VIPER12ADIP-E

VIPER12A-E Low power offline switched-mode power supply primary switcher Features ■ Fixed 60 kHz switching frequency ■ 9 V to 38 V wide range VDD voltage ■ Current mode control ■ Auxiliary undervoltage lockout with hysteresis ■ High voltage start-up current source ■ Overtemperature, overcurrent and overvoltage protection with auto-restart ■ Typical power capability – European (195 - 265 Vac) 8 W for SO-8, 13 W for DIP-8 – European (85 - 265 Vac) 5 W for SO-8, 8 W for DIP-8 SO-8 Typical applications cover off line power supplies for battery charger adapters, standby power supplies for TV or monitors, auxiliary supplies for motor control, etc. The internal control circuit offers the following benefits: Large input voltage range on the VDD pin accommodates changes in auxiliary supply voltage (This feature is well adapted to battery charger adapter configurations), automatic burst mode in low load condition and overvoltage protection in HICCUP mode. Description The VIPER12A combines a dedicated current mode PWM controller with a high voltage power MOSFET on the same silicon chip. Figure 1. DIP-8 Block diagram DRAIN ON/OFF 60kHz OSCILLATOR REGULATOR INTERNAL SUPPLY OVERTEMP. DETECTOR R1 S FF PWM LATCH Q R2 R3 R4 _ VDD 8/14.5V + BLANKING + + 42V _ S R FF _ 0.23 V OVERVOLTAGE LATCH 230 Ω Q 1 kΩ FB SOURCE December 2010 Doc ID 11977 Rev 2 1/21 www.st.com 21 Contents VIPER12A-E Contents 1 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Pin connections and function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4 Rectangular U-I output characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5 Wide range of VDD voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6 Feedback pin principle of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7 Startup sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8 Overvoltage threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 9 Operation pictures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 10 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 11 Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 12 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2/21 Doc ID 11977 Rev 2 VIPER12A-E Electrical data 1 Electrical data 1.1 Maximum rating Stressing the device above the rating listed in the “absolute maximum ratings” table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the Operating sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 1. Absolute maximum rating Symbol VDS(sw) VDS(st) ID Parameter Unit -0.3 ... 730 V -0.3 ... 400 V Internally limited A 0 ... 50 V 3 mA 200 1.5 V kV Internally limited °C Switching drain source voltage (TJ = 25 ... 125 °C) (1) Start-up drain source voltage (TJ = 25 ... 125 °C) (2) Continuous drain current VDD Supply voltage IFB Feedback current VESD Value Electrostatic discharge: Machine model (R = 0 Ω; C = 200 pF) Charged device model TJ Junction operating temperature TC Case operating temperature -40 to 150 °C Tstg Storage temperature -55 to 150 °C 1. This parameter applies when the start-up current source is OFF. This is the case when the VDD voltage has reached VDDon and remains above VDDoff. 2. This parameter applies when the start up current source is ON. This is the case when the VDD voltage has not yet reached VDDon or has fallen below VDDoff. 1.2 Thermal data Table 2. Symbol Thermal data Parameter SO-8 DIP-8 Unit RthJC Thermal resistance junction-case Max 25 15 °C/W RthJA Thermal resistance ambient-case (1) Max 55 45 °C/W 1. When mounted on a standard single-sided FR4 board with 200 mm2 of Cu (at least 35 µm thick) connected to all DRAIN pins. Doc ID 11977 Rev 2 3/21 Electrical characteristics 2 VIPER12A-E Electrical characteristics TJ = 25 °C, VDD = 18 V, unless otherwise specified Table 3. Power section Symbol Parameter BVDSS Drain-source voltage ID = 1 mA; VFB = 2 V OFF State drain current VDS = 500 V; VFB = 2 V; TJ = 125 °C Static drain-source ON state resistance ID = 0.2 A ID = 0.2 A; IDSS rDS(on) Test conditions Min Typ Max 730 Unit V 0.1 27 ID = 0.2 A ID = 0.2 A; TJ = 100 °C 30 mA Ω 54 tf Fall time ID = 0.1 A; VIN = 300 V (1) (See Figure 9 on page 13) 100 ns tr Rise time ID = 0.2 A; VIN = 300 V (1) (See Figure 9 on page 13) 50 ns Drain capacitance VDS = 25 V 40 pF COSS 1. On clamped inductive load Table 4. Symbol Supply section Parameter Test conditions Min Typ Max IDDch Start-up charging current 100 V ≤ VDS ≤ 400 V; VDD = 0 V ...VDDon (See Figure 10 on page 13) IDDoff Start-up charging current in thermal shutdown VDD = 5 V; VDS = 100 V TJ > TSD - THYST IDD0 Operating supply current not switching IFB = 2 mA IDD1 Operating supply current switching IFB = 0.5 mA; ID = 50 mA (1) 4.5 mA DRST Restart duty-cycle (See Figure 11 on page 13) 16 % VDDoff VDD undervoltage shutdown threshold (See Figure 10, Figure 11 on page 13) 7 8 9 V VDDon VDD start-up threshold (See Figure 10, Figure 11 on page 13)) 13 14.5 16 V VDDhyst VDD threshold hysteresis (See Figure 10 on page 13) 5.8 6.5 7.2 V VDDovp VDD overvoltage threshold 38 42 46 V -1 mA 0 mA 3 5 1. These test conditions obtained with a resistive load are leading to the maximum conduction time of the device. 4/21 Unit Doc ID 11977 Rev 2 mA VIPER12A-E Electrical characteristics Table 5. Symbol FOSC Table 6. Symbol Oscillation section Parameter Oscillator frequency total variation Test conditions VDD = VDDoff ... 35 V; TJ = 0 ... 100 °C Min Typ Max Unit 54 60 66 kHz Min Typ Max Unit 0.48 A PWM comparator section Parameter Test conditions GID IFB to ID current gain (See Figure 12 on page 14) IDlim Peak current limitation VFB = 0 V (See Figure 12 on page 14) IFBsd IFB shutdown current (See Figure 12 on page 14) 0.9 mA RFB FB pin input impedance ID = 0 mA (See Figure 12 on page 14) 1.2 kΩ td Current sense delay to turn-OFF ID = 0.2 A 200 ns tb Blanking time 500 ns Minimum Turn-ON time 700 ns tONmin Table 7. Symbol 0.32 0.4 Overtemperature section Parameter Test conditions TSD Thermal shutdown temperature (See Figure 13 on page 14) THYST Thermal shutdown hysteresis (See Figure 13 on page 14) Table 8. 320 Min Typ Max Unit 140 170 °C 40 °C Typical power capability Mains type SO-8 DIP-8 European (195 - 265 Vac) 8W 13W US / Wide range (85 - 265 Vac) 5W 8W Doc ID 11977 Rev 2 5/21 Pin connections and function 3 VIPER12A-E Pin connections and function Figure 2. Pin connection SOURCE 1 8 DRAIN SOURCE 1 8 DRAIN SOURCE 2 7 DRAIN SOURCE 2 7 DRAIN FB 3 6 DRAIN FB 3 6 DRAIN VDD 4 5 DRAIN VDD 4 5 DRAIN SO-8 Figure 3. DIP-8 Current and voltage conventions I DD ID VDD I FB FB VDD VFB Table 9. CONTROL VD SOURCE VIPer12A Pin function Pin Name Pin Function VDD Power supply of the control circuits. Also provides a charging current during start up thanks to a high voltage current source connected to the drain. For this purpose, an hysteresis comparator monitors the VDD voltage and provides two thresholds: - VDDon: Voltage value (typically 14.5 V) at which the device starts switching and turns off the start up current source. - VDDoff: Voltage value (typically 8 V) at which the device stops switching and turns on the start up current source. SOURCE 6/21 DRAIN Power MOSFET source and circuit ground reference. DRAIN Power MOSFET drain. Also used by the internal high voltage current source during start up phase for charging the external VDD capacitor. FB Feedback input. The useful voltage range extends from 0 V to 1 V, and defines the peak drain MOSFET current. The current limitation, which corresponds to the maximum drain current, is obtained for a FB pin shorted to the SOURCE pin. Doc ID 11977 Rev 2 VIPER12A-E 4 Rectangular U-I output characteristics Rectangular U-I output characteristics Figure 4. Rectangular U-I output characteristics for battery charger A complete regulation scheme can achieve combined and accurate output characteristics. Figure 4. presents a secondary feedback through an optocoupler driven by a TSM101. This device offers two operational amplifiers and a voltage reference, thus allowing the regulation of both output voltage and current. An integrated OR function performs the combination of the two resulting error signals, leading to a dual voltage and current limitation, known as a rectangular output characteristic. This type of power supply is especially useful for battery chargers where the output is mainly used in current mode, in order to deliver a defined charging rate. The accurate voltage regulation is also convenient for Li-ion batteries which require both modes of operation. Doc ID 11977 Rev 2 7/21 Wide range of VDD voltage 5 VIPER12A-E Wide range of VDD voltage The VDD pin voltage range extends from 9 V to 38 V. This feature offers a great flexibility in design to achieve various behaviors. In Figure 4 on page 7 a forward configuration has been chosen to supply the device with two benefits: 8/21 ● As soon as the device starts switching, it immediately receives some energy from the auxiliary winding. C5 can be therefore reduced and a small ceramic chip (100 nF) is sufficient to insure the filtering function. The total start up time from the switch on of input voltage to output voltage presence is dramatically decreased. ● The output current characteristic can be maintained even with very low or zero output voltage. Since the TSM101 is also supplied in forward mode, it keeps the current regulation up whatever the output voltage is.The VDD pin voltage may vary as much as the input voltage, that is to say with a ratio of about 4 for a wide range application. Doc ID 11977 Rev 2 VIPER12A-E 6 Feedback pin principle of operation Feedback pin principle of operation A feedback pin controls the operation of the device. Unlike conventional PWM control circuits which use a voltage input (the inverted input of an operational amplifier), the FB pin is sensitive to current. Figure 5. presents the internal current mode structure. Figure 5. Internal current control structure The power MOSFET delivers a sense current Is which is proportional to the main current Id. R2 receives this current and the current coming from the FB pin. The voltage across R2 is then compared to a fixed reference voltage of about 0.23 V. The MOSFET is switched off when the following equation is reached: R 2 ⋅ ( I S + I FB ) = 0.23V By extracting IS: 0.23V I S = ---------------- – I FB R2 Using the current sense ratio of the MOSFET GID: I D = G ID ⋅ I S = G ID ⋅ ⎛ 0.23V ---------------- – I FB⎞ ⎝ R ⎠ 2 Doc ID 11977 Rev 2 9/21 Feedback pin principle of operation VIPER12A-E The current limitation is obtained with the FB pin shorted to ground (VFB = 0 V). This leads to a negative current sourced by this pin, and expressed by: I FB = – 0.23V ---------------R1 By reporting this expression in the previous one, it is possible to obtain the drain current limitation IDlim: 1 1 I Dlim = G ID ⋅ 0.23V ⋅ ⎛⎝ ------- + -------⎞⎠ R2 R1 In a real application, the FB pin is driven with an optocoupler as shown on Figure 5 which acts as a pull up. So, it is not possible to really short this pin to ground and the above drain current value is not achievable. Nevertheless, the capacitor C is averaging the voltage on the FB pin, and when the optocoupler is off (start up or short circuit), it can be assumed that the corresponding voltage is very close to 0 V. For low drain currents, the formula (1) is valid as long as IFB satisfies IFB < IFBsd, where IFBsd is an internal threshold of the VIPER12A. If IFB exceeds this threshold the device will stop switching. This is represented on Figure 12 on page 14, and IFBsd value is specified in the PWM COMPARATOR SECTION. Actually, as soon as the drain current is about 12 % of Idlim, that is to say 50 mA, the device will enter a burst mode operation by missing switching cycles. This is especially important when the converter is lightly loaded. Figure 6. IFB transfer function It is then possible to build the total DC transfer function between ID and IFB as shown on Figure 6 on page 10. This figure also takes into account the internal blanking time and its associated minimum turn on time. This imposes a minimum drain current under which the device is no more able to control it in a linear way. This drain current depends on the primary inductance value of the transformer and the input voltage. Two cases may occur, depending on the value of this current versus the fixed 50 mA value, as described above. 10/21 Doc ID 11977 Rev 2 VIPER12A-E 7 Startup sequence Startup sequence Figure 7. Startup sequence This device includes a high voltage start up current source connected on the drain of the device. As soon as a voltage is applied on the input of the converter, this start up current source is activated as long as VDD is lower than VDDon. When reaching VDDon, the start up current source is switched off and the device begins to operate by turning on and off its main power MOSFET. As the FB pin does not receive any current from the optocoupler, the device operates at full current capacity and the output voltage rises until reaching the regulation point where the secondary loop begins to send a current in the optocoupler. At this point, the converter enters a regulated operation where the FB pin receives the amount of current needed to deliver the right power on secondary side. This sequence is shown in Figure 7. Note that during the real starting phase tss, the device consumes some energy from the VDD capacitor, waiting for the auxiliary winding to provide a continuous supply. If the value of this capacitor is too low, the start up phase is terminated before receiving any energy from the auxiliary winding and the converter never starts up. This is illustrated also in the same figure in dashed lines. Doc ID 11977 Rev 2 11/21 Overvoltage threshold 8 VIPER12A-E Overvoltage threshold An overvoltage detector on the VDD pin allows the VIPER12A to reset itself when VDD exceeds VDDovp. This is illustrated in Figure 8., which shows the whole sequence of an overvoltage event. Note that this event is only latched for the time needed by VDD to reach VDDoff, and then the device resumes normal operation automatically. Figure 8. Overvoltage sequence VDD VDDovp VDDon VDDoff t VDS t 12/21 Doc ID 11977 Rev 2 VIPER12A-E 9 Operation pictures Operation pictures Figure 9. Rise and fall time Figure 10. Start-up VDD current IDD IDD0 VDDhyst VDDoff IDDch VDD VDDon VDS = 100 V Fsw = 0 kHz Figure 11. Restart duty-cycle Doc ID 11977 Rev 2 13/21 Operation pictures VIPER12A-E Figure 12. Peak drain current vs feedback current Figure 13. Thermal shutdown 14/21 Doc ID 11977 Rev 2 VIPER12A-E Operation pictures Figure 14. Switching frequency vs temperature Figure 15. Current limitation vs temperature Doc ID 11977 Rev 2 15/21 Package mechanical data 10 VIPER12A-E Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK is an ST trademark. 16/21 Doc ID 11977 Rev 2 VIPER12A-E Package mechanical data Table 10. DIP8 mechanical data Databook (mm) Ref. Min. Nom. A Max. 5.33 A1 0.38 A2 2.92 3.30 4.95 b 0.36 0.46 0.56 b2 1.14 1.52 1.78 c 0.20 0.25 0.36 D 9.02 9.27 10.16 E 7.62 7.87 8.26 E1 6.10 6.35 7.11 e 2.54 eA 7.62 eB L 10.92 2.92 Package Weight 3.30 3.81 Gr. 470 Figure 16. Package dimensions Doc ID 11977 Rev 2 17/21 Package mechanical data Table 11. VIPER12A-E SO8 mechanical data Databook (mm) Dim. Nom Max A 1.35 1.75 A1 0.10 0.25 A2 1.10 1.65 B 0.33 0.51 C 0.19 0.25 D 4.80 5.00 E 3.80 4.00 e 1.27 H 5.80 6.20 h 0.25 0.50 L 0.40 1.27 k 8° (max.) ddd 0.1 Figure 17. Package dimensions 18/21 Min Doc ID 11977 Rev 2 VIPER12A-E 11 Order codes Order codes Table 12. Order codes Order codes Package Packaging VIPER12ASTR-E SO-8 Tape and reel VIPER12AS-E SO-8 Tube VIPER12ADIP-E DIP-8 Tube Doc ID 11977 Rev 2 19/21 Revision history 12 VIPER12A-E Revision history Table 13. 20/21 Document revision history Date Revision Changes 09-Jan-2006 1 Initial release. 13-Dec-2010 2 Updated Table 3 on page 4, Table 4 on page 4 and Figure 10 on page 13. Doc ID 11977 Rev 2 VIPER12A-E Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. 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