Sharp LC-19D1E/S-BK/WH, Service Manual

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LC-19D1E/S-BK/WH
5 – 10
2.5. IC502 (VHiM3221EIP-1Y)
2.5.1 Block Diagram
2.5.2 Pin Connections and short description
RS232C-DRIVER/RECEIVER
Pin No. Pin Name I/O Pin Function
1 EN I
Receiver Enable Control . Drive low for normal operation. Drive high to force the receiver outputs (R_OUT) into
a high-impedance state.
2 C1+ - Positive terminal of the voltage doubler Charge-Pump Capacitor
3 V+ - +5.5V generated by the charge pump
4 C1- - Negative terminal of the voltage doubler Charge-Pump Capacitor
5 C2+ - Positive terminal of inverting Charge-Pump Capacitor
6 C2- - Negative terminal of inverting Charge-Pump Capacitor
7 V- - -5.5V generated by the charge pump
8 R_IN I RS-232 Receiver Inputs
9 R_OUT O TTL/CMOS Receiver Outputs
10 INVALID I
Output of the Valid Signal Detector. INVALID is enabled high if a valid RS-232 level is present on any receiver
input.
11 T_IN I TTL/CMOS Transmitter Inputs
12 FORCEON I Drive high to override automatic circuitry keeping transmitters and charge pump on (FORCEOFF must be high)
13 T_OUT O RS-232 Transmitter Outputs
14 GND - Ground
15 VCC - +3.0V to +5.5V Supply Voltage
16 FORCEOFF I
Force-Off Input, active low. Drive low to shut down transmitters, receivers (MAX3243E, except R2OUTB), and
on-board charge pump . This overrides all automatic circuitry and FORCE ON