SLUS223G April 1997 – July 2022 UC1842 , UC1843 , UC1844 , UC1845 , UC2842 , UC2843 , UC2844 , UC2845 , UC3842 , UC3843 , UC3844 , UC3845
PRODUCTION DATA
The internal oscillator uses a timing capacitor (CCT) and a timing resistor (RRT) to program the oscillator frequency and maximum duty cycle. The operating frequency can be programmed based the curves in Section 9.2.3, where the timing resistor can be found once the timing capacitor is selected. It is best for the timing capacitor to have a flat temperature coefficient, typical of most COG or NPO type capacitors. For this converter, 15.4 kΩ and 1000 pF were selected for RRT and CCT to operate at 110-kHz switching.