NCP1200AP60G

NCP1200A PWM Current−Mode Controller for Universal Off−Line Supplies Featuring Low Standby Power Housed in SOIC−8 or PDIP−8 package, the NCP1200A enhances the previous NCP1200 series by offering a reduced optocoupler current together with an increased drive capability. Due to its novel concept, the circuit allows the implementation of complete off−line AC−DC adapters, battery charger or a SMPS where standby power is a key parameter. With an internal structure operating at a fixed 40 kHz, 60 kHz or 100 kHz, the controller supplies itself from the high−voltage rail, avoiding the need of an auxiliary winding. This feature naturally eases the designer task in battery charger applications. Finally, current−mode control provides an excellent audio−susceptibility and inherent pulse−by−pulse control. When the current setpoint falls below a given value, e.g. the output power demand diminishes, the IC automatically enters the so−called skip cycle mode and provides excellent efficiency at light loads. Because this occurs at a user adjustable low peak current, no acoustic noise takes place. The NCP1200A features an efficient protective circuitry which, in presence of an overcurrent condition, disables the output pulses while the device enters a safe burst mode, trying to restart. Once the default has gone, the device auto−recovers. Features 8 1 http://onsemi.com MINIATURE PWM CONTROLLER FOR HIGH POWER AC−DC WALL ADAPTERS AND OFFLINE BATTERY CHARGERS MARKING DIAGRAMS 8 8 1 SOIC−8 D SUFFIX CASE 751 1 8 PDIP−8 P SUFFIX CASE 626 1 1200APxxx AWL YYWW 200Ay ALYW • • • • • • • • • • • • Pb−Free Packages are Available No Auxiliary Winding Operation Auto−Recovery Internal Output Short−Circuit Protection Extremely Low No−Load Standby Power Current−Mode Control with Skip−Cycle Capability Internal Temperature Shutdown Internal Leading Edge Blanking 250 mA Peak Current Capability Internally Fixed Frequency at 40 kHz, 60 kHz and 100 kHz Direct Optocoupler Connection SPICE Models Available for TRANsient and AC Analysis Pin to Pin Compatible with NCP1200 xxx = Specific Device Code (40, 60 or 100) y = Specific Device Code (4 for 40, 6 for 60, 1 for 100) A = Assembly Location WL, L = Wafer Lot Y, YY = Year W, WW = Work Week PIN CONNECTIONS Adj 1 FB 2 CS 3 GND 4 (Top View) 8 HV 7 NC 6 VCC 5 Drv Typical Applications • AC−DC Adapters for Portable Devices • Offline Battery Chargers • Auxiliary Power Supplies (USB, Appliances, TVs, etc.) ORDERING INFORMATION See detailed ordering and shipping information in the package dimensions section on page 13 of this data sheet. © Semiconductor Components Industries, LLC, 2004 1 October, 2004− Rev. 5 Publication Order Number: NCP1200A/D NCP1200A * + NCP1200A 1 2 EMI FILTER UNIVERSAL INPUT 3 4 Adj FB CS VCC GND Drv HV 8 7 6 5 + VOUT + *Please refer to the application information section Figure 1. Typical Application Example PIN FUNCTION DESCRIPTION Pin No. 1 Pin Name Adj Function Adjust the skipping peak current Pin Description This pin lets you adjust the level at which the cycle skipping process takes place. Shorting this pin to ground, permanently disables the skip cycle feature. By connecting an optocoupler to this pin, the peak current setpoint is adjusted accordingly to the output power demand. This pin senses the primary current and routes it to the internal comparator via an L.E.B. − The driver’s output to an external MOSFET. This pin is connected to an external bulk capacitor of typically 10 mF. This unconnected pin ensures adequate creepage distance. Connected to the high−voltage rail, this pin injects a constant current into the VCC bulk capacitor. 2 3 4 5 6 7 8 FB CS GND Drv VCC NC HV Sets the peak current setpoint Current sense input The IC ground Driving pulses Supplies the IC − Generates the VCC from the line http://onsemi.com 2 NCP1200A Adj 1 HV CURRENT SOURCE 80 k SKIP CYCLE COMPARATOR INTERNAL VCC 24 k CURRENT SENSE 3 250 ns L.E.B. 40−60−100 kHz CLOCK SET Q FLIP−FLOP DCmax = 80% RESET UVLO HIGH AND LOW INTERNAL REGULATOR HV 8 FB 2 1.2 V + − NC 7 VCC Q 6 20 k GROUND 4 + − VREF 5V 57 k + − Drv 1V OVERLOAD? FAULT DURATION ±250 mA 5 25 k Figure 2. Internal Circuit Architecture MAXIMUM RATINGS Rating Power Supply Voltage Thermal Resistance Junction−to−Air, PDIP−8 Version Thermal Resistance Junction−to−Air, SOIC Version Maximum Junction Temperature Temperature Shutdown Storage Temperature Range ESD Capability, HBM Model (All pins except VCC and HV) ESD Capability, Machine Model Maximum Voltage on Pin 8 (HV), Pin 6 (VCC) Grounded Maximum Voltage on Pin 8 (HV), Pin 6 (VCC) Decoupled to Ground with 10 mF Minimum Operating Voltage on Pin 8 (HV) Symbol VCC RqJA RqJA TJ(max) − − − − − − − Value 16 100 178 150 145 −60 to +150 2.0 200 450 500 40 Unit V °C/W °C/W °C °C °C kV V V V V Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected. http://onsemi.com 3 NCP1200A ELECTRICAL CHARACTERISTICS (For typical values TJ = 25°C, for min/max values TJ = 0°C to +125°C, Max TJ = 150°C, VCC = 11 V unless otherwise noted.) Characteristic Dynamic Self−Supply (All frequency versions, otherwise noted) VCC Increasing Level at which the Current Source Turns−Off VCC Decreasing Level at which the Current Source Turns−On VCC Decreasing Level at which the Latchoff Phase Ends Internal IC Consumption, No Output Load on Pin 5 Internal IC Consumption, 1.0 nF Output Load on Pin 5, FSW = 40 kHz Internal IC Consumption, 1.0 nF Output Load on Pin 5, FSW = 60 kHz Internal IC Consumption, 1.0 nF Output Load on Pin 5, FSW = 100 kHz Internal IC Consumption, Latchoff Phase Internal Startup Current Source (TJ > 0°C, pin 8 biased at 50 V) High−Voltage Current Source, VCC = 10 V High−Voltage Current Source, VCC = 0 Drive Output Output Voltage Rise−Time @ CL = 1.0 nF, 10−90% of Output Signal Output Voltage Fall−Time @ CL = 1.0 nF, 10−90% of Output Signal Source Resistance Sink Resistance Current Comparator (Pin 5 unloaded unless otherwise noted) Input Bias Current @ 1.0 V Input Level on Pin 3 Maximum Internal Current Setpoint (Note 3) Default Internal Current Setpoint for Skip Cycle Operation Propagation Delay from Current Detection to Gate OFF State Leading Edge Blanking Duration (Note 3) Internal Oscillator (VCC = 11 V, pin 5 loaded by 1.0 kW) Oscillation Frequency, 40 kHz Version Built−in Frequency Jittering, fsw = 40 kHz Oscillation Frequency, 60 kHz Version Built−in Frequency Jittering, fsw = 60 kHz Oscillation Frequency, 100 kHz Version Built−in Frequency Jittering, fsw = 100 kHz Maximum Duty Cycle Feedback Section (VCC = 11 V, pin 5 unloaded) Internal Pullup Resistor Pin 3 to Current Setpoint Division Ratio Skip Cycle Generation Default Skip Mode Level Pin 1 Internal Output Impedance 1. Max value at TJ = 0°C. 2. Maximum value @ TJ = 25°C, please see characterization curves. 3. Pin 5 loaded by 1.0 nF. Vskip Zout 1 1 0.95 − 1.2 22 1.45 − V kW Rup Iratio 2 − − − 20 3.3 − − kW − fOSC fjitter fOSC fjitter fOSC fjitter Dmax − − − − − − − 37 − 53 − 90 − 74 43 350 61 460 103 620 83 48 − 68 − 114 − 87 kHz kHz kHz kHz kHz kHz % IIB ILimit ILskip TDEL TLEB 3 3 3 3 3 − 0.8 − − − 0.02 0.9 360 90 250 − 1.0 − 160 − mA V mV ns ns Tr Tf ROH ROL 5 5 5 5 − − 27 5.0 67 25 40 10 − − 61 21 ns ns W W IC1 IC2 8 8 4.0 − 7.0 13 − − mA mA VCC(off) VCC(on) VCC(latch) ICC1 ICC2 ICC2 ICC2 ICC3 6 6 6 6 6 6 6 6 11.2 9.0 − − − − − − 12.1 10 5.4 750 1.2 1.4 1.9 350 13.1 11 − 1000 (Note 1) 1.4 (Note 2) 1.6 (Note 2) 2.2 (Note 2) − V V V mA mA mA mA mA Symbol Pin Min Typ Max Unit http://onsemi.com 4 NCP1200A TYPICAL CHARACTERISTICS 70 60 50 LEAKAGE (mA) 40 30 20 10 0 −25 VCC(off), THRESHOLD (V) 12.5 12.3 12.1 11.9 11.7 11.5 11.3 11.1 −25 0 25 50 75 100 125 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) Figure 3. HV Pin Leakage Current vs. Temperature 10.2 10.1 10.0 ICC1 (mA) 9.9 9.8 9.7 9.6 −25 900 850 800 750 700 Figure 4. VCC(off) vs. Temperature 100 kHz VCC(on), (V) 60 kHz 40 kHz 650 600 −25 0 25 50 75 100 125 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) Figure 5. VCC(on) vs. Temperature Figure 6. ICC1 vs. Temperature 2.10 1.90 1.70 ICC2 (mA) FSW (kHz) 1.50 60 kHz 1.30 40 kHz 1.10 0.90 −25 100 kHz 110 104 98 92 86 80 74 68 62 56 50 44 0 25 50 75 100 125 38 −25 0 25 100 kHz 60 kHz 40 kHz 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) Figure 7. ICC2 vs. Temperature Figure 8. Switching Frequency vs. Temperature http://onsemi.com 5 NCP1200A TYPICAL CHARACTERISTICS 5.50 5.45 VCC LATCHOFF 5.40 ICC3 (mA) 0 25 50 75 100 125 5.35 5.30 5.25 5.20 5.15 −25 490 460 430 400 370 340 310 280 250 220 190 −25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) Figure 9. VCC Latchoff vs. Temperature 60 50 40 Ohm 30 20 Sink 10 0 −25 Source 1.00 Figure 10. ICC3 vs. Temperature CURRENT SETPOINT (V) 50 75 100 125 0.96 0.92 0.88 0.84 0 25 0.80 −25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) Figure 11. Drive and Source Resistance vs. Temperature 1.40 1.35 1.30 VSKIP (V) 1.25 1.20 1.15 1.10 1.05 1.00 −25 0 25 50 75 100 125 DUTY MAX (%) 83 81 79 77 75 87 85 Figure 12. Current Sense Limit vs. Temperature 73 −25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) Figure 13. VSKIP vs. Temperature Figure 14. Max Duty Cycle vs. Temperature http://onsemi.com 6 NCP1200A APPLICATION INFORMATION Introduction The NCP1200A implements a standard current mode architecture where the switch−off time is dictated by the peak current setpoint. This component represents the ideal candidate where low part−count is the key parameter, particularly in low−cost AC−DC adapters, auxiliary supplies, etc. Due to its high−performance High−Voltage technology, the NCP1200A incorporates all the necessary components normally needed in UC384X based supplies: timing components, feedback devices, low−pass filter and self−supply. This later point emphasizes the fact that ON Semiconductor’s NCP1200A does NOT need an auxiliary winding to operate: the product is naturally supplied from the high−voltage rail and delivers a VCC to the IC. This system is called the Dynamic Self−Supply (DSS). Dynamic Self−Supply The DSS principle is based on the charge/discharge of the VCC bulk capacitor from a low level up to a higher level. We can easily describe the current source operation with a bunch of simple logical equations: POWER−ON: IF VCC < VCCH THEN Current Source is ON, no output pulses IF VCC decreasing > VCCL THEN Current Source is OFF, output is pulsing IF VCC increasing < VCCH THEN Current Source is ON, output is pulsing Typical values are: VCCH = 12 V, VCCL = 10 V To better understand the operational principle, Figure 15’s sketch offers the necessary light: Vripple = 2 V VCC UVLOL = 10 V The DSS behavior actually depends on the internal IC consumption and the MOSFET’s gate charge Qg. If we select a MOSFET like the MTP2N60E, Qg max equals 22 nC. With a maximum switching frequency of 68 kHz for the P60 version, the average power necessary to drive the MOSFET (excluding the driver efficiency and neglecting various voltage drops) is: FSW ⋅ Qg ⋅ VCC with FSW = maximum switching frequency Qg = MOSFET’s gate charge VCC = VGS level applied to the gate To obtain the final IC current, simply divide this result by VCC: Idriver = FSW ⋅ Qg = 1.5 mA. The total standby power consumption at no−load will therefore heavily rely on the internal IC consumption plus the above driving current (altered by the driver’s efficiency). Suppose that the IC is supplied from a 350 VDC line. The current flowing through pin 8 is a direct image of the NCP1200A consumption (neglecting the switching losses of the HV current source). If ICC2 equals 2.3 mA @ TJ = 25°C, then the power dissipated (lost) by the IC is simply: 350 x 2.3 m = 805 mW. For design and reliability reasons, it would be interesting to reduce this source of wasted power which increases the die temperature. This can be achieved by using different methods: 1. Use a MOSFET with lower gate charge Qg 2. Connect pin through a diode (1N4007 typically) to one of the mains input. The average value on pin 8 becomes . Our power p contribution example drops to: 223 x 2.3 m = 512 mW. If a resistor is installed between the mains and the diode, you further force the dissipation to migrate from the package to the resistor. The resistor value should account for low−line startups. 3. Permanently force the VCC level above VCCH with an auxiliary winding. It will automatically disconnect the internal startup source and the IC will be fully self−supplied from this winding. Again, the total power drawn from the mains will significantly decrease. Make sure the auxiliary voltage never exceeds the 16 V limit. VMAINS(peak) @ 2 UVLOH = 12 V ON Current Source OFF OUTPUT PULSES 10.0 M 30.0 M 50.0 M 70.0 M 90.0 M Figure 15. The charge/discharge cycle over a 10 mF VCC capacitor http://onsemi.com 7 NCP1200A HV mains Cbulk 1 2 3 4 8 7 6 5 Figure 16. A simple diode naturally reduces the average voltage on pin 8 Skipping Cycle Mode The NCP1200A automatically skips switching cycles when the output power demand drops below a given level. This is accomplished by monitoring the FB pin. In normal operation, pin 2 imposes a peak current accordingly to the load value. If the load demand decreases, the internal loop asks for less peak current. When this setpoint reaches a determined level, the IC prevents the current from decreasing further down and starts to blank the output pulses: the IC enters the so−called skip cycle mode, also named controlled burst operation. The power transfer now depends upon the width of the pulse bunches (Figure 18). Suppose we have the following component values: Lp, primary inductance = 1 mH FSW, switching frequency = 61 kHz Ip skip = 200 mA (or 333 mV/RSENSE) The theoretical power transfer is therefore: 1 @ Lp @ Ip 2 @ F SW + 1.2 W 2 To better understand how this skip cycle mode takes place, a look at the operation mode versus the FB level immediately gives the necessary insight: FB 4.2 V, FB Pin Open NORMAL CURRENT MODE OPERATION 3.2 V, Upper Dynamic Range SKIP CYCLE OPERATION IP(min) = 333 mV/RSENSE 1V Figure 17. If this IC enters skip cycle mode with a bunch length of 20 ms over a recurrent period of 100 ms, then the total power transfer is: 1.2 . 0.2 = 240 mW. When FB is above the skip cycle threshold (1 V by default), the peak current cannot exceed 1 V/RSENSE. When the IC enters the skip cycle mode, the peak current cannot go below Vpin1 / 3.3. The user still has the flexibility to alter this 1 V by either shunting pin 1 to ground through a resistor or raising it through a resistor up to the desired level. Grounding pin 1 permanently invalidates the skip cycle operation. Power P1 Power P2 Power P3 Figure 18. Output Pulses at Various Power Levels (X = 5.0 ms/div) P1 t P2 t P3 http://onsemi.com 8 NCP1200A MAX PEAK CURRENT 300 M 200 M SKIP CYCLE CURRENT LIMIT 100 M 0 315.40 882.70 1.450 M 2.017 M 2.585 M Figure 19. The Skip Cycle Takes Place at Low Peak Currents which Guaranties Noise−Free Operation We recommend a pin 1 operation between 400 mV and 1.3 V that will fix the skip peak current level between 120 mV / RSENSE and 390 mV / RSENSE. Non−Latching Shutdown In some cases, it might be desirable to shut off the part temporarily and authorize its restart once the default has disappeared. This option can easily be accomplished through a single NPN bipolar transistor wired between FB and ground. By pulling FB below the Adj pin 1 level, the output pulses are disabled as long as FB is pulled below pin 1. As soon as FB is relaxed, the IC resumes its operation. Figure 20 depicts the application example: 1 2 ON/OFF Q1 3 4 8 7 6 5 Figure 20. Another Way of Shutting Down the IC without a Definitive Latchoff State http://onsemi.com 9 NCP1200A Power Dissipation The NCP1200A is directly supplied from the DC rail through the internal DSS circuitry. The average current flowing through the DSS is therefore the direct image of the NCP1200A current consumption. The total power dissipation can be evaluated using: (VHVDC − 11 V) ⋅ ICC2. If we operate the device on a 250 VAC rail, the maximum rectified voltage can go up to 350 VDC. However, as the characterization curves show, the current consumption drops at high junction temperature, which quickly occurs due to the DSS operation. At TJ = 50°C, ICC2 = 1.7 mA for the 61 kHz version over a 1 nF capacitive load. As a result, the NCP1200A will dissipate 350 . 1.7 mA@TJ = 50°C = 595 mW. The SOIC−8 package offers a junction−to−ambient thermal resistance RqJA of 178°C/W. Adding some copper area around the PCB footprint will help decreasing this number: 12 mm x 12 mm to drop RqJA down to 100°C/W with 35 m copper thickness (1 oz.) or 6.5 mm x 6.5 mm with 70 m copper thickness (2 oz.). With this later number, we can compute the maximum power dissipation the package accepts at an ambient of 50°C: T T Pmax + Jmax * Amax + 750 mW RqJA which is okay with @ 1.7 m + 380 mW b) put an p dissipation to: auxiliary winding to disable the DSS and decrease the power consumption to VCC x ICC2. The auxiliary level should be thus that the rectified auxiliary voltage permanently stays above 10 V (to not re−activate the DSS) and is safely kept below the 16 V maximum rating. Overload Operation 350 @ 2 our previous budget. For the DIP8 package, adding a min−pad area of 80 mm@ of 35 m copper (1 oz.), RqJA drops from 100°C/W to about 75°C/W. In the above calculations, ICC2 is based on a 1 nF output capacitor. As seen before, ICC2 will depend on your MOSFET’s Qg: ICC2 ≈ ICC1 + FSW x Qg. Final calculation shall thus accounts for the total gate−charge Qg your MOSFET will exhibit. The same methodology can be applied for the 100 kHz version but care must be taken to keep TJ below the 125°C limit with the D100 (SOIC) version and activated DSS in high−line conditions. If the power estimation is beyond the limit, other solutions are possible a) add a series diode with pin 8 (as suggested in the above lines) and connect it to the half rectified wave. As a result, it will drop the average input voltage and lower the In applications where the output current is purposely not controlled (e.g. wall adapters delivering raw DC level), it is interesting to implement a true short−circuit protection. A short−circuit actually forces the output voltage to be at a low level, preventing a bias current to circulate in the optocoupler LED. As a result, the FB pin level is pulled up to 4.2 V, as internally imposed by the IC. The peak current setpoint goes to the maximum and the supply delivers a rather high power with all the associated effects. Please note that this can also happen in case of feedback loss, e.g. a broken optocoupler. To account for this situation, NCP1200A hosts a dedicated overload detection circuitry. Once activated, this circuitry imposes to deliver pulses in a burst manner with a low duty cycle. The system auto−recovers when the fault condition disappears. During the startup phase, the peak current is pushed to the maximum until the output voltage reaches its target and the feedback loop takes over. This period of time depends on normal output load conditions and the maximum peak current allowed by the system. The time−out used by this IC works with the VCC decoupling capacitor: as soon as the VCC decreases from the UVLOH level (typically 12 V) the device internally watches for an overload current situation. If this condition is still present when the UVLOL level is reached, the controller stops the driving pulses, prevents the self−supply current source to restart and puts all the circuitry in standby, consuming as little as 350 mA typical (ICC3 parameter). As a result, the VCC level slowly discharges toward 0. http://onsemi.com 10 NCP1200A VCC REGULATION OCCURS HERE LATCHOFF PHASE 12 V 10 V 5.4 V TIME Drv DRIVER PULSES INTERNAL FAULT FLAG DRIVER PULSES TIME FAULT IS RELAXED TIME STARTUP PHASE FAULT OCCURS HERE Figure 21. If the fault is relaxed during the VCC natural fall down sequence, the IC automatically resumes. If the fault still persists when VCC reached UVLOL, then the controller cuts everything off until recovery. When this level crosses 5.4 V typical, the controller enters a new startup phase by turning the current source on: VCC rises toward 12 V and again delivers output pulses at the UVLOH crossing point. If the fault condition has been removed before UVLOL approaches, then the IC continues its normal operation. Otherwise, a new fault cycle takes place. Figure 21 shows the evolution of the signals in presence of a fault. Calculating the VCC Capacitor in either simulating or measuring in the lab how much time the system takes to reach the regulation at full load. Let’s suppose that this time corresponds to 6 ms. Therefore a VCC fall time of 10 ms could be well appropriated in order to not trigger the overload detection circuitry. If the corresponding IC consumption, including the MOSFET drive, establishes at 1.8 mA for instance, we can calculate the required capacitor using the following formula: , with i DV = 2 V. Then for a wanted Dt of 10 ms, C equals 9 mF or 22 mF for a standard value. When an overload condition occurs, the IC blocks its internal circuitry and its consumption drops to 350 mA typical. This happens at VCC = 10 V and it remains stuck until VCC reaches 5.4 V: we are in latchoff phase. Again, using the calculated 22 mF and 350 mA current consumption, this latchoff phase lasts: 296 ms. Dt + DV @ C As the above section describes, the fall down sequence depends upon the VCC level: how long does it take for the VCC line to go from 12 V to 10 V? The required time depends on the startup sequence of your system, i.e. when you first apply the power to the IC. The corresponding transient fault duration due to the output capacitor charging must be less than the time needed to discharge from 12 V to 10 V, otherwise the supply will not properly start. The test consists http://onsemi.com 11 NCP1200A Protecting the Controller Against Negative Spikes As with any controller built upon a CMOS technology, it is the designer’s duty to avoid the presence of negative spikes on sensitive pins. Negative signals have the bad habit to forward bias the controller substrate and induce erratic behaviors. Sometimes, the injection can be so strong that internal parasitic SCRs are triggered, engendering irremediable damages to the IC if they are a low impedance path is offered between VCC and GND. If the current sense pin is often the seat of such spurious signals, the high−voltage pin can also be the source of problems in certain circumstances. During the turn−off sequence, e.g. when the user unplugs the power supply, the controller is still fed by its VCC capacitor and keeps activating the MOSFET ON and OFF with a peak current limited by Rsense. Unfortunately, if the quality coefficient Q of the resonating network formed by Lp and Cbulk is low (e.g. the MOSFET Rdson + Rsense are small), conditions are met to make the circuit resonate and thus negatively bias the controller. Since we are talking about ms pulses, the amount of injected charge (Q = I x t) immediately latches the controller which brutally discharges its VCC capacitor. If this VCC capacitor is of sufficient value, its stored energy damages the controller. Figure 22 depicts a typical negative shot occurring on the HV pin where the brutal VCC discharge testifies for latchup. Figure 22. A negative spike takes place on the Bulk capacitor at the switch−off sequence Simple and inexpensive cures exist to prevent from internal parasitic SCR activation. One of them consists in inserting a resistor in series with the high−voltage pin to keep the negative current to the lowest when the bulk becomes negative (Figure 23). Please note that the negative spike is clamped to –2 x Vf due to the diode bridge. Please refer to AND8069/D for power dissipation calculations. 3 Rbulk > 4.7 k 2 + Cbulk 1 2 3 4 8 7 6 5 1+ CVCC Another option (Figure 24) consists in wiring a diode from VCC to the bulk capacitor to force VCC to reach UVLOlow sooner and thus stops the switching activity before the bulk capacitor gets deeply discharged. For security reasons, two diodes can be connected in series. 3 + Cbulk 1 2 3 4 8 7 6 5 D3 1N4007 1+ CVCC Figure 23. A simple resistor in series avoids any latchup in the controller Figure 24. or a diode forces VCC to reach UVLOlow sooner http://onsemi.com 12 NCP1200A ORDERING INFORMATION Device NCP1200AP40 NCP1200AP40G NCP1200AD40R2 NCP1200AP60 NCP1200AP60G NCP1200AD60R2 NCP1200AD60R2G NCP1200AP100 NCP1200AP100G NCP1200AD100R2 NCP1200AD100R2G FSW = 100 kHz 100 FSW = 60 kHz 60 FSW = 40 kHz Type Marking 1200AP40 1200AP40 200A4 1200AP60 1200AP60 200A6 200A6 1200AP100 1200AP100 200A1 200A1 Package PDIP−8 PDIP−8 (Pb−Free) SOIC−8 PDIP−8 PDIP−8 (Pb−Free) SOIC−8 SOIC−8 (Pb−Free) PDIP−8 PDIP−8 (Pb−Free) SOIC−8 SOIC−8 (Pb−Free) Shipping† 50 Units / Rail 50 Units / Rail 2500 Units /Reel 50 Units / Rail 50 Units / Rail 2500 Units /Reel 2500 Units /Reel 50 Units / Rail 50 Units / Rail 2500 Units / Reel 2500 Units / Reel †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. http://onsemi.com 13 NCP1200A PACKAGE DIMENSIONS SOIC−8 D SUFFIX CASE 751−07 ISSUE AC −X− A 8 5 B 1 4 S 0.25 (0.010) M Y M −Y− G C −Z− H D 0.25 (0.010) M SEATING PLANE K NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION 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. 6. 751−01 THRU 751−06 ARE OBSOLETE. NEW STANDARD IS 751−07. MILLIMETERS MIN MAX 4.80 5.00 3.80 4.00 1.35 1.75 0.33 0.51 1.27 BSC 0.10 0.25 0.19 0.25 0.40 1.27 0_ 8_ 0.25 0.50 5.80 6.20 INCHES MIN MAX 0.189 0.197 0.150 0.157 0.053 0.069 0.013 0.020 0.050 BSC 0.004 0.010 0.007 0.010 0.016 0.050 0_ 8_ 0.010 0.020 0.228 0.244 N X 45 _ 0.10 (0.004) M J ZY S X S DIM A B C D G H J K M N S SOLDERING FOOTPRINT* 1.52 0.060 7.0 0.275 4.0 0.155 0.6 0.024 1.270 0.050 SCALE 6:1 mm inches *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. http://onsemi.com 14 NCP1200A PACKAGE DIMENSIONS PDIP−8 P SUFFIX CASE 626−05 ISSUE L 8 5 −B− 1 4 NOTES: 1. DIMENSION L TO CENTER OF LEAD WHEN FORMED PARALLEL. 2. PACKAGE CONTOUR OPTIONAL (ROUND OR SQUARE CORNERS). 3. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. DIM A B C D F G H J K L M N MILLIMETERS MIN MAX 9.40 10.16 6.10 6.60 3.94 4.45 0.38 0.51 1.02 1.78 2.54 BSC 0.76 1.27 0.20 0.30 2.92 3.43 7.62 BSC −−− 10_ 0.76 1.01 INCHES MIN MAX 0.370 0.400 0.240 0.260 0.155 0.175 0.015 0.020 0.040 0.070 0.100 BSC 0.030 0.050 0.008 0.012 0.115 0.135 0.300 BSC −−− 10_ 0.030 0.040 F NOTE 2 −A− L C −T− SEATING PLANE J N D K M M TA M H G 0.13 (0.005) B M http://onsemi.com 15 NCP1200A The product described herein (NCP1200A), may be covered by the following U.S. patents: 6,271,735, 6,362,067, 6,385,060, 6,429,709, 6,587,357. There may be other patents pending. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC 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 special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC 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. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC 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 SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. 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