15

14

8

1

2

3

4

7

DIN1

PWRDOWN

NC

13

DOUT1

20

17

16

19

18

ROUT1

5

6

+

−

C3

VCC

C2+

C1

C2

C1+

GND

V−

C1−

RIN1

C2−

+

−

CBYPASS

= 0.1 µF

V+

+

−

+

−

DOUT2

EN

C4

+

−

9

10

Powerdown

12

11

DIN2

NC

RIN2

ROUT2

12

MAX3222

SLLS408H – JANUARY 2000 – REVISED OCTOBER 2016

www.ti.com

Product Folder Links: MAX3222

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Copyright © 2000–2016, Texas Instruments Incorporated

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

9.1 Application Information

The MAX3222 interfaces a universal asynchronous receiver / transmitter (UART) to RS-232 port voltage levels.

External capacitors are used to generate RS-232 compliant voltages. For proper operation, add capacitors as

shown in Figure 8.

9.2 Typical Application

ROUT and DIN connect to UART or general purpose logic lines. RIN and DOUT lines connect to a RS232

connector or cable.

C3 can be connected to VCC or GND.

Resistor values shown are nominal.

NC

− No internal connection

Nonpolarized ceramic capacitors are acceptable. If polarized tantalum or electrolytic capacitors are used, they should

be connected as shown.

Figure 8. Recommended Application Schematic

9.2.1 Design Requirements

•

Recommended VCC is 3.3 V or 5 V. 3 V to 5.5 V is also possible

•

Maximum recommended bit rate is 250 kbit/s.

Table 3. VCC vs Capacitor Values

VCC

C1

C2, C3, and C4

3.3 V ± 0.3 V

0.1 µF

0.1 µF

5 V ± 0.5 V

0.047 µF

0.33 µF

3 V ± 5.5 V

0.1 µF

0.47 µF