MP3202.pdf 데이터시트 (총 9 페이지) - 파일 다운로드 MP3202 데이타시트 다운로드

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The Future of Analog IC Technology
DESCRIPTION
The MP3202 is a step-up converter designed for
driving up to 39 white LEDs (13 strings of 3 LEDs
each) from a 5V system rail. The MP3202 uses a
current mode, fixed frequency architecture to
regulate the LED current, which is measured
through an external current sense resistor. Its low
104mV feedback voltage reduces power loss and
improves efficiency. The OV pin monitors the
output voltage and turns off the converter if an
over-voltage condition is present due to an open
circuit condition.
The MP3202 includes under-voltage lockout,
current limiting and thermal overload protection
preventing damage in the event of an output
overload.
The MP3202 is available in small 6-pin TSOT23
or 8-pin QFN (2mm x 2mm) packages.
MP3202
1.3A Fixed Frequency
White LED Driver
FEATURES
2.5V to 6V Input Voltage Range
On Board Power MOSFET
Drives up to 39 White LEDs at 5V Input
Up to 92% Efficiency
Over 1MHz Fixed Switching Frequency
Open Load Shutdown
Low 104mV Feedback Voltage
Soft-Start/PWM Dimming
UVLO, Thermal Shutdown
Internal 1.3A Current Limit
Available in TSOT23-6 and QFN8 Packages
APPLICATIONS
Cell Phones
Handheld Computers and PDAs
Digital Still Cameras
Small LCD Displays
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
VIN
4.5V - 6V
IN SW
EN EN MP3202 OV
GND
FB
13 Strings
Efficiency vs
Input Voltage
100
IOUT=100mA
90
IOUT=180mA
80
70
60
50
4.0
4.5 5.0 5.5
INPUT VOLTAGE (V)
6.0
MP3202 Rev. 0.91
9/21/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
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PACKAGE REFERENCE
TOP VIEW
SW 1
6 IN
GND 2
5 OV
FB 3
4 EN
MP3202 – 1.3A FIXED FREQUENCY WHITE LED DRIVER
TOP VIEW
GND 1
IN 2
OV 3
EN 4
8 SW
7 NC
6 FB
5 GND
Part Number*
Package
Temperature
MP3202DJ
TSOT23-6 –40°C to +85°C
* For Tape & Reel, add suffix –Z (eg. MP3202DJ–Z)
For RoHS compliant packaging, add suffix –LF
(eg. MP3202DJ–LF–Z)
ABSOLUTE MAXIMUM RATINGS (1)
SW Pin......................................–0.5V to +28.5V
All Other Pins ..............................–0.3V to +6.5V
Storage Temperature.............. –55°C to +150°C
Recommended Operating Conditions (2)
IN Supply Voltage ..............................2.5V to 6V
Output Voltage ....................................VIN to 25V
Operating Temperature............. –40°C to +85°C
Part Number**
MP3202DG
Package Temperature
QFN8
(2mm x 2mm)
–40°C to +85°C
** For Tape & Reel, add suffix –Z (eg. MP3202DG–Z)
For RoHS compliant packaging, add suffix –LF
(eg. MP3202DG–LF–Z)
Thermal Resistance (3) θJA θJC
TSOT23-6.............................. 220 .... 110.. °C/W
QFN8 (2mm x 2mm) ............... 80 ...... 16... °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
VIN = VEN = 5V, TA = +25°C, unless otherwise noted.
Parameters
Symbol Condition
Operating Input Voltage
Supply Current (Shutdown)
Supply Current (Quiescent)
Switching Frequency
Maximum Duty Cycle
Under Voltage Lockout
VIN
VEN = 0V
VFB = 0.15V
fSW
VFB = 0V
IN Under Voltage Lockout
Under Voltage Lockout
Hysteresis
UVLO VIN Rising
Open Lamp Shutdown
Threshold
VOV VOV Rising
Min Typ Max Units
2.5 6 V
0.1 1 µA
690 750 µA
1.0 1.3 1.5 MHz
85 92
%
2.25 2.45
92
V
mV
28 V
MP3202 Rev. 0.91
9/21/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
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MP3202 – 1.3A FIXED FREQUENCY WHITE LED DRIVER
ELECTRICAL CHARACTERISTICS (continued)
VIN = VEN = 5V, TA = +25°C, unless otherwise noted.
Parameters
Symbol Condition
Enable
EN Threshold
EN Threshold
EN Hysteresis
VEN Rising, VIN = 5V
VEN Rising, VIN = 2.5V
EN Input Bias Current
Feedback
VEN = 0V, 5V
FB Voltage
FB Input Bias Current
Output Switch
SW On-Resistance (4)
SW Current Limit (4)
Thermal Shutdown (4)
VFB = 0.1V
RON
Duty Cycle = 60%
Notes:
4) Guaranteed by design.
Min Typ Max Units
1.0 1.35 1.6
0.8
90
1
V
V
mV
µA
94 104 114 mV
–600 –300
nA
0.5
1.33
160
A
°C
PIN FUNCTIONS
TSOT23-6
Pin #
QFN8
Pin #
Name Description
Power Switch Output. SW is the drain of the internal MOSFET switch. Connect
1 8 SW the power inductor and output rectifier to SW. SW can swing between GND and
25V.
2 1, 5 GND Ground.
Feedback Input. The MP3202 regulates the voltage across the current sense
3
6
FB
resistor between FB and GND. Connect a current sense resistor from the bottom
of the LED string to GND. Connect the bottom of the LED string to FB. The
regulation voltage is 104mV.
Regulator On/Off Control Input. A high input at EN turns on the converter, and a
4 4 EN low input turns it off. When not used, connect EN to the input source for automatic
startup. The EN pin cannot be left floating.
5
3
OV
Over Voltage Input. OV measures the output voltage for open circuit protection.
Connect OV to the output at the top of the LED string.
6 2 IN Input Supply Pin. Must be locally bypassed.
7 NC No Connect.
MP3202 Rev. 0.91
9/21/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
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MP3202 – 1.3A FIXED FREQUENCY WHITE LED DRIVER
OPERATION
The MP3202 uses a constant frequency, peak
current mode boost regulator architecture to
regulate the strings of white LEDs. Refer to the
block diagram in Figure 1 for details.
At the start of each oscillator cycle the FET is
turned on through the control circuitry. To
prevent sub-harmonic oscillations at duty cycles
greater than 50%, a stabilizing ramp is added to
the output of the current sense amplifier and the
result is fed into the positive input of the PWM
comparator. When this voltage equals the
output voltage of the error amplifier the power
FET is turned off.
The voltage at the output of the error amplifier
is an amplified version of the difference
between the 104mV reference voltage and the
feedback voltage. In this way the peak current
level keeps the output in regulation.
If the feedback voltage starts to drop, the output
of the error amplifier increases. This results in
more current flowing through the power FET,
thus increasing the power delivered to the
output.
FB
104mV
+
-
AMPLIFIER
-
+
PWM
COMPARATOR
CONTROL
LOGIC
+
1.3MHz
OSC
-
+
CURRENT
SENSE
AMPLIFIER
Figure 1—Functional Block Diagram
M1 SW
GND
MP3202 Rev. 0.91
9/21/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
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MP3202 – 1.3A FIXED FREQUENCY WHITE LED DRIVER
APPLICATION INFORMATION
VIN
4V to 6V
MBR0520
9 Strings
Total
OFF ON
IN SW
EN MP3202 OV
GND
FB
Figure 2—Circuit for Driving 27 WLEDs
A typical application circuit is provided in Figure
2. The 27 white LEDs can be driven from a
voltage supply range of 4V to 6V at a total
output current of 180mA. A 2.2µF output
capacitor is sufficient for most applications but
up to 1µF may be used. A 10µH inductor with
low DCR (inductor resistance) is recommended
to improve efficiency. A 4.7µF ceramic
capacitor is recommended for the input
capacitance in the real system. Schottky diodes
with fast recovery and a low forward voltage are
recommended. Schottky diodes with a 500mA
rating are sufficient for the MP3202. The
switching characteristics during normal
operation can be seen in Figure 3. The MP3202
has internal soft-start to limit the amount of
current through the IN pin at startup and to also
limit the amount of overshoot on the output. The
current limit is increased by a fourth every 40µs
giving a total soft-start time of 120µs.
Steady State Operation
VIN = 5V, 27 LEDS, 180mA
VSW
5V/div.
VOUT AC
200mV/div.
IL
500mA/div.
400ns/div.
Figure 3—Steady State Operation
Figure 4 shows the startup behavior of the
MP3202. The ramped voltage added to the
current sense amplifier reduces the current
output as the duty cycle increases. As more
LEDs are added, the output voltage rises but
the current that can be delivered to the load is
reduced as well.
MP3202 Rev. 0.91
9/21/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
5