Reset conditions and reset process of reset circuit
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Reset conditions and reset process of reset circuit

Posted Date: 2024-01-17

What are the commonly used reset circuits?

Commonly used reset circuits include the following:

1. Power monitoring chip reset circuit: This is the most common type of reset circuit, which uses a dedicated power monitoring chip to monitor the power supply voltage and trigger a reset signal when the voltage is lower than or higher than a preset threshold.

2. RC reset circuit: This reset circuit uses a delay circuit composed of a capacitor and a resistor to provide a delay function for the reset signal through the charging and discharging process of the capacitor.

3. Gate circuit reset circuit: A reset circuit designed based on logic gate circuits can be a simple AND gate or a NOT gate, or a complex gate circuit array. The gate generates a reset signal based on the input supply voltage and other control signals.

4. Watchdog reset circuit: The watchdog reset circuit is a timed reset circuit. When the system is running normally, it needs to send a dog feeding signal to the watchdog circuit regularly. If the system malfunctions or stops responding, the watchdog reset circuit triggers a reset if a dog feed signal is not received within a specified time interval.

5. Internal reset circuit of the microcontroller: Many microcontrollers and microcontrollers have integrated reset circuits inside them, which can be set and adjusted according to the internal configuration bits.

6. Manual reset circuit: This reset circuit consists of manual input components (such as buttons, switches, etc.), and the user can achieve the reset operation through manual triggering.

Reset conditions for reset circuit

The reset condition of the reset circuit refers to the condition that triggers the reset signal. Specific reset conditions can be determined based on system requirements and design. The following are some common reset conditions:

1. Supply voltage below threshold: One of the most common reset conditions is when the supply voltage drops below a preset threshold. This is because when the power supply voltage drops to a certain level, the system may not be able to work properly or perform expected operations, so a reset process needs to be initiated to restore the system to its initial state.

2. The power supply voltage is above the threshold: Contrary to the power supply voltage being below the threshold, some systems require the power supply voltage to be above a preset threshold to work properly. If the supply voltage exceeds the threshold, system damage or instability may occur, requiring a reset operation to be triggered.

3. The rate of rise or fall of the power supply voltage: Some reset circuits require the rate of rise or fall of the power supply voltage to be within a certain range. This is to prevent transient changes or ripples in the supply voltage from affecting system stability.

4. Manual triggering: In some cases, the reset circuit requires manual triggering of the reset. This can be accomplished by pressing a reset button, a toggle switch, or other manual operation. Manual reset is often used for troubleshooting or system debugging.

5. External event trigger: Some reset circuits can trigger reset based on external events. For example, a reset operation may be triggered by receiving a signal from another system or device.

How the reset circuit generates a reset

The process by which a reset circuit generates a reset typically involves the following steps:

1. Monitor the power supply voltage: The reset circuit must first monitor the power supply voltage to determine the power status of the system. This is usually achieved through a power monitoring chip or sensor.

2. Determine the power supply status: Based on the monitored power supply voltage, the reset circuit will determine whether the power supply status meets the reset conditions. For example, a reset signal may be triggered when the supply voltage is too low or too high.

3. Generate reset signal: If the power state meets the reset conditions, the reset circuit generates a reset signal. The specific generation method depends on the design of the reset circuit.

- Power monitoring chip: Power monitoring chip usually has an internal integrated comparator that can be compared with a preset threshold. Once the power supply voltage is lower than or higher than the threshold, the chip will generate a reset signal.

- RC reset circuit: The RC reset circuit uses a delay circuit composed of a capacitor and a resistor. When the power supply is connected, the capacitor begins to charge. When the charge reaches the set threshold, the reset signal is triggered.

- Gate circuit: The gate circuit can perform logical operations on the power supply voltage and other control signals based on different logic gate combinations and input signals to generate a reset signal.

- Watchdog reset circuit: The watchdog reset circuit is usually a timer and must periodically receive a dog feeding signal. If the system does not send a dog feeding signal to the watchdog reset circuit within the set time interval, the watchdog reset circuit will trigger the reset signal.

4. Transmit the reset signal to the system: After generating the reset signal, the reset circuit will transmit the signal to various parts of the system to start the system reset process. This is usually accomplished by connecting to the reset control port or reset pin in the system.

5. System reset: After the system receives the reset signal, it will perform a reset operation. The exact reset behavior depends on the system design and implementation. Typically, the system will reset the registers to their initial state, clear any outstanding operations, and initialize external devices to return the system to a controllable initial state.

Review Editor: Huang Fei


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