1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-75 -50 -25 0255075 100 125 150
Junction Temperature (°C)
Normalized Trip Current
2.2
1.6
1.8
2.0
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-75 -50 -25 0255075 100 125 150
Junction Temperature (°C)
Normalized Resistance
TBU-CA Series - TBU
®
High-Speed Protectors
Reference Application
The TBU
®
devices are general use protectors used in a wide
variety of applications. The maximum voltage rating of the TBU
®
device should never be exceeded. Where necessary, an OVP
should be employed to limit the maximum voltage. A cost-
effective protection solution combines Bourns
®
TBU
®
protection
devices with a pair of Bourns
®
MOVs. For bandwidth sensitive
applications, a Bourns
®
GDT may be substituted for the MOV.
The TBU
®
device, constructed using MOSFET semiconductor
technology, placed in the system circuit will monitor the current
with the MOSFET detection circuit triggering to provide an
effective barrier behind which sensitive electronics are not
exposed to large voltages or currents during surge events. The
TBU
®
device operates in approximately 1 μs - once line current
exceeds the TBU
®
device’s trigger current I
trigger
. When operat-
ed, the TBU
®
device will limit the current to less than the I
trigger
value within the t
block
duration. If voltage above V
reset
is contin-
uously sustained, the TBU
®
device will subsequently reduce the
current to a quiescent current level within a period of time that is
dependent upon the applied voltage.
After the surge, the TBU
®
device resets when the voltage
across the TBU
®
device falls to the V
reset
level. The TBU
®
device will automatically reset on lines which have no DC bias
or have DC bias below V
reset
(such as unpowered signal lines).
If the line has a normal DC bias above V
reset
, the voltage
across the TBU
®
device may not fall below V
reset
after the
surge. In such cases, special care needs to be taken to ensure
that the TBU
®
device will reset, with software monitoring as one
method used to accomplish this. Bourns application
engineers can provide further assistance.
Basic TBU Operation
Performance Graphs
Typical V-I Characteristics (TBU-CA050-300-WH)
Typical Trigger Current vs. Temperature
Equip.
OVP
OVP
Line
Line
TBU
®
Device
TBU
®
Device
Line In /
Line Out
Line Out
/ Line In
Line Out
/ Line In
Line In /
Line Out
Typical Resistance vs. Temperature
Power Derating Curve
CURRENT
(100 mA/div)
VOLTAGE
(5 V/div)
I
TRIP
V
RESET
No Additional PCB Cu
0.5 sq. in. Additional PCB Cu
Junction Temperature (°C)
20
3.0
2.5
2.0
1.5
1.0
0.5
0.0
40 60 80 100 120 140
Total Max. Power (W)
Specifications are subject to change without notice.
The device characteristics and parameters in this data sheet can and do vary in different applications and actual device performance may vary over time.
Users should verify actual device performance in their specific applications.
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-75 -50 -25 0255075 100 125 150
Junction Temperature (°C)
Normalized Trip Current
2.2
1.6
1.8
2.0
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-75 -50 -25 0255075 100 125 150
Junction Temperature (°C)
Normalized Resistance
