With a small amount of additional circuitry, the device can be used in circuits subject to transients higher than
36 V. Use only zener diodes or zener-type transient absorbers (sometimes referred to as Transzorbs). Any other type of transient absorber has an unacceptable time delay. Start by adding a pair of resistors, as shown in Figure 7-11, as a working impedance for the zener diode. Keeping these resistors as small as possible is best, preferably 100 Ω or less. Larger values can be used with an additional error induced resulting from a reduced signal that reaches the device input terminals. Because this circuit limits only short-term transients, many applications are satisfied with a 100-Ω resistor along with conventional zener diodes of the lowest power rating available. This combination uses the least amount of board space. These diodes can be found in SOT-523 or SOD-523 packages.