JAJSNC5A April 2023 – July 2024 LM5171-Q1
ADVANCE INFORMATION
The LM5171-Q1 can synchronize to an external clock if FEX_CLK is within ±20% of FOSC. The SYNCIN clock pulse width must be in the range of 100ns to 0.8/FOSC, with a high voltage level > 2V and low voltage level < 1V.
FEX_CLK can be adjusted dynamically. However the LM5171-Q1 PLL takes approximately 150µs to settle down to the newly asserted frequency. During the PLL transient, the instantaneous FSW may temporarily drop by 25%. To avoid overstress during the transient, TI recommends the user to reduce the load current to less than 50% by lowering the ISET voltage, or to simply turn off the dual-channels by setting EN1 = EN2 = 0 when making an the external clock change.