PJ5121 Datasheet. Www.s Manuals.com. Noname
User Manual: Marking of electronic components, SMD Codes 51, 51**, 51***, 5103, 51031, 5108, 51117, 51123, 51123A, 51125, 5121*, 51216, 51219, 5121M, 51225, 5160x, 51716, 5173, 5193, 5198NL, 5199NL, 51A, 51AC30B, 51AC33, 51AC33B, 51Y. Datasheets 1.5SMC51AT3, AT5160TP1U, BZV49-C51, CS51031, FX011Z, G5108RDU, G5111T11, G5121TB1U, G5173R41U, G5193R41U, KB4312B-GRE, LP2951ACSDX-3.3, LP2951CSD-3.0, LP2951CSD-3.3, MM5Z2V7, MTP5103N3, PJ5121EMR, PJ5121EQFN, SST5198NL, SST5199NL, TPS51117PW, TPS51117RGY, TPS51123ARGER, TPS51123
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PJ5121 White LED Step-Up Converter GENERAL DESCRIPTION The PJ 5121 is a step-up DC/DC converter designed for driving up to 8 white LEDs in series from a single cell Lithium Ion battery with constant current. Because it directly regulates output current, the PJ5121 is i deal for driving light emitting diodes (LEDs) whose light intensity is proportional to the current passing through them, not the voltage across their terminals. A single external resistor sets LED current between 5mA and 20mA, which can then be easily adjusted using either a DC voltage or a pulse width modulated (PWM) signal. Its low 225mV 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 PJ5121 is available in SOT23-6 and QFN8 packages. FEATURES APPLICATIONS Drives Up to 5 Series White LEDs from 2.5V Cell Phones Drives Up to 6 Series White LEDs from 3.6V Handheld Computers and PDAs Up to 87% Efficiency Digital Cameras Small LCD Displays 1.2MHz Fixed Switching Frequency Low 225mV Feedback Voltage Open Load Shutdown Soft Start/PWM Dimming SOT23-6 and QFN-8 Packages TYPICAL APPLICATIONS Efficiency vs n(LED) 90.00% 3LED 4LED 5LED 85.00% 6LED PJ5121 7LED 80.00% 8LED 75.00% 5 10 15 Iout (mA) Figure 1. Li-Ion Driver for Six White LEDs 20 25 Vin=3.6V Figure 2. Efficiency vs Number of LEDs Page 1 PJ5121 White LED Step-Up Converter ORDERING INFORMATION PJ5121APPP Package Type MR: SOT-23-6 QFN: QFN-8 2x2 E: Pb Free Package PACKAGES Note: Pin 1 at the bottom-left corner of the digit “4” PIN DESCRIPTION SOT QFN Pin Pin No. Pin No. Names 1 8 SW 2 1,5 GND 3 6 FB Description Power Switch Output. Connect the inductor and the blocking Schottky diode to SW. Ground Feedback input pin. The reference voltage at this pin is 225mV. Connect the cathode of the lowest LED to FB and a current sense resistor between FB and GND. 4 4 EN Enable pin. A high input at EN enables the device and a low input disables the devices. When not used, connect EN to the input source for automatic startup. 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 Not Connected Page 2 PJ5121 White LED Step-Up Converter ABSOLUTE MAXIMUM RATINGS (Note 1) SYMBOL ITEMS VALUE UNIT VIN Input Voltage -0.3～6 V VSW Voltage at SW Pin -0.5～25 V VIO All Other I/O Pins GND-0.3 to VDD+0.3 V ΘJA 220 ℃/W ΘJC 110 Thermal Resistance，SOT-23-6 PTR1 Thermal Resistance，QFN-8 (2mm x 2mm) PTR2 Tstg Tsolder ΘJA 80 ΘJC 16 ℃/W Storage Temperature -55 to 150 Package Lead Soldering Temperature 260℃, 10s ℃ RECOMMANDED OPERATING RANGE (Note 2) SYMBOL ITEMS VALUE UNIT VIN VIN Supply Voltage 2.5 to +6 V VSW Output Voltage VIN to 28 V TOPT Operating Temperature -40 to +85 ℃ ELECTRICAL CHARACTERISTICS VIN=VEN=3V, Topt=25℃ unless specified otherwise. SYMBOL VIN ITEMS CONDITIONS Input Voltage Min. Typ. Max. UNIT 6 V 225 250 mV 0.05 1 µA 2.5 Feedback VFB FB Pin Voltage Ibias FB Pin Input Bias Current Driving 4xLED @15mA 200 Operating Current Ioff Operating Current（Shutdown） VSW-ON =0V 0.1 1 µA Isby Operating Current（Quiescent） VFB=0.3V 100 350 µA Fsw Switching Frequency 1.0 1.25 1.5 MHz Dmax Maximum Duty Cycle 85 90 VFB=0V % Chip Enable VEN_H EN Minimum High Level VEN_L EN Maximum Low Level VHYS EN Hysteresis EN Input Bias Current 1.5 V 0.4 90 VSW-ON =0V, 5V V mV 1 µA Page 3 PJ5121 White LED Step-Up Converter ELECTRICAL CHARACTERISTICS(contd.) VIN=VEN=3V, Topt=25℃ unless specified otherwise. SYMBOL ITEMS CONDITIONS Min. Typ. Max. UNIT Output Switch RON SW On Resistance (Note 3) 0.5 Ω ILIMIT SW Current Limit 400 mA ILEAK SW Leakage Current Vsw＝5V 0.01 Open Circuit Shutdown Threshold VOV Rising 30 V Soft Start Time (Note 3) VIN Power On 160 µS 1 µA Open Circuit Protection VOV Soft Start tss Notes: 1. Exceeding these ratings may damage the device 2. The device is not guaranteed to function outside of its operating rating. 3. Guaranteed by design. TESTING CIRCUIT 5121M Page 4 PJ5121 White LED Step-Up Converter TYPICAL PERFORMANCE CHARACTERISTICS 1. Driving Capability Vin ILED=15mA ILED=20mA 2.5V 5 x LED 4 x LED 3.0V 6 x LED 5 x LED 3.6V 8 x LED 8 x LED 2.Efficiency Figure 3. Efficiency vs Vin and ILED Figure 4. Efficiency vs Temperature Efficiency vs. Temperature Efficiency vs. Vin Efficiency 100.00% 95.00% 20mA 90.00% 15mA 10mA 85.00% 80.00% 5mA 75.00% 70.00% 90.00% 89.00% 88.00% 87.00% 20mA 86.00% 85.00% 4.5 4.4 4.3 4.2 4.1 4 3.9 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3 83.00% 82.00% 81.00% 80.00% -50 0 Vin (V) 1.6 200 1.4 1.2 150 100 Temp=-40℃ Temp=25℃ Temp=100℃ 50 0 4 4.5 5 5.5 6 Fosc(MHz) Iq(uA) Fosc VS Temp. 250 Vin(V) 150 Figure 6. Fosc vs. Temperature Iq VS Temperature 3.5 100 4.Switching Frequency vs Temperature Figure 5. Iq vs. Temperature 3 50 Temp (C) 3. Quiescent Current vs VIN and Temperature 2.5 10mA 15mA 84.00% 1 0.8 0.6 0.4 0.2 0 -40 25 100 Temp(℃) Page 5 PJ5121 White LED Step-Up Converter OPERATION Figure 7. Simplified Block Diagram of the PJ 5121 The PJ5121 uses a constan t frequency, peak current mode boost set by the output of error amplifier, the PWM comparator resets regulator architecture to regulate the series string of white LEDs. the latch in the control logic and turns off the power switch. In this The operation of the PJ5121 can be understood by referring to the manner, error amplifier sets the correct peak current level to keep simplified block diagram shown above in Figure 7. At the start of the LED current in regulation. If the feedback voltage starts to each oscillator cycle, the control logic turns on the power switch drop, the output of the error amplifier increases. This results in M1. The signal at the non-inverting input of the PWM comparator more current to flow through M1, hence increasing the power is proportional to the switch current, summed together with a delivered to the output. portion of the oscillator ramp. When this signal reaches the level APPLICATION INFORMATION Inductor Selections For most of the applications of the PJ512 1, it is smaller and thinner inductors give higher core losses at recommended to use an inductor of 22uH. Although small 1.25MHz and DRC, resulting in lower efficiencies. The size is one of the major factors in selecting an inductor, the following tab le provides a list of recommended inductors: PART DCR CURRENT RATING MANUFACTURER NUMBER （Ω） （mA） LQH3C220 0.71 250 MURATA CDRH3D16-220 0.53 350 SUMIDA LB2012B220M 1.7 75 TAIYO YUDEN LEM2520-220 5.5 125 TAIYO YUDEN EJPC220KF 4.0 160 PANASONIC Capacitor Selection The small size of ceramic capacitors makes them ideal for wider voltage and temperature ranges than other types such PJ5 121 as Y5V or Z5U. A 1µF input capacitor and a 0.22 µF output pplications. X5R and X7R types are recommended because they retain their capacitance over capacitor are sufficient for most PJ5121 applications. Page 6 PJ5121 White LED Step-Up Converter PACKAGE INFORMATION 1. SOT-23-6 2. QFN8 2x2 Page www.s-manuals.com
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