The TPS62851x has two operating modes: forced PWM mode, which is discussed in this section, and PWM/PFM as discussed in Section 9.4.2.
With the MODE/SYNC pin set to high, the TPS62851x operates with pulse width modulation in continuous conduction mode (CCM). The switching frequency is 2.25 MHz or defined by an external clock signal applied to the MODE/SYNC pin. With an external clock applied to MODE/SYNC, the TPS62851x follows the frequency applied to the pin. In general, the frequency range in forced PWM mode is 1.8 MHz to 4 MHz. However, the frequency needs to be in a range the TPS62851x can operate at, taking the minimum on-time into account.