Output Driver Control Circuit for Fast Turn-On and Slew Rate Control
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Solution Overview
Problem
Existing slew rate control circuits in output drivers face challenges in achieving short turn-on times while maintaining controlled slew rates, particularly in applications requiring low latency and minimal electromagnetic interference.
Innovation Solution
A control circuit with a turn-on facilitating module and a sensing module is introduced, which supplies a supplementary voltage to the output driver via a series-connected PMOS transistors, and a sensing module switches off the facilitating module when the input voltage reaches a threshold, ensuring rapid turn-on without affecting the slew rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a well-controlled current is injected into the driver by the slew rate control circuit, then the slew rate is well-controlled, but the turn-on time becomes large
Solution Approach 1:
The turn-on facilitating module is activated before the main output driver to pre-charge the gate voltage, reducing the turn-on time. This preliminary action prepares the driver for faster activation without affecting the subsequent slew rate control phase.
Solution Approach 2:
The driver activation process is segmented into two distinct phases: a fast turn-on phase using the turn-on facilitating module with higher current, and a controlled slew rate phase using the slew rate control circuit. This segmentation allows optimization of each phase independently.
2Speed
If the turn-on time is reduced by supplying supplementary voltage, then the propagation delay decreases, but the slew rate control may be impacted
Solution Approach 1:
The turn-on facilitating module operates only during a specific time period (turn-on phase) and is then deactivated. This periodic operation ensures that the supplementary voltage aids turn-on without interfering with the subsequent slew rate control phase.
Solution Approach 2:
A sensing module detects when the output driver has completed its turn-on process and provides feedback to deactivate the turn-on facilitating module. This feedback mechanism ensures precise timing and prevents the supplementary voltage from affecting the slew rate control.
Data Source
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AI summary
A control circuit for an output driver with a slew rate control circuit is disclosed. The control circuit comprises a turn-on facilitating module having a control input and configured to be connected to the output driver and to supply a supplementary voltage to the output driver in response to a control voltage at the control input; and a sensing module configured to be connected to the turn-on facilitating module and the output driver and to switch off the turn-on facilitating module in response to an input voltage of the output driver sensed by the sensing module.