Optocoupler Driver Circuit Voltage Clamping Power Dissipation
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Solution Overview
Problem
Existing optocoupler driver circuits for transferring data from a line level circuit to an isolated circuit require additional power supplies, increasing component and real estate costs due to the need for high current drive of the LED part, which is costly and space-intensive.
Innovation Solution
An optocoupler driver circuit with a voltage clamping element and a switching element connected in series with the optocoupler, utilizing the existing low power supply current to minimize additional components and power consumption, where the voltage clamping element has a clamping voltage lower than the main voltage level, allowing redirection of current through the optocoupler based on input signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate power supply is added to drive the optocoupler LED with high current, then secure and robust operation of the optocoupler is guaranteed, but component cost and board space increase significantly
Solution Approach 1:
The patent merges the optocoupler LED driving function with the existing low-power supply circuit by connecting the LED in parallel with the voltage clamping element. This eliminates the need for a separate high-current power supply while ensuring reliable optocoupler operation through the shared power path.
Solution Approach 2:
The existing low-power supply circuit serves dual purposes: powering the isolated circuit and driving the optocoupler LED. The voltage clamping element ensures the LED receives adequate current during transient conditions, allowing the supply to self-regulate without additional control circuitry.
2Power
If a separate power supply is added to drive the optocoupler LED, then sufficient driving current is provided, but power consumption and cost increase
Solution Approach 1:
The patent combines the LED driving function with the existing low-power supply, eliminating redundant power conversion circuits. The voltage clamping element ensures adequate LED current during transients without requiring continuous high-power supply operation, reducing overall energy consumption.
3Loss of energy
If voltage clamping element with low clamping voltage is used, then power dissipation is reduced to minimal levels, but the ability to handle high voltage transients may be compromised
Solution Approach 1:
The voltage clamping element is positioned specifically across the LED terminals to provide localized protection. Its low clamping voltage (5V) is optimized for the LED's specific requirements, protecting against overvoltage while minimizing power dissipation. This localized approach allows different voltage levels in different parts of the circuit.
Solution Approach 2:
The patent changes the clamping voltage parameter from typical high-voltage values to a low value (5V) matched to the LED's operational requirements. This parameter optimization reduces power dissipation (P=V²/R) while maintaining adequate protection for the LED, balancing energy loss with reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces power consumption to minimal levels, with power dissipation as low as 5mW, while maintaining galvanic isolation and ensuring secure operation of the optocoupler with negligible voltage drop, thus reducing overall costs and space requirements.
Implementation Method 1
a voltage clamping element connected between the first and second terminal, having a clamping voltage which is a factor x lower than the first voltage level
Implementation Method 2
an optocoupler providing an output signal to the isolated circuit
Data Source
Figure 1~2
Figure 3
AI summary
Optocoupler driver circuit for transferring data from a line level circuit to an isolated circuit. The optocoupler driver circuit has a first and second terminal (L1, L2) for a series connection of the optocoupler driver circuit in a supply mains line (L) operating on a first voltage level and supplying electrical power towards a low power supply (2) for powering the isolated circuit. An optocoupler (3) provides an output signal (out) to the isolated circuit. A voltage clamping element (4) is connected between the first and second terminal (L1, L2), having a clamping voltage which is a factor x lower than the first voltage level. A switching element (5) is driven by an input signal, and connected in series with an input side of the optocoupler (3). The series connection of the switching element (5) and the optocoupler (3) is connected in parallel to the voltage clamping element (4).