MARCH 1994 - REVISED MARCH 2006

Specifications are subject to change without notice.

Customers should verify actual device performance in their specific applications.

The protection voltage, (V(BO) ), increases under lightning surge conditions due to thyristor regeneration. This increase is dependent on the

rate of current rise, di/dt, when the TISP® device is clamping the voltage in its breakdown region. The V(BO) value under surge conditions can

be estimated by multiplying the 50 Hz rate V(BO) (250 V/ms) value by the normalized increase at the surge’s di/dt (Figure 7). An estimate of the

di/dt can be made from the surge generator voltage rate of rise, dv/dt, and the circuit resistance.

As an example, the ITU-T K.21 1.5 kV, 10/700 µs surge has an average dv/dt of 150 V/µs, but, as the rise is exponential, the initial dv/dt is

higher, being in the region of 450 V/µs. The instantaneous generator output resistance is 25 Ω. If the equipment has an additional series

resistance of 20 Ω, the total series resistance becomes 45 Ω. The maximum di/dt then can be estimated as 450/45 = 10 A/µs. In practice, the

measured di/dt and protection voltage increase will be lower due to inductive effects and the finite slope resistance of the TISP® breakdown

region.

Capacitance

Off-state Capacitance

Protection Voltage

TISP30xxF3 (LV) Overvoltage Protector Series

The off-state capacitance of a TISP® device is sensitive to junction temperature, TJ, and the bias voltage, comprising of the d.c. voltage, VD,

and the a.c. voltage, Vd. All the capacitance values in this data sheet are measured with an a.c. voltage of 100 mV. The typical 25 °C variation

of capacitance value with a.c. bias is shown in Figure 17. When VD >> Vd, the capacitance value is independent on the value of Vd. The

capacitance is essentially constant over the range of normal telecommunication frequencies.

APPLICATIONS INFORMATION

Figure 17.

V

1

10

100

1000

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

AIXXAA

Normalized to V

DC Bias, V

NORMALIZED CAPACITANCE

vs

RMS AC TEST VOLTAGE