TISP61089

DUAL FORWARD-CONDUCTING P-GATE THYRISTORS

PROGRAMMABLE OVERVOLTAGE PROTECTORS

6

NOVEMBER 1995 - REVISED FEBRUARY 1998

PR O D UC T

I N FO R M A T IO N

operation of gated protectors

Figures 4. and 5. show how the TISP61089 limits negative and positive overvoltages. Positive overvoltages

(Figure 5) are clipped by the antiparallel diodes in the TISP61089 and the resulting current is diverted to

ground. Negative overvoltages (Figure 4.) are initially clipped close to the SLIC negative supply rail value

voltage on-state condition. As the overvoltage subsides the high holding current of the crowbar prevents d.c.

track. To minimise this inductive voltage increase of protection voltage, the length of the capacitor to gate

terminal tracking should be minimised. Inductive voltages in the protector cathode wiring will also increase the

protection voltage. These voltages can be minimised by routing the SLIC connection through the protector as

shown in Figure 3.

Figure 3. TISP61089 BUFFERED GATE PROTECTOR (SECTION 4.5.12 TESTING CONDITION)

Figure 4. NEGATIVE OVERVOLTAGE CONDITION

Figure 5. POSITIVE OVERVOLTAGE CONDITION

R1a

>25

Ω

RING

WIRE

TIP

WIRE

SLIC

TISP61089

V

BAT

C1

220 nF

AI6XAG

600

Ω

600

Ω

A.C.

GENERATOR

0 - 600 Vrms

SWITCHING MODE

POWER SUPPLY

GENERATOR

SOURCE

RESISTANCE

I

BAT

I

G

I

SLIC

C2

D1

Tx

R1b

>25

Ω

Th4

Th5

C1

220 nF

I

G

Th5

SLIC

V

BAT

PROTECTOR

CROWBAR

OPERATION

TISP

61089

I

K

AI6XAH

Th5

SLIC

V

BAT

PROTECTOR

DIODE

OPERATION

TISP

61089

C1

220 nF

I

F

AI6XAI