Order this document by MC33363B/D The MC33363B is a monolithic high voltage switching regulator that is specifically designed to operate from a rectified 240 Vac line source. This integrated circuit features an on-chip 700 V/1.0 A SenseFET power switch, 450 V active off-line startup FET, duty cycle controlled oscillator, current limiting comparator with a programmable threshold and leading edge blanking, latching pulse width modulator for double pulse suppression, high gain error amplifier, and a trimmed internal bandgap reference. Protective features include cycle-by-cycle current limiting, input undervoltage lockout with hysteresis, overvoltage protection, and thermal shutdown. This device is available in a 16-lead dual-in-line and wide body surface mount packages. * On-Chip 700 V, 1.0 A SenseFET Power Switch * * * * * * * * HIGH VOLTAGE OFF-LINE SWITCHING REGULATOR SEMICONDUCTOR TECHNICAL DATA 16 1 Rectified 240 Vac Line Source Operation DW SUFFIX PLASTIC PACKAGE CASE 751N (SOP-16L) On-Chip 450 V Active Off-Line Startup FET Latching PWM for Double Pulse Suppression Cycle-By-Cycle Current Limiting Input Undervoltage Lockout with Hysteresis Over-Voltage Protection Trimmed Internal Bandgap Reference Internal Thermal Shutdown 16 1 P SUFFIX PLASTIC PACKAGE CASE 648E (DIP-16) Simplified Application AC Input Startup Input Regulator Output 1 Startup Mirror VCC Reg 8 UVLO 6 OVP RT CT PIN CONNECTIONS Osc PWM Latch 7 Driver S Q 3 Overvoltage Protection Input 11 16 Startup Input 1 VCC 3 Ipk 4 13 5 12 RT 6 11 CT 7 10 Regulator Output 8 9 Gnd Power Switch Drain LEB Gnd Overvoltage Protection Input Voltage Feedback Input Compensation (Top View) Compensation Thermal Power Switch Drain DC Output R PWM 16 9 EA Gnd 4, 5, 12, 13 10 Voltage Feedback Input ORDERING INFORMATION Device Operating Temperature Range MC33363BDW MC33363BP SOP-16L TJ = -25 to +125C Motorola, Inc. 1999 MOTOROLA ANALOG IC DEVICE DATA Package DIP-16 Rev 1 1 MC33363B MAXIMUM RATINGS AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA AAAAAAAAAAAAAA AAAA AAAAA AAA Rating Power Switch (Pin 16) Drain Voltage Drain Current Startup Input Voltage (Pin 1, Note 1) Pin 3 = Gnd Pin 3 1000 F to ground Symbol Value Unit VDS IDS 700 1.0 V A Vin V 400 500 Power Supply Voltage (Pin 3) VCC 40 V Input Voltage Range Voltage Feedback Input (Pin 10) Compensation (Pin 9) Overvoltage Protection Input (Pin 11) RT (Pin 6) CT (Pin 7) VIR -1.0 to Vreg V Thermal Characteristics P Suffix, Dual-In-Line Case 648E Thermal Resistance, Junction-to-Air Thermal Resistance, Junction-to-Case DW Suffix, Surface Mount Case 751G Thermal Resistance, Junction-to-Air Thermal Resistance, Junction-to-Case Operating Junction Temperature Storage Temperature NOTE: C/W RJA RJC 80 15 RJA RJC TJ 95 15 -25 to +150 C Tstg -55 to +150 C ESD data available upon request. ELECTRICAL CHARACTERISTICS (VCC = 20 V, RT = 10 k, CT = 390 pF, CPin 8 = 1.0 F, for typical values TJ = 25C, for min/max values TJ is the operating junction temperature range that applies (Note 2), unless otherwise noted.) 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Maximum power dissipation limits must be observed. 2. Tested junction temperature range for the MC33363B: Tlow = -25C Thigh = +125C 2 MOTOROLA ANALOG IC DEVICE DATA MC33363B ELECTRICAL CHARACTERISTICS (continued) (VCC = 20 V, RT = 10 k, CT = 390 pF, CPin 8 = 1.0 F, for typical values TJ = 25C, for min/max values TJ is the operating junction temperature range that applies (Note 2), unless otherwise noted.) AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAAAAAAAAAAAAAAAAAA AAAAA AAAA AAAA AAAA AAA Characteristic Symbol Min Typ Max Unit Input Threshold Voltage Vth 2.47 2.6 2.73 V Input Bias Current (Vin = 2.6 V, TJ = -25 - 125C) IIB - 100 500 nA DC(max) DC(min) 48 - 50 0 52 0 - - 15 - 17 39 - 0.2 100 OVERVOLTAGE DETECTION (Pin 11) PWM COMPARATOR (Pins 7, 9) Duty Cycle Maximum (VFB = 0 V) Minimum (VFB = 2.7 V) % POWER SWITCH (Pin 16) Drain-Source On-State Resistance (ID = 200 mA) TJ = 25C TJ = Tlow to Thigh RDS(on) Drain-Source Off-State Leakage Current VDS = 650 V A ID(off) Rise Time tr - 50 - ns Fall Time tf - 50 - ns Ilim 0.5 0.72 0.9 A - - 2.0 2.0 4.0 4.0 OVERCURRENT COMPARATOR (Pin 16) Current Limit Threshold (RT = 10 k) STARTUP CONTROL (Pin 1) Peak Startup Current (Vin = 400 V) (Note 3) VCC = 0 V VCC = (Vth(on) - 0.2 V) Istart mA Off-State Leakage Current (Vin = 50 V, VCC = 20 V) ID(off) - 40 200 A Vth(on) 11 15.2 18 V VCC(min) 7.5 9.5 11.5 V - - 0.25 3.2 0.5 5.0 UNDERVOLTAGE LOCKOUT (Pin 3) Startup Threshold (VCC Increasing) Minimum Operating Voltage After Turn-On TOTAL DEVICE (Pin 3) Power Supply Current Startup (VCC = 10 V, Pin 1 Open) Operating ICC mA Figure 1. Oscillator Frequency versus Timing Resistor f OSC , OSCILLATOR FREQUENCY (Hz) 1.0 M CT = 100 pF VCC = 20 V TA = 25C 500 k C = 200 pF T 200 k CT = 500 pF 100 k CT = 1.0 nF C = 2.0 nF 50 k T C = 5.0 nF 20 k T CT = 10 nF 10 k 7.0 10 15 20 30 RT, TIMING RESISTOR (k) MOTOROLA ANALOG IC DEVICE DATA 50 70 I PK, POWER SWITCH PEAK DRAIN CURRENT (A) NOTES: 3. The device can only guarantee to start up at high temperature below +115C. Figure 2. Power Switch Peak Drain Current versus Timing Resistor 1.0 0.8 VCC = 20 V CT = 1.0 F TA = 25C 0.6 0.4 0.3 0.2 0.15 0.1 7.0 Inductor supply voltage and inductance value are adjusted so that Ipk turn-off is achieved at 5.0 s. 10 15 20 30 40 50 70 RT, TIMING RESISTOR (k) 3 MC33363B Figure 4. Maximum Output Duty Cycle versus Timing Resistor Ratio Dmax, MAXIMUM OUTPUT DUTY CYCLE (%) Figure 3. Oscillator Charge/Discharge Current versus Timing Resistor VCC = 20 V TA = 25C 0.5 0.3 0.2 0.15 0.1 10 15 20 50 70 70 VCC = 20 V CT = 2.0 nF TA = 25C RD/RT Ratio Discharge Resistor Pin 6 to Gnd 60 50 40 RC/RT Ratio Charge Resistor Pin 6 to Vreg 30 1.0 2.0 3.0 5.0 7.0 RT, TIMING RESISTOR (k) TIMING RESISTOR RATIO Figure 5. Error Amp Open Loop Gain and Phase versus Frequency Figure 6. Error Amp Output Saturation Voltage versus Load Current 100 VCC = 20 V VO = 1.0 to 4.0 V RL = 5.0 M CL = 2.0 pF TA = 25C 80 Gain 60 0 30 60 Phase 40 90 20 120 0 150 100 1.0 k 10 k 100 k 1.0 M 180 10 M 0 Source Saturation (Load to Ground) -1.0 Vref - 2.0 2.0 Sink Saturation (Load to Vref) 1.0 VCC = 20 V TA = 25C Gnd 0 0 0.2 0.4 0.6 0.8 f, FREQUENCY (Hz) IO, OUTPUT LOAD CURRENT (mA) Figure 7. Error Amplifier Small Signal Transient Response Figure 8. Error Amplifier Large Signal Transient Response VCC = 20 V AV = -1.0 CL = 10 pF TA = 25C 1.75 V 1.0 VCC = 20 V AV = -1.0 CL = 10 pF TA = 25C 3.00 V 20 mV/DIV 1.80 V 10 0.5 V/DIV -20 10 1.75 V 0.50 V 1.70 V 1.0 s/DIV 4 30 Vsat , OUTPUT SATURATION VOLTAGE (V) A VOL, OPEN LOOP VOLTAGE GAIN (dB) 0.08 7.0 , EXCESS PHASE (DEGREES) I chg /I dscg , OSCILLATOR CHARGE/DISCHARGE CURRENT (mA) 0.8 1.0 s/DIV MOTOROLA ANALOG IC DEVICE DATA Figure 10. Peak Startup Current versus Power Supply Voltage Figure 9. Regulator Output Voltage Change versus Source Current 2.0 0 -20 I pk , PEAK STARTUP CURRENT (mA) VCC = 20 V RT = 10 k CPin 8 = 1.0 F TA = 25C -40 -60 -80 VPin 1 = 400 V TA = 25C 1.0 Pulse tested with an on-time of 20 s to 300 s at < 1.0% duty cycle. The on-time is adjusted at Pin 1 for a maximum peak current out of Pin 3. 0 4.0 0 8.0 12 16 20 4.0 6.0 8.0 10 12 Figure 11. Power Switch Drain-Source On-Resistance versus Temperature Figure 12. Power Switch Drain-Source Capacitance versus Voltage ID = 200 mA 24 16 8.0 Pulse tested at 5.0 ms with < 1.0% duty cycle so that TJ is as close to TA as possible. -25 0 25 50 75 100 125 VCC = 20 V TA = 25C 120 80 40 0 1.0 150 COSS measured at 1.0 MHz with 50 mVpp. 10 100 1000 VDS, DRAIN-SOURCE VOLTAGE (V) Figure 13. Supply Current versus Supply Voltage Figure 14. DW and P Suffix Transient Thermal Resistance 100 R JA , THERMAL RESISTANCE JUNCTION-TO-AIR (C/W) CT = 390 pF CT = 2.0 nF 2.4 1.6 RT = 10 k Pin 1 = Open Pin 4, 5, 10, 11, 12, 13 = Gnd TA = 25C 0.8 0 14 160 TA, AMBIENT TEMPERATURE (C) 3.2 I CC, SUPPLY CURRENT (mA) 2.0 VCC, POWER SUPPLY VOLTAGE (V) 32 0 -50 0 Ireg, REGULATOR SOURCE CURRENT (mA) COSS, DRAIN-SOURCE CAPACITANCE (pF) R DS(on), DRAIN-SOURCE ON-RESISTANCE ( ) V reg, REGULATOR VOLTAGE CHANGE (mV) MC33363B 0 10 20 VCC, SUPPLY VOLTAGE (V) MOTOROLA ANALOG IC DEVICE DATA 30 40 L = 12.7 mm of 2.0 oz. copper. Refer to Figures 15 and 16. 10 1.0 0.01 0.1 1.0 10 100 t, TIME (s) 5 MC33363B 90 2.4 III III IIIIII IIIIII 80 Printed circuit board heatsink example 70 2.0 oz Copper L 60 L 3.0 mm Graphs represent symmetrical layout 50 2.0 1.6 1.2 0.8 RJA 0.4 40 30 10 0 20 30 40 0 50 III III III III 100 5.0 Printed circuit board heatsink example 80 L RJA 60 4.0 2.0 oz Copper L 3.0 mm Graphs represent symmetrical layout 3.0 40 2.0 PD(max) for TA = 70C 20 0 0 10 L, LENGTH OF COPPER (mm) 20 1.0 30 40 0 50 P D , MAXIMUM POWER DISSIPATION (W) R JA , THERMAL RESISTANCE JUNCTION-TO-AIR (C/W) PD(max) for TA = 50C Figure 16. P Suffix (DIP-16) Thermal Resistance and Maximum Power Dissipation versus P.C.B. Copper Length R JA, THERMAL RESISTANCE JUNCTION-TO-AIR (C/W) 2.8 100 PD, MAXIMUM POWER DISSIPATION (W) Figure 15. DW Suffix (SOP-16L) Thermal Resistance and Maximum Power Dissipation versus P.C.B. Copper Length L, LENGTH OF COPPER (mm) AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA PIN FUNCTION DESCRIPTION Pin Description 1 Startup Input This pin connects directly to the rectified ac line voltage source. Internally Pin 1 is tied to the drain of a high voltage startup MOSFET. During startup, the MOSFET supplies internal bias, and charges an external capacitor that connects from the VCC pin to ground. 2 - This pin has been omitted for increased spacing between the rectified ac line voltage on Pin 1 and the VCC potential on Pin 3. 3 VCC This is the positive supply voltage input. During startup, power is supplied to this input from Pin 1. When VCC reaches the UVLO upper threshold, the startup MOSFET turns off and power is supplied from an auxiliary transformer winding. Ground These pins are the control circuit grounds. They are part of the IC lead frame and provide a thermal path from the die to the printed circuit board. 6 RT Resistor RT connects from this pin to ground. The value selected will program the Current Limit Comparator threshold and affect the Oscillator frequency. 7 CT Capacitor CT connects from this pin to ground. The value selected, in conjunction with resistor RT, programs the Oscillator frequency. 8 Regulator Output This 6.5 V output is available for biasing external circuitry. It requires an external bypass capacitor of at least 1.0 F for stability. 9 Compensation This pin is the Error Amplifier output and is made available for loop compensation. It can be used as an input to directly control the PWM Comparator. 10 Voltage Feedback Input This is the inverting input of the Error Amplifier. It has a 2.6 V threshold and normally connects through a resistor divider to the converter output, or to a voltage that represents the converter output. 11 Overvoltage Protection Input This input provides runaway output voltage protection due to an external component or connection failure in the control loop feedback signal path. It has a 2.6 V threshold and normally connects through a resistor divider to the converter output, or to a voltage that represents the converter output. - These pins have been omitted for increased spacing between the high voltages present on the Power Switch Drain, and the ground potential on Pins 12 and 13. Power Switch Drain This pin is designed to directly drive the converter transformer and is capable of switching a maximum of 700 V and 1.0 A. 4, 5, 12, 13 14, 15 16 6 Function MOTOROLA ANALOG IC DEVICE DATA MC33363B Figure 17. Representative Block Diagram AC Input Startup Input Startup Control Current Mirror Regulator Output 6.5 V 8 Band Gap Regulator I VCC CT 3 UVLO 2.25 I 4I OVP 11 2.6 V Oscillator 7 DC Output Overvoltage Protection Input 14.5 V/ 9.5 V 6 RT 1 16 PWM Latch Power Switch Drain Driver S Q R PWM Comparator Leading Edge Blanking 8.1 Thermal Shutdown Current Limit Comparator Compensation 405 270 A Gnd 9 Error Amplifier 2.6 V 10 Voltage Feedback Input 4, 5, 12, 13 Figure 18. Timing Diagram 2.6 V Capacitor CT 0.6 V Compensation Oscillator Output PWM Comparator Output PWM Latch Q Output Current Limit Propagation Delay Power Switch Gate Drive Current Limit Threshold Leading Edge Blanking Input (Power Switch Drain Current) Normal PWM Operating Range MOTOROLA ANALOG IC DEVICE DATA Output Overload 7 MC33363B OPERATING DESCRIPTION Introduction The MC33363B represents a new higher level of integration by providing all the active high voltage power, control, and protection circuitry required for implementation of a flyback or forward converter on a single monolithic chip. This device is designed for direct operation from a rectified 240 Vac line source and requires a minimum number of external components to implement a complete converter. A description of each of the functional blocks is given below, and the representative block and timing diagrams are shown in Figures 17 and 18. The formula for the charge/discharge current along with the oscillator frequency are given below. The frequency formula is a first order approximation and is accurate for CT values greater than 500 pF. For smaller values of CT, refer to Figure 1. Note that resistor RT also programs the Current Limit Comparator threshold. Oscillator and Current Mirror The oscillator frequency is controlled by the values selected for the timing components RT and CT. Resistor RT programs the oscillator charge/discharge current via the Current Mirror 4 I output, Figure 3. Capacitor CT is charged and discharged by an equal magnitude internal current source and sink. This generates a symmetrical 50 percent duty cycle waveform at Pin 7, with a peak and valley threshold of 2.6 V and 0.6 V respectively. During the discharge of CT, the oscillator generates an internal blanking pulse that holds the inverting input of the AND gate Driver high. This causes the Power Switch gate drive to be held in a low state, thus producing a well controlled amount of output deadtime. The amount of deadtime is relatively constant with respect to the oscillator frequency when operating below 1.0 MHz. The maximum Power Switch duty cycle at Pin 16 can be modified from the internal 50% limit by providing an additional charge or discharge current path to CT, Figure 19. In order to increase the maximum duty cycle, a discharge current resistor RD is connected from Pin 7 to ground. To decrease the maximum duty cycle, a charge current resistor RC is connected from Pin 7 to the Regulator Output. Figure 4 shows an obtainable range of maximum output duty cycle versus the ratio of either RC or RD with respect to RT. PWM Comparator and Latch The pulse width modulator consists of a comparator with the oscillator ramp voltage applied to the non-inverting input, while the error amplifier output is applied into the inverting input. The Oscillator applies a set pulse to the PWM Latch while CT is discharging, and upon reaching the valley voltage, Power Switch conduction is initiated. When CT charges to a voltage that exceeds the error amplifier output, the PWM Latch is reset, thus terminating Power Switch conduction for the duration of the oscillator ramp-up period. This PWM Comparator/Latch combination prevents multiple output pulses during a given oscillator clock cycle. The timing diagram shown in Figure 18 illustrates the Power Switch duty cycle behavior versus the Compensation voltage. Figure 19. Maximum Duty Cycle Modification Current Mirror Regulator Output 1.0 8 2.25 I I RC Current Limit Reference 6 RT 4I RD CT 7 Oscillator PWM Comparator 8 Blanking Pulse I + 5.4 R chgdscg T f [ I chg dscg 4C T Current Limit Comparator and Power Switch The MC33363B uses cycle-by-cycle current limiting as a means of protecting the output switch transistor from overstress. Each on-cycle is treated as a separate situation. Current limiting is implemented by monitoring the output switch current buildup during conduction, and upon sensing an overcurrent condition, immediately turning off the switch for the duration of the oscillator ramp-up period. The Power Switch is constructed as a SenseFET allowing a virtually lossless method of monitoring the drain current. It consists of a total of 1462 cells, of which 36 are connected to a 8.1 ground-referenced sense resistor. The Current Sense Comparator detects if the voltage across the sense resistor exceeds the reference level that is present at the inverting input. If exceeded, the comparator quickly resets the PWM Latch, thus protecting the Power Switch. The current limit reference level is generated by the 2.25 I output of the Current Mirror. This current causes a reference voltage to appear across the 405 resistor. This voltage level, as well as the Oscillator charge/discharge current are both set by resistor RT. Therefore when selecting the values for RT and CT, RT must be chosen first to set the Power Switch peak drain current, while CT is chosen second to set the desired Oscillator frequency. A graph of the Power Switch peak drain current versus RT is shown in Figure 2 with the related formula below. I + 8.8 pk R T - 1.077 1000 MOTOROLA ANALOG IC DEVICE DATA MC33363B The Power Switch is designed to directly drive the converter transformer and is capable of switching a maximum of 700 V and 1.0 A. Proper device voltage snubbing and heatsinking are required for reliable operation. A Leading Edge Blanking circuit was placed in the current sensing signal path. This circuit prevents a premature reset of the PWM Latch. The premature reset is generated each time the Power Switch is driven into conduction. It appears as a narrow voltage spike across the current sense resistor, and is due to the MOSFET gate to source capacitance, transformer interwinding capacitance, and output rectifier recovery time. The Leading Edge Blanking circuit has a dynamic behavior in that it masks the current signal until the Power Switch turn-on transition is completed. The current limit propagation delay time is typically 262 ns. This time is measured from when an overcurrent appears at the Power Switch drain, to the beginning of turn-off. Error Amplifier An fully compensated Error Amplifier with access to the inverting input and output is provided for primary side voltage sensing, Figure 17. It features a typical dc voltage gain of 82 dB, and a unity gain bandwidth of 1.0 MHz with 78 degrees of phase margin, Figure 5. The noninverting input is internally biased at 2.6 V 3.1% and is not pinned out. The Error Amplifier output is pinned out for external loop compensation and as a means for directly driving the PWM Comparator. The output was designed with a limited sink current capability of 270 A, allowing it to be easily overridden with a pull-up resistor. This is desirable in applications that require secondary side voltage sensing. Overvoltage Protection An Overvoltage Protection Comparator is included to eliminate the possibility of runaway output voltage. This condition can occur if the control loop feedback signal path is broken due to an external component or connection failure. The comparator is normally used to monitor the primary side VCC voltage. When the 2.6 V threshold is exceeded, it will immediately turn off the Power Switch, and protect the load from a severe overvoltage condition. This input can also be driven from external circuitry to inhibit converter operation. Undervoltage Lockout An Undervoltage Lockout comparator has been incorporated to guarantee that the integrated circuit has sufficient voltage to be fully functional before the output stage is enabled. The UVLO comparator monitors the VCC voltage at Pin 3 and when it exceeds 14.5 V, the reset signal is removed from the PWM Latch allowing operation of the Power Switch. To prevent erratic switching as the threshold is crossed, 5.0 V of hysteresis is provided. MOTOROLA ANALOG IC DEVICE DATA Startup Control An internal Startup Control circuit with a high voltage enhancement mode MOSFET is included within the MC33363B. This circuitry allows for increased converter efficiency by eliminating the external startup resistor, and its associated power dissipation, commonly used in most off-line converters that utilize a UC3842 type of controller. Rectified ac line voltage is applied to the Startup Input, Pin 1. This causes the MOSFET to enhance and supply internal bias as well as charge current to the VCC bypass capacitor that connects from Pin 3 to ground. When VCC reaches the UVLO upper threshold of 15.2 V, the IC commences operation and the startup MOSFET is turned off. Operating bias is now derived from the auxiliary transformer winding, and all of the device power is efficiently converted down from the rectified ac line. The startup MOSFET will provide a steady current of 1.7 mA, Figure 10, as VCC increases or shorted to ground. The startup MOSFET is rated at a maximum of 400 V with VCC shorted to ground, and 500 V when charging a VCC capacitor of 1000 F or less. Regulator A low current 6.5 V regulated output is available for biasing the Error Amplifier and any additional control system circuitry. It is capable of up to 10 mA and has short-circuit protection. This output requires an external bypass capacitor of at least 1.0 F for stability. Thermal Shutdown and Package Internal thermal circuitry is provided to protect the Power Switch in the event that the maximum junction temperature is exceeded. When activated, typically at 150C, the Latch is forced into a `reset' state, disabling the Power Switch. The Latch is allowed to `set' when the Power Switch temperature falls below 140C. This feature is provided to prevent catastrophic failures from accidental device overheating. It is not intended to be used as a substitute for proper heatsinking. The MC33363B is contained in a heatsinkable plastic dual-in-line package in which the die is mounted on a special heat tab copper alloy lead frame. This tab consists of the four center ground pins that are specifically designed to improve thermal conduction from the die to the circuit board. Figures 15 and 16 show a simple and effective method of utilizing the printed circuit board medium as a heat dissipater by soldering these pins to an adequate area of copper foil. This permits the use of standard layout and mounting practices while having the ability to halve the junction to air thermal resistance. The examples are for a symmetrical layout on a single-sided board with two ounce per square foot of copper. 9 MC33363B OUTLINE DIMENSIONS DW SUFFIX PLASTIC PACKAGE CASE 751N-01 (SOP-16L) ISSUE O -A- T 16 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 0.13 (0.005) TOTAL IN EXCESS OF D DIMENSION AT MAXIMUM MATERIAL CONDITION. 9 -B- 1 0.010 (0.25) P M B M 8 13X J D 0.010 (0.25) M T A S B DIM A B C D F G J K M P R S T S F R X 45 _ C -T- S K 9X M SEATING PLANE G P SUFFIX PLASTIC PACKAGE CASE 648E-01 (DIP-16) ISSUE O -A- R 16 9 1 8 M L F J C -T- SEATING PLANE S K H G D 13 PL 0.25 (0.010) 10 M T B S A S INCHES MIN MAX 0.400 0.411 0.292 0.299 0.093 0.104 0.014 0.019 0.020 0.035 0.050 BSC 0.010 0.012 0.004 0.009 0_ 7_ 0.395 0.415 0.010 0.029 0.100 BSC 0.150 BSC 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 A AND B DOES NOT INCLUDE MOLD PROTRUSION. 5. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.25 (0.010). 6. ROUNDED CORNER OPTIONAL. -B- P MILLIMETERS MIN MAX 10.15 10.45 7.40 7.60 2.35 2.65 0.35 0.49 0.50 0.90 1.27 BSC 0.25 0.32 0.10 0.25 0_ 7_ 10.05 10.55 0.25 0.75 2.54 BSC 3.81 BSC DIM A B C D F G H J K L M P R S INCHES MIN MAX 0.740 0.760 0.245 0.260 0.145 0.175 0.015 0.021 0.050 0.070 0.100 BSC 0.050 BSC 0.008 0.015 0.120 0.140 0.295 0.305 0_ 10 _ 0.200 BSC 0.300 BSC 0.015 0.035 MILLIMETERS MIN MAX 18.80 19.30 6.23 6.60 3.69 4.44 0.39 0.53 1.27 1.77 2.54 BSC 1.27 BSC 0.21 0.38 3.05 3.55 7.50 7.74 0_ 10 _ 5.08 BSC 7.62 BSC 0.39 0.88 MOTOROLA ANALOG IC DEVICE DATA MC33363B Motorola reserves the right to make changes without further notice to any products herein. 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MOTOROLA ANALOG IC DEVICE DATA 11 MC33363B Mfax is a trademark of Motorola, Inc. How to reach us: USA / EUROPE / Locations Not Listed: Motorola Literature Distribution; P.O. Box 5405, Denver, Colorado 80217. 1-303-675-2140 or 1-800-441-2447 JAPAN: Motorola Japan Ltd.; SPD, Strategic Planning Office, 141, 4-32-1 Nishi-Gotanda, Shinagawa-ku, Tokyo, Japan. 81-3-5487-8488 Customer Focus Center: 1-800-521-6274 Mfax: RMFAX0@email.sps.mot.com - TOUCHTONE 1-602-244-6609 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; Silicon Harbour Centre, Motorola Fax Back System - US & Canada ONLY 1-800-774-1848 2, Dai King Street, Tai Po Industrial Estate, Tai Po, N.T., Hong Kong. - http://sps.motorola.com/mfax/ 852-26629298 HOME PAGE: http://motorola.com/sps/ 12 MC33363B/D MOTOROLA ANALOG IC DEVICE DATA