Band Gap Reference Circuit Startup Without Abnormal Diode-Off State
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Solution Overview
Problem
Conventional band gap power supply circuits transition through an abnormal operation state during startup, where both diodes are in an off state but currents flow through the resistors, before reaching the normal operation state.
Innovation Solution
The band gap power supply circuit incorporates a band gap core circuit with first and second switches and rectifier elements, along with a switch control circuit, to control current paths and voltages such that the circuit transitions directly to the normal operation state without passing through the abnormal state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional band gap core circuit is used with diodes and resistors, then the circuit can generate reference voltage, but the circuit passes through an abnormal operation state during startup where diodes are off but currents flow through resistors
Solution Approach 1:
The switch control circuit activates switches in advance before the diodes are forward-biased, preventing the abnormal operation state from occurring. By preliminarily establishing the correct current paths through the switches and resistors, the circuit transitions directly from startup to normal operation without passing through the abnormal state where diodes are off but resistor currents flow.
Solution Approach 2:
The switch control circuit acts as an intermediary that coordinates the activation of switches and diodes. It ensures that switches are turned on at the appropriate timing to guide current flow through proper paths, preventing the abnormal operation state. The intermediary control logic manages the transition from startup to normal operation by controlling switch states based on circuit conditions.
2Reliability
If switches are added to control current paths, then the circuit can avoid abnormal operation state, but the device complexity increases
Solution Approach 1:
The switch control circuit performs multiple functions: it controls switch activation timing, prevents abnormal operation states, ensures proper current distribution, and manages the transition from startup to normal operation. By consolidating these control functions into a single multi-functional block, the patent avoids adding excessive complexity while achieving reliable operation.
Solution Approach 2:
The invention changes the operational parameters of the circuit by introducing controlled switching actions that alter current paths and voltage distributions during startup. By dynamically adjusting switch states and timing, the circuit transitions smoothly from startup to normal operation, avoiding the abnormal state without requiring complex additional components.
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 configuration allows the band gap power supply circuit to directly transition to the normal operation state without experiencing the abnormal operation state, ensuring stable and efficient power supply.
Implementation Method 1
The operational amplifier OP1 controls the currents flowing through the diodes D1 and D2 in such a way that the sum of the forward direction voltage of the diode D2 having a larger junction area and a voltage drop across the resistor R3 connected in series to the diode D2 becomes equal to the forward direction voltage of the diode D1 having a small junction area.
Implementation Method 2
a first rectifier element connected in parallel to the first current path, a second rectifier element to make up a current path in which a third resistor is connected in series to the second rectifier element
Data Source
AI summary
Disclosed is a band gap power supply circuit including a band gap core circuit to perform control in such a way that the sum of a current flowing through a diode and a current flowing through a first current path becomes equal to the sum of a current flowing through a diode and a current flowing through a second current path, and the sum of the forward direction voltage of the diode and a voltage drop across a resistor becomes equal to the forward direction voltage of the diode; and a switch control circuit to control a switch and a switch from off to on at a time of a startup of a power supply.