CD4045B is a timing circuit consisting of 21 counter stages, two output-shaping flip-flops, two inverter output drivers, and input inverters for use in a crystal oscillator. The CD4045B configuration provides 21 flip-flop counting stages, and two flip-flops for shaping the output waveform for a 3.125% duty cycle. Push-pull operation is provided by the inverter output drivers.
The first inverter is intended for use as a crystal oscillator/amplifier. However, it may be used as a normal logic inverter if desired. A crystal oscillator circuit can be made less sensitive to voltage-supply variations by the user of source resistors. In this device, the sources of the p and n transistors have been brought out to package terminals. If external resistors are not required, the sources must be shorted to their respective substrates (Sp to VDD, Sn to VSS). See Fig. 1. The first inverter in conjunction with an outboard inverter, such as 1/6 CD4069, and RX, CX, and RS can also be used to construct an RC oscillator. The following data is supplied as a guide in the selection of values for RX, RS, and CX used in Fig. 11:
- RX max = 10 M and CX = 50 pF
- CX max = 25 µF with RS = 560 k
The CD4045B types are supplied in 16-lead dual-in-line plastic packages (E suffix), 16-lead small-outline package (NSR suffix), and 16-lead thin shrink small-outline packages (PW and PWR suffixes).
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