MP3202
1.3A Fixed Frequency
White LED Driver
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 us a current mode, fixed frequency architecture to regulate the LED current, which is measured through an external current n 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 prent 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.
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
图塔V IN
4.5V - 6V
EN 100
9080706050E F F I C I E N C Y (%)
4.0
4.5
5.0 5.5
6.0
INPUT VOLTAGE (V)
Efficiency vs Input Voltage
PACKAGE REFERENCE
* For Tape & Reel, add suffix –Z (eg. MP3202DJ–Z)
For RoHS compliant packaging, add suffix –LF
(eg. MP3202DJ–LF–Z)
ABSOLUTE MAXIMUM RATINGS (1) –0.5V to +28.5V All .–0.3V to +6.5V –55°C to +150°C Recommended Operating Conditions (2) IN .2.5V to 6V V IN to 25V –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
<.110..°C/W QFN8 (2mm x 2mm)...............80......16...°C/W Notes:
1) Exceeding the 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
V IN = V EN = 5V, T A = +25°C, unless otherwi noted.
Parameters Symbol
Condition Min
Typ
Max
Units
Operating Input Voltage V IN 2.5 6 V
Supply Current (Shutdown) V EN = 0V 0.1 1 µA
Supply Current (Quiescent) V FB = 0.15V 690 750 µA
Switching Frequency f SW 1.0 1.3 1.5 MHz Maximum Duty Cycle V FB = 0V 85 92 %
Under Voltage Lockout
主板型号
IN Under Voltage Lockout UVLO V IN Rising 2.25 2.45 V
Under Voltage Lockout
Hysteresis
92 mV
Open Lamp Shutdown
Threshold
V OV V OV Rising 28 V
ELECTRICAL CHARACTERISTICS (continued)
V IN = V EN = 5V, T A = +25°C, unless otherwi noted.
Parameters Symbol Condition Min Typ Max Units Enable
EN Threshold V EN Rising, V IN = 5V 1.0 1.35 1.6 V EN Threshold V EN Rising, V IN = 2.5V 0.8 V EN Hysteresis
90 mV EN Input Bias Current V EN = 0V, 5V
1
µA
吉祥安坤丸Feedback FB Voltage
94 104 114 mV FB Input Bias Current
V FB = 0.1V
–600 –300 nA Output Switch
SW On-Resistance (4) R ON
0.5 Ω SW Current Limit (4)
Duty Cycle = 60%
1.33 A Thermal Shutdown (4)
160 °C
Notes:
4) Guaranteed by design.
PIN FUNCTIONS
TSOT23-6 Pin # QFN8
海底世界的描写Pin #
Name Description理财理财
1 8 SW Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the power inductor and output rectifier to SW. SW can swing between GND and
25V.
2 1, 5 GND Ground.
分析心理学
3 6 FB
Feedback Input. The MP3202 regulates the voltage across the current n resistor between FB and GND. Connect a current n resistor from the bottom
of the LED string to GND. Connect the bottom of the LED string to FB. The regulation voltage is 104mV.
4 4 EN Regulator On/Off Control Input. A high input at EN turns on the converter, and a腼腆什么意思
low input turns it off. When not ud, connect EN to the input source for automatic
包青天的故事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 bypasd.
7 NC No Connect.
OPERATION
The MP3202 us 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 n 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 increas. This results in more current flowing through the power FET,
thus increasing the power delivered to the output.
SW
GND
-
+FB
Figure 1—Functional Block Diagram
APPLICATION INFORMATION
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 ud. 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 en 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 o
n the output. The current limit is incread by a fourth every 40µs giving a total soft-start time of 120µs.
V SW 5V/div.V OUT AC 200mV/div.
I L
500mA/div.
400ns/div.
Steady State Operation
V IN = 5V, 27 LEDS, 180mA
Figure 3—Steady State Operation Figure 4 shows the startup behavior of the MP3202. The ramped voltage added to the current n amplifier reduces the current output as the duty cycle increas. As more LEDs are added, the output voltage ris but the current that can be delivered to the load is reduced as well.
