SP721
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
temperatures of 25
o
C and 105
o
C and a 15V power supply
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.
+
V
X
-
R
1
VARIABLE TIME DURATION
CURRENT PULSE GENERATOR
CURRENT
SENSE
(-)
(+)
1 IN
2 IN
3 IN
VOLTAGE
PROBE
4
V-
SP721
V+ 8
IN
IN
IN
7
+
6
5
C1
-
R
1
~ 10Ω TYPICAL
V
X
ADJ. 10V/A TYPICAL
C1 ~ 100µF
FIGURE 5. TYPICAL SP721 PEAK CURRENT TEST CIRCUIT
WITH A VARIABLE PULSE WIDTH INPUT
7
6
5
4
3
2
1
0
0.001
0.01
0.1
1
PULSE WIDTH TIME (ms)
10
100
1000
T
A
= 105
o
C
T
A
= 25
o
C
CAUTION: SAFE OPERATING CONDITIONS LIMIT
THE MAXIMUM PEAK CURRENT FOR A GIVEN
PULSE WIDTH TO BE NO GREATER THAN 75%
OF THE VALUES SHOWN ON EACH CURVE.
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
PEAK CURRENT (A)
6-12
HARRIS [ HARRIS CORPORATION ]
