ZHCSE74C September 2015 – May 2025 LMK61E2
PRODUCTION DATA
The LMK61E2 features a fully integrated loop filter for the PLL and supports programmable loop bandwidth from 100kHz to 1MHz. The loop filter components, R2, C1, R3, and C3 can be configured by programming R36, R37, R38, and R39 respectively. The LMK61E2 features a fixed value of C2 of 10nF. When PLL is configured in the fractional mode, R35.2 must be set to 1. When reference doubler is disabled for integer mode PLL, R35.2 must be set to 0 and R38[6-0] must be set to 0x00. When reference doubler is enabled for integer mode PLL, R35.2 must be set to 1 and R38 and R39 are written with the appropriate values. Figure 7-2 shows the loop filter structure of the PLL. Set the PLL to best possible bandwidth to minimize output jitter. TI provides the WEBENCH® Clock Architect Tool that makes selecting the right loop filter components simple.