Datasheet
SPI/MICROWIRE-Compatible UART and ±15kV ESD-
Protected RS-232 Transceivers with Internal Capacitors
Pin Description
Positive terminal of internal inverting charge-pump capacitor. Do not make any connection to this terminal.
C2+24
Negative terminal of internal inverting charge-pump capacitor. Do not make any connection to this terminal.
C2-25
-5.5V generated by the internal charge pump. Do not make any connection to this terminal.
V-26
GroundGND27
RS-232 Transmitter Output 2T2OUT28
UART Active-Low Interrupt Output. Open-drain interrupt output to microprocessor.
IRQ
19
Hardware Shutdown Input. Drive SHDN low to shut down the RS-232 transmitters and charge pump. Drive
high for normal operation.
SHDN
20
+5.5V generated by the internal charge pump. Do not make any connection to this terminal.
V+21
Positive terminal of the internal voltage-doubler charge-pump capacitor. Do not make any connection to
this terminal.
C1+22
Negative terminal of the internal voltage-doubler charge-pump capacitor. Do not make any connection to
this terminal.
C1-23
SPI/MICROWIRE Serial-Data Input. Schmitt-trigger Input.DIN15
SPI/MICROWIRE Serial-Data Output. High impedance when CS is high.
DOUT16
SPI/MICROWIRE Serial-Clock Input. Schmitt-trigger input.SCLK17
UART Active-Low Chip-Select Input. DOUT goes high impedance when CS is high. IRQ, TX, and RTS are
always active. Schmitt-trigger input.
CS
18
UART Asynchronous Serial-Data (transmitter) OutputTX14
UART Crystal Connection. Leave X2 unconnected when using an external CMOS clock. See the
Crystals,
Oscillators, and Ceramic Resonators
section.
X29
UART Crystal Connection. X1 also serves as an external CMOS clock input. See the
Crystals, Oscillators,
and Ceramic Resonators
section.
X110
UART Clear-to-Send Active-Low Input. Read via the CTS bit.
CTS
11
UART Request-to-Send Active-Low Output. Controlled by the RTS bit. Also used to control the driver enable
in RS-485 networks.
RTS
12
UART Asynchronous Serial-Data (receiver) Input. The serial information received from the RS-232 receiver.
A transition on RX while in shutdown generates an interrupt (Table 1).
RX13
RS-232 Receiver Output 1, TTL/CMOSR1OUT5
RS-232 Receiver Input 1R1IN6
RS-232 Transmitter Output 1T1OUT7
Positive Supply VoltageV
CC
8
RS-232 Transmitter lnput 1, TTL/CMOST1IN4
RS-232 Transmitter lnput 2, TTL/CMOST2IN3
PIN
RS-232 Receiver Output 2, TTL/CMOSR2OUT2
RS-232 Receiver Input 2R2IN1
FUNCTIONNAME
Maxim Integrated
9
MAX3110E/MAX3111E