MS1003SH･MS1004SH

Application Note Ver.2.2

SHINDENGEN ELECTRIC MFG. CO. , LTD

21/41

5.4 Checking the operating points

The MS1003SH and MS1004SH have points of change at which the oscillation frequency changes

according to the functions of the control IC.

Identifying each point helps predict the behavior of a prototype power supply. The following chart shows a

model of operating frequency characteristics relative to output power. Knowing each operating point will

provide approximate levels of the power, hysteresis width and droop point at these points of change.

The operating points to be calculated in this section are circled on the chart above.

 Trough skip start and end points

 Auto burst start and end points

 Droop point

Obtain these points to check the following:

Is the standby operation properly performed in standby mode?

Is the trough skip hysteresis sufficient?

Is the droop point sufficiently greater than the output?

MS1003SH and MS1004SH

operating frequency

characteristic model

Output power [W]

Auto burst start point

Trough skip start point

Auto burst

hysteresis

Droop point

Trough skip

hysteresis

Auto burst end point

Trough skip end

point