Sharp FO IS125N - B/W Laser - All-in-One Service Manual page 112

FO-IS125N
CX20548 (IC1100, IC1200) Terminal description
Pin Name Pin No.
PWR 15
VC 3
AVDD 2
DVDD 1
PADDLE (AGND) 17
DIBP 14
DIBN 16
RAC, TAC 4, 5
EIC 11
EIO 10
EIF 9
RXI 6
TXO 8
TXF 7
GPIO 1
Notes:
1. I/O types*:
Ia Analog input
It Digital input*
Oa Analog output
Ot12 Digital output*
AGND_LSD Isolated LSD Analog Ground (isolated from the host system ground)
*See CX20548 LSD GPIO DC Electrical Characteristics. (Page 5-20).
2. Refer to applicable reference design for exact component placement and values.
Pin I/O
System Interface Signals
PWR PWR
REF REF
PWR PWR
PWR PWR
AGND_LSD AGND_LSD
DIB Interface Signals
I/O I/O
I/O I/O
TIP and RING Interface Signals
I, I Ia, a
O Oa
O Oa
I Ia
I Ia
O Oa
I Ia
I/O It/Ot12
I/O Type
Unregulated Power Output. Unregulated power output
from the internal rectifier, connect to AGND_LSD through
C870.
Output Middle Reference Voltage. Connect to
AGND_LSD through C844, which must be placed close to
pin 3. Use a short path and a wide trace to AGND_LSD pin.
Analog Power Output. Provides external connection point
for decoupling. (AVDD is routed internally to LSD analog
circuits.). Connect to AGND_LSD through C828. C828
must be placed close to pins 2.
Digital Power Output. Provides external connection point
for decoupling. Connect to AGND_LSD through C830.
Place C830 near pin 1.
Paddle Analog Ground. The conductive surface located
on the bottom of the package is connected internally to
device analog ground. Connect to AGND_LSD.
DIB Positive. Positive terminal of DIB, connect to second-
ary of DIB transformer.
DIB Negative. Negative terminal of DIB, connect to sec-
ondary of DIB transformer.
RING DC Coupled and TIP DC Coupled. Un-rectified volt-
age from telephone line used to detect ring.
Connect RAC to the diode bridge DC node (RING) through
R802 (connects to pin 4).
Connect TAC to the diode bridge DC node (TIP) through
R804 (connects to pin 5).
Electronic Inductor Capacitor. Electronic inductor filtering
capacitor. Connect to AGND_LSD through C858.
Electronic Inductor Output. Calculated voltage is applied
to this output to control off-hook and DC VI mask operation.
Connect to base of Q804.
Electronic Inductor Feedback. Connect to emitter of
Q804 through R826.
Receive Analog Input. Receiver operational amplifier
inverting input. AC coupled to the Bridge_CC node through
R810 (connects to pin 6) and C810 in series. R810 and
C810 must be placed very close to pin 6. The length of the
PCB trace connecting R810 to the RXI pin must be kept at
an absolute minimum.
Transmit Output. Outputs transmit signal and impedance
matching signal; connect to base of transistor Q802.
Transmit Feedback. Connect to emitter of transistor Q802
Not Used
General Purpose I/O. Leave open if not used.
5 – 21
Signal Description