ML4804CS

March 2001 PRELIMINARY ML4804 Power Factor Correction and PWM Controller Combo GENERAL DESCRIPTION The ML4804 is a controller for power factor corrected, switched mode power supplies. Power Factor Correction (PFC) allows the use of smaller, lower cost bulk capacitors, reduces power line loading and stress on the switching FETs, and results in a power supply that fully complies with IEC1000-3-2 specification. Intended as a BiCMOS enhancement of the industry-standard ML4824, the ML4804 includes circuits for the implementation of leading edge, average current, “boost” type power factor correction and a trailing edge, pulse width modulator (PWM). It also includes a TriFault Detect™ function to help ensure that no unsafe conditions will result from single component failure in the PFC. 1A gate-drive outputs minimize the need for external driver circuits. Low power requirements improve efficiency and reduce component costs. An over voltage comparator shuts down the PFC section in the event of a sudden decrease in load. The PFC section also includes peak current limiting and input voltage brownout protection. The PWM section can be operated in current or voltage mode, at up to 250kHz, and includes an accurate 50% duty cycle limit to prevent transformer saturation. FEATURES I Internally synchronized leading-edge modulated PFC and trailing-edge modulated PWM in one IC TriFault DetectTM for UL1950 compliance and enhanced safety VCCOVP provides additonal PFC fault protection Slew rate enhanced transconductance error amplifier for ultra-fast PFC response Low power: 200µA startup current, 5.5mA operating current Low total harmonic distortion, high PF Reduces ripple current in the storage capacitor between the PFC and PWM sections Average current, continuous boost leading edge PFC PWM configurable for current-mode or voltage mode operation Overvoltage and brown-out protection, UVLO, and soft start I I I I I I I I I BLOCK DIAGRAM 16 VEAO VFB 15 2.5V IAC 2 VRMS 4 ISENSE 3 RAMP 1 7 RAMP 2 8 OSCILLATOR DUTY CYCLE LIMIT + + 1 IEAO POWER FACTOR CORRECTOR TRI-FAULT + – 13 OVP + 2.75V VCCOVP VCC 16.4V + + – - VCC 17V VCC 7.5V REFERENCE Q Q PFC OUT S R Q Q 12 VREF 14 VEA 1.6kΩ + - IEA 0.5V S -1V + - GAIN MODULATOR 1.6kΩ R - PFC ILIMIT VDC 6 VCC SS 5 25µA 1.25V S VFB 2.45V + Q Q PWM OUT 11 VIN OK 1.0V + + R DC ILIMIT DC ILIMIT 9 VREF PULSE WIDTH MODULATOR VCC UVLO REV. 1.0.2 3/9/2001 ML4804 PIN CONFIGURATION ML4804 16-Pin PDIP (P16) 16-Pin Narrow SOIC (S16N) IEAO 1 IAC 2 ISENSE 3 VRMS 4 SS 5 VDC 6 RAMP 1 7 RAMP 2 8 16 VEAO 15 VFB 14 VREF 13 VCC 12 PFC OUT 11 PWM OUT 10 GND 9 DC ILIMIT TOP VIEW PIN DESCRIPTION PIN NAME FUNCTION PIN NAME FUNCTION 1 2 3 4 5 6 7 8 IEAO IAC I SENSE V RMS SS VDC RAMP 1 RAMP 2 Slew rate enhanced PFC transconductance error amplifier output PFC AC line reference input to Gain Modulator Current sense input to the PFC Gain Modulator PFC Gain Modulator RMS line voltage compensation input Connection point for the PWM soft start capacitor 9 10 11 12 13 14 15 DC ILIMIT GND PWM OUT PFC OUT VCC V REF V FB VEAO PWM cycle-by-cycle current limit comparator input Ground PWM driver output PFC driver output Positive supply Buffered output for the internal 7.5V reference PFC transconductance voltage error amplifier input PFC transconductance voltage error amplifier output PWM voltage feedback input Oscillator timing node; timing set by RTCT When in current mode, this pin functions as the current sense input; when in voltage mode, it is the PWM modulation ramp input. 16 2 REV. 1.0.2 3/9/2001 ML4804 ABSOLUTE MAXIMUM RATINGS 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. VCC .............................................................................................. 18V ISENSE Voltage ............................................... -5V to 0.7V Voltage on Any Other Pin ..... GND - 0.3V to VCCZ + 0.3V I REF ........................................................................................... 10mA IAC Input Current ..................................................... 10mA Peak PFC OUT Current, Source or Sink ....................... 1A Peak PWM OUT Current, Source or Sink ..................... 1A PFC OUT, PWM OUT Energy Per Cycle ................... 1.5µJ Junction Temperature ............................................. 150°C Storage Temperature Range ....................... -65°C to 150°C Lead Temperature (Soldering, 10 sec) ..................... 260°C Thermal Resistance (θJA) Plastic DIP ........................................................... 80°C/W Plastic SOIC ...................................................... 105°C/W OPERATING CONDITIONS Temperature Range ML4804CX .................................................... 0°C to 70°C ML4804IX .................................................. -40°C to 85°C ELECTRICAL CHARACTERISTICS Unless otherwise specified, VCC = 15V, RT = 52.3kΩ, CT = 470pF, TA = Operating Temperature Range (Note 1) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VOLTAGE ERROR AMPLIFIER Input Voltage Range Transconductance Feedback Reference Voltage Input Bias Current Output High Voltage Output Low Voltage Source Current Sink Current Open Loop Gain Power Supply Rejection Ratio CURRENT ERROR AMPLIFIER Input Voltage Range Transconductance Input Offset Voltage Input Bias Current Output High Voltage Output Low Voltage Source Current Sink Current Open Loop Gain Power Supply Rejection Ratio OVP COMPARATOR Threshold Voltage Hysteresis 2.65 180 2.75 280 2.85 350 V mV 11V < VCC < 16.5V VIN = ± 0.5V, VOUT = 6V VIN = ± 0.5V, VOUT = 1.5V -40 40 60 60 6.0 VNON INV = VINV, VEAO = 3.75V -1.5 50 0 100 4 -0.5 6.7 0.65 -104 160 70 75 1.0 2 150 15 -1.0 V µ 11V < VCC < 16.5V VIN = 2.5V ± 0.5V, VOUT = 6V VIN = 2.5V ± 0.5V , VOUT = 1.5V -40 40 50 50 Note 2 6.0 VNON INV = VINV, VEAO = 3.75V 0 30 2.43 65 2.5 -0.5 6.7 0.1 -140 140 60 60 0.4 5 90 2.57 -1.0 V µ V µA V V µA µA dB dB mV µA V V µA µA dB dB REV. 1.0.2 3/9/2001 Ω Ω 3 ML4804 ELECTRICAL CHARACTERISTICS SYMBOL TRI-FAULT DETECT Fault Detect HIGH Time to Fault Detect HIGH Fault Detect LOW VCCOVP COMPARATOR Threshold Voltage Hysteresis PFC ILIMIT COMPARATOR Threshold Voltage (PFC ILIMIT VTH - Gain Modulator Output) Delay to Output DC ILIMIT COMPARATOR Threshold Voltage Input Bias Current Delay to Output VIN OK COMPARATOR Threshold Voltage Hysteresis GAIN MODULATOR Gain (Note 3) IAC = 100µA, VRMS = VFB = 0V IAC = 50µA, VRMS = 1.2V, VFB = 0V IAC = 50µA, VRMS = 1.8V, VFB = 0V IAC = 100µA, VRMS = 3.3V, VFB = 0V Bandwidth Output Voltage OSCILLATOR Initial Accuracy Voltage Stability Temperature Stability Total Variation Ramp Valley to Peak Voltage PFC Dead Time fOSC = 250kHz, RT = 75.0kΩ, CT = 100pF CT Discharge Current VRAMP 2 = 0V, VRAMP 1 = 2.5V 3.5 Line, Temp 68 2.5 520 250 5.5 600 330 7.5 TA = 25°C 11V < VCC < 16.5V 71 76 1 2 84 81 kHz % % kHz V ns ns mA IAC = 100µA IAC = 350µA, VRMS = 1V, VFB = 0V 0.60 0.60 1.8 0.85 0.20 0.80 2.0 1.0 0.30 10 0.75 0.9 1.05 2.40 1.25 0.40 MHz V 2.35 0.8 2.45 1.0 2.55 1.2 V V 0.95 1.0 ± 0.3 150 1.05 ±1 300 V µA ns -0.9 120 -1.0 220 150 300 -1.1 V mV ns TA = Operation Temp Range TA = Operation Temp Range 1.7 16.4 2.0 2.3 V V VFB = VFAULT DETECT LOW to VFB =OPEN; 470pF from VFB to GND 0.4 2.65 2.75 2 0.5 2.85 4 0.6 V ms V PARAMETER CONDITIONS MIN TYP MAX UNITS 4 REV. 1.0.2 3/9/2001 ML4804 ELECTRICAL CHARACTERISTICS SYMBOL REFERENCE Output Voltage Line Regulation Load Regulation TA = 25°C, I(VREF) = 1mA 11V < VCC < 16.5V 0mA < I(VREF) < 10mA; TA = 0ºC to 70ºC 0mA