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SIP12501
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Vishay Siliconix
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Boost Converter for Single/Double AA Cell or NiMH Battery for White LED Applications
FEATURES
D Voltage Mode Control with Internal Frequency Compensation D 0.65-V to 3.3-V Input Voltage Range D Low Startup Voltage: 0.65 V D PWM Control with 600-kHz Fixed Switching Frequency D Analog Control of LED Intensity D Power Supply from Output Voltage D Regulated Output Current D Integrated UVLO and Soft-Start D Logic Controlled Shutdown (t1 mA) D High Efficiency: Typical 75% D D D D D Internal Power MOS Antiringing Switch to Minimize EMI Thermal Shutdown Minimum External Components PowerPAKr MLP33-6 Package
APPLICATIONS
D D D D D White LED Backlighting Handheld Devices Digital Cameras Portable Applications LCD Bias Supplies
DESCRIPTION
SIP12501 is a boost converter IC for single or double cell NiMH or Alkaline battery pack, which can drive white LEDs connected in parallel to provide backlight in hand-held devices. Designed with an internal low threshold power MOSFET, it is capable of starting up with a low battery voltage of 0.65 V. For best efficiency performance, the SIP12501 is designed to operate in PWM mode with 600-kHz switching. The voltage-mode PWM design is internally compensated, reducing the external parts count. It accepts input voltages from 0.65 V to 3.3 V, regulates output current of up to 60 mA from a 0.9-V input. The LED current can be adjusted externally for its brightness control. SIP12501 features low shutdown current of under 1-mA, internal power MOS, thermal shutdown protection and antiringing control. SIP12501 is available in a lead (Pb)-free 6-pin, PowerPAK MLP33 package and is specified to operate over the industrial temperature range of -40 C to 85 C.
TYPICAL APPLICATION CIRCUIT
VIN 10 mF 2 VIN XSHD 1 XSHD
10 mH
LX
6
MBR0520
4.7 mF
SIP12501
5 4
GND VOUT 3
FB
15 W
15 W
15 W
15 W
Document Number: 73192 S-50205--Rev. A, 21-Feb-05
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SIP12501
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ABSOLUTE MAXIMUM RATINGS (ALL VOLTAGES REFERENCED TO GND = 0 V)
Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 6 V LX Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to VOUT +0.5V Output Voltage, VOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 6 V XSHD Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to VIN +0.5V FB Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 6 V Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150_C Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to 150_C Operating Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125_C Power Dissipationa PowerPAK MLP33-6 (TA = 70 _C)a . . . . . . . . . . . . . . . . . . . . . . . . . 1100 mW Thermal Resistanceb PowerPAK MLP33-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50_C/W Notes a. Derate 20mW/_C above 70_C b. Device mounted with all leads soldered or welded to PC board.
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING RANGE (ALL VOLTAGES REFERENCED TO GND = 0 V)
Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.65 to 3.3 V Output Voltage, VOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 to 5 V XSHD Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to VIN LX Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to VOUT + 0.5 V FB Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to 5 V Operating Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . -40 to 85_C
SPECIFICATIONSa
Test Conditions Unless Specified p Parameter
Minimum Start-Up Voltage Minimum Operating Voltaged Feedback Voltage Feedback Input Current Maximum PWM Duty Cycle PWM Switching Frequency Quiescent Current Stand-By Current NMOS Switch Leakage NMOS Switch On Resistance XSHD Input High Level XSHD Input Low Level Thermal Shutdown Thermal Shutdown Hysteresus
Tempa
Limits Minb Typc
0.65 0.55 0.291 0.3 1 80 87 600 200 1 775 300 1 2 10 0.24 0 24 W 0.55 0.8 1.2 0.2 160 20 _C V mA 0.309 0.318 nA % kHz 0.282
Symbol
VSTART VHOLD VFB IFB MAXDTY fOSC IQ ISTB ILEAK rDS( ) DS(on) VXSHDH VXSHDL TSHD THYST
VIN = 1.2 V, VOUT = 3.9 V, TA = 25_C
Maxb
0.85
Unit
ILOAD = 1 mA XSHD = VIN
Full Full Full
V
VFB = 0.3 V Full VFB = 0.4 V XSHD = 0 V, Not Including Switch Leakage LX = 5 V VOUT = 3 3 V 3.3 0.8 V v VIN v 0.9 V 0.9 V t VIN v 2 V 2 V t VIN v 5 V Full Full Full Full Full Full Full 425
Notes a. Full = -40 to 85_C b. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum (-40_ to 85_C). c. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing. d. Minimum Operating Voltage is determined by the battery's capability to provide energy as it is deeply discharged.
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Document Number: 73192 S-50205--Rev. A, 21-Feb-05
SIP12501
New Product
PIN CONFIGURATION AND TRUTH TABLE
Vishay Siliconix
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PowerPAK MLP33-6
XSHD
1
6
LX
VIN
2
5
GND
VOUT
3
4
FB
Top View
ORDERING INFORMATION
Part Number
SIP12501DMP-T1-E3
Temperature Range
-40 to 85_C
Marking
2501
PIN DESCRIPTION
Pin Number
1 2 3 4 5 6
Name
XSDH VIN VOUT FB GND LX Battery Input Voltage
Function
Logic Controlled Shutdown Input, XSHD = High: Normal Operation, XSHD = Low: Shutdown Output of the Boost Converter and Power Source for the IC Feedback Pin Signal and Power Ground Switch Pin
PIN FUNCTIONS
XSHD (Pin 1) XSHD is the logic controlled shutdown input pin. When XSHD is low, the IC is shutdown and an antiringing switch is connected between LX and VIN. When XSHD is high, the IC is working in normal operation. VIN (Pin 2) VIN is the pin connected to battery input voltage. The IC gets its start-up bias from VIN at the beginning. Once VOUT exceeds VIN, bias will come from VOUT. Thus, once started, operation is completely independent from VIN. Operation is only limited by the output voltage level and the battery's internal series resistance. VOUT (Pin 3) VOUT is the output of the boost converter and also the power source for the IC.
Document Number: 73192 S-50205--Rev. A, 21-Feb-05
FB (Pin 4) FB is the feedback voltage pin, it senses the LED current through the ballast resistor, the difference between it and the internal 0.3 V reference is amplified by the error amplifier. GND (Pin 5) GND is the pin for signal and power ground. LX (Pin 6) LX is the pin of the drain for internal power MOS. LX is also connected to inductor and Schottky diode. If the inductor current falls to zero, or XSHD is low, an internal antiringing switch is connected from LX to VIN to minimize EMI.
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SIP12501
Vishay Siliconix
FUNCTIONAL BLOCK DIAGRAM
VOUT VIN GND Antiringing SW Start-Up FB - E/A + + PWM - LX Driver
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Thermal Shutdown Compensation
XSHD
Reference and Soft-Start
Oscillator
DETAILED OPERATION
SIP12501 is a 600-kHz boost converter IC, packaged in 6-pin MLP33, for white LED applications. With start-up from low battery input voltage of 0.65 V, this device features fixed frequency voltage mode PWM control with internal frequency compensation. With its low rDS(on) internal power MOSFET, this device maintains high efficiency over a wide range of load current. Low Voltage Start-Up SIP12501 is designed to start-up at input voltage of typically 0.65 V. In the beginning, VOUT is lower than VIN because of the voltage drop of the Schottky diode, the device uses VIN as the power source for the start-up circuit and uses current limit with fixed off-time to control the increase of the output voltage. Once VOUT exceeds VIN, the device uses VOUT as the power source. When VOUT exceeds 1.89 V, the device switches to soft-start. Soft-Start During soft-start, , the loop compensation guarantees the slow increase of the output voltage and inrush current, so that no large voltage overshoot and inrush current occur when the soft-start is ended. PWM operation After soft-start, the device works in PWM operation with a fixed frequency of 600 kHz.
VIN
Thermal Shutdown Protection If the temperature of the device is above160 _C, the device will turn off the internal power MOSFET and wait until the temperature drops below 140 _C, then the device goes into the soft-start process again and finally the system recovers. During thermal shutdown, the output voltage drops below 1.89 V minus UVLO hysteresis, start-up will be triggered to keep the output voltage above 1.89 V. Antiringing Control The antiringing control circuitry prevents high frequency ringing of the LX pin as the inductor current goes to zero by damping the resonant circuit formed by L and CLX (capacitance on LX pin). When the IC is shutdown, this antiringing switch is also turned on.
Application Information
White LED Brightness Control The current of white LED can be adjusted by a PWM signal on XSHD or by a variable dc voltage to control its brightness. (See Figure 1.) As control voltage VCTRL increases, the voltage drop on R2 increases and the voltage drop on R1 decreases. Thus, the LED current decreases. The selection of R2 and R3 will make the current from VCTRL much smaller than LED current and much larger than the FB pin bias current.
0.3 * V CTRL R2 @ 15W R3
10 mF 1
2 VIN XSHD
10 mH LX 6 MBR0520
ILED + 0.3V ) 15W
XSHD
4.7 mF
SIP12501
5 XSHD VOUT 3 FB 4
R2 1 kW R3 3.9 kW VCTRL R1 15 W 15 W 15 W 15 W
Figure 1.
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SIP12501
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TYPICAL CHARACTERISTICS
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Maixmum PWM Duty Cycle vs. Temperature
90 89 88 % Duty Cycle 87 86 85 84 83 82 81 80 -50 -30 -10 10 30 50 70 90 Supply Curremt (mA) 0.160 0.158 0.156 0.154 0.152 0.150 0.148 0.146 0.144 0.142 0.140 -50
Supply Current vs. Temperature
-30
-10
10
30
50
70
90
Temperature (_C)
Temperature (_C)
Feedback Voltage vs. Temperature
4 3 Feedback Voltage Accuracy (%) 2 1 0 -1 -2 -3 -4 -50 0.2 0.0 -50 VOUT = 3.9 V Shutdown Threshold (V) 1.2 1.0 0.8
Shutdown Threshold vs. Temperature
VIN = 5 V
VIN = 2 V 0.6 VIN = 0.8 V 0.4
-30
-10
10
30
50
70
90
-30
-10
10
30
50
70
90
Temperature (_C)
Temperature (_C)
Document Number: 73192 S-50205--Rev. A, 21-Feb-05
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SIP12501
Vishay Siliconix
TYPICAL WAVEFORMS
PWM Dimming Control Startup
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Figure 2.
Figure 3.
200 Hz 50% Duty Cycle PWM Signal on XSHD Pin VXSHD 0.5 V/div
VIN = VXSHD = 0 to 0.8 V
VIN 0.5 V/div
VOUT 1 V/div
VFB 0.2 V/div
VOUT 2 V/div 100 ms/div
VIN = 0.8 V Four LEDs in series
1 ms/div
Figure 4.
Switching Waveforms: VLX, VOUT and VFB
VIN = 0.8 V, L = 10 mH, COUT = 4.7 mF, Four LEDs in Parallel
VLX 2 V/div
VOUT 50 mV/div ac coupled VFB 20 mV/div ac coupled 0.5 ms/div
Vishay Siliconix maintains worldwide manufacturing capability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon Technology and Package Reliability represent a composite of all qualified locations. For related documents such as package/tape drawings, part marking, and reliability data, see http://www.vishay.com/ppg?73192. www.vishay.com Document Number: 73192 S-50205--Rev. A, 21-Feb-05
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