HCNW 4504 PDF

The LED ycnw to turn on Q2 should be delayed enough so that an optocoupler with the very fastest turn-on propagation delay tPHLmin will never turn on before an optocoupler with the very slowest turn-off propagation delay tPLHmax turns off. Pins 1, 2, 3, and 4 shorted together and Pins 5, 6, 7, and 8 shorted together. For creepage, the shortest distance path along the surface of a printed circuit board between the solder fillets of the input and output leads must be considered. F bypass capacitor between pins 5 and 8 is recommended.

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Fekree Most inverters are designed such that the power transistor turns on when the optocoupler turns on; this ensures that both power transistors will be off in the event of a power loss in the control circuit. Inverters can also be designed such that the power transistor turns off when the optocoupler LED turns on; this type of design, however, requires additional fail-safe circuitry to turn off the power transistor if an over-current condition is detected.

To ensure this, the turn-on of the optocoupler should be delayed by an amount no less than tPLHmax — tPHLminwhich also happens to be the maximum data sheet value for the propagation delay difference specification, tPLH — tPHL.

These dimensions are needed as a starting point for the equipment designer when determining the circuit insulation requirements.

Separate connections for the photodiode bias and outputtransistor collector increase the speed up to a hundred times that of a conventional phototransistor coupler by reducing the base collector capacitance. Propagation Delay Time vs. When inverter power transistors switch Q1 and Q2 in Figure 17it is essential that they never conduct at the same time. Use of nonchlorine activated fluxes is highly recommended.

See Option data sheet for more information. Creepage and clearance distances will also change depending on factors such as pollution degree and insulation hvnw. Extremely large currents will flow if there is any overlap in their conduction during switching transitions, potentially damaging the transistors and even the surrounding circuitry. For creepage, the shortest distance path along the surface of a printed circuit board between the solder fillets of the input and output leads must be considered.

Maintenance of the safety data shall be ensured by means of protective circuits. The difference between the maximum and minimum values depends directly on the total spread in propagation hdnw and sets the limit on how good the worst-case dead time can be for a given design. Therefore, optocouplers with tight propagation delay specifications and hcnd just shorter delays or lower pulse-width distortion can achieve short dead times in power inverters. The LED is optically coupled to an integrated high gain photo detector.

The LED signal to on Q2 should be delayed enough so that an optocoupler with the very fastest turn-on propagation delay tPHLmin will never turn on before an optocoupler with the very slowest turn-off propagation delay tPLHmax turns off. The timing illustrated in Figure 17 assumes that the power transistor turns on when the optocoupler LED turns on. The Input-Output Momentary Withstand Voltage is a dielectric voltage rating that should not be interpreted as an input-output continuous voltage rating.

Use of a 0. Calculating the maximum dead time is slightly more complicated. Device considered a two-terminal device: Under TTL load and drive conditions: An hcna layer between a LED and an integrated photodetector provide electrical insulation between input and output.

For technical assistance call: There are recommended techniques such as grooves and ribs which may be used on a printed circuit board to achieve desired creepage and hcmw. Current Transfer Ratio vs. Minimizing this dead time is an important design goal for an inverter designer. However, once mounted on a printed circuit board, minimum creepage and clearance requirements must be met as specified for individual equipment standards. Contact Agilent sales representative or authorized distributor for information.

F bypass capacitor connected between Pins 5 and 8 is recommended. Logic High Output Current vs. Although tPLH-tPHL max tells the designer how much delay is needed to ncnw shoot-through current, it is insufficient to tell the designer how much dead time a design will have. Pins 1, 2, 3, and 4 shorted together and Pins 5, 6, 7, and 8 shorted together. Related Articles.

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HCNW 4504 PDF

Fekree Most inverters are designed such that the power transistor turns on when the optocoupler turns on; this ensures that both power transistors will be off in the event of a power loss in the control circuit. Inverters can also be designed such that the power transistor turns off when the optocoupler LED turns on; this type of design, however, requires additional fail-safe circuitry to turn off the power transistor if an over-current condition is detected. To ensure this, the turn-on of the optocoupler should be delayed by an amount no less than tPLHmax — tPHLminwhich also happens to be the maximum data sheet value for the propagation delay difference specification, tPLH — tPHL. These dimensions are needed as a starting point for the equipment designer when determining the circuit insulation requirements. Separate connections for the photodiode bias and outputtransistor collector increase the speed up to a hundred times that of a conventional phototransistor coupler by reducing the base collector capacitance. Propagation Delay Time vs.

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Samumuro Calculating the maximum dead time is slightly more complicated. The LED signal to turn on Q2 should be delayed enough so that an optocoupler with the very fastest turn-on propagation delay tPHLmin will never turn on before an optocoupler with the very slowest turn-off propagation delay tPLHmax turns off. The difference between the maximum and minimum values depends directly on the total hvnw in propagation delays and sets the limit on how good the worst-case dead time can be for a given design. Therefore, optocouplers with tight propagation delay specifications and not just shorter delays or lower pulse-width distortion can achieve short dead times in power inverters.

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