Typical Characteristics

Transmitter Output High Voltage vs. Load Capacitance

Transmitter Slew Rate vs. Load Capacitance

20048002

20048003

Application Information

CAPACITOR SELECTION

The recommended capacitors are 0.1µF. However, larger

capacitors for the charge pump may be used to minimized

ripples on V+ and V− pins.

POWER SUPPLY DECOUPLING

In some applications that are sensitive to power supply noise

from the charge pump, place a decoupling capacitor, Cbp,

from V

size as the charge pump capacitors (C1 − C4).

CHARGED PUMP

transmitters. Using capacitor C1, the charge pump converts

+5V to +10V then stores the +10V in capacitor C3. The

charge pump uses capacitor C2 to invert the +10V to −10V.

The −10V is then stored in capacitor C4.

ELECTROSTATIC DISCHARGE PROTECTION

ESD protection has been placed at all pins to protect the

device from ESD. All pins except for the transmitter output

pins (pins 7 and 14) and receiver input pins (pins 8 and 13)

have a ESD rating of 2kV Human Body Model (HBM) and

200V Machine Model (MM). The RS-232 bus pins (pins 7, 8,

13 and 14) have a more robust ESD protection. The RS-232

bus pins have a ESD rating of 15kV HBM and IEC 1000-4-2,

air-gap. In addition the bus pins meet an ESD rating of 8kV

with IEC 1000-4-2, contact. The ESD structures can with-

stand a high ESD event under the following conditions:

powered-on, powered-off, and Input connected to high and

low with outputs unloaded.

HUMAN BODY MODEL

The Human Body Model is an ESD testing standard, defined

in Mil-STD-883C method 3015.7. It simulates a human dis-

charging an ESD charge to the IC device. The rise time is

approximately 10 ns and decay time is approximately 150

ns. The waveform is obtained by discharging 2kV volts ca-

pacitor through a resistor, R2 = 1.5 k

Ω. The peak current is

approximately 1.33A.

20048004

FIGURE 1. HBM ESD Test Model

20048005

FIGURE 2. HBM Waveform

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