TVS Diode Arrays

236

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SP720

Electronic Protection Array for ESD and Overvoltage Protection

Peak Transient Current Capability of the SP720

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

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

SP720’s ability to withstand a wide range of transient current pulses. 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 SP720 ‘IN’

input pin and the (+) current pulse input goes to the SP720 V- pin. The

V+ to V- supply of the SP720 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 V+ to V-

voltage supply level, improving as the supply voltage is reduced. Values

of 0, 5, 15 and 30 voltages are shown. 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 Figure 6.

When adjacent input pins are paralleled, the sustained peak current

capability is increased to nearly twice that of a single pin. For compari-

son, tests were run using dual pin combinations 1+2, 3+4, 5+6, 7+9,

10+11, 12+13 and 14+15.

The overstress curve is shown in Figure 6 for a 15V supply condition. The

dual pins are capable of 10A peak current for a 10µs pulse and 4A peak

current for a 1ms pulse. The complete for single pulse peak current vs.

pulse width time ranging up to 1 second are shown in Figure 6.

+

-

CURRENT

SENSE

VOLTAGE

PROBE

14

15

16

9

13

12

11

10

1

2

3

4

5

7

6

8

IN

IN

IN

IN

IN

IN

V-

IN

V+

IN

IN

IN

IN

IN

IN

IN

+

-

SP720

(-)

(+)

C1

C1

VARIABLETIME DURATION

CURRENT PULSE GENERATOR

FIGURE 5. TYPICAL SP720 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

0V

5V

15V

V+ TO V- SUPPLY

100

1000

10

9

30V

15V

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

SINGLE PIN STRESS CURVES

DUAL PIN STRESS CURVE

8

FIGURE 6. SP720 TYPICAL SINGLE PULSE PEAK CURRENT CURVES SHOWING THE MEASURED POINT OF OVER-STRESS IN