APL5901-25KC Ver la hoja de datos (PDF) - Anpec Electronics
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APL5901-25KC Datasheet PDF : 21 Pages
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APL5901/2
Thermal Protection
Thermal protection limits total power dissipation in the
device. When the junction temperature exceeds
TJ=+150℃, the thermal sensor generates a logic sig-
nal to turn off the pass transistor and allows IC to
cool. When the IC’s junction temperature is down by
10℃, the thermal sensor will turn the pass transistor
on again, resulting in a pulsed output during continu-
ous thermal protection. Thermal protection is designed
to protect the APL5901/2 in the event of fault
conditions. For continuous operation, do not exceed
the absolute maximum junction temperature of
TJ=+150℃.
Operating Region and Power Dis-
sipation
The thermal resistance of the case to circuit board,
and the rate of air flow all control the APL5901/2’s
maximum power dissipation. The power dissipation
across the device is PD = IOUT (VIN-VOUT) and the maxi-
mum power dissipation is:
PDMAX = (TJ-TA) / (θ JC + θ CA)
where T -T is the temperature difference between the
JA
junction
and
ambient
air,
θ
JC
is
the
thermal
resis-
tance
of
the
package,
and
θ
CA
is
the
thermal
resis-
tance through the printed circuit board, copper traces,
and other materials to the ambient air.
The GND pin of the APL5901 provide an electrical con-
nection to ground and channeling heat away. If power
dissipation is large, connect the GND pin to ground
using a large pad or ground plane, can improve the
problem of over heat of IC.
Copyright © ANPEC Electronics Corp.
11
Rev. B.2 - May., 2005
www.anpec.com.tw
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