JW5022S

JW5022S 2A, 24V Synchronous Step-Down Converter Parameters Subject to Change Without Notice DESCRIPTION FEATURES The JW ®5022S is a current mode monolithic buck voltage converter. Operating with an input range of 4.5-24V, the JW5022S delivers 2A of continuous output current with two integrated N-Channel MOSFETs. At light loads, regulators operate in low frequency to maintain high efficiency and low output ripple. The JW5022S guarantees robustness with over current protection, thermal protection, start-up current run-away protection, and input under voltage lockout. The JW5022S is available in a 8-pin SOP8 package, which provides a compact solution with minimal external components.
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4.5V to 24V operating input range 2A output current Up to 94% efficiency High efficiency (85>%) at light load Fixed 500kHz Switching frequency Input under voltage lockout Available in SOP8 package Start-up current run-away protection Over current protection and Hiccup Thermal protection APPLICATIONS




Distributed Power Systems Networking Systems FPGA, DSP, ASIC Power Supplies Green Electronics/ Appliances Notebook Computers TYPICAL APPLICATION JW5022S Rev.0.31 JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. 1 JW5022S JoulWatt ORDER INFORMATION TOP LEAD FREE FINISH TAPE AND REEL PACKAGE Note ： MARKING JW5022SSOPB#PBF JW5022SSOPB#TRPBF SOP8 JW5022S PIN CONFIGURATION TOP VIEW ABSOLUTE MAXIMUM RATING1） VIN, EN, SW Pin ................................................................................................................. -0.3V to 24V BST Pin ................................................................................................................... SW-0.3V to SW+5V All other Pins ......................................................................................................................... -0.3V to 6V Junction Temperature2) 3) ..................................................................................................................150ºC Lead Temperature ......................................................................................................................260ºC Storage Temperature .................................................................................................. -65ºC to +150ºC RECOMMENDED OPERATING CONDITIONS Input Voltage VIN ................................................................................................................4.5V to 24V Output Voltage Vout................................................................................................................. 0.6V to 22V Operating Junction Temperature(TJ)....................................................................................-40ºC to 125ºC THERMAL PERFORMANCE4） θJA θJc SOP8 ..................................................................................................................................... 96...45ºC/W Note 1) 2) 3) 4) ： Exceeding these ratings may damage the device. The JW5022S guarantees robust performance from -40°C to 150°C junction temperature. The junction temperature range specification is assured by design, characterization and correlation with statistical process controls. The JW5022S includes thermal protection that is intended to protect the device in overload conditions. Thermal protection is active when junction temperature exceeds the maximum operating junction temperature. Continuous operation over the specified absolute maximum operating junction temperature may damage the device. Measured on JESD51-7, 4-layer PCB. JW5022S Rev.0.31 JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. 2 JW5022S JoulWatt ELECTRICAL CHARACTERISTICS VIN=12V, TA=25 ℃, unless otherwise stated. Item Symbol Condition Min. Typ. Max. Units VIN Undervoltage Lockout Threshold VIN_MIN VIN falling 3.8 V VIN Undervoltage Lockout Hysteresis VIN_MIN_HYST VIN rising 300 mV Shutdown Supply Current ISD VEN=0V Supply Current IQ VEN=5V, VFB=2V Feedback Voltage VFB Top Switch Resistance RDS(ON)T 170 mΩ Bottom Switch Resistance RDS(ON)B 110 mΩ Top Switch Leakage Current ILEAK_TOP Bottom Switch Leakage Current ILEAK_BOT Top Switch Current Limit ILIM_TOP Switch Frequency 1 µA 50 0.895 0.923 VIN=24V, VEN=0V, VSW=0V VIN=24V, VEN=0V, VSW=0V 0.951 V 0.5 uA 0.5 uA 3.8 A FSW 500 kHz Minimum On Time TON_MIN 100 ns Minimum Off Time TOFF_MIN VFB=0.7V 100 ns EN shut down threshold voltage VEN_TH VEN falling, FB=0V 1.2 V EN shut down hysteresis VEN_HYST VEN rising, FB=0V 100 mV Thermal Shutdown TTSD 145 Temperature Hysteresis THYS 19 JW5022S Rev.0.31 Minimum Duty Cycle µA JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. ℃ ℃ 3 JW5022S JoulWatt PIN DESCRIPTION PIN NAME Description 1 BST 2 IN 3 SW 4 GND 5 FB 6 NC Not Connected. 7 EN Drive EN pin high to turn on the regulator and low to turn off the regulator. 8 NC Not Connected. Bootstrap pin for top switch. A 0.1uF or larger capacitor should be connected between this pin and the SW pin to supply current to the top switch and top switch driver. Input voltage pin. VIN supplies power to the IC. Connect a 4.6V to 24V supply to VIN and bypass VIN to GND with a suitably large capacitor to eliminate noise on the input to the IC. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. Power ground pin. Output feedback pin. FB senses the output voltage and is regulated by the control loop to 0.923V. Connect a resistive divider at FB. BLOCK DIAGRAM VIN + Current Ramp Current Sensor + Oscillator - CLK 3.3V BST + SS Current Comparator + 0.6V Error + Amplifier - SW Logic Control - FB - 3.3V LDO Current Sensor + 1.3V + GND EN JW5022S Rev.0.31 - JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. 4 JW5022S JoulWatt TYPICAL PERFORMANCE CHARACTERISTICS Vin =12V, Vout = 3.3V, L = 4.7µH, Cout = 22µF, TA = +25°C, unless otherwise noted Steady State Test Startup through Enable Shutdown through Enable VIN=12V, Vout=3.3V Iout=2A VIN=12V, Vout=3.3V Iout=2A(Resistive load) VIN=12V, Vout=3.3V Iout=2A(Resistive load) Heavy Load Operation Medium Load Operation Light Load Operation 2A LOAD 1A LOAD 0 A LOAD Short Circuit Protection VIN=12V, Vout=3.3V Iout=2A- Short JW5022S Rev.0.31 Short Circuit Recovery VIN=12V, Vout=3.3V Iout= Short-2A JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. Load Transient 1A LOAD → 2A LOAD → 1A LOAD 5 JW5022S JoulWatt FUNCTIONAL DESCRIPTION The JW5022S is a synchronous, buck voltage converter. Current-Mode Control The JW5022S utilizes current-mode control to regulate the FB voltage. Voltage at the FB pin is regulated at 0.923V so that by connecting an appropriate resistor divider between VOUT and GND, designed output voltage can be achieved. PFM Mode The JW5022S operates in PFM mode at light load. In PFM mode, switch frequency is continuously controlled in proportion to the load current, i.e. switch frequency is decreased when load current drops to boost power efficiency at light load by reducing switch-loss, while switch frequency is increased when load current rises, minimizing both load current and output voltage ripples. Internal Soft-Start. Soft-start makes output voltage rising smoothly by following an internal SS voltage until SS voltage is higher than the internal reference voltage. It can prevent the overshoot of output voltage during startup. Power Switch N-Channel MOSFET switches are integrated on the JW5022S to down convert the input voltage to the regulated output voltage. Since the top MOSFET needs a gate voltage greater than the input voltage, a boost capacitor connected between BST and SW pins is required to drive JW5022S Rev.0.31 the gate of the top switch. The boost capacitor is charged by the internal 3.3V rail when SW is low. Vin Under-Voltage Protection A resistive divider can be connected between Vin and ground, with the central tap connected to EN, so that when Vin drops to the pre-set value, EN drops below 1.2V to trigger input under voltage lockout protection. Output Current Run-Away Protection At start-up, due to the high voltage at input and low voltage at output, current inertia of the output inductance can be easily built up, resulting in a large start-up output current. A valley current limit is designed in the JW5022S so that only when output current drops below the valley current limit can the bottom power switch be turned off. By such control mechanism, the output current at start-up is well controlled. Over Current Protection and Hiccup JW5022S has a cycle-by-cycle current limit. When the inductor current triggers current limit, JW5022S enters hiccup mode and periodically restart the chip. JW5022S will exit hiccup mode while not triggering current limit. Thermal Protection When the temperature of the JW5022S rises above 140°C, it is forced into thermal shut-down. Only when core temperature drops below 130°C can the regulator becomes active again. JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. 6 JW5022S JoulWatt APPLICATION INFORMATION Output Voltage Set The output voltage is determined by the resistor divider connected at the FB pin, and the voltage ratio is: VFB VOUT ⋅ R3 C1 R 2 + R3 where VFB is the feedback voltage and VOUT is the output voltage. Choose R3 around 10kΩ, and then R2 can be calculated by: R2 Thus the input capacitor can be calculated by the following equation when the input ripple voltage is determined.  VOUT − 1  0.923 V  R3 ⋅  The following table lists the recommended values. VOUT(V) R3(kΩ) R2(kΩ) 2.5 10 17 3.3 10 26.1 5 11 48.4 ILOAD VOUT  fs ⋅ ∆V IN VIN  ⋅ ⋅ 1 − VOUT  VIN   where C1 is the input capacitance value, fs is the switching frequency, current. △V IN is the input ripple The input capacitor can be electrolytic, tantalum or ceramic. To minimizing the potential noise, a small X5R or X7R ceramic capacitor, i.e. 0.1uF, should be placed as close to the IC as possible when using electrolytic capacitors. A 10uF ceramic capacitor is recommended in typical application. Output Capacitor The output capacitor is required to maintain the DC output voltage, and the capacitance value determines the output ripple voltage. The output voltage ripple can be calculated by: ∆V OUT Input Capacitor The input capacitor is used to supply the AC input current to the step-down converter and maintaining the DC input voltage. The ripple current through the input capacitor can be calculated by: IC1 ILOAD ⋅ VOUT  VIN  ⋅ 1 − VOUT  VIN   where ILOAD is the load current, VOUT is the output voltage, VIN is the input voltage. JW5022S Rev.0.31 VOUT  fs ⋅ L  ⋅ 1 − VOUT  1  ⋅  RESR +  VIN   8 ⋅ fs ⋅ C2  where C2 is the output capacitance value and RESR is the equivalent series resistance value of the output capacitor. The output capacitor can be low ESR electrolytic, tantalum or ceramic, which lower ESR capacitors get lower output ripple voltage. The output capacitors also affect the system stability and transient response, and a 22uF ceramic capacitor is recommended in typical application. JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. 7 JW5022S JoulWatt Inductor PCB Layout Note The inductor is used to supply constant current For minimum noise problem and best operating performance, the PCB is preferred to following the guidelines as reference. to the output load, and the value determines the ripple current which affect the efficiency and the output voltage ripple. The ripple current is typically allowed to be 30% of the maximum switch current limit, thus the inductance value can be calculated by: L VOUT  VOUT  ⋅ 1 −  fs ⋅ ∆I L  VIN  where VIN is the input voltage, VOUT is the output voltage, fs is the switching frequency, and △I L is the peak-to-peak inductor ripple 1. Place the input decoupling capacitor as close to JW5022S (VIN pin and PGND) as possible to eliminate noise at the input pin. The loop area formed by input capacitor and GND must be minimized. 2. Put the feedback trace as far away from the inductor and noisy power traces as possible. 3. The ground plane on the PCB should be as large as possible for better heat dissipation. current. External Boostrap Capacitor A boostrap capacitor is required to supply voltage to the top switch driver. A 0.1uF low ESR ceramic capacitor is recommended to connected to the BST pin and SW pin. External Soft-start Capacitor A soft-start capacitor is required to set the soft-start period which controls the rate of the output voltage rise. Take the startup current and voltage rise rate into consideration, a 0.1uF ceramic capacitor is recommended. ， JW5022S Rev.0.31 JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. 8 JW5022S JoulWatt REFERENCE DESIGN Reference 1： ： VIN: 4.5V ~ 24V VOUT: 3.3V IOUT: 0~2A Reference 2： ： VIN: 8V ~ 24V VOUT: 5V IOUT: 0~2A JW5022S Rev.0.31 JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. 9 JW5022S JoulWatt PACKAGE OUTLINE SOP8 UNIT: UNIT: mm 0.42 ± 0.10 0.5 3.81 2.03 7.62 6.0 ± 0.51 1.27 1.27TYP RECOMMENDED LAND PATTERN TOP VIEW ± 0.5 3.9 0.20 ± 0.10 “ ” A 0.15 ± 0.4 SEE DETAIL 1.75MAX 5.0 ± 0.10 SIDE VIEW 0.50 FRONT VIEW 0.25 0.25 ～ 0 ～ 8° 0.4 ～ 1.27 DETAIL “ A” BOTTOM VIEW JW5022S Rev.0.31 JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. 10 JW5022S JoulWatt IMPORTANT NOTICE
Joulwatt Technology Inc. reserves the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein.
Any unauthorized redistribution or copy of this document for any purpose is strictly forbidden.
Joulwatt Technology Inc. does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channel. Copyright © 2016 JW5022S Incorporated. All rights are reserved by Joulwatt Technology Inc. JW5022S Rev.0.31 JoulWatt® Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. 11