Mechanism For Automatic Mode Switching In Ucd3138 - Texas Instruments UCD3138 Technical Reference Manual

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High – Lower Threshold
Low – Lower Threshold
Figure 2-12. Mechanism for Automatic Mode Switching in UCD3138
As shown, the registers are used in pairs for hysteresis. The transition from Control Register 1 to Auto
Config Mid only takes place when the Filter Duty goes above the Low Upper threshold. It does not go
back to Control Register 1 until the Low Lower Threshold is passed. This prevents oscillation between
modes if the filter duty is close to a mode switching point. In some applications it is necessary to make the
values the same, disabling hysteresis. This has to be done to make the DPWM signals from the two
modes match properly at the mode switching point.
SNIU028A – February 2016 – Revised April 2016
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Automatic Mode Switching
With Hysteresis
Filter Duty
Auto Config High
Auto Config Mid
Control
Register 1
Copyright © 2016, Texas Instruments Incorporated
Automatic Mode Switching
Full Range
High – Upper Threshold
Low – Upper Threshold
0
Digital Pulse Width Modulator (DPWM)
49