9

current limiting resistor coupled with the larger charge

storage capacitor yields a test that is much more severe than

the HBM test. The extra ESD protection built into this

device’s RS-232 pins allows the design of equipment

meeting level 4 criteria without the need for additional board

level protection on the RS-232 port.

AIR-GAP DISCHARGE TEST METHOD

For this test method, a charged probe tip moves toward the

IC pin until the voltage arcs to it. The current waveform

delivered to the IC pin depends on approach speed,

humidity, temperature, etc., so it is difficult to obtain

repeatable results.The “E” device RS-232 pins withstand

±15kV air-gap discharges.

CONTACT DISCHARGE TEST METHOD

During the contact discharge test, the probe contacts the

tested pin before the probe tip is energized, thereby

eliminating the variables associated with the air-gap

discharge. The result is a more repeatable and predictable

test, but equipment limits prevent testing devices at voltages

higher than

±8kV. All “E” family devices survive ±8kV contact

discharges on the RS-232 pins.

FIGURE 8. TRANSMITTER OUTPUT VOLTAGE vs LOAD

CAPACITANCE

FIGURE 9. SLEW RATE vs LOAD CAPACITANCE

FIGURE 10. SUPPLY CURRENT vs LOAD CAPACITANCE

WHEN TRANSMITTING DATA

FIGURE 11. SUPPLY CURRENT vs SUPPLY VOLTAGE

-6

-4

-2

0

2

4

6

1000

2000

3000

4000

5000

0

LOAD CAPACITANCE (pF)

1 TRANSMITTER AT 250kbps

OTHER TRANSMITTERS AT 30kbps

LOAD CAPACITANCE (pF)

0

1000

2000

3000

4000

5000

5

10

15

20

25

+SLEW

-SLEW

-SLEW

20

25

30

35

40

55

45

50

0

1000

2000

3000

4000

5000

LOAD CAPACITANCE (pF)

20kbps

250kbps

120kbps

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

0

0.5

1.0

1.5

2.0

SUPPLY VOLTAGE (V)

2.5

3.0

3.5

NO LOAD

ALL OUTPUTS STATIC

ISL83239E