CPC1560 Datasheet, PDF (10/14 Pages) Clare, Inc. – Solid State Relay with Integrated Current Limit

CPC1560
(C_LOAD) and load Inductance (L_LOAD), along with other
recommended operating conditions given in this
datasheet, are constrained by the 85°C operation of
most industrial applications. For lower operating
temperature ranges, these values can be de-rated
using the information provided in the temperature
graphs in this datasheet.
5.2.1 Effects of Ambient Temperature
One of the most important factors is the temperature
variation of the environment. From the Maximum
Allowed Energy Dissipation During t_RISE graphs
(AC and DC) in this datasheet, the user can see how
the energy dissipated in the part during t_RISE
increases with increasing ambient temperature.
The operating frequency of the device is directly
related to the amount of energy dissipated in it during
the transition times, t_RISE and t_FALL, which increases
rapidly with temperature, as seen in the previously
mentioned graphs. Depending on the operating
temperature range of the application, the user must
derate the maximum allowed energy in the part during
t_RISE and t_FALL (according to the temperature graphs
provided) in order to limit the operating switching
frequency.
5.3 Current Limit and Thermal Shutdown
5.3.1 Current Limit
The CPC1560 has a current limit feature in which
current through the output switches is limited to a
value larger than the recommended operating current.
In the AC/DC configuration, the CPC1560 has
bidirectional current limiting, which consists of current
limit circuits in both positive and negative polarities. In
the DC-only configuration, the DC current limit
consists of the parallel of the two AC current limit
circuits in the positive DC polarity.
The current limit function has a negative temperature
coefficient in which increasing temperature lowers the
current limit threshold of the device. Prolonged periods
of current limiting will cause the temperature of the
device to increase, and, if allowed to continue, will
activate the device’s thermal shutdown circuitry,
forcing the output switches to turn off.
The thermal shutdown feature and the current limit
feature provide great power cross immunity to the
device for improved survivability in harsh
environments.
5.4 dV/dt Fault Tolerance
The CPC1560 device has a finite dV/dt fault tolerance
for both the AC/DC and DC-only configurations, which
must not be exceeded.
The dV/dt tolerance for the device in the AC/DC
configuration is double that of the DC-only
configuration (see “Absolute Maximum Ratings” on
page 3). This is because the dV/dt value of the
CPC1560 is inversely proportional to the size of the
output switch’s C_rss, or “reverse transfer capacitance,”
and this capacitance in the DC-only configuration is
double that in the AC/DC configuration.
5.5 Power Derating
Bear in mind the power rating of the CPC1560 when
operating the device at elevated temperatures. The
Absolute Maximum Ratings table shows that the
maximum allowed power dissipation at 25°C is
800mW, which is the maximum power that can be
dissipated before the junction temperature of the
device reaches 125°C.
In order to keep the CPC1560 operating within its
power rating, use the Maximum Allowed Load Current
graphs provided earlier in this document.
5.3.2 Thermal Shutdown
The purpose of the thermal shutdown feature is to
completely shut down the operation of the device
when its junction temperature has gone above 130°C,
whether this is due to high power dissipation in the
device in the form of heat or an increase in the
ambient temperature.
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PRELIMINARY
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