Wavelength Electronics WTC3293, Datasheet And Operating Manual

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WTC3243 TEMPERATURE CONTROLLER
SAFE OPERATING AREA CALCULATION
The Safe Operating Area of the WTC controller is determined
by the amount of power that can be dissipated within the
output stage of the controller. If that power limit is exceeded
permanent damage can result.
!
Do not exceed the Safe Operating Area (SOA).
Exceeding the SOA voids the warranty.
Refer to the Wavelength Electronics website for the most
up-to-date SOA calculator for our products. The online tool
is fast and easy to use, and also takes into consideration
operating temperature.
www.teamwavelength.com/support/design-tools/soa-tc-calculator/
SOA charts are included in this datasheet for quick reference,
however we recommend you use the online tools instead.
Follow these steps to determine if the driver will be operating
within the SOA.
• Refer to the thermoelectric datasheet to find the
maximum voltage (V
MAX
) and current (I
MAX
) specifications
• Calculate the voltage drop across the controller:
V
DROP
= V
S
- V
MAX
(V
S
is the power supply voltage)
• Mark V
DROP
on the X-axis, and extend a line upward
• Mark I
MAX
on the Y-axis, and extend a line to the right
until it intersects the V
DROP
line
• On the X-axis, mark the value of V
S
• Extend a diagonal line from V
S
to the intersection of the
V
DROP
and I
MAX
lines; this is the Load Line
• If the Load Line crosses the Safe Operating Area line at
any point, the configuration is not safe
If the SOA Calculator indicates the WTC will be outside of the
Safe Operating Area, the system must be changed so that
less power is dissipated within the driver. See Wavelength
Electronics Application Note
AN-LDTC01: The Principle of
the Safe Operating Area
for information on shifting the Load
Line.
Figure 34 illustrates the SOA curve for the WTC.
Figure 34. SOA for WTC3243
An example SOA calculation is shown in Figure 35 where:
V
S
= 12 Volts (Point C)
V
MAX
= 5 Volts
I
MAX
= 1 Amp (Point B)
V
DROP
= 12 - 5 = 7 Volts (Point A)
Figure 35. Example SOA Calculation
Refer to
Figure 35
above and note that the Load Line is in
the Unsafe Operating Areas for use with no heatsink (1) or
the heatsink alone (2), but is outside of the Unsafe Operating
Area for use with heatsink and fan (3).