DC-DC Converter Ripple Suppression via Secondary Shunt Switch
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Solution Overview
Problem
Existing DC-DC conversion circuits face challenges in reducing output voltage fluctuations without increasing the size of discrete elements, leading to higher costs and power consumption, as well as severe electromagnetic interferences.
Innovation Solution
A DC-DC conversion circuit system comprising a primary switch circuit, a charge/discharge circuit, and a secondary switch circuit, where the secondary switch circuit shunts excessive currents when they exceed a threshold, effectively suppressing output voltage ripples through a feedback mechanism and frequency dividing circuits, utilizing smaller transistors to maintain stability without altering the overall output current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large discrete element is used at the output stage, then the fluctuation of the DC-DC output is reduced, but the cost increases, power consumption increases, and electromagnetic interferences become severe
Solution Approach 1:
The patent introduces a secondary switch circuit that segments the current path by providing an alternative current channel. When the main switch is off, the secondary switch circuit activates to provide a discharge path for the inductor current, thereby segmenting the current flow and reducing electromagnetic interference while maintaining output stability.
Solution Approach 2:
The secondary switch circuit acts as an intermediary element between the inductor and the output capacitor. It provides a controlled path for current flow during switching transitions, mediating the energy transfer and reducing voltage fluctuations without requiring large discrete output elements.
2Stability of the object's composition
If a large discrete element is used at the output stage, then the fluctuation of the DC-DC output is reduced, but the power consumption increases
Solution Approach 1:
The secondary switch circuit ensures continuous useful action by providing an always-available current path. During the main switch off-time, the secondary switch immediately activates to maintain current flow through the inductor, eliminating gaps in energy transfer and reducing the need for large output capacitors, thereby lowering power consumption while maintaining stability.
3Stability of the object's composition
If a large discrete element is used at the output stage, then the fluctuation of the DC-DC output is reduced, but the cost increases
Solution Approach 1:
The secondary switch circuit provides multi-functionality by serving multiple purposes: it acts as a current path during off-times, provides ripple current reduction, and enables the use of smaller, less expensive output components. This universal approach achieves output stability without requiring large, costly discrete output elements.
4Device complexity
If the dimension of the second PMOS transistor is made smaller, then the circuit complexity is reduced, but the current handling capability may be affected
Solution Approach 1:
The patent employs dynamic switching control where the second PMOS transistor's operation is timed to complement the main switch. By controlling the timing and duration of the secondary switch's activation, the transistor can be smaller while still handling the necessary current during its active period, as it operates dynamically rather than continuously.
Data Source
AI summary
The present application relates to the field of circuit design, and discloses a DC-DC conversion circuit system and a forming method thereof. The system may include a primary switch circuit, a charge/discharge circuit, and a secondary switch circuit. The primary switch circuit includes a voltage supply end configured to receive a first direct current voltage and an output end. The charge/discharge circuit includes an input end connected to the output end of the primary switch circuit, and a first output end configured to output a second direct current voltage. The secondary switch circuit includes a voltage supply end configured to receive the first direct current voltage, and an output end connected to the output end of the primary switch circuit. The primary switch circuit is configured to control the charge/discharge circuit to charge or discharge. When a charging current or a discharging current of the charge/discharge circuit is greater than a corresponding threshold, the secondary switch circuit is configured to shunt the charging current or the discharging current. The present application can effectively suppress a ripple of an output voltage, and improve stability of the DC-DC conversion circuit system.