BAV99 vs. TVS
BAV99 is a popular choice among our engineers for electrostatic protection applications. They believe thatBAV99 tubes can take the role of TVS tubes. In actuality, this viewpoint is incorrect.
BAV99 is a diode, as we all know. Although diodes and TVS can both be employed to defend against transient interference, their protection mechanisms are not the same.
The forward conduction characteristic is used by the diode. The diode is turned on and the subsequent circuit is protected when the surge interference voltage is greater than the diode's forward conduction voltage.
TVS is a unique diode that protects against overvoltage by using the reverse breakdown principle. TVS offers high anti-surge capabilities, as well as low operating and startup voltages, a fast transient reaction time, and low junction capacitance. Fast TVS response and low clamping voltage are not features of diodes. If a diode is utilized to protect against transient disturbances, a diode with a faster response time is suggested.
An Overview of BAV99:
Structure: The interior is the same as two diodes, but the switching speed is faster than regular diodes. Generally employed as a kind of defence.
The common terminal is attached to the signal terminal output, while the other two are connected to the power supply and the last terminal is connected to the ground.
Function:
1. Limiting;
2. Protection (since the rear stage is the output terminal, it will act as a protective device if the rear stage terminal is accidentally introduced from the outside, such as a power supply device);
It has the effect of avoiding over-voltage and negative pulses when positioned near the IC.
Its purpose is to lower conducted immunity if it is positioned in the interface circuit part. A bidirectional high voltage will be generated on the signal line after the interface circuit's common-mode interference is linked in. The voltage amplitude will be clamped at the interaction with BAV99. When there is external interference, however, the power source for positive voltage clamping generates a lot of noise. The negative pressure clamp, likewise, will make a lot of noise on the ground. As a result, BAV99 with interface RC filtering is frequently recommended.
The following circuit shows the BAV99 electrostatic applications circuit:
D2 works but D1 does not when positive static occurs, hence the clamping voltage is 5V + D2's forward voltage.
D1 works but D2 does not when negative static electricity develops, hence this clamping voltage is D1's forward voltage.
