CPC1465D datasheet(10/15 Pages) IXYS

10 / 15 page

INTEGRATED CIRCUITS DIVISION

CPC1465

www.ixysic.com

R05

2. Functional Description

2.1 Introduction

The CPC1465 can be used for a number of designs

requiring a dc hold circuit such as SHDSL modem and

ISDN NT1 terminal applications. Typical SHDSL

applications will use a circuit design similar to the one

shown in Figure 10‚ “Typical ISDN NT1 Application

Diagram” on page 9 while the typical ISDN NT1 circuit

design will be similar to the one shown in Figure 10‚

“Typical ISDN NT1 Application Diagram” on page 9.

The DC Termination IC performs two functions in an

ISDN NT1 terminal; as an electronic inductor providing

a low impedance dc termination with a high

impedance ac termination, and second as part of the

dc signalling system for automated line testing

capability. The CPC1465 meets or exceeds the

requirements for an NT1 dc termination as described

in ANSI T1.601-1991.

Whereas the SHDSL modem application does not

have a signalling requirement, the signaling function

provides an excellent method to monitor for the loss of

sealing current. Generally, loss of sealing current in an

SHDSL application indicates loop loss.

As can be seen in the application circuit in Figure 1 on

page 1, CPC1465 designs require few external

components. For the most basic design, all that is

needed is a circuit protector, two resistors and a

capacitor.

2.2 Surge Protection

Although the CPC1465 is current limited, it is not an

over-voltage surge protector. To protect the CPC1465

against destructive over-voltage transients, IXYS

Integrated Circuits recommends the use of a

crowbar-type surge protector that limits the surge

voltage seen by the CPC1465 to 250 V. The protection

device must be able to withstand the surge

requirements specified by the appropriate governing

agency in regions where the product will be deployed.

Littelfuse, Inc. makes suitable surge protectors for

most applications. Devices such as Littelfuse's

P1800SCL or P2000SCL SIDACtor devices should

provide suitable protection.

2.3 Bridge Rectifier

The bridge rectifier in the CPC1465 ensures that the

device is polarity insensitive and provides consistent

operational characteristics if the tip and ring leads are

reversed.

2.4 State Transitions

The dc tip to ring voltage-current characteristics of the

CPC1465 are shown in Figure 2‚ “I-V Requirements

Template, 0 V to 50 V”, and in Figure 3‚ “I-V

Requirements Template, 0 V to 250 V” on page 5.

Transition timings are illustrated in Figure 7‚ “Applied

Waveform for Activation Test”, and in Figure 8‚

“Applied Waveform for Deactivation Test”. The test

configuration for these timings is given in Figure 6‚

“Test Circuit for Activate and Deactivate Times”. All

timing figures are located on page 7.

State transition timings are set by the 1

F capacitor

connected between the TC and COM pins.

2.4.1 Activation - On-State

Application of battery voltage to the loop causes the

CPC1465 to conduct whenever the voltage exceeds

approximately 35 V. With application of sufficient

voltage applied across the tip and ring terminals, the

CPC1465 will initially conduct a nominal 150

A of

sealing current for approximately 20 ms prior to

activation. Once activated, the CPC1465 will remain in

the on state for as long as the loop current exceeds a

nominal 0.5 mA.

The CPC1465 turn-on timing circuit assures device

activation will occur within 50 ms of an applied voltage

greater than 43.5 V but not within the first 3 ms.

2.4.2 Deactivation - Off-State

While the CPC1465 activation protocol is based on an

initial minimum voltage level, deactivation is based on

a diminished sealing current level. Deactivation occurs

when the nominal sealing current level drops below

0.5 mA with guaranteed deactivation occurring for

sealing current levels less than 0.1 mA

CPC1465D Datasheet(PDF) 10 Page - IXYS Corporation

CPC1465D Datasheet(HTML) 10 Page - IXYS Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Datasheet Download

Link URL