6-12

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 curves are shown for ambient

condition. The safe operating range of the transient peak

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

measured overstress 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 ~ 100

µF

C1

VARIABLE TIME 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 VARIABLE PULSE 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

SP721