Datasheet > L7556

L7556

更新时间： 2024-02-27 14:08:39

品牌	Logo	应用领域
杰尔 - AGERE		电池开关
页数	文件大小	规格书
28页	676K
描述
Low-Power SLICs with Battery Switch

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L7556 数据手册

Data Sheet

January 2000

L7556, L7557 Low-Power SLICs

with Battery Switch

Features

Description

■ Auxiliary input for second battery, and internal

switch to enable its use to save power

These electronic subscriber loop interface circuits

(SLICs) are optimized for low power consumption

while providing an extensive set of features.

■ Low active power (typical 125 mW during on-hook

transmission)

The SLICs include an auxiliary battery input and a

built-in switch. In short-loop applications, they can be

used in high battery to present a high on-hook volt-

age, and then switched to low battery to reduce off-

hook power.

■ Supports meter pulse injection

■ Spare op amp for meter pulse filtering

■ –16 V to –60 V power supply operation

■ Distortion-free on-hook transmission

The SLICs also include a summing node for meter

pulse injection to 2.2 Vrms. A spare, uncommitted op

amp is included for meter pulse filtering.

■ Convenient operating states:

— Forward powerup

— Disconnect (high impedance)

— 2-wire wink (zero loop voltage)

The switched battery is applied to the power amplifi-

ers of the device. There are two versions. The L7556

has the battery switch completely under processor

control. The L7557 can automatically switch to lower

battery when appropriate and includes hysteresis to

avoid frequent switching. To make the switch silent,

an external capacitor can be added to slow the tran-

sition.

■ Adjustable supervision functions:

— Off-hook detector with longitudinal rejection

— Ground key detector

— Ring trip detector

■ Independent, adjustable, dc and ac parameters:

— dc feed resistance

— Loop current limit

The L7556 is suited for applications serving only

short loops, where a high on-hook voltage is required

for compatibility with preexisting standards.

— Termination impedance

■ Thermal protection

The L7557 is suited for applications where a full loop

range is needed, but low short-loop power is desired.

It is a much lower-cost solution than a switching reg-

ulator, and also occupies much less PCB area, need-

ing only a battery filter capacitor and a diode for

implementation.

The device is available in a 32-pin PLCC package. It

is built by using a 90 V complementary bipolar inte-

grated circuit (CBIC) process.

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