em78p811 ELAN Microelectronics Corp, em78p811 Datasheet - Page 25

• Manufacturer Part Number: em78p811
• Description: 8-bit Micro-controller
• Manufacturer: ELAN Microelectronics Corp

VII.9 FSK FUNCTION
VII.9.1 Functional Block Diagram
VII.9.2 Function Descriptions
the Regional Bell Operating Companies.The FSK block comprises two paths: the signal path and the ring indicator path.
The signal path consist of an input differential buffer,a band pass filter, an FSK demodulator and a data valid with carrier
detect circuit. The ring detector path includes a clock generator, a ring detect circuit .
are inhibited. If a ring signal is sent, the /RINGTIME pin will has a low signal. User can use this signal to wake up
whole chip or read /RD signal from RA register.
/FSKPWR is sent low, the FSK block will power down whenever it detects a valid ring signal, it will power on when
/FSKPWR is high.
signal to a band pass filter. Once the signal is filtered, the FSK demodulator decodes the information and sends it to a post
filter. The output data is then made available at DATA OUT pin. This data, as sent by the central office, includes the
header information (alternate "1" and "0") and 150 ms of marking which precedes the date , time and calling number. If no
data is present, the DATA OUT pin is held in a high state. This is accomplished by an carrier detect circuit which
determines if the in-band energy is high enough. If the incoming signal is valid and thus the demodulated data is
transferred to DATA OUT pin . If it is not, then the FSK demodulator is blocked.
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* This specification is subject to be changed without notice.
/Ring Time
Ring det1
Ring
Tip
The CALLER ID IC is a CMOS device designed to support the Caller Number Deliver feature which is offered by
In a typical application, the ring detector maintains the line continuously while all other functions of the chip
A /FSKPWR input is provided to activate the block regardless of the presence of a power ring signal. If
The input buffer accepts a differential AC coupled input signal through the TIP and RING input and feeds this
Ring
Det
Circuit
Band Pass
Filter
OSC out
OSC in
Fig15. FSK Block Diagram
FSK
demodul
Power
Up
24
CLOCK
Data Valid
Energy Det
Circuit
/FSKPWR
8-bit OTP Micro-controller
DATA OUT
/CD
/RD
EM78P811