AM79489 Ver la hoja de datos (PDF) - Unspecified

Número de pieza

componentes Descripción

Lista de partido

AM79489

Subscriber Line Interface Circuit

Unspecified 

State

0

1

2

3

4

5

6

7

C3 C2 C1

0 00

0 01

0 10

0 11

1 00

1 01

1 10

1 11

Table 1. SLIC Decoding

DET Output

2-Wire Status

E1 = 1

E1 = 0

Standby, Reverse Polarity Loop detector

GK

Reserved

X

X

Active, Reverse Polarity

Loop detector

GK

Tip Open

GK or loop detector GK

Disconnect

Ring trip

Ring trip

Ringing

Ring trip

Ring trip

Active, Normal

Loop detector

GK

Standby, Normal

Loop detector

GK

ZT = 253(Z2WIN – 2RF)

Table 2. User-Programmable Components

ZT is connected between the VTX and RSN pins. The fuse

resistors are RF, and Z2WIN is the desired two-wire AC input

impedance. When computing ZT, the internal current

amplifier pole and any external stray capacitance between

VTX and RSN must be taken into account. The internal

amplifier pole is:

-2--2------k---H-----z----•----R----L---A----C-

600 Ω ±10%

ZRX

=

---Z----L---- • ---------------5----0---0----(--Z----T---)----------------

G42L ZT + 253(ZL + 2RF)

ILIMIT

=

----6---2---5---(---G----F----A-----)----

RDC1 + RDC2

CDC

=

1.5

ms

•

-R----D---C---1----+-----R----D---C---2-

RDC1 • RDC2

ZRX is connected from VRX to RSN. ZT is defined above, and

G42L is the desired receive gain. ZL is the 2-wire load

impedance.

RDC1, RDC2, and CDC form the network connected to the RDC

pin. RDC1 and RDC2 are approximately equal. ILIMIT is the

desired loop current in the constant-current region.

GFA

=

0.99

•

(---R----F----A------+-----3---0---.-1-----k---Ω-----)-

(RFA + 32 kΩ)

RCL

=

1.4

•

(RDC1

+

RDC2)

•

--(--R-----F---A------+-----6---0-----k---Ω-----)--

(RFA + 100 kΩ)

RD

=

3----6---5- ,

IT

CD

=

0----.-5-----m----s-

RD

CCAS

=

--------------1---------------

3.4 • 105πfc

IS tandby

=

--V-----B---A----T---1-----–-----3----V---

400 Ω + RL

RD and CD form the network connected from RD to AGND/

DGND and IT is the threshold current between on hook and

off hook in the Active state.

CCAS is the regulator filter capacitor and fc is the desired filter

cutoff frequency.

Standby loop current (resistive region).

10

Am79489 Data Sheet

Share Link: