The synchronization pin (pin 5) can be configured as external clock signal used to set the switching frequency between 200 kHz to 1 MHz. When not used, this pin should be tied to AGND as shown in the Section 8.2.

When using as an external clock signal to set switching frequency, a resistor must be connected from the FREQ pin to ground and the external clock frequency must be within ±20% of the corresponding frequency set by the resistor. A typical example of this operation is shown in Figure 9-1. The required levels for the external clock are shown in Table 9-1. The recommended duty cycle of the clock is in the range of 10% to 90%.