SNVSBK9D November 2019 – September 2022 LM63635-Q1
The choice of switching frequency is a compromise
between conversion efficiency and overall solution size. Lower switching frequency
implies reduced switching losses and usually results in higher system efficiency.
However, higher switching frequency allows the use of smaller inductors and output
capacitors, and hence, a more compact design. There are several options to set the
switching frequency of the LM63635-Q1. For the LM63635D-Q1, either the RT or the SYNC pin
can be used to set the switching frequency. For the
LM63635C-Q1, the internal (default) frequency is set at 2.1 MHz or can be set externally via the SYNC pin. When the SYNC pin is being used, avoid asserting or de-asserting the SYNC signal during operation to prevent disturbances in the output voltage. For the application example, the switching frequency (Fsw) was chosen to be 2100 kHz.