The servo mode of the LTC2977 has
・High-speed servo mode
・Normal servo mode
There are two. The DAC output update is 1LSB (standard: 1.38V ÷ 10bit = 1.347mV) in both modes. The update rate is different in the two modes.

・In high-speed servo mode, when the servo mode is ON, the target DAC output value is determined from the difference between the current DCDC output value and the target value, and the DAC is changed by 1LSB every tS_VDACP (250μS) toward that voltage.

・In normal servo mode, check the voltage every tCONV_ADC, and if it deviates from the target value, change the value so that it approaches the target value voltage by 1 LSB.
* tCONV_ADC is about 43mS when only 1ch is used according to data sheet (JP) P9 NOTE4.
When the DAC output value approaches the target value in high-speed servo mode, it shifts to normal servo mode (according to the setting) or turns off servo mode.

(Published in August 2021)