Most systems that require more than a single mode of operation from the LMR436x0-Q1 are controlled by digital circuitry such as a microprocessor. These systems can generate dynamic signals easily but have difficulty generating multi-level signals. Pulse-dependent MODE/SYNC pin control is useful with these systems. To initiate pulse-dependent MODE/SYNC pin control, a valid sync signal must be applied. Table 8-1 shows a summary of the pulse dependent mode selection settings.
|> VMODE_H||FPWM with spread spectrum factory setting|
|< VMODE_L||Auto mode with spread spectrum factory setting|
|Synchronization Clock||SYNC mode|
Figure 8-4 shows the transition between auto mode and FPWM mode while in pulse-dependent MODE/SYNC control. The LMR436x0-Q1 transitions to a new mode of operation after the time, tMODE. Figure 8-4 and Figure 8-5 show the details.
If MODE/SYNC voltage remains constant longer than tMODE, the LMR436x0-Q1 enters either auto mode or FPWM mode with spread spectrum turned on (if factory setting is enabled) and MODE/SYNC continues to operate in pulse-dependent scheme.