CS1500 Digital Power Factor Correction IC Features □ Digital EMI Noise Shaping □ Excellent Efficiency Under All Load Conditions □ Minimal External Devices Required □ Optimized Digital Loop Compensation □ Comprehensive Safety Features Undervoltage Lockout (UVLO) Օ Output Overvoltage Protection Input Current Limiting Օ Open/short Loop Protection for IAC & IFB Pins Thermal Shutdown Applications □ LCD and LED TVs □ Monitor Supplies □ Battery Chargers Description The CS1500 is a high-performance power factor correction (PFC) controller for universal AC input, which uses a proprietary digital algorithm for discontinuous conduction mode (DCM) with variable on-time and variable frequency control, ensuring unity power factor. The CS1500 incorporates all the safety features necessary for robust and compact PFC stages. In addition, it has burst mode control to lower the light-load/standby losses to a minimum. Protection features such as overvoltage, open- and short-circuit protection, and overtemperature help protect the device during abnormal transient conditions. The digital controller optimizes the system stability and transient performance, simplifies the PFC design, reduces the external component count and BOM costs. The simple design and minimum cost makes CS1500 the ideal choice for PFC up to 300 watts. Ordering Information See page 13. D1 T՗Tw-׮ <»»-- L B D2 AC Mains Vdd -O J_C3 Regulated DC Output -O CirrufLogic, Inc. @ ^ N°V "10 http://www.cirrus.com י »(AK RjgMs Resyerved) DS849F1

CS1500 1. INTRODUCTION Voltage 1^ R VDD Regulator POR Von v th(STP 15k IAC R 24 k J ADC Vnn R GD 15k IFB R R GND Figure 1. CS1500 Block Diagram The CS1500 digital power factor controller operates in variable on-time, variable frequency, discontinuous conduction mode (DCM). The CS1500 uses a proprietary digital algorithm to maximize the efficiency and reduce the conductive EMI. The analog-to-digital converter (ADC) shown in the CS1500 block diagram in Figure 9 is used to sense the PFC output voltage ( ) and the rectified AC line voltage ( Vrect ) by measuring currents through their respective...

CS1500 'CIRRUS LO< 2. PIN DESCRIPTION No Connection NC [ZZ No Connection NC cz Rectifier Voltage Sense IAC [ZZ Link Voltage Sense IFB I 1 8 ZZI NC No Connection 2 1=1 VDD IC Supply Voltage 3 6 =1 GD pfc Gate Driver 4 5 l GND Ground 8-leadSOIC Figure 2. CS1500 Pin Assignments Table 1. Pin Descriptions Pin Name Pin # I/O Description NC 1,2,8 - NC ח No connections IAC 3 IN Rectifier Voltage Sense A current proportional to the rectified line voltage (Vrect) is fed into this pin. The current is measured with an A/D converter. IFB 4 IN Link Voltage Sense ח A current proportional to the output link...

CS1500 'CIRRUS LOGIC 3. CHARACTERISTICS AND SPECIFICATIONS 3.1 Electrical Characteristics Typical characteristics conditions: Minimum/Maximum characteristics conditions: TA = 25°C, VDD = 13 V, GND = 0 V Tj = -40°to +125° C, VDD = 10 Vto 15 V, GND = 0 V All voltages are measured with respect to GND. Unless otherwise specified, all currents are positive when flowing into the IC. Parameter Condition Symbol Min Typ Max Unit VDD Supply Voltage Turn-on Threshold Voltage VDD Increasing VDD(on) 8.4 8.8 9.3 V Turn-off Threshold Voltage (UVLO) VDD Decreasing VDD(off) 7.1 7.4 7.9 V UVLO Hysteresis VHys...

CS1500 OG/C 3.2 Absolute Maximum Ratings Pin Symbol Parameter Value Unit 7 Vdd IC Supply Voltage Vz V 1,3,4,5 - Analog Input Maximum Voltage -0.5 to Vz v 1,3,4,5 - Analog Input Maximum Current 50 mA 7 Vgd Gate Drive Output Voltage -0.3 to Vz v 7 'gd Gate Drive Output Current -1.0 / +0.5 A - Pd Total Power Dissipation @ Ta=50° C 600 mW - Junction-to-Ambient Thermal Impedance 107 °C/W - Ta Operating Ambient Temperature Range1 -40 to +125 °C - Tj Junction Temperature Operating Range -40 to +125 °C - TStg Storage Temperature Range -65 to +150 °C All Pins ESD Electrostatic Discharge Capability Human...

CS1500 5. GENERAL DESCRIPTION The CS1500 offers numerous features, options, and functional capabilities to the designer of switching power converters. This digital PFC control IC is designed to replace legacy analog PFC controllers with minimal design effort. 5.1 PFC Opration One key feature of the CS1500 is its operating frequency profile. Figure 11 illustrates how the frequency varies over half cycle of the line voltage in steady-state operation. When power is first applied to the CS1500, it examines the line voltage and adapts its operating frequency to the line voltage as shown in Figure...

CS1500 5.4 Output Power and PFC Boost Inductor In normal operating mode, the nominal output power is estimated by the following equation. 5.5 PFC Output Capacitor The value of the PFC output capacitor should be chosen based upon voltage ripple and hold-up requirements. To ensure system stability with the digital controller, the recommended value of the capacitor is within the range of 0.5 uF/watt to 2.0 ^F/watt. 5.6 Output IFB Sense & Input IAC Sense A current proportional to the PFC output voltage, Vlink, is supplied to the IC on pin IFB and is used as a feedback control signal. This current...

CS1500 5.7 Brownout Protection As an added protection to the PFC boost stage, the CS1500 includes a failure mechanism that detects high average currents that occur under abnormal brownout conditions. The brownout protection feature monitors the Vrect input signal and suspends the gate-drive switching when a brownout threshold breach is detected. Under normal conditions, the CS1500 will never reach the brownout threshold, as the PFC stage is automatically protected by the power limitation of Equation 2, see section 5.4 Output Power and PFC Boost Inductor on page 9. In the event that the boost...

CS1500 6. SUMMARY OF EQUATIONS Eq. # Equation Variables/Recommended Values 1 Output Power (paqe 9) P _ r..n..(w .2 * Wli nk " ( W i n( mi n ) * V2) po /in(min)) * 2 * f * . * w 2 * 'max * LB* wlink P0 rated output power of the system n efficiency of the boost converter (estimated as 100% by the PFC algorithm) Vin(min) minimum RMS line voltage is 90W, measured after the rectifier and EMI filter W|ink nominal PFC output voltage must be 400 W fmax maximum switching frequency is 70 kHz |B boost inductor specified by rated power requirement a margin factor to guarantee rated output power (Po) against...