74LS629 Voltage Controlled Oscillators IC (74629) DIP-16 Package

These voltage-controlled oscillators (VCOs) are Improved versions of the original VCO family: SN54LS124, SN54LS324 thru SN54LS327, SN74LS124, and SN74LS324 thru SN74LS327. These new devices feature improved voltage-to frequency linearity, range, and compensation. With the exception of the “LS624 and LS628, all of these devices feature two independent VCOs in a single monolithic chip. The ‘LS624, ‘LS625, LS626, and LS628 have complementary Z outputs. The output frequency for each VCO is established by a single external component (either a capacitor or crystal) in combination with voltage-sensitive inputs used for frequency control and frequency range. Each device has a voltage-sensitive input for frequency control; however, the ‘LS624, ‘LS628, and ‘LS629 devices also have one for frequency range. (See Figures 1 thru 6).

The LS628 offers more precise temperature compensation than its ‘LS624 counterpart. The LS624 features a 600 ohm internal timing resistor. The ‘LS628 requires a timing resistor to be connected externally across Rext pins. Temperature compensation will be improved dur to the temperature coefficient of the external resistor.

Figure 3 and Figure 6 contain the necessary information to choose the proper capacitor value to obtain the desired operating frequency.