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1.4 Pin Description
Note: The signal and pin names prefixed by # in this manual are those of active-low signals and pins.
Pin name Pin No.
Type
INP
1
Input
Analog
INN
2
Input
Analog
FB
3
Output
Analog
CASIN
4
Input
Analog
CASFB
5
Output
Analog
V
6
Output
REF
Analog
EXTREF
7
Input
Analog
HOOK
8
Input
Analog
RDIN
9
Schmitt
trigger input
S1C05251 TECHNICAL MANUAL
Table 1.4.1 Pin description
Power-down
status
Off/
+ Input: Non-inverting amplifier input. This pin is connected to the
Active
telephone wire through an input gain-setting resistor and a DC cut
capacitor. Under the power down mode, this pin is functionary
disconnected from the internal circuitry when the MODE1 pin is set to
low level. When the MODE1 pin is set to high level, this pin stays
active to detect FSK signal energy to send wake up signal to the host
through the #IRQ pin. Do not connect any external components to this
pin except gain setting resistors to this pin. Excess load may cause
improper operation of the circuit.
Off/
- Input: Inverting amplifier input. This pin is connected to the
Active
telephone wire through an input gain-setting resistor and a DC cut
capacitor. Under the power down mode, this pin is functionary
disconnected from the internal circuitry when the MODE1 pin is set to
low level. When the MODE1 pin is set to high level, this pin stays
active to detect FSK signal energy to send wake up signal to the host
through the #IRQ pin. Do not connect any external components to this
pin except gain setting resistors to this pin. Excess load may cause
improper operation of the circuit.
High-Z/
Amplifier Output: A feed back resistor is connected between this pin
Active
and the INN pin to set gain. Under the power down mode, this output
pin is set to high impedance when the MODE1 pin is set to low level.
When the MODE1 pin is set to high level in power down, this pin stays
active to detect FSK signal energy to send wake up signal to the host
through the #DET pin. Do not connect any external components to
this pin except a gain setting resistor to this pin. Excess load may
cause improper operation of the circuit.
Off
CAS Tone Input: CAS tone amplifier input. For the telephone
application, this pin is connected to the output of telephone hybrid
circuit through input gain-setting resistor and a DC cut capacitor.
Under the power down mode, this pin is functionary disconnected
from the internal circuitry. Do not connect any external components to
this pin except gain setting resistors to this pin. Excess load may
cause improper operation of the circuit.
High-Z
CAS Amplifier Output: A feed back resistor is connected between
this pin and the CASIN pin to set CAS gain. Under the power down
mode, this output pin is set to high impedance. Do not connect any
external components to this pin except a gain setting resistor to this
pin. Excess load may cause improper operation of the circuit.
High-Z/
Reference Voltage Output: 1/2 V
bypassed to ground through 0.1 µF capacitor. During power down
V
/2 level
DD
mode, this output pin is set to high impedance when the MODE1 pin
is low level. When the MODE1 pin is set to high level in power down,
this pin stays at V
this pin except a jumper to V
Excess load may cause improper operation of the circuit.
Active
External Reference Voltage Input: External DC reference voltage is
connected to this pin. This voltage set the off-hook detection threshold
level.
Active
Off-Hook Detection Input: Diode bridge output from the TIP/RING
lines is connected to this pin through external resistor divider to detect
off-hook/on-hook states.
Active
Ring Detect Input: The attenuated ring signal is connected to this pin
for the ring detection. This circuit is always active even if the device is
in the power down mode.
EPSON
Description
voltage output. This pin must be
DD
/2. Do not connect any external components to
DD
pin or a bypass capacitor to ground.
REF
1 OVERVIEW
3
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