MP1528DG-Z [MPS]
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| 型号： | MP1528DG-Z |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | 暂无描述 驱动器 |
| 文件： | 总9页 (文件大小：240K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TM
MP1528
9 Lamp, 36V Precision White LED Driver
TM
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP1528 is a step-up converter designed
for driving up to nine (9) series White LEDs
(LED) from a single cell Lithium-Ion battery. It
regulates the LED current and includes an
analog input for varying the LED brightness.
•
•
•
•
•
•
•
•
•
•
•
Drives up to 9 Series White LEDs
Integrated 0.63ꢀ Power MOSFET
Low 0.4V Full-Scale Current Sense Threshold
Over 20mA Output Current Capacity
Analog and Digital PWM Brightness Control
Open Load Shutdown
Soft-Start
Internal Current Limit
Under Voltage Lockout
Thermal Shutdown
The MP1528 uses current limited, variable
frequency architecture to regulate the LED
current while maintaining high efficiency. The
BIAS pin measures the output voltage and turns
off the converter if an over voltage condition is
present to prevent damage due to an open
circuit condition. The LED current is measured
with an external current sense resistor. The low
0.4V full-scale regulation threshold and 0.63Ω
power switch minimize power loss.
Available in 8-Pin MSOP and Tiny 3mm x 3mm
6-Pin QFN Packages
APPLICATIONS
•
•
•
•
•
Handheld Computers
PDAs
PDA Phones
Digital and Video Cameras
Small LCD Displays
The MP1528 is available in an 8 pin MSOP and
a tiny 6 pin 3mm x 3mm QFN packages.
EVALUATION BOARD REFERENCE
Board Number
Dimensions
“MPS” and “The Future of Analog IC Technology” are Trademarks of Monolithic
Power Systems, Inc.
EV1528DQ-00A
2.0” x 1.5” x 0.5”
TYPICAL APPLICATION
Efficiency vs
LED Current
D1
B160B
V
V
= 12V
IN
IN
100
90
80
70
60
50
40
30
6 LEDs
7 LEDs
LED1
LED9
5
3
C3
10nF
EN
EN
SW
8 LEDs
MP1528
9 LEDs
6
2
4
1
BRT
BRT
BIAS
GND
FB
0
5
10 15 20 25 30 35
LED CURRENT (mA)
MP1528_TAC01
MP1528_EC01
MP1528 Rev. 1.7
2/21/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
1
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
PACKAGE REFERENCE
TOP VIEW
TOP VIEW
FB
GND
SW
1
2
3
6
5
4
BRT
EN
NC
FB
1
2
3
4
8
7
6
5
NC
BRT
EN
GND
SW
BIAS
BIAS
MP1528_PD02-MSOP8H
EXPOSED PAD
ON BACKSIDE
MP1528_PD01_QFN6
Part Number**
Package
Temperature
–40°C to +85°C
Part Number*
Package
Temperature
–40°C to +85°C
QFN6
(3mm x 3mm)
MP1528DQ
MP1528DK
MSOP8
For Tape & Reel, add suffix –Z (eg. MP1528DQ–Z)
For Lead Free, add suffix –LF (eg. MP1528DQ–LF–Z)
** For Tape & Reel, add suffix –Z (eg. MP1528DK–Z)
*
For Lead Free, add suffix –LF (eg. MP1528DK–LF–Z)
ABSOLUTE MAXIMUM RATINGS (1)
Recommended Operating Conditions (2)
Supply Voltage VBIAS........................ 2.7V to 36V
Operating Temperature .............–40°C to +85°C
Supply Voltage VBIAS to GND....................... 42V
VSW to GND..................................–0.5V to +42V
VEN, VBRT, VFB to GND....................–0.3V to +6V
Storage Temperature.............. –65°C to +150°C
Thermal Resistance (3)
θJA
θJC
QFN6 (3mm x 3mm)...............50...... 14... °C/W
MSOP8..................................150..... 65... °C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The device is not guaranteed to function outside of its
operating conditions.
3) Measured on approximately 1” square of 1 oz copper.
ELECTRICAL CHARACTERISTICS
VBIAS = VEN = 5.0V, VBRT = 1.2V, TA = +25°C, unless otherwise noted.
Parameter
Symbol Condition
Min
Typ
1
Max
3
Units
µA
Supply Current (Shutdown)
Supply Current (Quiescent)
VEN < 0.4V
VEN > 2.0V, BRT = GND
650
800
µA
Minimum Off Time (Normal
Operation)
330
1.2
ns
µs
Minimum Off Time (Startup)
Under Voltage Lock Out
V
BIAS Rising,
BIAS Under Voltage Lock Out
UVLO
2.1
0.8
2.65
V
100mV Hysteresis
Enable
EN High Threshold
EN Hysteresis
1.2
60
1.5
V
mV
nA
EN Input Leakage Current
150
MP1528 Rev. 1.7
2/21/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
2
TM
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
ELECTRICAL CHARACTERISTICS (continued)
VBIAS = VEN = 5.0V, VBRT = 1.2V, TA = +25°C, unless otherwise noted.
Parameter
Symbol Condition
Min
Typ
40
Max
Units
Open Load Shutdown
Threshold
Measured at BIAS
VBIAS = 20V, VEN < 0.4V
BIAS = 40V, VEN < 0.4V
V
5
µA
µA
Bias Current
V
70
100
Feedback Comparator
FB Regulation Threshold
FB Hysteresis
VFB
VBRT = 1.2V
VFB = 0.2V
0.38
0.40
10
0.42
V
mV
nA
FB Input Leakage Current
PWM Mode Using BRT
Output-Off Threshold
BRT Input Leakage Current
BRT Full-Scale Threshold
Output Switch
–150
–80
0.18
0.27
1.2
V
nA
V
VBRT = 0.6V
VBIAS = 5.0V
–100
SW On-Resistance
RON
0.63
950
160
ꢀ
SW Current Limit
mA
°C
Thermal Shutdown
MP1528 Rev. 1.7
2/21/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
3
TM
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
TYPICAL PERFORMANCE CHARACTERISTICS
Circuit on front page, VIN = 3.6V, 9 LEDs, ILED = 20mA, VBRT = 1.2V, TA = +25°C, unless otherwise
noted.
Feedback Voltage vs
Input Voltage
Feedback Voltage vs
BRT Voltage
LED Current vs
BRT Duty Cycle @ 200Hz
430
420
410
400
390
380
370
500
400
300
200
100
0
20
18
16
14
12
10
8
6
4
2
0
2.5 3.0 3.5 4.0 4.5 5.0 5.5
0
1
2
3
4
5
0
20
40
60
80
100
INPUT VOLTAGE (V)
BRT VOLTAGE (V)
BRT DUTY CYCLE (%)
MP1528_TPC01
MP1528_TPC02
MP1528_TPC03
Startup into an
Open Load
Steady-State Operation
Startup
V
EN
5V/div.
V
EN
5V/div.
V
V
V
SW
10V/div.
SW
SW
10V/div.
20V/div.
V
BIAS AC
0.2V/div.
V
BIAS
20V/div.
V
I
BIAS
INDUCTOR
0.5A/div.
10V/div.
MP1528_TPC06
MP1528_TPC05
MP1528_TPC04
Efficiency vs
LED Current
(9 LEDs)
Efficiency vs
LED Current
(8 LEDs)
Efficiency vs
LED Current
(6 LEDs)
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
30
V
=
V
=
IN
IN
V
=
IN
12V
7.5V
5V
4.2V
3V
12V
7.5V
5V
4.2V
3V
12V
7.5V
5V
4.2V
3V
0
5
10
15
20
25
0
5
10
15
20
25
0
5
10
15
20
25
LED CURRENT (mA)
LED CURRENT (mA)
LED CURRENT (mA)
MP1528_TPC08
MP1528_TPC09
MP1528_TPC07
MP1528 Rev. 1.7
2/21/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
4
TM
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
PIN FUNCTIONS
Pin #
Name Description
QFN6 MSOP8
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 VBRT ≥ 1.2V.
1
2
FB
2
3
3
4
GND Ground.
Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the
SW
power inductor and output rectifier to SW, which can swing between GND and 42V.
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.
4
5
5
6
BIAS
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 100kꢀ resistor in series with EN.
Never leave EN floating.
EN
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.
6
7
BRT
NC
1, 8
No Connect
MP1528 Rev. 1.7
2/21/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
5
TM
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
OPERATION
INTERNAL
BIAS
EN
4
5
UVLO &
THERMAL
SHUTDOWN
REGULATOR
& ENABLE
CIRCUIT
3
SW
29V
CONTROL
+
--
LOGIC &
OUTPUT
DRIVER
1.23V
OPEN LOAD
SHUTDOWN
COMPARATOR
2
1
GND
330ns
ONE-SHOT
TIMER
+
--
CURRENT LIMIT
COMPARATOR
0.6V
FEEDBACK
COMPARATOR
FB
+
--
6
BRT
+
--
1.2V
MP1528_F01_BD01
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.
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, VOUT will rise up,
as the FB pin has no voltage. Once VOUT
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.
Analog Brightness Adjust
Analog
brightness
adjustments
are
accomplished by applying a voltage between
0.27V to 1.2V on the BRT pin.
MP1528 Rev. 1.7
2/21/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
6
TM
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
Diode Selection
APPLICATION INFORMATION
Setting the LED Current
The LED current is set by the voltage at BRT
(VBRT) and the sense resistor (R1) at FB. The
VBRT range for adjusting the LED current is
0.27V to 1.2V. Over this range, the LED current
can be calculated as:
The MP1528’s high switching frequency
demands a high speed rectifier (D1) for
optimum efficiency. A Schottky diode is
recommended due to its fast recovery time and
low forward voltage drop. Ensure the diode’s
average and peak current ratings exceed the
average output current and peak inductor
current. In addition, the diode’s reverse
breakdown voltage must exceed the output
voltage.
VBRT
ILED
=
3 × R1
Voltages greater than 1.2V can be applied to
BRT. Use 1.2V in the equation if VBRT ≥ 1.2V or
the BRT pin is left open.
Layout
Careful PC board layout is required due to fast
switching. All components must be placed as
close to the IC as possible. Keep the path
between the inductor L1, diode D1, and output
capacitor C2 extremely short for minimal noise
and ringing. The feedback components such as
the sense resistor R1 must be kept close to the
FB pin to prevent noise injection on the FB pin
trace. The ground return of C1 and C2 should
be tied close to the GND pin. See the MP1528
demo board layout for reference.
For example, the LED current is set to 20mA if
VBRT ≥ 1.2V (or left open) and R1 = 20ꢀ.
Capacitor Selection
A 4.7µF to 10µF ceramic input capacitor (C1)
and a 0.47µF to 1µF ceramic output capacitor
(C2) are recommended for most applications. A
capacitor (C3, typically 1nF to 10nF) in parallel
with the LED string improves stability, input
ripple and output ripple, especially when large
inductance values (10µH or above) are used.
For the best stability over a wide temperature
range, use capacitors with a X5R or X7R
dielectric.
Inductor Selection
The MP1528 has a 950mA inductor current limit
and can drive up to 9 LEDs at 20mA.
Inductance values (for L1) from 4.7µH to 22µH
will work as well. 6.2µH or 6.8µH is a good
choice for high efficiency and small size. To
prevent saturation, use an inductor with a
saturation current rating that is higher than the
device current limit.
MP1528 Rev. 1.7
2/21/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
7
TM
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
PACKAGE INFORMATION
MSOP8
MP1528 Rev. 1.7
2/21/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
8
TM
MP1528 – 9 LAMP, 36V PRECISION WHITE LED DRIVER
QFN6 (3mm x 3mm)
2.90
3.10
0.35
0.55
1.40
1.60
PIN 1 ID
SEE DETAIL A
PIN 1 ID
MARKING
0.35
0.45
1
3
6
2.90
3.10
2.20
2.40
PIN 1 ID
INDEX AREA
0.95
BSC
4
TOP VIEW
BOTTOM VIEW
PIN 1 ID OPTION A
R0.20 TYP.
PIN 1 ID OPTION B
R0.20 TYP.
0.80
1.00
0.20 REF
0.00
0.05
SIDE VIEW
DETAIL A
2.90
1.50
NOTE:
1) ALL DIMENSIONS ARE IN MILLIMETERS.
0.80
0.40
2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.
3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX.
4) JEDEC REFERENCE IS MO-229, VARIATION VEEA-2.
5) DRAWING IS NOT TO SCALE.
2.30
0.95
RECOMMENDED LAND PATTERN
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications.
Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS
products into any application. MPS will not assume any legal responsibility for any said applications.
MP1528 Rev. 1.7
2/21/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
9
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