tisp4125f3 Bourns, Inc., tisp4125f3 Datasheet - Page 8

• Manufacturer Part Number: tisp4125f3
• Description: Symmetrical Transient Voltage Suppressors - Power Innovations Ltd
• Manufacturer: Bourns, Inc.

TISP4125F3, TISP4150F3, TISP4180F3
SYMMETRICAL TRANSIENT
VOLTAGE SUPPRESSORS
MARCH 1994 - REVISED SEPTEMBER 1997
protection voltage
capacitance
off-state capacitance
8
P R O D U C T
The protection voltage, (V
This increase is dependent on the rate of current rise, di/dt, when the TISP is clamping the voltage in its
breakdown region. The V
V
can be made from the surge generator voltage rate of rise, dv/dt, and the circuit resistance.
As an example, the CCITT IX K17 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
becomes 45
measured di/ dt and protection voltage increase will be lower due to inductive effects and the finite slope
resistance of the TISP breakdown region.
The off-state capacitance of a TISP is sensitive to junction temperature, T
of the dc voltage, V
with an ac voltage of 100 mV. The typical 25°C variation of capacitance value with ac bias is shown in Figure
13 When V
constant over the range of normal telecommunication frequencies.
(BO)
(250 V/ms) value by the normalised increase at the surge’s di/dt (Figure 7.) . An estimate of the di/dt
D
>> V
.
I N F O R M A T I O N
d
. If the equipment has an additional series resistance of 20
The maximum di/dt then can be estimated as 450/45 = 10 A/µs.
D
the capacitance value is independent on the value of V
, and the ac voltage, V
1.05
1.00
0.95
0.90
0.85
0.80
0.75
0.70
(BO)
(BO)
1
value under surge conditions can be estimated by multiplying the 50 Hz rate
), increases under lightning surge conditions due to thyristor regeneration.
Normalised to V
DC Bias, V
APPLICATIONS INFORMATION
NORMALISED CAPACITANCE
RMS AC TEST VOLTAGE
V
d
- RMS AC Test Voltage - mV
D
= 0
10
d
Figure 13.
. All the capacitance values in this data sheet are measured
d
= 100 mV
vs
100
AIXXAA
1000
J
, and the bias voltage, comprising
d
. The capacitance is essentially
, the total series resistance
In practice the