ZHCSKE6C July 2019 – February 2020 TPS63810 , TPS63811
PRODUCTION DATA.
The device uses a constant off-time, peak-current-mode control scheme where an outer voltage control loop generates the demand signal for an inner current control loop. During the on-time, the inner current control loop monitors the inductor current, and when the inductor current equals the demand signal from the error amplifier, the on-time stops and the next part of the switching cycle starts.
The off-time is a function of VI and VO and the operating mode (buck, boost, or buck-boost) of the converter.
Figure 7. Peak Current Control (Buck and Boost Operation)
Figure 8. Peak Current Control – Buck-Boost Operation with VI < VO
Figure 9. Peak Current Control – Buck-Boost Operation with VI > VO
Figure 10. Peak Current Control – Buck-Boost Operation with VI = VO During PWM operation, current can flow in the reverse direction (from output to input). In this case, the error amplifier provides a negative peak current target. Note that the average reverse current is greater (more negative) than the peak current (see Figure 11 and Figure 12).
Figure 11. Reverse Peak Current Control – Buck and Boost Operation
Figure 12. Reverse Peak Current Control – Buck-Boost Operation, with VI > VO