functional Block Diagram
The MP1528 utilizes a constant off-time control
scheme. For maximum brightness, the BRT pin
is biased at or above 1.2V. Its voltage is routed
through the unity gain buffer whose output is
clamped at 1.2V. A resistor divider from the
buffer to the inverting input of the feedback
comparator divides the BRT voltage by three to
set the current sense threshold. If the FB pin
voltage is lower than this threshold the power
MOSFET is turned on. The MOSFET and
inductor currents increase until the current limit
comparator trips at 950mA, turning off the
MOSFET for at least 330ns. At the end of the
330ns, if the FB pin is still lower than the
current sense threshold, the MOSFET is turned
on again.
Analog Brightness Adjust
Analog brightness adjustments are
accomplished by applying a voltage between
0.27V to 1.2V on the BRT pin.
PWM Brightness Adjust
PWM brightness adjustments are accomplished
by driving the BRT pin with a digital signal
whose low voltage is below 0.18V and high
voltage is greater than 1.2V. A voltage below
0.18V forces the power MOSFET to turn off. A
voltage greater than 1.2V will cause the FB pin
to regulate at 0.4V.
Open Load Shutdown
Open Load Shutdown is implemented by
connecting the BIAS pin to the top of the LED
string. In the fault condition where the
connection to the LED is open, V
OUT
will rise up,
as the FB pin has no voltage. Once V
OUT
exceeds 40V, the MP1528 will cease operation
until the EN pin is cycled off and on. Connecting
the BIAS pin to the input will disable Open Load
Shutdown.
P1-P3P4-P6P7-P9P10-P10

MP1528DQ-LF-Z

Mfr. #:
Buy MP1528DQ-LF-Z
Manufacturer:
Monolithic Power Systems (MPS)
Description:
LED Lighting Drivers 6 LED, 2.5 - 36Vin Switch Driver
Lifecycle:
New from this manufacturer.
Delivery:
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