Date: 03/08/05

SP385E Enhanced +3V to +5V RS-232 Line Driver/Receiver

© Copyright 2005 Sipex Corporation

7

Shutdown (ON/OFF)

The SP385E has a shut-down/standby mode to

conserve power in battery-powered systems. To

activate the shutdown mode, which stops the

operation of the charge pump, a logic "0" is

applied to the appropriate control line. The

shutdown mode is controlled on the SP385E by

a logic "0" on the ON/OFF control line (pin 18

for the SOIC and pin 20 for the SSOP packages);

this puts the transmitter outputs in a tri-state mode.

ESD Tolerance

The SP385E device incorporates ruggedized

ESD cells on all driver output and receiver input

pins. The ESD structure is improved over our

previous family for more rugged applications

and environments sensitive to electro-static

discharges and associated transients. The

improved ESD tolerance is at least

±15KV with-

out damage nor latch-up.

There are different methods of ESD testing

applied:

a) MIL-STD-883, Method 3015.7

b) IEC1000-4-2 Air-Discharge

c) IEC1000-4-2 Direct Contact

The Human Body Model has been the generally

accepted ESD testing method for semiconductors.

This method is also specified in MIL-STD-883,

Method 3015.7 for ESD testing. The premise of

this ESD test is to simulate the human body’s

potential to store electro-static energy and

discharge it to an integrated circuit.

The

simulation is performed by using a test model as

shown in Figure 6. This method will test the IC’s

capability to withstand an ESD transient during

normal handling such as in manufacturing areas

where the ICs tend to be handled frequently.

The IEC-1000-4-2, formerly IEC801-2, is

generally used for testing ESD on equipment and

systems. For system manufacturers, they must

guarantee a certain amount of ESD protection

since the system itself is exposed to the outside

environment and human presence. The premise

with IEC1000-4-2 is that the system is required

to withstand an amount of static electricity when

ESD is applied to points and surfaces of the

equipment that are accessible to personnel during

normal usage. The transceiver IC receives most

of the ESD current when the ESD source is

applied to the connector pins. The test circuit for

IEC1000-4-2 is shown on Figure 7. There are

two methods within IEC1000-4-2, the Air

Discharge method and the Contact Discharge

method.

Figure 4. Charge Pump — Phase 3

–5V

+5V

–5V

+

+

++

–

–

–

–

Figure 5. Charge Pump — Phase 4

+10V

+

+

++

–

–

–

–

Figure 6. ESD Test Circuit for Human Body Model

SW1

SW2

Device

Under

Test

DC Power

Source

SW1

SW2

Figure 7. ESD Test Circuit for IEC1000-4-2

RS and RV add up to 330Ω for IEC1000-4-2.

RS and RV add up to 330Ω for IEC1000-4-2.

Contact-Discharge Module

SW1

SW2

Device

Under

Test

DC Power

Source

SW1

SW2

Contact-Discharge Module