HT95LXXX

Rev. 1.20

27

May 26, 2004

Line Control Function (Supported for HT95L400/40P, HT95L300/30P, HT95L200/20P, HT95L100/10P)

Register

Label

Bits

R/W

Function

LINE

(22H)

¾

6~0

RO

Unused bit, read as

²0²

LINEC

7

RW

1: Enable the line control function

0: Disable the line control function

The line control function is enabled by 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

When the line control source is activated, the PO pin will be set to high signal. Clearing LINEC to 0 will terminate the line

control function and drive PO pin outputs low signal.

RTC Function

Register

Label

Bits

R/W

Function

RTCC

(24H)

¾

6, 4~0

RO

Unused bit, read as

²0²

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

L i n e C o n t r o l

C i r c u i t

R T C I n t e r r u p t

P o r t A W a k e - u p F u n c t i o n

L I N E C = 1

P O = 1

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

(Supported for HT95L400/40P, HT95L300/30P,

HT95L200/20P, HT95L100/10P)

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

ms 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.

L B I N

L B F G

1 . 1 5 V R e f e r e n c e V o l t a g e

L B E N

The battery low threshold is determined by external R1

and R2 resistors.

1.15=

VxR2

R1+ R2

DET

1.15x(R1+ R2)

R2

then 2.4V=

1.15x(R1+ R2)

R2

® R1=1.087R2