The oscillator can be synchronized by an external pulse inserted in series with the timing capacitor (see Figure 7-2). Program the free running frequency of the oscillator to be 10% to 15% slower than the desired synchronous frequency. The pulse width must be greater than 10 ns and less than half the discharge time of the oscillator. Figure 7-3 shows how to synchronize two ICs, with one as primary and one as secondary. Figure 7-4 shows the waveforms in a primary and secondary configuration.

Figure 7-2 General Oscillator Synchronization

Figure 7-3 Two Unit Interface

Figure 7-4 Operational Waveforms