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Moteur de recherche de fiches techniques de composants électroniques |
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Moteur de recherche de fiches techniques de composants électroniques |
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TC7662B Fiches technique(PDF) 6 Page - TelCom Semiconductor, Inc |
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TC7662B Fiches technique(HTML) 6 Page - TelCom Semiconductor, Inc |
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6 / 9 page  4-88 TELCOM SEMICONDUCTOR, INC. TC7662B CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER 1 2 3 4 8 7 6 5 + V + VOUT C1 COSC + C2 TC7662B Figure 8. Lowering Oscillator Frequency Positive Voltage Doubling The TC7662B may be employed to achieve positive voltage doubling using the circuit shown in Figure 9. In this application, the pump inverter switches of the TC7662B are used to charge C1 to a voltage level of V + – V F (where V + is the supply voltage and VF is the forward voltage on C1 plus the supply voltage (V +) applied through diode D 2 to capacitor C2). The voltage thus created on C2 becomes (2 V +) – (2 V F), or twice the supply voltage minus the combined forward voltage drops of diodes D1 and D2. The source impedance of the output (VOUT) will depend on the output current, but for V + = 5V and an output current of 10 mA, it will be approximately 60 Ω. Combined Negative Voltage Conversion and Positive Supply Multiplication Figure 10 combines the functions shown in Figures 3 and 9 to provide negative voltage conversion and positive voltage doubling simultaneously. This approach would be, for example, suitable for generating +9V and –5V from an existing +5V supply. In this instance, capacitors C1 and C3 perform the pump and reservoir functions, respectively, for the generation of the negative voltage, while capacitors C2 and C4 are pump and reservoir, respectively, for the doubled positive voltage. There is a penalty in this configuration which combines both functions, however, in that the source impedances of the generated supplies will be somewhat higher due to the finite impedance of the common charge pump driver at pin 2 of the device. 1 2 3 4 8 7 6 5 + V + VOUT = (2 V +) – (2 VF) C1 D1 + + C3 C4 VOUT = –(V+–VF) C2 TC7662B D2 + Figure 10. Combined Negative Converter and Positive Doubler Figure 9. Positive Voltage Multiplier Voltage Splitting The bidirectional characteristics can also be used to split a higher supply in half, as shown in Figure 11. The combined load will be evenly shared between the two sides and a high value resistor to the LV pin ensures start-up. Because the switches share the load in parallel, the output impedance is much lower than in the standard circuits, and higher currents can be drawn from the device. By using this circuit, and then the circuit of Figure 6, +15V can be converted (via +7.5V and –7.5V) to a nominal –15V, though with rather high series resistance (~250 Ω). 1 2 3 4 8 7 6 5 V+ VOUT = (2 V+) – (2 VF) + C2 D1 D2 + C1 TC7662B + RL1 RL2 VOUT = V + –V – 2 50 µF 50 µF V + V – 50 µF + 1 2 8 7 TC7662B 3 4 6 5 - - + - Figure 11. Splitting a Supply in Half |
Numéro de pièce similaire - TC7662B |
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Description similaire - TC7662B |
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