HT95LXXX
Dialer I/O Function
A special dialer I/O circuit is built into the telephone controller for dialing application. These specially designed I/O cells
allows the controller to work under a low voltage condition that usually happens when the subscriber¢s loop is long.
Dialer I/O pin function:
Name
I/O
Description
XMUTE pin output is controlled by software. This is an NMOS open drain structure
XMUTE
NMOS Output pulled to VSS during dialing signal transmission. Otherwise, it is an open circuit.
XMUTE is used to mute the speech circuit when transmitting the dialer signal.
DNPO pin is an NMOS output, usually by means of software to make/break the line.
DNPO
PO
NMOS Output
This pin is only controlled by software.
This pin is controlled by the HKS, HFI and HDI pins.
CMOS Output When PO pin is high, the telephone line is make.
When PO pin is low, the telephone line is break.
This pin controls the PO pin directly.
This pin is used to monitor the status of the hook-switch and its combination with
HFI/HDI can control the PO pin output to make or break the line.
Schmitt Trigger
HKS
A rising edge to HKS pin will cause the dialer I/O to be on-hook status and generate
Input
an interrupt, its vector is 18H.
A falling edge to HKS pin will cause the dialer I/O to be off-hook status and clear HFO
and HDO flags to 0. This falling edge will also generate an interrupt, its vector is 18H.
Supported for HT95L400/40P, HT95L300/30P, HT95L200/20P, HT95L100/10P
This pin is controlled directly by HDI, HKS and HFI pin.
CMOS Output
HDO
HDI
When HDO pin is high, the hold-line function is enabled and PO outputs a high signal
to make the line.
Supported for HT95L400/40P, HT95L300/30P, HT95L200/20P, HT95L100/10P
A low pulse to HDI pin (hold-line function request) will clear HFO to 0 and toggle HDO
Schmitt Trigger and generates an interrupt, its vector is 18H.
Input
This pin controls the HFO and HDO pins directly.
This pin is functional only when the line is made, that is, off-hook or hand-free
(PO output high signal).
This pin is controlled directly by HFI, HDI and HKS pins.
HFO
HFI
CMOS Output When HFO pin is high, the hand-free function is enabled and PO outputs a high
signal to make the line.
A high pulse to HFI pin (hand-free function request) will clear HDO to 0 and toggle
Schmitt Trigger
HFO and generates an interrupt, its vector is 18H.
Input
This pin controls the PO, HFO and HDO pins directly.
The following are the recommended circuit for HFI and HDI pins.
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Rev. 1.20
25
May 26, 2004
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
