HCPL-8100 데이터 시트보기 (PDF) - HP => Agilent Technologies

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HCPL-8100

High Current Line Driver

HP => Agilent Technologies 

Although the series coupling

impedance is minimized to

reduce insertion loss, it has to

be sufficiently large to limit

the peak current to the

desired level in the worst

expected powerline load

condition. The peak output

current is effectively limited by

the total series coupling

resistance, which is made up

of the series resistance of L2,

the series resistance of the

fuse and any other resistive

element connected in the

coupling network.

To reduce power dissipation

when not operating in transmit

mode the line driver stage is

shut down to a low power

high impedance state by

pulling the Tx-en input (pin 2)

to logic low state.

External Transient Voltage

Protection

To protect the HCPL-8100 and

HCPL-0810 from high voltage

transients caused by power

surges and disconnecting/

connecting the modem, it is

necessary to add an external

6.8 V bi-directional transient

voltage protector (as

component D1 shown in Figure

17).

Additional protection from

powerline voltage surges can

be achieved by adding an

appropriate Metal Oxide

Varistor (MOV) across the

powerline terminals after the

fuse.

Internal Protection and Sensing

The HCPL-8100 and HCPL-

0810 include several sensing

and protection functions to

ensure robust operation under

wide ranging environmental

conditions.

The first feature is the VCC

Under Voltage Detection (UVD).

In the event of VCC dropping

to a voltage less than 4 V, the

output status pin is switched

to a logic high state.

The next feature is the over-

temperature shutdown. This

particular feature protects the

line driver stage from over-

temperature stress. Should the

IC junction temperature reach

a level above 150°C, the line

driver circuit will be shut

down and the output of Status

(pin 1) is pulled to the logic

high state simultaneously.

The final feature is load

detection function. The

powerline impedance is quite

unpredictable and varies not

just at different connection

points but is also time variant.

The HCPL-8100 and HCPL-

0810 include a current sense

feature, which may be utilized

to feedback information on the

instantaneous powerline load

condition. Should the peak

current reach a level greater

than 0.5 APP, the output of

status pin is pulled to a logic

high state for the entire period

the peak current exceeds -0.25

A as shown in Figure 12.

Using the period of the pulse

together with the known

coupling impedance, the actual

powerline load can be

calculated. Table 2 shows the

logic output of the Status pin.

Table 2. Status pin logic

Status output

Normal

Low

VCC < 4 V

High

Over-Temperature

High

ITx-out < − 0.25 A

High (pulsed)

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