CYT9174
2.0A BUS Termination Regulator
Application Information
Internal parasitic diode
Layout Consideration
Avoid forward-bias internal parasitic diode,
VOUT to VCNTL, and VOUT to VIN, the VOUT
should not be forced same voltage respect to
ground on this pin while the VCNTL or VIN is
disappeared. Consideration while designs the
resistance of voltage divider
The CYT9174 regulator is packaged in
thermally enhanced plastic SOP-8 package.
This small footprint package is unable to
convectively dissipate the heat generated when
the regulator is operating at high current levels.
In order to control die operating temperatures,
the PC board layout should allow for maximum
possible copper area at the VCNTL pins of the
CYT9174.
Make sure the sinking current capability of
pull-down NMOS if the lower resistance was
chosen so that the voltage on VREFEN is below
0.2V. In addition to item1, the capacitor and
voltage divider form the low-pass filter. There
are two reasons doing this design; one is for
output voltage soft-start while another is for
noise immunity.
The multiple VCNTL pins on the SOP-8
package are internally connected, but lowest
thermal resistance will result if these pins are
tightly connected on the PC board. This will also
aid heat dissipation at high power levels.
If the large copper around the IC is
unavailable, a buried layer may be used as a
heat spreader, Use via to conduct the heat into
the buried or backside of PCB layer. The via
should be small enough to retain solder when
the board is wave-soldered.
Thermal Consideration
CYT9174 regulators have internal thermal
limiting circuitry designed to protect the device
during overload conditions. For continuous
normal load conditions however, the maximum
junction temperature rating of 150°C must not be
exceeded.Higher
continuous
currents
or
ambient temperature
require
additional
heatsinking. Heat sinking to the IC package
must consider the worst case power dissipation
which may occur.
It should also be noted that with the VCNTL equal
to 5V, the point of thermal shutdown will be degraded
by approx. 20°C compared to the VCNTL equipped
with 3.3V. It is highly recommended that to use the
3.3V rail acting as the VCNTL so as to minimize the
thermal concern of the CYT9174 in the SOP-8 package.
ShenZhen CYT IC Design CO ,Ltd
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