TISP61089BSD Bourns, Inc., TISP61089BSD Datasheet - Page 8

• Manufacturer Part Number: TISP61089BSD
• Description: Dual Forward-conducting P-gate Thyristors Programmable Overvoltage Protectors
• Manufacturer: Bourns, Inc.

SLICs have become more sophisticated. To minimize power consumption, some designs automatically adjust the driver supply voltage to a
value that is just sufficient to drive the required line current. For short lines the supply voltage would be set low, but for long lines, a higher
supply voltage would be generated to drive sufficient line current. The optimum protection for this type of SLIC would be given by a protection
voltage which tracks the SLIC supply voltage. This can be achieved by connecting the protection thyristor gate to the SLIC V
Figure 6. This gated (programmable) protection arrangement minimizes the voltage stress on the SLIC, no matter what value of supply voltage.
Operation of Gated Protectors
Figure 7 and Figure 8 show how the TISP61089BSD limits negative and positive overvoltages. Positive overvoltages (Figure 8) are clipped by
the antiparallel diode of Th5 and the resulting current is diverted to ground. Negative overvoltages (Figure 7) are initially clipped close to the
SLIC negative supply rail value (V
condition. As the overvoltage subsides the high holding current of Th5 prevents d.c. latchup. The protection voltage will be the sum of the gate
supply (V
gate decoupling capacitor, C1, and the gate terminal. During the initial rise of a fast impulse, the gate current (I
current (I
Gated Protectors (Continued)
TISP61089BSD High Voltage Ringing SLIC Protector
K
BATH
). Rates of 80 A/µs can cause inductive voltages of 0.8 V in 2.5 cm of printed wiring track. To minimize this inductive voltage increase of
Figure 7. Negative Overvoltage Condition
) and the peak gate-cathode voltage (V
AI6XAHBa
I
K
PROTECTOR
V
Figure 6. TISP61089BSD Buffered Gate Protector ('1089 Section 4.5.12 Testing)
61089BSD
BATH
SLIC
TISP
0 - 600 V r.m.s.
RESISTANCE
GENERATOR
GENERATOR
BATH
Th5
SOURCE
600 Ω
600 Ω
A.C.
). If sufficient current is available from the overvoltage, then Th5 will switch into a low voltage on-state
I
G
220 nF
WIRE
WIRE
RING
C1
TIP
SLIC
40 Ω
40 Ω
R1
R2
GK(BO)
). The protection voltage will be increased if there is a long connection between the
TISP61089BSD
220 nF
C1
I
G
Customers should verify actual device performance in their specific applications.
SLIC
Figure 8. Positive Overvoltage Condition
V
BATH
AI6XAIBa
I
F
I
I
V
BATH
SLIC
BATL
PROTECTOR
V
61089BSD
SWITCHING MODE
BATH
POWER SUPPLY
C2
TISP
SLIC
D1
Specifications are subject to change without notice.
Th5
Tx
AI6XCCa
G
) is the same as the cathode
SEPTEMBER 2005 - REVISED MAY 2007
220 nF
C1
SLIC
BATH
supply,