SEPTEMBER 2001 - REVISED FEBRUARY 2005

Specifications are subject to change without notice.

Customers should verify actual device performance in their specific applications.

TISP4xxxJ1BJ Overvoltage Protector Series

ITU-T K.20, K.45 and K.21 Designs (Continued)

An ITU-T compliant design would probably require the replacement of the fuses by coordination resistors. With a ±410 V off-state voltage, this

may seem unnecessary as modern primary protectors will switch at lower voltages and automatically coordinate. On a perfect longitudinal

waveform this is true. However, the ITU-T also applies a transverse (metallic) test as well, to simulate non-simultaneous switching of the

primary protection. In this case, one conductor is grounded, which places the RING to TIP protection in parallel with the unswitched primary

protector. The ±270 V off-state voltage is likely to be lower than the primary switching voltage and there isn’t coordination. Under GR-1089-

CORE conditions with non-simultaneous switching, the 100 A 10/1000 current, which should have gone through the unswitched primary

protector, is diverted through the top arms of the Y into the switched primary, causing a 200 A current flow in that primary protector.

±550

±700

±550

±700

TISP3350T3BJ

TISP4350J1BJ

±275

±350

±640

±790

±640

±790

TISP3395T3BJ

TISP4395J1BJ

±320

±395

RING to TIP Voltages

RING to GROUND,

TIP to GROUND Voltages

ITU-T Y Configuration Parts and Part Voltages

R1a = R1b = 6.5 Ω

V

V

V

V

Th1a + Th1b

Part #

Th2

Part #

V

V

Asymmetrical Designs

These designs are for special needs, where the RING to TIP protection voltage must be different to the RING to GROUND and TIP to

GROUND voltages. ADSL modem interfaces often have a need for asymmetric voltage limiting, see Figure 16. Here, the RING to TIP voltage

limitation is given by the d.c. blocking capacitor, C1, and the RING to GROUND and TIP to GROUND limitation is insulation breakdown. Often

Figure 17 and its following table is for a GR-1089-CORE compliant design.

RING to TIP Voltages

RING to GROUND,

TIP to GROUND Voltages

GR-1089-CORE Y Configuration Parts and Part Voltages

V

V

V

V

Th1a, Th1b

Th2

Part #

V

V

Part #

V

V

±270

±330

±410

±515

TISP4165H3BJ

±135

±165

TISP4350J1BJ

±275

±350

Figure 16. ADSL Modem Interface Voltage Limitations

Figure 17. Asymmetrical Design for US ADSL Modems

T1

TIP

RING

C1

T1 or PW

Insulation

Breakdown

C1

Voltage

Limit

AI4JAH

Th1a

TISP4165H3BJ

Th2

TISP4350J1BJ

Th1b

TISP4165H3BJ

F1a

F1b

RING

TIP