AS2525F datasheet(10/28 Pages) AMSCO

10 / 28 page

Datasheet AS2525

austriamicrosystems

Revision 2.1

Page 9 of 27

Memory Allocation

The EEPROM memory consists of three areas:

A = factory settings; B = user settings; C = stored numbers

A) factory settings

B) user settings

C) stored numbers

programmed in factory

Set-up programming

User-code programming

"reset to factory settings"

…write/read by AS2525

EEPROM

Figure 3: Memory allocation for external EEPROM

The AS2525 is writing and reading to and from area B and

C during normal operation and user-code programming.

Area A is protected during normal operation and contains a

back-up copy of the factory settings. This back-up copy

can be loaded into area B by the user with the user-code

programming procedure "reset to factory settings". The

only way to change the factory settings in area A is by set-

up programming using password. After changing area A by

set-up programming, the AS2525 automatically performs a

"reset to factory settings" to load this changes also into

area B.

Functional Description

DC Conditions

The normal operating mode is from 15 mA to 100 mA. An

operating mode with reduced performance is from 5 mA to

15 mA. In the line-hold range from 0 mA to 5 mA the device

is in a power down mode.

The dc characteristic is determined by the voltage at LI pin

and a 30

Ω resistor between pin LI and LS. It can be

calculated by the following equation:

VLS = VLI + ILINE * 30

Ω

VLI can be programmed to be 3.5 V or 4.5 V.

Table 7: DC mask selection

[PG] + [0] + (Password) + [#] + [3] + (digit) + [PG]

Digit

DC Mask (dc voltage at pin LI)

[0]

Low dc mask, VLI = 3.5 Volt

[1]

High dc mask, VLI = 4.5 Volt

100

ILine

VLine

VLS

VLI

(V)

(mA)

Figure 4: DC characteristic with low dc mask

2/4 Wire Conversion

AS2525 has a built-in dual Wheatstone bridge with one

common ground. This provides a maximum of

independence of ac impedance and side-tone from each

other. One can adapt side-tone without changing the ac

impedance.

AC Impedance

The ac impedance of AS2525 is set to 1000

Ω. A complex

impedance can be adjusted by connecting an external

capacitor to the CI pin. With an external resistor of

approximately 1.5 k

Ω connected to the LS pin, it can be

programmed to 600

Ω.

ZAC(syn) = 33

∗ 30

Ω

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