The TPS62850x-Q1 can be externally synchronized by applying an external clock on the MODE/SYNC pin. There is no need for any additional circuitry as long as the input signal meets the requirements given in the electrical specifications. The clock can be applied / removed during operation, allowing you to switch from an externally defined fixed frequency to power-save mode or to internal fixed frequency operation.

The value of the R_CF resistor must be chosen such that the internally defined frequency and the externally applied frequency are close to each other. This ensures a smooth transition from internal to external frequency and vice versa.

Figure 9-58 Schematic using External Synchronization

VIN = 5 V	RCF = 8.06 kΩ	IOUT = 0.1 A
VOUT = 1.8 V	fEXT = 2.5 MHz

Figure 9-59 Switching from External Syncronization to Power-Save Mode (PFM)

VIN = 5 V	RCF = 8.06 kΩ	IOUT = 0.1 A
VOUT = 1.8 V	fEXT = 2.5 MHz

Figure 9-60 Switching from External Synchronizaion to Internal Fixed Frequency