RS2052 100mW Standby Power Green PWM Controller DESCRIPTION The RS2052 is a highly integrated low cost current mode PWM controller, which is ideal for small power current mode of offline AC-DC fly-back converter applications. Making use of external resistors, the IC changes the operating frequency and automatically enters the PFM/CRM (Cycle Reset Mode) under light-load/zero-load conditions. This can minimize standby power consumption and achieve powersaving functions. With a very low start-up current, the RS2052 could use a large value start-up resistor (2MΩ). Built-in synchronized slope compensation enhances the stability of the system and avoids sub-harmonic oscillation. Dynamic peak current limiting circuit minimizes output power change caused by delay time of the system over a universal AC input range. Leading edge blanking circuit on current sense input could remove the signal glitch due to snubbed circuit diode reverse recovery and thus greatly reduces the external component count and system cost in the design. Cycle-by-Cycle current limiting ensures safe operation even during short-circuit. Excellent EMI performance is achieved built-in soft driver and low EMI technique. APPLICATIONS FEATURES Low standby power（<0.1W） Low startup current (about 5μA) Low operating current (about 1.5mA) Power on Soft Start Reducing Power MOSFET Vds Stress Adjustable OTP Over Voltage (fixed or adjustable) Protection (OVP) OLP, OVP and OTP coverage with autorecovery PWM&PFM&CRM Current Control Mode Built-in Synchronized Slope Compensation Frequency shuffling for Excellent EMI Performance Fixed 65KHz Switching Frequency Audio Noise Free Operation Leading edge Blanking on Sense input Constant output power limiting for universal AC input Range Soft Clamped GATE output voltage 12.0V Good Protection Coverage With Under Voltage Lockout (UVLO)/Cycle-by-cycle current limiting/Power On Soft Start/OTP/SCP/OLP SOT-23-6L, DIP-8L Package 3000V HBM ESD Switching AC/DC Adaptor Open Frame Switching Power Supply Standby Power Supplies Set-Top Box Power Supplies Tel: 886-66296288‧Fax: 886-29174598‧ http://www.princeton.com.tw‧2F, No.233-1, Baociao Rd., Sindian Dist., New Taipei City 23145, Taiwan RS2052 BLOCK DIAGRAM V1.0 2 August 2013 RS2052 APPLICATION CIRCUITS L EMI Filter AC IN Vo DC Out N GND RS2052 GND GATE FB VDD RT CS NTC ORDERING INFORMATION Device RS2052 Y Z V1.0 Device Code Y is package & Pin Assignments designator : P : DIP-8 N: SOT-23-6 Z is Lead Free designator : P: Commercial Standard, Lead (Pb) Free and Phosphorous (P) Free Package G: Green (Halogen Free with Commercial Standard) 3 August 2013 RS2052 PIN ASSIGNMENTS SOT-23-6 DIP-8 PIN DESCRIPTION Pin Name Description GATE VDD NC CS Totem output to drive the external power MOSFET. Power Supply Voltage. No Connect. Current Sense Input pin. Connected to MOSFET Current Sensing Node. Connect through a NTC resistor to GND for OTP protect, connect through zener to VDD for adjustable over voltage protect. No Connect. Voltage feedback pin. Output current of this pin could controls the PWM duty cycle, OLP and SCP. Ground pin. RT NC FB GND V1.0 4 Pin No. DIP SOT-23 1 6 2 5 3 4 4 5 3 6 - 7 2 8 1 August 2013 RS2052 FUNCTION DESCRIPTION STARTUP AND UNDER VOLTAGE LOCKOUT The RS2052 is a highly integrated low cost current mode PWM controller, which is ideal for small power current mode of offline AC-DC fly-back converter applications. Making use of external resistors, the IC changes the operating frequency and automatically enters the PFM/CRM (Cycle Reset Mode) under light-load/zero-load conditions. This can minimize standby power consumption and achieve powersaving functions. With a very low start-up current, the RS2052 could use a large value start-up resistor (2MΩ). The turn-on and turn-off threshold of the RS2052 is designed to 13.5V/7V. During startup, the hold-up capacitor must be charge to 13.5V through the startup resistor. The hysteretic is implemented to prevent the shutdown from the voltage dip during startup. GREEN POWER OPERATION The power dissipation of switching mode power supply is very important in zero load or light load condition. The major dissipation results from conduction loss, switching loss and consume of the control circuit. However, all of them relates to the switching frequency. There are many difference topologies has been implemented in different chip. The basic operation theory of all these approaches intends to reduce the switching frequency under light-load or no-load condition. The RS2052’s green power function adapts PWM, PFM and CRM combining modulation. The PWM frequency is fixed 65KHz in medium or heavy load operation. Through modifying the pulse width, The RS2052 could control output voltage. The current of FB pin increases when the load is in light condition and the internal mode controller enters PFM & PWM when the feedback voltage is lower than 1.4V. The operation frequency of oscillator is to descend gradually. When the feedback current is lower than 0.575V, the frequency of oscillator is invariable, namely 22KHz. RS2052 Green-Power Function To decrease the standby consumption of the power supply, PTC Corp introduces the Cycle Reset Mode technology (CRM). If the feedback voltage goes on descending, the RS2052 would reset internal register all the time and cut off the GATE pin. While the output voltage is lower than the set value, the register would be set, the GATE pin operate again. So the frequency of the internal OSC is invariable, the register would reset some pulses so that the practical frequency is decreased at the GATE pin. LOW EMI TECHNIQUE The frequency low EMI technique is introduced in the RS2052. As following figure, the internal oscillation frequency is modulated by itself. A whole surge cycle includes 128 pulses and the jittering ranges from -4% to +4%. Thus, the function could minimize the electromagnetic interferer from the power supply module. V1.0 5 August 2013 RS2052 INTERNAL SYNCHRONIZED SLOP COMPENSATION Although there are more advantages of the current mode control than conventional voltage mode control, there are still several drawbacks of peak-sensing current-mode converter, especially the open loop instability when it operates in higher than 50% of the duty-cycle. To solve this problem, the RS2052 is introduced an internal slope compensation adding voltage ramp to the current sense input voltage for PWM generation. It improves the close loop stability greatly at CCM, prevents the sub-harmonic oscillation and thus reduces the output ripple voltage OLP & SCP To protect the circuit from being damaged under the over load or short circuit condition, a smart OLP&SCP function is implemented in the RS2052. When short circuit or over load occurs in the output end, the feedback cycle would enhance the voltage of FB pin, while the voltage is over 3.4V, the internal detective circuit would send a signal to shut down the GATE and pull down the VDD voltage, then the circuit is restart. To avoid the wrong operation when circuit starts, the delay time is set. The delay time TOLP&SCP is between 80mS and 96mS. SOFT START Each time the VDD powers descend lower than UVLO_ON, Soft Start will be triggered. So during the Soft Start time(about 4ms), the current of SEN is increasing from 0 to maximum for reducing Power MOSFET Vds stress. Warning: Each protect leading VDD starts again, Soft Start will be triggered. LEADING-EDGE BLANKING (LEB) Each time the power MOSFET is switched on, a turn-on spike will inevitably occur at the Sense pin, which would disturb the internal signal from the sampling of the RCS. There is a 300nS leading edge blanking time built in to avoid the effect of the turn-on spike, and the power MOSFET cannot be switched off during the moment. So the conventional external RC filtering on sense input is no longer required. OVER VOLTAGE PROTECTION (OVP) The RS2052 output designs a totem pole to drive a periphery power MOSFET. The dead time is introduced to minimize the transfixion current during the output operating. The novel soft clamp technology is introduced to protect the periphery power MOSFET from breaking down.RS2052’s output driver is soft clamped to maximum 12V to protect the power MOSFET. V1.0 6 August 2013 RS2052 CHARACTERISTICS CURVE V1.0 7 August 2013 RS2052 ABSOLUTE MAXIMUM RATINGS Parameter Supply voltage Pin Voltage VDD OVP maximal Enter Current Input Voltage to FB Pin Input Voltage to CS Pin Power Dissipation ESD Capability, HBM Model ESD Capability, Machine Model Lead Temperature (Soldering) for 20S Symbol VDD IOVP VFB VCS PD ESD DIP-8 SOT-23-6 TL Junction Temperature Range Operating Junction Temperature Range Tj TSTG Ratings 30 10 -0.3 to 6 -0.3 to 6 300 3000 300 220 260 -40 to 150 -40 to 150 Unit V mA V V mW V V °C °C o C o C Note: Stress beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. Exposure to absolute maximum-rated conditions for extended periods may affect device reliability. RECOMMENDED OPERATING RANGE Parameter VDD Supply Voltage Operation Ambient Temperature Maximal Output Power V1.0 Symbol VDD TOA PO 8 Ratings 10 to 23 -20 to 85 0 to 60 Unit V o C W August 2013 RS2052 ELECTRICAL CHARACTERISTICS (TA=25°C, unless otherwise specified) Parameter Supply Voltage Section (VDD Pin) Startup Current Operating Current Turn-on Threshold Voltage Turn-off Threshold Voltage Pull-up PMOS Active VDD Clamp Voltage VDD OVP Voltage Voltage Feedback (FB Pin) Short Circuit Current Open Loop Voltage Maximum Duty Cycle PWM Enter PFM REF Voltage Quit CRM REF Voltage Enter CRM REF Voltage Enter OLP FB Voltage OLP Delay Time Inductor(CS Pin) Section Soft Start Time Leading Edge Blanking Time Input Impedance Delay to Output CS Maximum Voltage Level（Dmin=0%） CS Maximum Voltage Level (Dmax=80%) Oscillator Section PWM Normal Frequency PFM Minimum Frequency Frequency VDD. Stability Frequency Temp. Stability Frequency jitter GATE Drive Output (GATE Pin) Section Output Low Level Output High Level Rising Time Falling Time Output Clamp Voltage OTP(RT) Section RT Bias Current Threshold Voltage for OTP OTP Debounce Time RT Float Voltage External OVP Threshold voltage V1.0 Symbol IST IOP UVLO_OFF UVLO_ON Vpull-up VDD_CLAMP VDD_OVP IFB VFB Dmax Test Conditions Min. VFB=3V 12.5 6 IVDD=10mA 30 24 VFB=0V VFB=Open 75 VREF_GREEN VREF_CRM_H VREF_CRM_L VOLP TOLP 80 SST T_blanking ZCS_IN TD_OC VTH_L VTH_H FOSC FPFM ΔFVDD ΔFTEMP FJITTER VOL VOH TR1 TF1 VG_CLAMP IRT VOTP TD_OTP VRT_NC VTH_OVP 9 Typ. Max. Unit 5.0 1.5 13.5 7 13 32 26 20.0 2.5 14.5 8 μA mA V V V V V 0.4 4.2 80 1.4 0.675 0.575 3.5 88 34 28 85 96 4 220 40 120 0.75 0.9 60 -30 to 100℃ 65 22 1 1 -4 VDD=14V, IO=5mA VDD=14V, IO=5mA CL=500pF CL=500pF VDD=20V mS nS KΩ nS V V 70 4 1 6 123 71 12 0.95 100 1 32 2.3 4 mA V % V V V V mS 1.05 KHz KHZ % % % V V ns ns V μA V Cycle V V August 2013 RS2052 PACKAGE INFORMATION 6-PIN, SOT-23 Note: 1. All dimensions are in millimeters. V1.0 10 August 2013 RS2052 8-PIN, DIP Notes:. 1. All dimensions are in millimeters. 2. Refer to JEDEC MS‐001 V1.0 11 August 2013 RS2052 IMPORTANT NOTICE Princeton Technology Corporation (PTC) reserves the right to make corrections, modifications, enhancements, improvements, and other changes to its products and to discontinue any product without notice at any time. PTC cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a PTC product. No circuit patent licenses are implied. Princeton Technology Corp. 2F, 233-1, Baociao Road, Sindian Dist., New Taipei City 23145, Taiwan Tel: 886-2-66296288 Fax: 886-2-29174598 http://www.princeton.com.tw V1.0 12 August 2013