ZHCSJK9H June 2001 – October 2015 TPS54610
PRODUCTION DATA.
The oscillator frequency can be set to internally fixed values of 350 kHz or 550 kHz using the SYNC pin as a static digital input. If a different frequency of operation is required for the application, the oscillator frequency can be externally adjusted from 280 to 700 kHz by connecting a resistor between the RT pin and AGND and floating the SYNC pin. The switching frequency is approximated by the following equation, where R is the resistance from RT to AGND:
External synchronization of the PWM ramp is possible over the frequency range of 330 kHz to 700 kHz by driving a synchronization signal into SYNC and connecting a resistor from RT to AGND. Choose a resistor between the RT and AGND which sets the free running frequency to 80% of the synchronization signal. Table 1 summarizes the frequency selection configurations:
SWITCHING FREQUENCY | SYNC PIN | RT PIN |
---|---|---|
350 kHz, internally set | Float or AGND | Float |
550 kHz, internally set | ≥ 2.5 V | Float |
Externally set 280 kHz to 700 kHz | Float | R = 180 kΩ to 68 kΩ |
Externally synchronized frequency | Synchronization signal | R = RT value for 80% of external synchronization frequency |