AN4569 datasheet(9/29 Pages) STMICROELECTRONICS

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AN4569

2.1-channel application using one device

2.1.4

Snubber network

Figure 5. Schematic for snubber section

The function of a snubber network is to absorb energy from reactance in the power circuit.

The purpose of the RC snubber is to avoid unnecessary high pulse energy such as a spike

in the power circuit which is dangerous to the system. By using the snubber network, the

energy (big spike) is transferred within the snubber network, allowing safe operation of the

system.

The snubber network is a part of the schematic that is layout dependent. The values shown

in the schematic (R = 22 ohm, C = 330 pF) represent the best solution for the ST demo

board.

In Figure 5 there are two types of snubber: BTL and single-ended.

Differential snubber

The power on this network is dependent on the power supply, frequency and capacitor value

using the following formula:

PDiff = C * f * (2 * VCC)2

The power must be dissipated on the series resistor.

Single-ended snubber

This type of snubber is used to increase the efficiency or, otherwise, must be used if the

output configuration is single-ended. In a single-ended snubber the power on the network is:

Equation 1

2.1-channel single device - power on snubber

PSE = C * f * (VCC)2

PSE = PDiff / 4

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