MH88437AS-PI datasheet(4/16 Pages) MITEL

4 / 16 page

MH88437-P

Advance Information

applying a logic 0 to Pin 17, CL, the loop current will

be limited to below 60mA as required in France and

the European TBR21 speciﬁcation. For all other

countries where current limiting is not required, CL

should be set to 1.

The AC input impedance should be set by the user to

match the line impedance.

Input Impedance

The MH88437 has a programmable input impedance

set by ﬁtting external components between the ZA

pin and AGND.

For complex impedances the conﬁguration shown in

Figure 4 (below) is most commonly found.

Figure 4 - Complex Impedances

To ﬁnd the external programming components for

conﬁguration 4, the following formula should be

used:

Zext = [(10 x R1)-1k3]+[(10 x R2)//(C1/10)]

e.g. If the required input impedance = 220

Ω + (820Ω/

/115nF), the external network to be connected to ZA

will be:

ZA = 900

Ω + (8k2Ω//12nF)

Where the input impedance (Z) = 600R the equation

can be simpliﬁed to:

ZA = (10 x Z) - 1k3

Ω

ZA = 4k7

Ω

Note: A table of commonly used impedances can be

found in the DAA Application’s document MSAN-154.

Where Zext = external network connected between

ZA and AGND and Zint = 1.3k

Ω (internal resistance)

between NB1 and NB2. For countries where the

balance impedance matches the line impedance, a

16k

Ω resistor should be added between NB1 and

NB2.

Figure 3 - DC Programming Capability

Iloop=15mA

Iloop=20mA

Iloop=26mA

150

250

350

450

550

650

750

850

950

R2(kOhms)

V(t-r)

MH88437AS-PI Datasheet(PDF) 4 Page - Mitel Networks Corporation

MH88437AS-PI Datasheet(HTML) 4 Page - Mitel Networks Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Datasheet Descarga

Enlace URL