Electronic Design
Voltage Limiter Generates Supplies That Improve Standard Diode Technique

Voltage Limiter Generates Supplies That Improve Standard Diode Technique

Some systems require a voltage limiter to protect the input circuit. Designers can connect diodes (Fig. 1) to VCC and Gnd to create a simple solution. This simplicity, however, comes at a disadvantage: the input circuit can see voltages within a range of Gnd – VDup to VCC + VD.

If the circuit is sensitive and can handle only voltages between Gnd and VCC, the circuit in Figure 2 is a better alternative. The improved limiter includes circuitry to generate two voltage power supplies:

VP = VCC – VD

which can sink current, and:

VN = Gnd + VD

which can source current.

The circuit assumes that VD = VBE. In this case, the protection diodes at the input will clamp the input voltage at no more than VCC and no less than Gnd.

Hide comments

Comments

  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
Publish