SP3220EB datasheet(14/21 Pages) SIPEX

14 / 21 page

Date: 8/30/05

SP3220E/EB/EU High ESD RS-232 Driver/Receiver

Date: 8/22/05

SP3220E/EB/EU High ESD RS-232 Driver/Receiver

SW1

SW2

Device

Under

Test

DC Power

Source

SW1

SW2

Figure 20. ESD Test Circuit for Human Body Model

ESD TOLERANCE

The SP3220E/EB/EU device incorporates rugge-

dized 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 im-

proved ESD tolerance is at least ±15kV without

damage nor latch-up.

There are different methods of ESD testing ap-

plied:

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 20. 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 gener-

allyusedfortestingESDonequipmentandsystem

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 IEC-1000-4-2 is shown in Figure 21.

There are two methods within IEC-4-2: the Air

Discharge method and the Contact Discharge

method.

With the Air Discharge Method, an ESD voltage is

applied to the equipment under test (EUT) through

air. This simulates an electrically charged person

ready to connect a cable onto the rear of the

system only to find an unpleasant zap just before

the person touches the back panel. The high

energy potential on the person discharges through

an arcing path to the rear panel system before he

or she even touches the system. This energy,

whether discharged directly or through air, is pre-

dominantly a function of the discharge current

rather than the discharge voltage.

Variables with an air discharge -- such as ap-

proach speed of the object carrying the ESD

potential to the system and humidity -- will tend to

change the discharge current. For example, the

rise time of the discharge current varies with the

approach speed.

Date: 8/22/05

SP3220E/EB/EU High ESD RS-232 Driver/Receiver

The Contact Discharge Method applies the

ESD current directly to the EUT. This method

was devised to reduce the unpredictability

of the ESD arc. The discharge current rise

time is constant since the energy is directly

transfered without the air-gap arc. In situa-

tions such as hand held systems, the ESD

charge can be directly discharged to the

equipment from a person in contact with the

equipment. The current is transferred on to

the keypad or the serial port of the equip-

ment directly and then travels through the

PCB and finally to the IC.

The circuit models in Figure 20 and 21

represent the typical ESD testing circuits

used for all three methods. The C

S is initially

charged with the DC power supply when

the first switch (SW1) is on. Now that the

capacitor is charged, the second switch

(SW2) is on while SW1 switches off. The

voltage stored in the capacitor is then ap-

plied through R

S, the current limiting resis-

tor, onto the device under test (DUT). In

ESD tests, the SW2 switch is pulsed so that

the device under test recives a duration of

voltage.

Figure 21. ESD Test Circuit for IEC1000-4-2

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

Contact-Discharge Module

SW1

SW2

Device

Under

Test

DC Power

Source

SW1

SW2

Contact-Discharge Module

For the Human Body Model, the current

limiting resistor (R

S) and the source capaci-

tor (C

S) are 1.5k

and 100pF, respectively.

For IEC-1000-4-2, the current limiting resis-

tor (RS) and the source capacitor (CS) are

330 and 150pF, respectively.

The higher CS value and lower RS value in

the IEC1000-4-2 model are more stringent

than the Human Body Model. The larger

storage capacitor injects a higher voltage to

the test point when SW2 is switched on. The

lower current limiting resistor increases the

current charge onto the test point.

30A

15A

t=0nS

t=30nS

Figure 22. ESD Test Waveform for IEC1000-4-2

Device Pin

Human Body

IEC1000-4-2

Tested

Model

Air Discharge Direct Contact Level

Driver Ouputs

15kV

8kV

Receiver Inputs

15kV

8kV

SP3220EB Datasheet(PDF) 14 Page - Sipex Corporation

SP3220EB Datasheet(HTML) 14 Page - Sipex Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Datasheet Descarga

Enlace URL