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KA3524 データシート(PDF) 4 Page - Fairchild Semiconductor |
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KA3524 データシート(HTML) 4 Page - Fairchild Semiconductor |
4 / 12 page KA3524 4 Application Information Voltage Reference An internal series regulator provides a nominal 5 volt output which is used both to generate a reference voltage and is the regulated source for all the internal timing and controlling circuitry. This regulator may be bypassed for operation from a fixed 5 volt supply by connecting pins 15 and 16 together to the input voltage. In this configuration, the maximum input voltage is 6.0 volts. This reference regulator may be used as a 5 volt source for other circuitry. It will provide up to 50mA of current itself and can easily be expanded to higher current with an external PNP as shown in Figure 2. Expanded Reference Current Capability Oscillator The oscillator in the KA3524 uses an external resistor (RT) to establish a constant charging current into an external capacitor (CT), While this uses more current than a series connected PC, it provides a linear ramp voltage on the capacitor which is also used as a reference for the comparator. The charging current is equal to 3.6V/RT and should be kept within the range of approximately 30uA to 2mA, i.e., 1.8K< RT <100K. The range of values for CT also has limits as the discharge time of Ct determines the pulse width of the oscillator output pulse. This pulse is used (among other things) as a blanking pulse to both outputs to insure that there is no possibility of having both outputs on simultaneously during transitions. This output dead time relationship is shown in Figures. A pulse width below approximately 0.5 microseconds may allow false triggering of one out- put by removing he blanking pulse prior to the flip-flops reaching a stable state. If small values of CT must be used, the pulse width may still be expanded by adding a shunt capacitance (= 100pF) to ground at the oscillator output. (Note: Although the oscillator output is a convenient oscilloscope sync input, the cable and input capacitance may increase the blanking pulse width slightly.) Obviously, the upper limit of the pulse width is determined by the maximum duty cycle acceptable. Practical values of CT fall between 0.01 and0.1 micro farad. The oscillator period is approximately t = RTCT where t is in microsec- onds when RT ohms and CT = micro farads. The selection of RT and CT can be made for a wide range of operating frequen- cies by using Fig. 7. Note that for sense regulator applications, the two outputs can be connected in parallel for an effective 0- 90% duty cycle and the frequency of the oscillator is the frequency of the output. For push-pull applications, the outputs are separated and the flip-flop divides the frequency such that each output duty cycle is 0-45% and the overall frequency is one- half that of the oscillator. External Synchronization If It is desired to synchronize the KA3524 to an external clock, a pulse of +3 volts may be applied to the oscillator output terminal with RTCT set slightly greater than the clock period. The same considerations of pulse width apply. The impedance to ground at this point is approximately 2K ohms. If two or more KA3524s must be synchronized together, one must be desig- nated as the master with its RTCT set for the correct period. The slaves should each have an RTCT set for an approximately 10% longer period than the master with the added requirement that CT (slave) = one-half CT (master). Then connecting Pin 3 on all units together will insure that the master output pulse-which occurs first and has a wider pulse width - will reset the slave units. |
同様の部品番号 - KA3524 |
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同様の説明 - KA3524 |
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