SPI/MICROWIRE-Compatible UART and ±15kV ESD-

Protected RS-232 Transceivers with Internal Capacitors

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9

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

Ground

GND

27

RS-232 Transmitter Output 2

T2OUT

28

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.

DIN

15

SPI/MICROWIRE Serial-Data Output. High impedance when CS is high.

DOUT

16

SPI/MICROWIRE Serial-Clock Input. Schmitt-trigger input.

SCLK

17

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) Output

TX

14

UART Crystal Connection. Leave X2 unconnected when using an external CMOS clock. See the

Crystals,

Oscillators, and Ceramic Resonators section.

X2

9

UART Crystal Connection. X1 also serves as an external CMOS clock input. See the

Crystals, Oscillators,

and Ceramic Resonators section.

X1

10

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).

RX

13

RS-232 Receiver Output 1, TTL/CMOS

R1OUT

5

RS-232 Receiver Input 1

R1IN

6

RS-232 Transmitter Output 1

T1OUT

7

Positive Supply Voltage

8

RS-232 Transmitter lnput 1, TTL/CMOS

T1IN

4

RS-232 Transmitter lnput 2, TTL/CMOS

T2IN

3

PIN

RS-232 Receiver Output 2, TTL/CMOS

R2OUT

2

RS-232 Receiver Input 2

R2IN

1

FUNCTION

NAME