Order this document by MC33368/D The MC33368 is an active power factor controller that functions as a boost preconverter in off-line power supply applications. MC33368 is optimized for low power, high density power supplies requiring a minimum board area, reduced component count and low power dissipation. The narrow body SOIC package provides a small footprint. Integration of the high voltage startup saves approximately 0.7 W of power compared to resistor bootstrapped circuits. The MC33368 features a watchdog timer to initiate output switching, a one quadrant multiplier to force the line current to follow the instantaneous line voltage a zero current detector to ensure critical conduction operation, a transconductance error amplifier, a current sensing comparator, a 5.0 V reference, an undervoltage lockout (UVLO) circuit which monitors the VCC supply voltage and a CMOS driver for driving MOSFETs. The MC33368 also includes a programmable output switching frequency clamp. Protection features include an output overvoltage comparator to minimize overshoot, a restart delay timer and cycle-by-cycle current limiting. * * * * * HIGH VOLTAGE GREENLINE POWER FACTOR CONTROLLER SEMICONDUCTOR TECHNICAL DATA 16 1 P SUFFIX PLASTIC PACKAGE CASE 648 (DIP-16) Lossless Off-Line Startup 16 1 Output Overvoltage Comparator D SUFFIX PLASTIC PACKAGE CASE 751K (SO-16) Leading Edge Blanking (LEB) for Noise Immunity Watchdog Timer to Initiate Switching Restart Delay Timer PIN CONNECTIONS Device Operating Temperature Range MC33368D MC33368P Package SO-16 TJ = -25 to +125C 1 16 Line 2 15 N/C Voltage FB 3 14 N/C Comp 4 Mult 5 Current Sense 6 12 VCC 11 Gate Zero Current 7 10 PGnd AGnd 8 9 LEB DIP-16 DIP-16 ORDERING INFORMATION 5.0 Vref Restart Delay 13 Frequency Clamp (Top View) 16 Line 5.0 Vref Restart Delay 1 Voltage FB 3 Comp 4 Mult 5 Current Sense 6 12 VCC 11 Gate Zero Current 7 10 PGnd AGnd 8 9 LEB 2 SO-16 GreenLine is a trademark of Motorola, Inc. 13 Frequency Clamp (Top View) This document contains information on a new product. Specifications and information herein are subject to change without notice. MOTOROLA ANALOG IC DEVICE DATA Motorola, Inc. 1997 Rev 2 1 MC33368 Representative Block Diagram Line Restart Delay Restart Delay VCC Output Overvoltage FB Comp Mult UVLO Multiplier/ Error Amplifier LEB PWM R Q Gate PGnd WatchdogTimer/ Zero Current Detector ZC Det Vref AGnd S Current Sense Current Sense Internal Bias Generator S Frequency Clamp Frequency Clamp This device contains 240 active transistors. MAXIMUM RATINGS (TA = 25C, unless otherwise noted.) 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0 1.0 A Input Offset Voltage (VComp = 3.0 V) VIO - 2.0 50 mV Transconductance (VComp = 3.0 V) gm 30 51 80 mho Output Source (VFB = 4.6 V, VComp = 3.0 V) Output Sink (VFB = 5.4 V, VComp = 3.0 V) IO IO 9.0 9.0 17.5 17.5 30 30 A VFB(OV) 1.07 VFB 1.084 VFB 1.1 VFB V TP - 705 - ns IIB - -0.2 -1.0 A Vth(M) 1.8 2.1 2.4 V VMult VComp 0 to 2.5 Vth(M) to (Vth(M) + 1.0) 0 to 3.5 Vth(M) to (Vth(M) + 2.0) - - K 0.25 0.51 0.75 1/V Vref 4.95 5.0 5.05 V Line Regulation (VCC = 10 V to 16 V) Regline - 5.0 100 mV Load Regulation (IO = 0 - 5.0 mA) Regload - 5.0 100 mV Vref 4.8 - 5.2 V Maximum Output Current IO 5.0 10 - mA Reference Undervoltage Lockout Threshold Vth - 4.5 - V Input Threshold Voltage (Vin Increasing) Vth 1.0 1.2 1.4 V Hysteresis (Vin Decreasing) VH 100 200 300 mV Delay to Output Tpd - 127 - ns Input Bias Current (VCS = 0 to 2.0 V) IIB - 0.2 1.0 A Input Offset Voltage (VMult = -0.2 V) VIO - 4.0 50 mV Vth(max) 1.3 1.5 1.8 V tPHL(in/out) 50 270 425 ns Vth(FC) 1.9 2.0 2.1 V Frequency Clamp Capacitor Reset Current (VFC = 0.5 V) Ireset 0.5 1.7 4.0 mA Frequency Clamp Disable Voltage VDFC - 7.3 8.0 V AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAA AAAAA AAAAA AAAA AAA + AAA AAAAA AAAAA AAAAA AAAA AAA AAAAA AAAAA AAAAA AAAA AAA AAAAA AAAAA AAAAA AAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA ERROR AMPLIFIER OVERVOLTAGE COMPARATOR Voltage Feedback Input Threshold Propagation Time to Output MULTIPLIER Input Bias Current, VMult (VFB = 0 V) Input Threshold, VComp Dynamic Input Voltage Range Multiplier Input Compensation Multiplier Gain (VMult = 0.5 V, VComp = Vth(M) + 1.0 V) V K V CS Mult V V Threshold - V th(M) Comp VOLTAGE REFERENCE Voltage Reference (IO = 0 mA, TJ = 25C) Total Output Variation Over Line, Load and Temperature ZERO CURRENT DETECTOR CURRENT SENSE COMPARATOR Maximum Current Sense Input Threshold (VComp = 5.0 V, VMult = 5.0 V) Delay to Output (VLEB = 12 V, VComp = 5.0 V, VMult = 5.0 V) (VCS = 0 to 5.0 V Step, CL = 1.0 nF) FREQUENCY CLAMP Frequency Clamp Input Threshold MOTOROLA ANALOG IC DEVICE DATA 3 MC33368 ELECTRICAL CHARACTERISTICS (continued) (VCC = 14.5 V, for typical values TA = 25C, for min/max values TJ = -25 to +125C) AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA AAAAAAAAAAAAAAAAA AAAAA AAAAA AAAAA AAAA AAA Characteristic Symbol Min Typ Max Unit Source Resistance (Current Sense = 0 V, VGate = VCC - 1.0 V) Sink Resistance (Current Sense = 3.0 V, VGate = 1.0 V) ROH ROL 4.0 4.0 8.6 7.2 20 20 Output Voltage Rise Time (25% - 75%) (CL = 1.0 nF) tr - 55 200 ns Output Voltage Fall Time (75% - 25%) (CL = 1.0 nF) tf - 70 200 ns VO(UV) - 0.01 0.25 V Input Bias Current Ibias - 0.1 0.5 A Threshold (as Offset from VCC) (VLEB Increasing) VLEB 1.0 2.25 2.75 V VH 100 270 500 mV Vth(on) 11.5 13 14.5 V VShutdown 7.0 8.5 10 V VH - 4.5 - V tDLY 180 385 800 s Vth(restart) 1.5 2.3 3.0 V Irestart 3.1 5.2 7.1 mA Line Startup Current (VCC = 0 V, VLine = 50 V) ISU 5.0 16 25 mA Line Operating Current (VCC = Vth(on), VLine = 50 V) IOP 3.0 12.9 20 mA VCC Dynamic Operating Current (50 kHz, CL = 1.0 nF) VCC Static Operating Current (IO = 0) ICC - - 5.3 3.0 8.5 - mA Line Pin Leakage (VLine = 500 V) ILine - 30 80 A DRIVE OUTPUT Output Voltage in Undervoltage (VCC = 7.0 V, ISink = 1.0 mA) LEADING EDGE BLANKING Hysteresis (VLEB Decreasing) UNDERVOLTAGE LOCKOUT Startup Threshold (VCC Increasing) Minimum Operating Voltage After Turn-On (VCC Decreasing) Hysteresis TIMER Watchdog Timer Restart Timer Threshold Restart Pin Output Current (Vrestart = 0 V, Vref = 5.0 V) TOTAL DEVICE 4 MOTOROLA ANALOG IC DEVICE DATA MC33368 1.6 VCC = 14 V TA = 25C 1.4 VCS, CURRENT SENSE PIN 6 THRESHOLD (V) VCS, CURRENT SENSE PIN 6 THRESHOLD (V) Figure 1. Current Sense Input Threshold versus Multiplier Input VPin 4 = 4.0 V = 3.75 V = 3.0 V 1.2 = 3.5 V 1.0 = 2.75 V = 3.25 V 0.8 = 2.5 V 0.6 0.4 = 2.25 V 0.2 = 2.0 V 0.6 1.4 2.2 3.0 0.08 = 3.0 V 0.06 = 2.75 V 0.05 0.04 = 2.5 V 0.03 0.02 = 2.25 V 0.01 = 2.0 V 0 -0.12 -0.06 0 0.06 0.12 0.20 VM, MULTIPLIER PIN 5 INPUT VOLTAGE (V) Figure 3. Reference Voltage versus Temperature Figure 4. Overvoltage Comparator Input Threshold versus Temperature 16 VCC = 14 V 12 8.0 4.0 0 -4.0 -55 -25 0 25 50 75 100 125 TA, AMBIENT TEMPERATURE (C) 110 VCC = 14 V 109 108 107 106 -55 30 60 60 Transconductance 0 -20 10 90 VCC = 14 V VO = 2.0 to 4.0 V RL = 10 k TA = 25C 100 120 150 1.0 k 10 k 100 k f, FREQUENCY (Hz) MOTOROLA ANALOG IC DEVICE DATA 1.0 M 180 10 M , EXCESS PHASE (DEGREES) 80 20 25 50 75 100 125 Figure 6. Error Amplifier Transient Response Phase 40 0 6.0 V 0 100 -25 TA, AMBIENT TEMPERATURE (C) Figure 5. Error Amplifier Transconductance and Phase versus Frequency g m, TRANSCONDUCTANCE ( mho) VPin 4 = 4.0 V 0.07 VM, MULTIPLIER PIN 5 INPUT VOLTAGE (V) VFB(OV), OVERVOLTAGE INPUT THRESHOLD (% VFB ) VFB , VOLTAGE FEEDBACK THRESHOLD CHANGE (mV) 0 -0.2 Figure 2. Current Sense Input Threshold versus Multiplier Input, Expanded View VCC = 14 V TA = 25C 4.0 V 2.0 V 0V -1.0 V 5.0 s/DIV 5 MC33368 1.50 1.80 VCC = 14 V Voltage 1.76 1.10 1.72 Current 1.68 1.64 -55 -25 0 25 50 75 100 0.90 0.70 125 500 VCC = 14 V 460 420 380 340 -55 -25 0 25 50 75 100 TA, AMBIENT TEMPERATURE (C) TA, AMBIENT TEMPERATURE (C) Figure 9. Drive Output Waveform Figure 10. Supply Current versus Supply Voltage 125 6.0 20 VCC = 14 V CL = 1000 pF TA = 25C 15 OUTPUT VOLTAGE (V) 1.30 I chg, QUICKSTART CHARGE CURRENT (mA) t DLY, WATCHDOG TIME DELAY ( s) Figure 8. Watchdog Timer Delay versus Temperature I CC, SUPPLY CURRENT (mA) Vchg, QUICKSTART CHARGE VOLTAGE (V) Figure 7. Quickstart Charge Current versus Temperature 10 5.0 0 Pulse tested with a 4.0 V peak, 50 kHz square wave through a 22 k resistance into Pin 7. 4.0 2.0 0 2.0 -5.0 CO = 1000 pF Pin 3, 6, 8= Gnd Pin 5 = 1.0 k to Gnd TA = 25C 4.0 6.0 8.0 10 5.0 s/DIV VCC, SUPPLY VOLTAGE (V) Figure 11. Transient Thermal Resistance Figure 12. Low Load Detection Response Waveform 12 14 1000 200 Output Voltage 2.0 1.0 0 Load Current OUTPUT CURRENT (A) OUTPUT VOLTAGE (V) R JA(t), THERMAL RESISTANCE JUNCTION-TO-AIR (C/W) 100 0 10 0.01 0.1 1.0 t, TIME (s) 6 3.0 400 10 100 200 ms/DIV MOTOROLA ANALOG IC DEVICE DATA MC33368 FUNCTIONAL DESCRIPTION INTRODUCTION With the goal of exceeding the requirements of legislation on line current harmonic content, there is an ever increasing demand for an economical method of obtaining a unity power factor. This data sheet describes a monolithic control IC that was specifically designed for power factor control with minimal external components. It offers the designer a simple cost effective solution to obtain the benefits of active power factor correction. Most electronic ballasts and switching power supplies use a bridge rectifier and a bulk storage capacitor to derive raw dc voltage from the utility ac line, Figure 13. Figure 13. Uncorrected Power Factor Circuit Converter Rectifiers Bulk Storage Capacitor AC Line Load This simple rectifying circuit draws power from the line when the instantaneous ac voltage exceeds the capacitor voltage. This occurs near the line voltage peak and results in a high charge current spike, Figure 14. Since power is only taken near the line voltage peaks, the resulting spikes of current are extremely nonsinusoidal with a high content of harmonics. This results in a poor power factor condition where the apparent input power is much higher than the real power. Power factor ratios of 0.5 to 0.7 are common. Figure 14. Uncorrected Power Factor Input Waveforms Vpk Rectified DC 0 Line Sag AC Line Voltage 0 AC Line Current Power factor correction can be achieved with the use of either a passive or active input circuit. Passive circuits usually contain a combination of large capacitors, inductors, and rectifiers that operate at the ac line frequency. Active circuits incorporate some form of a high frequency switching converter for the power processing with the boost converter MOTOROLA ANALOG IC DEVICE DATA being the most popular topology. Since active input circuits operate at a frequency much higher than that of the ac line, they are smaller, lighter in weight, and more efficient than a passive circuit that yields similar results. With proper control of the preconverter, almost any complex load can be made to appear resistive to the ac line, thus significantly reducing the harmonic current content. Operating Description The MC33368 contains many of the building blocks and protection features that are employed in modern high performance current mode power supply controllers. Referring to the block diagram in Figure 15, note that a multiplier has been added to the current sense loop and that this device does not contain an oscillator. A description of each of the functional blocks is given below. Error Amplifier An Error Amplifier with access to the inverting input and output is provided. The amplifier is a transconductance type, meaning that it has high output impedance with controlled voltage-to-current gain (gm 50 mhos). The noninverting input is internally biased at 5.0 V 2.0%. The output voltage of the power factor converter is typically divided down and monitored by the inverting input. The maximum input bias current is -1.0 A which can cause an output voltage error that is equal to the product of the input bias current and the value of the upper divider resistor R2. The Error Amplifier output is internally connected to the Multiplier and is pinned out (Pin 4) for external loop compensation. Typically, the bandwidth is set below 20 Hz so that the amplifier's output voltage is relatively constant over a given ac line cycle. In effect, the error amplifier monitors the average output voltage of the converter over several line cycles resulting in a fixed Drive Output on-time. The amplifier output stage can sink and source 11.5 A of current and is capable of swinging from 1.7 to 5.0 V, assuring that the Multiplier can be driven over its entire dynamic range. Note that by using a transconductance type amplifier, the input is allowed to move independently with respect to the output, since the compensation capacitor is connected to ground. This allows dual usage of the Voltage Feedback pin by the Error Amplifier and Overvoltage Comparator. Overvoltage Comparator An Overvoltage Comparator is incorporated to eliminate the possibility of runaway output voltage. This condition can occur during initial startup, sudden load removal, or during output arcing and is the result of the low bandwidth that must be used in the Error Amplifier control loop. The Overvoltage Comparator monitors the peak output voltage of the converter, and when exceeded, immediately terminates MOSFET switching. The comparator threshold is internally set to 1.08 Vref. In order to prevent false tripping during normal operation, the value of the output filter capacitor C3 must be large enough to keep the peak-to-peak ripple less than 16% of the average dc output. 7 MC33368 Multiplier A single quadrant, two input multiplier is the critical element that enables this device to control power factor. The ac haversines are monitored at Pin 5 with respect to ground while the Error Amplifier output at Pin 4 is monitored with respect to the Voltage Feedback Input threshold. A graph of the Multiplier transfer curve is shown in Figure 1. Note that both inputs are extremely linear over a wide dynamic range, 0 to 3.2 V for Pin 5 and 2.5 to 4.0 V for Pin 4. The Multiplier output controls the Current Sense Comparator threshold as the ac voltage traverses sinusoidally from zero to peak line. This has the effect of forcing the MOSFET on-time to track the input line voltage, thus making the preconverter load appear to be resistive. Pin 6 Threshold [ 0.55 V Pin 4 - V Pin 3 V Pin 5 Zero Current Detector The MC33368 operates as a critical conduction current mode controller, whereby output switch conduction is initiated by the Zero Current Detector and terminated when the peak inductor current reaches the threshold level established by the Multiplier output. The Zero Current Detector initiates the next on-time by setting the RS Latch at the instant the inductor current reaches zero. This critical conduction mode of operation has two significant benefits. First, since the MOSFET cannot turn-on until the inductor current reaches zero, the output rectifier's reverse recovery time becomes less critical allowing the use of an inexpensive rectifier. Second, since there are no deadtime gaps between cycles, the ac line current is continuous thus limiting the peak switch to twice the average input current The Zero Current Detector indirectly senses the inductor current by monitoring when the auxiliary winding voltage falls below 1.2 V. To prevent false tripping, 200 mV of hysteresis is provided. The Zero Current Detector input is internally protected by two clamps. The upper 10 V clamp prevents input overvoltage breakdown while the lower -0.7 V clamp prevents substrate injection. An external resistor must be used in series with the auxiliary winding to limit the current through the clamps to 5.0 mA or less. Current Sense Comparator and RS Latch The Current Sense Comparator RS Latch configuration used ensures that only a single pulse appears at the Drive Output during a given cycle. The inductor current is converted to a voltage by inserting a ground-referenced sense resistor R7 in series with the source of output switch. This voltage is monitored by the Current Sense Input and compared to a level derived from the Multiplier output. The peak inductor current under normal operating conditions is controlled by the threshold voltage of Pin 6 where: Pin 6 Threshold I pk R7 Abnormal operating conditions occur when the preconverter is running at extremely low line or if output voltage sensing is lost. Under these conditions, the Current Sense Comparator threshold will be internally clamped to 1.5 V. Therefore, the maximum peak switch current is: + I 8 pk(max) With the component values shown in Figure 15, the Current Sense Comparator threshold, at the peak of the haversine, varies from 110 mV at 90 Vac to 100 mV at 268 Vac. The Current Sense Input to Drive Output propagation delay is typically 200 ns. Timer A watchdog timer function was added to the IC to eliminate the need for an external oscillator when used in stand alone applications. The Timer provides a means to automatically start or restart the preconverter if the Drive Output has been off for more than 385 s after the inductor current reaches zero. Undervoltage Lockout and Quickstart The MC33368 has a 5.0 V internal reference brought out to Pin 1 and capable of sourcing 10 mA typically. It also contains an Undervoltage Lockout (UVLO) circuit which suppresses the Gate output at Pin 11 if the VCC supply voltage drops below 8.5 V typical. A Quickstart circuit has been incorporated to optimize converter startup. During initial startup, compensation capacitor C1 will be discharged, holding the Error Amplifier output below the Multiplier's threshold. This will prevent Drive Output switching and delay bootstraping of capacitor C4 by diode D6. If Pin 4 does not reach the multiplier threshold before C4 discharges below the lower SMPS UVLO threshold, the converter will hiccup and experience a significant startup delay. The Quickstart circuit is designed to precharge C1 to 1.7 V. This level is slightly below the Pin 4 Multiplier threshold, allowing immediate Drive Output switching. Restart Delay A restart delay pin is provided to allow hiccup mode fault protection in case of a short circuit condition and to prevent the SMPS from repeatedly trying to restart after the input line voltage has been removed. When power is first applied, there is no startup delay, but subsequent cycling of the VCC voltage will result in delay times that are programmed by an external resistor and capacitor. The Restart Delay, Pin 2, is a high impedance, so that an external capacitor can provide delay times as long as several seconds. If the SMPS output is short circuited, the transformer winding, which provides the VCC voltage to the control IC and the MC33368, will be unable to sustain VCC to the control circuits. The restart delay capacitor at Pin 2 of the MC33368 prevents the high voltage startup transistor within the IC from maintaining the voltage on C4. After VCC drops below the UVLO threshold in the SMPS, the SMPS switching transistors are held off for the time programmed by the values of the restart capacitor (C9) and resistor (R8). In this manner, the SMPS switching transistors are operated at very low duty cyles, preventing their destruction. If the short circuit fault is removed, the power supply system will turn on by itself in a normal startup mode after the restart delay has timed out. + 1.5R7V MOTOROLA ANALOG IC DEVICE DATA MC33368 Output Switching Frequency Clamp In normal operation, the MC33368 operates the boost inductor in the critical mode. That is, the inductor current ramps to a peak value, ramps down to zero, then immediately begins ramping positive again. The peak current is programmed by the multiplier output within the IC. As the input voltage haversine declines to near zero, the output switch on-time becomes constant, rather than going to zero because of the small integrated dc voltage at Pin 5 caused by C2, R3 and R5. Because of this, the average line current does not exactly follow the line voltage near the zero crossings. The Output Switching Frequency Clamp remedies this situation to improve power factor and minimize EMI generated in this operating region. The values of R10 and C7, as shown in Figure 15, program a minimum off-time in the frequency clamp which overrides the zero current detect signal, forcing a minimum off-time. This allows discontinuous conduction operation of the boost inductor in the zero crossing region, and the average line current more nearly follows the voltage. The Output Switching Frequency Clamp function can be disabled by connecting the FC input, Pin 13, to the VCC supply Pin 12. For best results, the minimum off-time, determined by the values of R10 and C7, should be chosen so that MOTOROLA ANALOG IC DEVICE DATA ts(min) = t(on) + t(off)fc. Output drive is inhibited when the voltage at the frequency clamp input is less than 2.0 V. When the output drive is high, C7 is discharged through an internal 100 A current source. When the output drive switches low, C7 is charged through R10. The drive output is inhibited until the voltage across C7 reaches 2.0 V, establishing a minimim off-time where: t (off)fc + * R10 C7 loge 1 * 2 V CC Output The IC contains a CMOS output driver that was specifically designed for direct drive of power MOSFETs. The Gate Output is capable of up to 1500 mA peak current with a typical rise and fall time of 50 ns with a 1.0 nF load. Additional internal circuitry has been added to keep the Gate Output in a sinking mode whenever the Undervoltage Lockout is active. This characteristic eliminates the need for an external gate pull-down resistor. The totem-pole output has been optimized to minimize cross-conduction current during high speed operation. 9 MC33368 Table 1. Design Equations Calculation Formula Notes + VO IO 2 2 P O I + L(pk) h Vac Converter Output Power P Peak Indicator Current Inductance L P + t Switch Off-Time t V O -Vac 2 t Delay Time t + h V +t Peak Switch Current R7 2 O L + The off-time t(off) is greatest at the peak of the ac line voltage and approaches zero at the ac line zero crossings. Theta () represents the angle of the ac line voltage. -1 I P L(pk) V O V - 2 CC V CC ) t(off) V Converter Output Voltage Converter Output Peak-to-Peak Ripple Voltage Error Amplifier Bandwidth V O BW Set the mulltiplier input voltage VM to 3.0 V at high line. Empirically adjust VM for the lowest distortion over the ac line voltage range while guaranteeing startup at minimum line. Vac + Vref DV O(pp) + IL(pk) 2 R5 )1 R3 ) + M R2 R1 2 1 - I IB R1 p 1 f ac C3 + 2 gpmC1 The delay time is used to override the minimum off-time at the ac line zero crossings by programming the Frequency Clamp with C7 and R10. Set the current sense threshold VCS to 1.0 V for universal input (85 to 265 Vac) operation and to 0.5 V for fixed input (92 to 138 Vac, or 184 to 276 Vac) operation. Note that VCS must be less than 1.4 V. + I VCS L(pk) Multiplier Input Voltage The off-time is at a minimum at ac line crossings. This equation is used to calculate t(off) as Theta approaches zero. The minimum switching frequency occurs at the peak of the ac line voltage. As the ac line voltage traverses from peak to zero, t(off) approaches zero producing an increase in switching frequency. 1 (on) Let the switching cycle t = 40 s for universal input (85 to 265 Vac) operation and 20 s for fixed input (92 to 138 Vac, or 184 to 276 Vac) operation. In theory, the on-time t(on) is constant. In practice, t(on) tends to increase at the ac line zero crossings due to the charge on capacitor C5. Let Vac = Vac(LL) for initial t(on) and t(off) calculations. (on) 2 Vac Sin q min (LL) L O P Vac 2 + - R10 C7 ln d f Vac 2 P t (off) Switching Frequency h (LL) 2 VO PO (on) + (off) Minimum Switch Off-Time Calculated at the minimum required ac line voltage for output regulation. Let the efficiency = 0.92 for low line operation. (LL) Switch On-Time t Calculate the maximum required output power. O 2 ) ESR2 The IIB R1 error term can be minimized with a divider current in excess of 100 A. The calculated peak-to-peak ripple must be less than 16% of the average dc output voltage to prevent false tripping of the Overvoltage Comparator. Refer to the Overvoltage Comparator Text. ESR is the equivalent series resistance of C3. The bandwidth is typically set to 20 Hz. When operating at high ac line, the value of C1 may need to be increased. NOTE: The following converter characteristics must be chosen: VO = Desired output voltage. Vac(LL) = AC RMS minimum required operating line voltage for output regulation. IO = Desired output current. VO = Converter output peak-to-peak ripple voltage. Vac = AC RMS operating line voltage. 10 MOTOROLA ANALOG IC DEVICE DATA MC33368 Figure 15. 80 W Power Factor Controller 1N4006 D4 D2 EMI Filter 92 to 270 Vrms D1 C5 1.0 D3 16 Vref Line MC33368 Vref D6 D8 R13 VCC 1N4744 51 1N4934 15 V R8 10 k RD C9 330 F 2 AGnd UVLO Q 8 Timer R RS Latch R R S S Q S Set Dominant 1.5 V 12 Zero Current Detect 7 15 V ZCD 1.2/1.0 T R4 22 k Gate 320 H MUR130 MTP8N50E R2 470 k 10 Low Load Detect FC 9 Quickstart LEB 6 Leading Edge Blanking CS Mult R7 0.1 0.25 W 5.0 V Reference 5 C2 0.01 R10 10 C7 10 pF 13 Frequency Clamp 1.08 x Vref Multiplier 4 1 Comp 3 Vref C1 0.68 FB Vref C6 0.1 VO D5 C3 220 To VCC Pin 12 PGnd R5 1.3 M Q1 R11 10 11 Overvoltage Comparator R3 20 k C4 100 13/8.0 T: Coilcraft N2881-A Primary = 62 turns of #22 AWG Secondary = 5 turns of #22 AWG Core = Coilcraft PT2510, EE25 Gap = 0.072 total for a primary inductance (Lp) of 320 H R1 10 k Not Used: D7, C8, R6, R9 Power Factor Controller Test Data DC Output AC Line Input Vrms Pin PF Ifund Current Harmonic Distortion (% Ifund) THD 2 3 5 7 VO(pp) VO IO PO n(%) 90 79.7 0.999 0.89 0.5 0.15 0.09 0.06 0.09 3.0 244.4 0.31 76.01 95.4 100 79.3 0.998 0.79 0.5 0.14 0.09 0.08 0.10 3.0 242.9 0.31 75.54 95.3 110 78.9 0.997 0.72 0.5 0.16 0.13 0.08 0.10 3.0 242.9 0.31 75.30 95.4 120 78.5 0.996 0.66 0.5 0.15 0.12 0.08 0.13 3.0 243.0 0.31 75.57 96.3 130 78.1 0.994 0.60 0.5 0.14 0.12 0.07 0.14 3.0 243.0 0.31 75.57 96.7 138 77.8 0.991 0.57 0.5 0.15 0.14 0.08 0.14 3.0 243.0 0.31 75.57 97.1 Heatsink = AAVID Engineering Inc., 590302B03600, or 593002B03400 MOTOROLA ANALOG IC DEVICE DATA 11 MC33368 Figure 16. 175 W Universal Input Power Factor Controller 1N5406 D2 EMI Filter 92 to 270 Vrms C5 1.0 D4 D1 D3 16 Vref Line MC33368 Vref D8 R13 D6 VCC 1N4744 51 1N4934 15 V R8 1.0 M RD C9 2.2 2 AGnd UVLO Q 8 Timer R RS Latch R R S S Q S Set Dominant 1.5 V 12 Zero Current Detect 7 15 V ZCD R4 22 k 6.9 V 1.2/1.0 T MUR460 Gate R11 10 11 Overvoltage Comparator PGnd R5 1.3 M C3 330 To VCC Pin 12 MTW20N50E R2 820 k 13 Frequency Clamp 1.08 x Vref FC 9 Quickstart LEB 6 Leading Edge Blanking CS Mult C2 0.01 R7 0.1 5.0 V Reference 5 Multiplier 4 Comp 1 C1 2.2 3 Vref FB Vref C6 0.1 VO D5 Q1 10 Low Load Detect R3 10 k C4 100 13/8.0 T: Coilcraft N2880-A L = 870 Hy Primary: 78 turns of #16 AWG Secondary: 6 turns of #18 AWG Core: Coilcraft PT4215, EE42-15 Gap: 0.104 total Not Used: D7, C7, C8, R6, R9, R10 R1 10 k Power Factor Controller Test Data DC Output AC Line Input Current Harmonic Distortion (% Ifund) Vrms 90 Pin PF 190.4 0.995 Ifund THD 2 3 5 7 VO(pp) VO IO PO n(%) 2.11 5.8 0.16 0.32 0.24 0.80 3.6 398.0 0.44 175.9 92.4 120 192.1 0.997 1.60 3.2 0.08 0.17 0.07 0.30 3.6 398.9 0.44 177.1 92.2 138 192.7 0.997 1.40 0.9 0.08 0.24 0.03 0.15 3.6 402.3 0.45 179.0 92.9 180 194.3 0.995 1.08 0.9 0.04 0.18 0.04 0.08 3.6 409.1 0.45 182.9 94.1 240 189.3 0.983 0.80 0.7 0.08 0.21 0.08 0.06 3.6 407.0 0.45 181.1 95.7 268 186.3 0.972 0.71 0.6 0.11 0.32 0.10 0.10 3.6 406.2 0.44 180.4 96.8 Heatsink = AAVID Engineering Inc., 590302B03600 12 MOTOROLA ANALOG IC DEVICE DATA MC33368 Figure 17. Power Factor Test Setup Line 2X Step-up Isolation Autoformer Transformer EMI Filter AC Power Analyzer PM 1000 HI W 115 Vrms Input VA HI T PF Vrms Arms 0.1 A V VD Acf Ainst Freq HARM 1 0 L.O. 0 to 270 Vac 1.0 Output to Power Factor Correction Circuit L.O. Neutral Voltech An RFI filter is required for best performance when connecting the preconverter directly to the ac line. The filter attenuates the level of high frequency switching that appears on the ac line current waveform. Figures 15 and 16 work well with commercially available two stage filters such as the Delta Electronics 03DPCG6. Shown above is a single stage test filter that can easily be constructed with four ac line rated capacitors and a common-mode transformer. Coilcraft CMT3-28-2 was used to test Figures 15 and 16. It has a minimum inductance of 28 mH and a maximum current rating of 2.0 A. Coilcraft CMT4-17-9 was used to test Figure 19. It has a minimum inductance of 17 mH and a maximum current rating of 9.0 A. Circuit conversion efficiency (%) was calculated without the power loss of the RFI filter. Figure 18. On/Off Control D2 92 to 270 Vrms EMI Filter D1 D4 C5 1.0 D3 Line 16 Vref Vref MC33368 R8 10 k 15 V RD C9 330 F UVLO 8 On/Off Input 5.0 V Off 0V On R 12 Zero Current Detect 13/8.0 RS Latch R R S S Q S Set Dominant 1.5 V 1N4148 Timer Q 2 AGnd 1.2/1.0 6.9 V 10 13 Leading Edge Blanking C1 22 1 VCC Vref C6 0.1 MTW14N50E R2 820 k R7 0.1 5.0 V Reference Comp C3 330 CS Mult 4 Q1 LEB 6 Quickstart Multiplier R11 10 DC Out D5 FC 9 1.08 x Vref R3 10 k T PGnd Frequency Clamp 5 7 15 V ZCD R4 22 k 11 Low Load Detect C2 0.01 C4 100 Gate Overvoltage Comparator R5 1.3 M R13 51 D6 VCC D8 Vref 10 k 1.0 k 3 FB R1 10 k 2N3904 1.0 k MOTOROLA ANALOG IC DEVICE DATA 13 MC33368 Figure 19. 400 W Power Factor Controller D2 1N5406 D4 D1 D3 EMI Filter 92 to 270 Vac C5 1.0 16 Vref Vref MC33368 R8 1.0 M 15 V RD C9 330 F Line UVLO Q 2 AGnd 8 Timer R 1.5 V 12 Zero Current Detect RS Latch R R S S Q S Set Dominant 13/8.0 1.2/1.0 1.5 V 7 15 V ZCD R4 22 k T MUR460 D5 Q1 11 C3 330 R11 10 PGnd R5 1.3 M 13 Frequency Clamp 1.08 x Vref R2 820 k CS Mult 5.0 V Reference 5 Multiplier 4 Comp C1 1.0 1 Vref C6 0.1 C7 470 pF LEB 6 Leading Edge Blanking C2 0.01 R10 10 k FC 9 Quickstart 3 400 V MTW20N50E Vref 10 Low Load Detect 14 1N4934 C4 100 Gate Overvoltage Comparator R3 10.5 k R13 51 D6 1N4744 VCC D8 R9 10 C8 0.001 R7 0.1 FB Vref R1 10 k MOTOROLA ANALOG IC DEVICE DATA MC33368 Figure 20. Printed Circuit Board and Component Layout (Circuits of Figures 15 and 16) D3 DC Output C6 AC Input D1 R3 C2 C5 D7 R5 R1 R2 R8 R6 C1 D2 R4 D6 IC1 C9 C7 J C8 J D4 R7 C4 IIIII IIIII IIIII IIIII IIIII III IIIII R13 R10 R11 J J R9 Transformer D8 Q1 C3 S D G D5 J = Jumper (Top View) 4.5 MC33368 3.0 (Bottom View) MOTOROLA ANALOG IC DEVICE DATA 15 MC33368 OUTLINE DIMENSIONS P SUFFIX PLASTIC PACKAGE CASE 648-08 (DIP-16) ISSUE R -A- 16 9 1 8 NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION L TO CENTER OF LEADS WHEN FORMED PARALLEL. 4. DIMENSION B DOES NOT INCLUDE MOLD FLASH. 5. ROUNDED CORNERS OPTIONAL. B F C L DIM A B C D F G H J K L M S S -T- SEATING PLANE K H G D M J 16 PL 0.25 (0.010) T A M M INCHES MIN MAX 0.740 0.770 0.250 0.270 0.145 0.175 0.015 0.021 0.040 0.70 0.100 BSC 0.050 BSC 0.008 0.015 0.110 0.130 0.295 0.305 0_ 10 _ 0.020 0.040 MILLIMETERS MIN MAX 18.80 19.55 6.35 6.85 3.69 4.44 0.39 0.53 1.02 1.77 2.54 BSC 1.27 BSC 0.21 0.38 2.80 3.30 7.50 7.74 0_ 10 _ 0.51 1.01 D SUFFIX PLASTIC PACKAGE CASE 751K-01 (SO-16) ISSUE O -A16 M B S 9 P 1 M_ 0.25 (0.010) -B- F 8 G R X 45 _ C -TK NOTES: 1 DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2 CONTROLLING DIMENSION: MILLIMETER. 3 DIMENSIONS A AND B DO NOT INCLUDE MOLD PROTRUSION. 4 MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5 DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. D 14 PL 0.25 (0.010) SEATING PLANE J M T A S B S DIM A B C D F G J K M P R MILLIMETERS MIN MAX 9.80 10.00 3.80 4.00 1.35 1.75 0.35 0.49 0.40 1.25 1.27 BSC 0.19 0.25 0.10 0.25 0_ 7_ 5.80 6.20 0.25 0.50 INCHES MIN MAX 0.368 0.393 0.150 0.157 0.054 0.068 0.014 0.019 0.016 0.049 0.050 BSC 0.008 0.009 0.004 0.009 0_ 7_ 0.229 0.244 0.010 0.019 Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. "Typical" parameters which may be provided in Motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. Motorola does not convey any license under its patent rights nor the rights of others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury or death may occur. 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Box 5405, Denver, Colorado 80217. 303-675-2140 or 1-800-441-2447 JAPAN: Nippon Motorola Ltd.; Tatsumi-SPD-JLDC, 6F Seibu-Butsuryu-Center, 3-14-2 Tatsumi Koto-Ku, Tokyo 135, Japan. 81-3-3521-8315 Mfax: RMFAX0@email.sps.mot.com - TOUCHTONE 602-244-6609 INTERNET: http://www.mot.com/SPS/ ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; 8B Tai Ping Industrial Park, 51 Ting Kok Road, Tai Po, N.T., Hong Kong. 852-26629298 16 MC33368/D MOTOROLA ANALOG IC DEVICE DATA