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| (R) VB408 / VB408B / VB408FI HIGH VOLTAGE LINEAR REGULATOR POWER I.C. PRELIMINARY DATA TYPE VB408 VB408FI VB408B VIN,OUT 400 V ILIM 40 mA V OUT 1.25 to VIN-30 V 2 3 3 INPUT VOLTAGE UP TO 400 V DC OR 285 V RMS RECTIFIED s OUTPUT VOLTAGE ADJUSTABLE FROM 1.25 TO VIN-30V s OUTPUT CURRENT LIMITED TO 40 mA s THERMAL SHUT-DOWN PROTECTION s SHORT CIRCUIT PROTECTION s 1 TO-220 ISOWATT220 1 2 3 1 DESCRIPTION The VB408, VB408B, VB408FI are fully protected positive adjustable voltage regulators made using a proprietary High Voltage VIPowerTM technology. The device can be connected to a D.C. source (up to 400V) or in off-line application directly to the rectified main (110V/ 230V). It is particularly suitable to be used in the manufacture of DC/DC converters, AC/DC converters, D2PAK ORDER CODES : VB408 TO-220 ISOWATT220 VB408FI D2PAK VB408B start-up circuits, pneumatic valve drivers and current sources. The device is able to drive resistive or inductive loads with an output voltage from 1.25V to VIN-30V providing an internally limited output current; it has built in short circuit and thermal shutdown protections. The device does not provide galvanic insulation from main. BLOCK DIAGRAM VIN Power Stage BIAS CIRCUIT CURRENT SENSE VOUT Current Limitation + _ Thermal RE F 3 REF 2 + _ Protection C ontrol Signal + _ RE F 1 AD J FC00410 September 1999 1/8 1 VB408 / VB408B / VB408FI ABSOLUTE MAXIMUM RATING Symbol Parameter Input to Output Voltage at 20 mA Output current Electrostatic discharge (R=1.5k, C=100pF) Power dissipation at TC=25oC Junction operating temperature Storage temperature TO-220 Value ISOWATT220 - 0.2 to 420 Internally limited 2000 31 - 40 to150 - 55 to 150 D2PAK Unit V mA V W C C VIN,OUT IOUT VESD Ptot Tj TSTG 89 89 THERMAL DATA Symbol Rthj-case Rthj-amb Parameter Thermal resistance junction-case Thermal resistance junction-ambient (MAX) (MAX) TO-220 1.4 60 Value ISOWATT220 4 60 D2PAK 1.4 35 (*) Unit C/W C/W (*) When mounted using the minimum recommended pad size on FR-4 board (1 inch2 ) CONNECTION DIAGRAM (TOP VIEW) 3 2 1 VOUT VIN ADJ 3 2 1 VOUT VIN ADJ TO-220 / ISOWATT220 D2PAK ELECTRICAL CHARACTERISTICS (VIN=300VDC; -25C 1.24 50 1.2 40 135 70 2/8 1 VB408 / VB408B / VB408FI Figure 1: Typical application diagram VIN VIN VOUT ADJ VREF VOUT VB408 C1 R1 C2 R2 FC00420 OPERATION DESCRIPTIO N The VB408, VB408B, VB408FI are positive voltage regulators continuously adjustable from 1.25V to the input voltage minus a dropout of 30V through an external divider. In order to set the proper internal reference voltage, a typical 70A current has to be drawn from the ADJ pin. Considering that, it results: V OUT = VREF (1+R 2/R1) + IADJR 2 To simplify this formula, neglecting IADJ with respect to the term V REF /R1 R 1 must be chosen so to obtain a minimum 1.2mA current flowing through the divider. In such a way the VOUT value will be affected by an error <5%. The current set resistor R 1 should be tied directly to the output terminal of the regulator rather than near the load. This eliminates line drops from appearing in series with the reference and degrading regulation. The output voltage can also be set by a zener diode put between the adjustment pin and ground (Figure 2). The biasing current of the zener is properly chosen by R1 resistor. The zener diode improves the ripple rejection and reduces the value of the worst case output voltage error. In this case the output voltage is given by: V OUT = VREF+VZ In order to reduce excessive output ringing, a minimum output capacitor C 2 of 0.1F is suggested. This capacitor will improve loop stability and output impedance. The VB408/VB408B/VB408FI can be connected both to a DC source or to a 285V r.m.s. line by a rectifier diode that prevents a negative voltage to be applied to the device. In the first case the input capacitor C 1 is not needed, whereas in the second case a high value of C1 (> 1F) must be chosen. In fact, in this kind of application, C1 has to supply to the input pin the minimum allowed voltage during the negative half wave. Obviously bigger C1 value, more constant the input voltage is and consequently smaller the output voltage ripple. For the right choice of the input capacitor, you have also to remember that increasing its value you will obtain an increased power dissipation, and a heatsink could be required. The right heatsink is determined by the load current, input voltage and ambient temperature. In case of pulse or A.C. operation the junction temperature is limited by the thermal capacitances since the package and the heatsink masses are able to absorb heat. If the junction temperature reaches the thermal shutdown limit the output stage of the regulator is turned-off so that only the biasing current of the device can flow into the input pin. Thermal hysteresis is added just to prevent oscillations. The device is able to provide minimum 40 mA for a time that is function of dissipated power and consequently of the used heatsink. In general the device is also suitable in electronically switched motor housekeeping supply, consumer equipments controls power supply or constant current source. APPLICATION EXAMPLE The most common application for the device is in the DC/ DC converters with an input voltage up to 400 VDC and a C2 suggested value of 0,1F. Using an external rectifier an AC/DC converter can be easily implemented, in this case the device can operate with an AC voltage up to 285VRMS. In this case must be used a minimum 1F input capacitor to provide the load current during the negative half cycle of the main. Another important circuit that can be implemented is the start up function for low voltage input PWM ICs directly from a high voltage source (see figure 3). 3/8 1 VB408 / VB408B / VB408FI Figure 2: Regulation with Zener VIN VIN VOUT ADJ Vout R1 C2 VB408 C1 Z1 FC00430 Figure 3: Start-up circuit VOUT VIN VIN ADJ VOUT VB408 R1 C2 PWM C1 R2 FC00470 4/8 VB408 / VB408B / VB408FI TO-220 MECHANICAL DATA mm. DIM. MIN. A C D D1 E F F1 F2 G H2 L2 L4 L5 L6 L7 L9 DIA. 13.0 2.65 15.25 6.2 3.5 3.75 0.49 0.61 1.14 1.14 4.95 10.0 16.4 14.0 2.95 15.75 6.6 3.93 3.85 0.511 0.104 0.600 0.244 0.137 0.147 0.154 0.151 4.40 1.23 2.40 1.27 0.70 0.88 1.70 1.70 5.15 10.40 0.019 0.024 0.044 0.044 0.194 0.393 0.645 0.551 0.116 0.620 0.260 TYP MAX. 4.60 1.32 2.72 MIN. 0.173 0.048 0.094 0.050 0.027 0.034 0.067 0.067 0.203 0.409 TYP. MAX. 0.181 0.051 0.107 inch 5/8 1 1 1 VB408 / VB408B / VB408FI ISOWATT220 MECHANICAL DATA mm. MIN. 4.4 2.5 2.5 0.4 0.75 1.15 1.15 4.95 2.4 10 16 28.6 9.8 15.9 9 3 30.6 10.6 16.4 9.3 3.2 1.126 0.385 0.626 0.354 0.118 TYP MAX. 4.6 2.7 2.75 0.7 1 1.7 1.7 5.2 2.7 10.4 MIN. 0.173 0.098 0.098 0.015 0.030 0.045 0.045 0.195 0.094 0.393 0.630 1.204 0.417 0.645 0.366 0.126 inch TYP. MAX. 0.181 0.106 0.108 0.027 0.039 0.067 0.067 0.204 0.106 0.409 DIM. A B D E F F1 F2 G G1 H L2 L3 L4 L6 L7 A B L3 L6 L7 F1 F D G1 E H F2 123 L2 L4 6/8 G 1 VB408 / VB408B / VB408FI D2PAK MECHANICAL DATA mm. DIM. MIN. A A1 B B2 C C2 D E G L L2 L3 4.30 2.49 0.70 1.25 0.45 1.21 8.95 10 4.88 15 1.27 1.4 TYP MAX. 4.60 2.69 0.93 1.4 0.6 1.36 9.35 10.28 5.28 15.85 1.4 1.75 MIN. 0.169 0.098 0.027 0.049 0.017 0.047 0.352 0.393 0.192 0.590 0.050 0.055 TYP. MAX. 0.181 0.106 0.036 0.055 0.023 0.053 0.368 0.404 0.208 0.625 0.055 0.068 inch D A C A2 DETAIL "A" A1 B2 B G C2 DETAIL "A" E L2 L L3 7/8 VB408 / VB408B / VB408FI Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may results from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics (c) 1999 STMicroelectronics - Printed in ITALY- All Rights Reserved. STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Italy - Japan - Korea - Malaysia - Malta - Mexico - Morocco The Netherlands- Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. http://www.st.com 8/8 1 |
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