HT95C200/20P/300/30P
Rev. 0.10
29
October 1, 2002
Preliminary
Line control function
Register
Label
Bits
R/W
Function
LINE
(22H)
6~0
RO
Unused bit, read as 0
LINEC
7
RW
1: Enable the line control function
0: Disable the line control function
The line control function is enabled by the flag LINEC
Conditions
Source to Enable
Line Control Function
LINEC
Operation Mode
1
Normal or Green mode
RTC time out interrupt
1
Sleep mode
Port A wake-up
RTC time out interrupt
1
Idle mode
Port A wake-up
Whenthelinecontrolsourceisactivated,thePOpinwillbesettohighsignal.ClearingLINECto0willterminatetheline
control function and drive PO pin outputs low signal.
RTC function
Register
Label
Bits
R/W
Function
RTCC
(24H)
6, 4~0
RO
Unused bit, read as 0
RTCEN
5
RW
1: Enable RTC function
0: Disable RTC function
RTCTO
7
RW
1: RTC time-out occurs
0: RTC time-out not occurs
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The real time clock (RTC) is used to supply a regular in-
ternal interrupt. Its time-out period is 1000ms. If the RTC
time-out occurs, the interrupt request flag RTCF and the
RTCTO flag will be set to 1. The interrupt vector for the
RTC is 14H. When the interrupt subroutine is serviced,
the interrupt request flag (RTCF) will be cleared to 0, but
the flag RTCTO remain in its original value. If the
RTCTO flag is not cleared, next RTC time-out interrupt
will occur.
Low battery detection
The phone controller provides a circuit that detects the
LBIN pin voltage level. To enable this detection func-
tion, the LBEN should be written as 1. Once this function
is enabled, the detection circuit needs 50 s to be stable.
After that, the user could read the result from LBFG. The
low battery detect function will consume power. For
power saving, write 0 to LBEN if the low battery detec-
tion function is unnecessary.
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The battery low threshold is determined by external R1
and R2 resistors.
1.15=V
R2
R1
R2
DET
V
DET
=1.15
(R1
R2)
R2
If we want to detect V
DET
=2.4V
then 2.4V=1.15
(R1
R2)
R2
R1=1.087R2