MMBZ5V6ALT1_07 Datasheet, PDF (24/27 Pages) Motorola, Inc – SOT-23 Dual Monolithic Common Anode Zener Transient Voltage Suppressor For ESD Protection

GENERAL DATA — 1500 WATT PEAK POWER
APPLICATION NOTES
RESPONSE TIME
In most applications, the transient suppressor device is
placed in parallel with the equipment or component to be pro-
tected. In this situation, there is a time delay associated with
the capacitance of the device and an overshoot condition
associated with the inductance of the device and the induc-
tance of the connection method. The capacitive effect is of mi-
nor importance in the parallel protection scheme because it
only produces a time delay in the transition from the operating
voltage to the clamp voltage as shown in Figure 5.
The inductive effects in the device are due to actual turn-on
time (time required for the device to go from zero current to full
current) and lead inductance. This inductive effect produces
an overshoot in the voltage across the equipment or compo-
nent being protected as shown in Figure 6. Minimizing this
overshoot is very important in the application, since the main
purpose for adding a transient suppressor is to clamp voltage
spikes. The SMC series have a very good response time, typi-
cally < 1 ns and negligible inductance. However, external
inductive effects could produce unacceptable overshoot.
Proper circuit layout, minimum lead lengths and placing the
suppressor device as close as possible to the equipment or
components to be protected will minimize this overshoot.
Some input impedance represented by Zin is essential to
prevent overstress of the protection device. This impedance
should be as high as possible, without restricting the circuit
operation.
DUTY CYCLE DERATING
The data of Figure 1 applies for non-repetitive conditions
and at a lead temperature of 25°C. If the duty cycle increases,
the peak power must be reduced as indicated by the curves of
Figure 7. Average power must be derated as the lead or ambi-
ent temperature rises above 25°C. The average power derat-
ing curve normally given on data sheets may be normalized
and used for this purpose.
At first glance the derating curves of Figure 7 appear to be in
error as the 10 ms pulse has a higher derating factor than the
10 µs pulse. However, when the derating factor for a given
pulse of Figure 7 is multiplied by the peak power value of Fig-
ure 1 for the same pulse, the results follow the expected trend.
TYPICAL PROTECTION CIRCUIT
Zin
Vin
LOAD
VL
Vin (TRANSIENT)
Vin (TRANSIENT)
V
V
OVERSHOOT DUE TO
INDUCTIVE EFFECTS
VL
VL
Vin
td
tD = TIME DELAY DUE TO CAPACITIVE EFFECT
t
Figure 5.
1
0.7
0.5
t
Figure 6.
0.3
0.2
PULSE WIDTH
10 ms
0.1
0.07
0.05
1 ms
0.03
0.02
100 µs
0.01
0.1 0.2
0.5 1 2
10 µs
5 10 20
50 100
D, DUTY CYCLE (%)
Figure 7. Typical Derating Factor for Duty Cycle
1500 Watt Peak Power Data Sheet
5-78
Motorola TVS/Zener Device Data