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5

TVS Diode Arrays

SP721

Electronic Protection Array for ESD and Overvoltage Protection

Peak Transient Current Capability of the SP721

The peak transient current capability rises sharply as the width of the

current pulse narrows. Destructive testing was done to fully evaluate the

SP721’s ability to withstand a wide range of peak current pulses vs time.

The circuit used to generate current pulses is shown in Figure 5.

The test circuit of Figure 5 is shown with a positive pulse input. For a

negative pulse input, the (-) current pulse input goes to an SP721 ‘IN’

input pin and the (+) current pulse input goes to the SP721 V- pin. The

V+ to V- supply of the SP721 must be allowed to float. (i.e., It is not tied

to the ground reference of the current pulse generator.) Figure 6 shows

the point of overstress as defined by increased leakage in excess of the

data sheet published limits.

The maximum peak input current capability is dependent on the ambient

temperature, improving as the temperature is reduced. Peak current

power supply condition. The safe operating range of the transient peak

current should be limited to no more than 75% of the measured over-

stress level for any given pulse width as shown in the curves of Figure 6.

Note that adjacent input pins of the SP721 may be paralleled to improve

current (and ESD) capability. The sustained peak current capability is

increased to nearly twice that of a single pin.

+

-

VOLTAGE

PROBE

+

-

(-)

(+)

C1 ~ 100µF

C1

VARIABLETIME DURATION

CURRENT PULSE GENERATOR

1

2

3

4

8

7

6

5

V+

IN

IN

IN

IN

IN

IN

V-

SP721

CURRENT

SENSE

FIGURE 5. TYPICAL SP721 PEAK CURRENT TEST CIRCUIT

WITH A VARIABLEPULSE WIDTH INPUT

0.001

0.01

0.1

1

PULSE WIDTH TIME (ms)

10

7

6

5

4

3

2

1

0

100

1000

CAUTION: SAFE OPERATING CONDITIONS LIMIT

OF THE VALUES SHOWN ON EACH CURVE.

PULSE WIDTH TO BE NO GREATER THAN 75%

THE MAXIMUM PEAK CURRENT FOR A GIVEN

V+ TO V- SUPPLY = 15V

FIGURE 6. SP721 TYPICAL SINGLE PULSE PEAK CURRENT CURVES SHOWING THE MEASURED POINT OF OVERSTRESS IN

AMPERES vs PULSE WIDTH TIME IN MILLISECONDS