MAX211

5V MULTICHANNEL RS232 LINE DRIVER/RECEIVER

WITH ±15kV ESD PROTECTION

SLLS567E − MAY 2003 − REVISED JANUARY 2004

11

POST OFFICE BOX 655303

APPLICATION INFORMATION

capacitor selection

The capacitor type used for C1−C4 is not critical for proper operation. The MAX211 requires 0.1-

µF capacitors,

although capacitors up to 10

µF can be used without harm. Ceramic dielectrics are suggested for the 0.1-µF

capacitors. When using the minimum recommended capacitor values, make sure the capacitance value does

not degrade excessively as the operating temperature varies. If in doubt, use capacitors with a larger (e.g., 2

×)

nominal value. The capacitors’ effective series resistance (ESR), which usually rises at low temperatures,

influences the amount of ripple on V+ and V−.

Use larger capacitors (up to 10

µF) to reduce the output impedance at V+ and V−.

capacitors (C1−C4).

electrostatic discharge (ESD) protection

Texas Instruments MAX211 devices have standard ESD protection structures incorporated on the pins to

protect against electrostatic discharges encountered during assembly and handling. In addition, the RS232 bus

pins (driver outputs and receiver inputs) of these devices have an extra level of ESD protection. Advanced ESD

structures were designed to successfully protect these bus pins against ESD discharge of

±15 kV when powered

down.

ESD test conditions

ESD testing is stringently performed by TI, based on various conditions and procedures. Please contact TI for

a reliability report that documents test setup, methodology, and results.

Human-Body Model

The Human-Body Model (HBM) of ESD testing is shown in Figure 7. Figure 8 shows the current waveform that

is generated during a discharge into a low impedance. The model consists of a 100-pF capacitor charged to

the ESD voltage of concern and subsequently discharged into the DUT through a 1.5-k

Ω resistor.

−

+

DUT

RD

1.5 k

Ω

VHBM

100 pF

CS

Figure 7. HBM ESD Test Circuit