UNISONIC TECHNOLOGIES CO., LTD UD38501 CMOS IC 38V 5A SYNCHRONOUS BUCK CONVERTER DESCRIPTION The UTC UD38501 is a monolithic synchronous buck regulator. The device integrates internal high side and external low side power MOSFETs, and provides 5A of continuous load current over a wide input voltage of 8V to 38V. Current mode control provides fast transient response and cycle-by-cycle current limit. An internal soft-start prevents inrush current at turn-on, provides a very compact solution with minimal external components. HSOP-8 FEATURES * Wide 8V to 38V Operating Input Range * Integrated 80mΩ high side Power MOSFET Switches * Output Adjustable from VFB(1V) to 20V * Up to 95% Efficiency * Internal Soft-Start * Stable with Low ESR Ceramic Output Capacitors * Fixed 160KHz Frequency * Cycle-by-Cycle Over Current Protection * Input Under/Over Voltage Lockout ORDERING INFORMATION Ordering Number UD38501G-SH2-R Package HSOP-8 Packing Tape Reel UD38501G-SH2-R (1)Packing Type (1) R: Tape Reel (2)Package Type (2) SH2: HSOP-8 (3)Green Package (3) G: Halogen Free and Lead Free MARKING www.unisonic.com.tw Copyright © 2015 Unisonic Technologies Co., Ltd 1 of 7 QW-R115-009.A UD38501 CMOS IC PIN CONFIGURATION BS 1 8 VDD IN 2 7 EN SW 3 6 COMP LG 4 5 FB GND PIN DESCRIPTION PIN NO. PIN NAME 1 BS 2 IN 3 SW 4 LG PAD 5 FB 6 COMP 7 8 EN VDD DESCRIPTION Boot-Strap Pin. Supply high side gate driver. Decouple this pin to LX pin with 0.1uF ceramic cap. Power Input pin. Bypass IN to GND with a suitably large capacitor to eliminate noise on the input to the IC. Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. Gate drive for external low side N-MOSFET.. Ground (Connect to GND). Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a resistive voltage divider from the output voltage. Compensation Node. COMP is used to compensate the regulation control loop. Connect a series RC network from COMP to GND to compensate the regulation control loop. Enable control. Pull high to turn on. Do not float. Internal regulator pin BLOCK DIAGRAM IN VDD Internal Regulator CURRENT SENSE AMPLIFIER Input UVLO 7.0V VDD BS EN M1 2.5V 1.1V FB PWM Control & Protect Logic 1V COMP Softstart GND SW LG Thermal Protection UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 7 QW-R115-009.A UD38501 CMOS IC ABSOLUTE MAXIMUM RATING (TA=25°C, unless otherwise specified) PARAMETER SYMBOL RATINGS UNIT Supply Voltage VIN -0.3 ~ +42 V Switch Node Voltage VSW -0.3 ~ VIN+0.3 V Boost Voltage VBS VSW-0.3 ~ VSW+ 6 V All Other Pins Voltage -0.3 ~ +6 V Lead Temperature TL 260 °C Junction Temperature TJ 150 °C Storage Temperature TSTG -65 ~ +150 °C Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. RECOMMENDED OPERATING CONDITIONS PARAMETER Input Supply Voltage Output Voltage Ambient Temperature SYMBOL VIN VOUT TA RATINGS 8 ~ 38 VFB ~ 20 -40 ~ +85 UNIT V V °C THERMAL CHARACTERISTICS PARAMETER SYMBOL RATINGS UNIT Junction To Ambient θJA 15 °C/W Junction to Case θJC 40 °C/W Note: θJA is measured with the PCB copper area of approximately 1 in2(Multi-layer). That need connect to exposed pad. ELECTRICAL CHARACTERISTICS (VIN=12V, TA=25°C, unless otherwise specified) PARAMETER Input Voltage Range Shutdown Supply Current Quiescent Current Feedback Voltage Feedback Overvoltage Threshold High-Side Switch On Resistance (Note) High-Side Switch Leakage Current Upper Switch Current Limit LG Rise Time LG Fall Time LG Driver Bias Supply Voltage Oscillation Frequency Short Circuit Oscillation Frequency Maximum Duty Cycle Minimum On Time (Note) EN Lockout Threshold Voltage EN Lockout Hysterisis Input Under Voltage Lockout Threshold Input Under Voltage Lockout Threshold Hysteresis Input Over Voltage Lockout Threshold Input Over Voltage Lockout Threshold Hysteresis Soft-Start Period Thermal Shutdown Thermal Shutdown Hysterisis Note: Guaranteed by design. SYMBOL VIN ISD ICCQ VFB OVP_FB RDS(ON) TLXR TLXF FOSC1 FOSC2 DMAX TON(min) ENH(LOCK) UVLO VEN= 0V VEN=5.0V, VFB=1.05V 8V≤VIN≤38V VEN=0V, VSW=0V Minimum Duty Cycle CLX=1000pF CLX=1000pF MIN 8 0.98 VIN Rising TYP 0.7 0.7 1.00 1.1X 80 MAX 38 1.3 1.5 1.02 10 5.1 VFB=<0.5V UVLO-Hys 6.5 6.0 40 40 5 160 60 90 220 2.5 210 7.0 7.5 UNIT V mA mA V VFB mΩ μA A ns ns V KHz KHz % ns V mV V 800 mV 40 V OVLO-Hys 5 V TSD TSH 3 150 30 ms °C °C OVLO UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw TEST CONDITIONS VIN Rising 3 of 7 QW-R115-009.A UD38501 CMOS IC FUNCTION DESCRIPTIONS The UTC UD38501 is a synchronous rectified, current-mode, step-down regulator. It regulates input voltages from 8V to 38V down to an output voltage as low as VFB, and supplies up to 5A of load current. The UTC UD38501 uses current-mode control to regulate the output voltage. The output voltage is measured at FB through a resistive voltage divider and amplified through the internal Tran conductance error amplifier. The voltage at the COMP pin is compared to the switch current measured internally to control the output voltage. The converter uses internal N-Channel MOSFET switches to step-down the input voltage to the regulated output voltage. Since the high side MOSFET requires a gate voltage greater than the input voltage, a boost capacitor connected between SW and BS is needed to drive the high side gate. The boost capacitor is charged from the internal 5V rail when SW is low. When the UTC UD38501 FB pin exceeds 10% of the nominal regulation voltage of VFB, the over voltage comparator is tripped and the COMP pin is discharged to GND, forcing the high-side switch off. APPLICATION INFORMATION COMPONENT SELECTION Setting the Output Voltage The output voltage is set using a resistive voltage divider from the output voltage to FB pin. The voltage divider divides the output voltage down to the feedback voltage by the ratio. Thus the output voltage is: VOUT VFB R1 R2 R2 For example, VFB =1.00V for a 5.0V output voltage, R2 is 10kΩ, and R1 is 40kΩ. Inductor Selection The inductor is required to supply constant current to the output load while being driven by the switched input voltage. A larger value inductor will result in less ripple current that will result in lower output ripple voltage. However, the larger value inductor will have a larger physical size, higher series resistance, and/or lower saturation current. A good rule for determining the inductance to use is to allow the peak-to-peak ripple current in the inductor to be approximately 30% of the maximum switch current limit. VIN Inductor <28V 47uH <35V 33uH The choice of which style inductor to use mainly depends on the price vs. size requirements and any EMI requirements. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 4 of 7 QW-R115-009.A UD38501 CMOS IC TYPICAL APPLICATION CIRCUIT Input R5 C17 220µF 50V C6 0Ω C5 0.1µF 100nF R4 100kΩ C7 10µF 20V EN IN UTC UD38501 PDA(GND) VDD COMP C4 C3 0.1µF 3.3nF L1 33µH BS R3 15kΩ FB SW LG Output 5V 5A Q1 NMOS R1 40kΩ R2 10kΩ C2 470µF 10V C8 22µF 10V VOUT=VFB × (1+R1/R2), VFB= 1.00V, R2 suggest 10k~30kΩ UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 5 of 7 QW-R115-009.A UD38501 CMOS IC TYPICAL CHARACTERISTICS Quiescent Current vs. Input Voltage Efficiency, EFF (%) 12VIN 24VIN 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Output Current, IOUT (A) Quiescent Current, ICCQ (mA) Efficiency Test (VOUT=5V) 100 90 80 70 60 50 40 30 20 10 0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 5 10 15 20 25 30 Input Voltage, VIN (A) 35 40 Power On VIN=12V, VOUT=5V, IOUT=0A Load Regulation 5.25 Quiescent Current, ICCQ (mA) 0 5.20 5.15 VIN 5.10 5.05 5.00 SW 12VIN 24VIN VOUT IOUT 4.95 4.90 0 0.1 0.2 0.3 0.4 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Input Voltage, VIN (A) Power On VIN=12V, VOUT=5V, ILOAD=5A Enoble On VIN=12V, VOUT=5V, ILOAD=5A VIN VIN SW SW VOUT IOUT VOUT IOUT UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 7 QW-R115-009.A UD38501 CMOS IC UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 7 of 7 QW-R115-009.A