RY3750

RY3750 1.2MHz, 30V, Step-Up Converter Features • • • • 2.5V to 5.5V Input Voltage 1.23V Feedback Voltage 1.2MHz Fixed Switching Frequency Internal 0.6A Switch Current Limit • • • Internal Compensation Thermal Shutdown Available in a 5-pin SOT-23 package • PDA LED back light Applications • • Camera Flash White LED Digital still cameras General Description The Y3750 is a step-up converter. Its 1.23V feedback voltage reduces power loss and improves efficiency. Optimized operation frequency can meet the requirement of small LC filters value and low operation current with high efficiency. Internal soft start function can reduce the inrush current. Tiny package type provides the best solution for PCB space saving and total BOM cost. Typical Application Circuit L1 VIN VIN VOUT D1 SW R1 RY3750 CFF COUT FB CIN ON/ OFF EN GND R2 Figure1. Basic Application Circuit Email: support@rychip.com ©RYCHIP Semiconductor Inc. 7 http://www.rychip.com Page 1 / RY3750 1.2MHz, 30V, Step-Up Converter Package and Pin Description TOP VIEW LX 1 GND 2 FB 3 5 IN 4 EN SOT23-5 Top Marking: KFYLL (device code: KF, Y=year code, LL= lot number code) Pin Name Function 1 LX Power Switch Output. LX is the drain of the internal MOSFET switch. Connect the power inductor and output rectifier to LX. LX can swing between GND and 30V. 2 GND 3 FB Feedback Input. The FB voltage is 1.23V. Connect a resistor divider to FB. 4 EN Regulator On/Off Control Input. A high input at EN turns on the converter, and a low input turns it off. When not used, connect EN to the input supply for automatic startup. 5 IN Input Supply Pin. Must be locally bypassed. Ground Pin Order Information Marking Part No. Model Description Package T/R Qty KFYLL 70390005 RY3750 RY3750 Step-up Converter, 2.5-5.5V, Vout 30V, 1.2MHz, SOT23-5 SOT23-5 3000PCS Email: support@rychip.com ©RYCHIP Semiconductor Inc. 7 http://www.rychip.com Page 2 / RY3750 1.2MHz, 30V, Step-Up Converter Absolute Maximum Ratings Parameter Absolute Maximum Ratings Unit VIN, VEN VSW All Other Pins -0.3 to 6 -0.3 to 30 -0.3 to 6 V V V Continuous Power Dissipation(TA=+25℃) 0.6 W Junction Temperature Operating Temperature Range Lead Temperature Storage Temperature Thermal Resistance θJA Thermal Resistance θJC 150 -40 to 85 260 -65 to 150 250 130 °C °C °C °C °C /W °C /W Parameter Recommended Unit Supply Voltage VIN Output Voltage VOUT Operating Junction Temp.(TJ) 2.5 to 5.5 VIN to 30 -40 to 125 V V °C Recommended Operating Conditions Electrical Characteristics Parameter Symbol Supply Current(Shutdown) Quiescent Current SW Leakage SW On Resistance Operating Input Voltage Current Limit Oscillator Frequency Maximum Duty Cycle Feedback Voltage FB Input Bias Current EN Threshold Thermal Shutdown Supply Current(Shutdown) IIN Email: support@rychip.com ©RYCHIP Semiconductor Inc. 7 Test Conditions Min Typ Max Unit VEN=0V 0.1 1 µA VFB=1V, switch VSW = 20V 0.15 0.3 1 650 5.5 mA µA mΩ V A MHz % V nA V °C 400 2.5 ILIMIT fSW DMAX VFB VIN= 4V, Duty cycle=50% VFB=1V VFB=1.23V VEN IIN VEN=0V 1.21 -50 0.6 1.2 90 1.23 -10 1 160 1.25 0.1 1 µA http://www.rychip.com Page 3 / RY3750 1.2MHz, 30V, Step-Up Converter Typical Performance Characteristics Note (1): Performance waveforms are tested on the evaluation board. Note (2): VIN =5V, VOUT=24V, L = 10µH, COUT=22uF TA = +25ºC, unless otherwise noted Efficiency vs Output Current Load Regulation Line Regulation VOUT = 24V VOUT = 24V VOUT = 24V, IOUT = 60mA Current Limit vs Duty Output Ripple Voltage Output Ripple Voltage VIN=5V IOUT = 0mA IOUT = 60mA Output Ripple Voltage VIN Power On VIN Power Off IOUT = 120mA IOUT = 60mA IOUT = 60mA Email: support@rychip.com ©RYCHIP Semiconductor Inc. 7 http://www.rychip.com Page 4 / RY3750 1.2MHz, 30V, Step-Up Converter EN Power On EN Power Off Load Transient IOUT = 60mA IOUT = 60mA VIN=5V, IOUT=50mA to 100mA@300mA/µs Email: support@rychip.com ©RYCHIP Semiconductor Inc. 7 http://www.rychip.com Page 5 / RY3750 1.2MHz, 30V, Step-Up Converter Application Information Setting the Output Voltage The internal reference VREF is 1.23V (Typical). The output voltage is divided by a resistor divider, R1 and R2 to the FB pin. The output voltage is given by R2 = VOUT R1 / V FB − 1 Inductor Selection The recommended values of inductor are 2.2μH to 10μH. Small size and better efficiency are the major concerns for portable device, such as RY3750 used for mobile phone. The inductor should have low core loss at 1.2MHz and low DCR for better efficiency. To avoid inductor saturation current rating should be considered. Capacitor Selection Input and output ceramic capacitors of 22μF are recommended for RY3750 applications. For better voltage filtering, ceramic capacitors with low ESR are recommended. X5R and X7R types are suitable because of their wider voltage and temperature ranges. Diode Selection Schottky diode is a good choice for RY3750 because of its low forward voltage drop and fast reverses recovery. Using Schottky diode can get better efficiency. The high speed rectification is also a good characteristic of Schottky diode for high switching frequency. Current rating of the diode must meet the root mean square of the peak current and output average current multiplication as following: I D ( RMS )  I OUT  I PEAK The diode’ s reverse breakdown voltage should be larger than the output voltage. Layout Consideration For best performance of the RY3750, the following guidelines must be strictly followed. 1、Input and Output capacitors should be placed close to the IC and connected to ground plane to reduce noise coupling. 2、The GND should be connected to a strong ground plane for heat sinking and noise protection. 3、Keep the main current traces as possible as short and wide. 4、LX node of DC-DC converter is with high frequency voltage swing. It should be kept at a small area. 5、Place the feedback components as close as possible to the IC and keep away from the noisy devices. Email: support@rychip.com ©RYCHIP Semiconductor Inc. 7 http://www.rychip.com Page 6 / RY3750 1.2MHz, 30V, Step-Up Converter Package Description SOT23-5 2.80 3.00 0.95 BSC 0.60 TYP 1.20 TYP EXAMPLE TOP MARK AAAAA 1.50 2.60 1.70 3.00 2.60 TYP PIN 1 TOP VIEW RECOMMENDED PAD LAYOUT GAUGE PLANE 0.25 BSC 0.90 1.30 1.45 MAX SEATING PLANE 0.30 0.50 0.95 BSC FRONT VIEW 0.00 0.15 0.09 0.20 0.30 0.55 0°~8° SIDE VIEW Note: 1. All dimensions are in millimeters. 2. Package length does not include mold flash, protrusion or gate burr. 3. Package width does not include flash or protrusion. 4. Lead coplanarity (bottom of leads after forming) shall be 0.10 millimeters max. 5. Pin 1 is lower left pin when reading top mark from left to right. Email: support@rychip.com ©RYCHIP Semiconductor Inc. 7 http://www.rychip.com Page 7 /