WS2259

WS2259 Features ■ Burst Mode function ■ Low startup current (4uA) ■ Low operation current (1.7mA) ■ Built in Leading edge blanking (LEB) ■ Built in Synchronous slope compensation ■ Current mode operates ■ External programmable switching frequency ■ Cycle by cycle Over Current Protection ■ over temperature protection(OTP） ■ Soft-start ■ VDD over voltage protection and clamp ■ under voltage lockout with hysteresis(UVLO） ■ Driver Output clamped(13V) ■ Soft-driver function for lower EMI ■ Frequency jitter ■ Constant output power limited ■ Over load protection(OLP) ■ Free audio noise operation General Description WS2259 which is optimized for high performance is a highly integrated current mode PWM control IC. It is applied for switch power of the small-sized and medium-sized for example the power adaptor. For lower the standby power and higher RoHS compliant, the IC has the Burst Mode function and very low startup current and working current. At the condition of no load or light load, the IC operates in extended ‘burst mode’ to minimize switching loss by lower the switching frequency. The low startup current and low operating current contribute to a reliable power on startup design with WS2259. A large value resistor could thus be used in the startup circuit to minimize the power consumption and improve the efficiency of the power convert. The internal synchronous slope compensation circuit improves system large signal stability and reduces the possible subharmonic oscillation at high PWM duty cycle output. Leading-edge blanking on current sense(SENSE) input removes the signal glitch due to snubber circuit diode reverse recovery and thus greatly reduces the external component count and system cost in the design. WS2259 offers complete protection coverage with automatic self-recovery feature including cycle by cycle over current protection (OCP), over load protection (OLP), over temperature protection (OTP), VDD Over Voltage Protection, under voltage lockout (UVLO). The gate-driven output is clamped to maximum 13V to protect the external MOSFET. Excellent EMI performance is achieved by using the frequency jitter and the soft-switching at the totem pole gate drive output. The tone energy at below 20KHZ is minimized in the design and audio noise is eliminated during operation. The IC can be used as the best alternative products of the linear power supply or the RCC-mode power to improve the whole performance of the switch power system and lower the cost. WS2259 is offered in SOT23-6, SOP-8 and DIP-8 packages. Applications Universal switch power supply and offline AC/DC flyback converter: ■ Battery Charger ■ Power Adaptor ■ Set-Top Box Power Supplies ■ Open-frame SMPS Typical Application Circuit Rev.A Apr.2011 Copyright@W ins emi Microelectronics Co., Ltd., All right reserved. WS2259 Pin Definition and Device Marking WS2259 is offered in SOT23-6, SOP-8 and DIP-8 packages，as shown below： 1 GND 6 GATE 2 FB 3 RI S O T2 3-6 5 VDD 4 SENSE 59: WS2259 Y: Year Code (1:2011; 2:2012……) WW: Week Code (1-52) GATE 1 8 GND 7 FB 2 VDD 3 NC 4 SENSE D I P8 S O P8 6 NC 5 RI WS2259XP Dvf YWW X: D = DIP8 ， S = SOP8 P: P = Pb-free package D: 芯片代码 V: 内部版本号 (可选 1-9) f: 工厂代码 Y: Year Code (1:2011; 2:2012……) WW: Week Code (1-52) Ordering Information Package 8-Pin DIP8, 8-Pin SOP8, Pb-free Pb-free IC Marking Information WS2259DP WS2259SP 59XXX Purchasing Device Name WS2259DP WS2259SP WS2259YP（SOT23-6） 6-Pin SOT23-6, Pb-free 2/11 Steady, Steady, keep you advance WS2259 Pin Function Description Pin Name GATE VDD NC SENSE Pin No. DIP8/SOT23 1/6 2/5 3 4/4 Pin Type Output Power Floating Current Monitoring Frequency Setting Floating Feedback Input Ground Function Description Totem-pole gate drive output for the power MOSFET Power Supply Floating Current sense input. RI NC FB GND 5/3 6 7/2 8/1 Internal oscillator frequency setting pin. A resistor which is connected between RI and GND sets the PWM frequency Floating Feedback input pin. The PWM duty cycle is determined by voltage into this pin and the current-sense signal at Pin 4 Ground Block Diagram OSC VDD clamp Logic OCP Slope UVLO PWM compensation Soft driver Soft Start LEB Internal Supply OLP Burst Mode Voltage Divider 3/11 Steady, Steady, keep you advance WS2259 Recommended Operating Condition Symbol VDD RI TA Parameter VDD Supply Voltage RI Resistor Operating temperature Value 10~30 100 -20~85 Unit V Kohm ℃ Absolute Maximum Ratings ( Note 1) Symbol VDD VFB VSENSE VRI TJ TSTG VCV ICC Parameter DC Power Supply FB input voltage SENSE input voltage RI input voltage Operation Junction Temperature Storage Temperature Vcc Clamp Voltage Vcc Clamp Continuous Current Value 30 -0.3~7 -0.3~7 -0.3~7 -20~150 -40~150 31 10 Unit V V V V ℃ ℃ V mA Note 1: Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, functional operation of the device at these or any other conditions beyond those indicated in the Recommended Operating Conditions section are not implied. Exposure to absolute maximum-rated conditions for extended periods may affect device reliability. ESD Information Symbol VESD-HBM VESD-MM Parameter Human body model on all pins Machine model on all pins Value 3 300 Unit KV V 4/11 Steady, Steady, keep you advance WS2259 Electrical Characteristics (TA=25℃，VCC=16V, if not otherwise noted) Supply Voltage (VDD) Parameter Operation voltage Turn on threshold Voltage Turn-off threshold Voltage Start up current Operation Current Symbol VDD_OP UVLO_ON UVLO_OFF I_VDD_ST I_VDD_OP Test condition Min 6.8 13.5 Typ 7.5 14.5 4 1.7 Max 30 8 15.5 10 2.3 Unit V V V uA mA V V VDD=13V,RI=100K VDD=16V,RI=100K,VFB=3V GATE with 1nF to GND VDD_OVP VDD Zener Clamp Voltage VDD_Clamp IVDD=10mA 29 31 Feedback Input Section VFB Open Loop Voltage FB Pin Short Current Power limiting FB Threshold Power limiting Debounce Input Impedance Maximum duty cycle VFB_Open IFB_Short VTH_PL TD_PL ZFB_IN Max_Duty VDD=16V,FB open, FB Shorted to GND VDD=16V, RI=100K VDD=16V,FB open,RI=100KΩ VDD=16V,FB=2V/3V,CS open VDD=16V,FB open, CS=0,RI=100KΩ 5.4 0.3 3.2 48 11.5 72 5.9 0.45 3.65 60 14.5 77 6.4 0.6 4.0 72 18 82 V mA V ms kΩ % Current Sense Section Leading edge Blanking Time OCP control delay OCP threshold TLEB TD_OC TTH_OC GATE with 1nF to GND FB＝3.2V 0.68 330 70 0.78 0.78 ns ns V Oscillator Section Frequency Fosc Jitter period Jitter range Burst mode frequency Frequency variation versus temp. Deviation Frequency variation versus VDD Fosc_BM ∆f_temp ∆f_VDD VDD=9.5V,RI=100K, FB=1V TEMP = -20 to 85℃ VDD = 12 to 25V VDD=16V,RI=100K,,FB=3.2V For 65K 60 65 4 ±5 22 5 5 70 khz ms % khz % % RI Section RI voltage VRI VDD=16V,RI=100KΩ,CS=1V 1.94 2 2.06 V Thermal protection Thermal shutdown temperature T_shutdown 150 ℃ GATE Output Section Output voltage Low Output voltage high Output clamp voltage Rising time Falling time VOL VOH VClamp Tr Tf VDD = 16V, Io = -20mA VDD = 16V, Io = 20mA VDD = 20V VDD = 16V, GATE with 1nF to GND VDD = 16V, GATE with 1nF to GND 9 11 13 250 75 14.5 0.8 V V V ns ns 5/11 Steady, Steady, keep you advance WS2259 Typical Operating Characteristics 6/11 Steady, Steady, keep you advance WS2259 Function Description WS2259 is a highly integrated current mode PWM control IC which is optimized for high performance. It is applied for switch power of the small-sized and medium-sized for example the power adaptor. The low startup current, operation current and burst mode function at the condition of no load and low load can decrease the standby power of the system, and improve the power convert efficiency. The internal synchronous slope compensation, the leading edge blanking function of the Sense pin not only decrease the component number, but also improve the stability of the system and avoid the harmonics generation. WS2259 also have multiform general recovery protection mode. The main function is described as below. At very light load or no load condition, the IC operates in Burst Mode. In this condition, the voltage at FB is below burst mode threshold level, thus system goes into burst mode. The gate dive output switches only when VCC voltage drops below a preset level or FB input is active to output an on state. Otherwise the gate drive remains at off state to minimize the switching loss thus reduce the standby power consumption. The standby current of WS2259 is low as 800uA, Thus the standby of WS2259 can be low than 100mW. The frequency control also eliminates the audio noise at any loading conditions. Oscillator Operation A resistor connected between RI and GND sets the Startup Current and Startup Control Startup current of WS2259 is designed to be very low （ 4uA ） so that VDD could be charged up above UVLO threshold level and starts up quickly. A large value startup resistor can therefore be used to minimize the power loss, predigest the design of startup circuit and provides reliable startup in application. For the design of AC/DC adaptor with universal input range, a startup resistor of 2 MΩ, 1/8 W could be used together with a VDD capacitor to provide a fast startup and low power dissipation solution. charge/discharge time of the constant current source to the internal cap and thus the PWM oscillator frequency is determined. The relationship between RI and switching frequency follows the below equation: FOSC = 6500 (Khz ) RI(Kohm ) If RI floating, the frequency will be internal set at 50 KHz Current Sensing and Leading Edge Blanking Cycle-by-Cycle current limiting is offered in WS2259. The Operating Current The operating current of WS2259 is very low .Good efficiency is achieved with low operating current together with extended burst mode control circuit which can easy the design of VDD capacitor. switch current is detected by a sense resistor into the SENSE pin. The internal Leading-edge blanking chops off the sense voltage spike at initial MOSFET on state due to snubber diode circuit reverse recovery and thus reduce the external RC filter circuit. The current limit comparator is disabled and cannot turn off the external MOSFET during the blanking period. PWM duty cycle is determined by voltage level into SENSE pin and FB pin. Soft-start As soon as VDD reaches UVLO(on), the soft-start function operates, the peak current is then gradually increased from zero. Every restart attempt is followed by 4ms soft-start. Internal Synchronized Slope Compensation Built-in slope compensation circuit adds slope voltage onto the current sense input voltage for PWM generation. This greatly improves the close loop stability at CCM and prevents the sub-harmonic oscillation and thus reduces Burst Mode Rev.A Apr.2011 the output ripple voltage. 7/11 Steady, keep you advance WS2259 Gate Driver GATE pin of WS2259 is connected to the gate of an external power switch. The gate drive strength which is too weak leads to over switch loss of MOSFET while too strong gate drive output compromises in the over EMI. A good tradeoff between output strength and dead time control is achieved through the design of the built-in totem pole gate in WS2259. The low standby dissipation and good EMI system design is easier to achieve through this dedicated devise. For MOSFET gate protection, an internal 13V clamp is added at higher than expected VCC input. Protection Controls Good power supply system reliability is achieved with auto-recovery Cycle-by-Cycle protection current limiting features (OCP), including Over Load Protection (OLP), Under Voltage Lockout on VDD (UVLO), Over Temperature Protection (OTP), and VDD Over Voltage Protection & VDD clamp. Internal line voltage compensation of OCP help to achieve constant output power limit over the universal input voltage range. 8/11 Steady, Steady, keep you advance WS2259 SOT23-6 Package Dimension 9/11 Steady, Steady, keep you advance WS2259 DIP-8 Package Dimension 10/11 Steady, Steady, keep you advance WS2259 SOP-8 Package Dimension Unit: mm 11/11 Steady, Steady, keep you advance