S1T8527C Datasheet, PDF (5/20 Pages) Samsung semiconductor – 1 CHIP CLP SUBSYSTEM IC

1 CHIP CLP SUBSYSTEM IC
S1T8527C
PIN DESCRIPTION (Continued)
Pin No
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Symbol
Description
SAO 1
Output terminal of Speaker amp 1.
DC voltage level is ( Vcc — 0.7V ) / 2.
SAI
Speaker Amp 1 input terminal.
Between this terminal and Expander output terminal, uses a AC coupled.
EO
Output terminal of Expander, from which a regenerated voice signals are emitted.
ERC
Converts waveform from the full wave rectifier to DC element at the rectifier block of
Expander. ( RC = 33 msec )
EPI −
Pre-amp inverting input terminal of Expander.
Adjusts the negative feedback loop gain. ( in application, gain is 5 ).
ALC
Reference current input terminal of Automatic Level Control ( ALC); Adjusts THD of
compressor output voltage to less than 3% or limits the frequency deviation of TX if the
input is higher than a certain level. The ALC circuit may be turned off depending on the
ALC reference current or the magnitude of output voltage may be limited if it is higher
than a certain level.
V_REF(COMP) Reference voltage ( V_REF= 1V ). Supplies a regulator voltage to the Compressor and
Expander of COMPANDER.
MDO
Output terminal of the Meter Driver.
Amplitude of RF input signal for useful frequency is detected by Meter Driver circuit.
The Meter Driver circuit has perfect linear characteristic of 60dB range for input signal
level. ( 0.1µA / dB ).
DSCO
Output terminal of Data Slicing comparator.
Separates Frequency Shift Keying ( FSK ) serial data and executes data shaping and
limiting.
DSCI
Input terminal of Data slicing comparator.
Non-inverting type with the negative input terminal biased to 1/2 Vcc.
RAO
Recovered Audio Output terminal. Voice signals detected by the Quadrature Detector
are amplified and then output through this terminal.
QCI3
Quadrature coil input terminal.
The 455kHz oscillator circuit is an Lp = 680uH, Cp = 180pF valued LC tank circuit.
Voice signals are detected by mixture of 455kHz ( by phase difference ) which is
converted from mixer 2.
GND_RX
Ground .
Ground for Receiver.
LD
Limiter input and decoupling terminal.
LI
Removes amplitude modulation elements caused by fading or FM signal noise. Limiting
IF amplifies and limits the second intermediate frequency, 455kHz.The input
impedance of the limiting IF amplifier is set to 1.5kΩ. While FM waves are transmitted
with constant magnitude, their magnitudes are slightly modulated due to reflection from
obstacles, fading phenomenon, noise wave, and mixing with AM wave elements before
entering the receiver’s antenna.The limiter makes amplitude uniform by removing these
AM wave elements.
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