pip401-03 NXP Semiconductors, pip401-03 Datasheet - Page 11

• Manufacturer Part Number: pip401-03
• Description: Pip401 Or-ing Intelligent Switch
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 10578
Product data
11.3.1 On-state
11.3.2 Off-state
11.3 Overtemperature detection
Figure 8
power supply in the event of overtemperature. In this circuit, there are pull-up
resistors from TFL to both the 5 V and 12 V supplies.
The overtemperature flag can be used to detect excessive load current. The
overtemperature flag will operate when the power dissipation due to load current is
sufficient to raise the junction temperature to approximately 160 C. The typical
on-state voltage of the PIP401 at 25 C is 70 mV. To calculate the on-state voltage at
160 C, the 25 C value is multiplied by the normalized on-state voltage factor given
in
thermal resistance from junction to ambient of 15 K/W and an ambient temperature of
55 C, the overtemperature flag will operate when the current exceeds:
One possible use of the overtemperature flag is to detect failure of the cooling fan, in
applications where forced air cooling is used.
If the thermal resistance from junction to ambient is higher, then the temperature flag
will operate at a lower value of output current.
If the 12 V supply to V
cause the PIP401 to turn off, and the voltage drop to increase from a few millivolts to
approximately 0.7 V. The increased dissipation in the PIP401 will cause its junction
temperature to rise. Taking a junction to ambient thermal resistance of 15 K/W and an
ambient temperature of 55 C, the overtemperature flag will operate when the
dissipation in the PIP401 is greater than:
P
Fig 8. Overtemperature detection.
Figure
tot
=
160 55
-------------------- -
shows how the thermal flag output of the PIP401 is used to shut down a
6. This factor is 1.6 giving an on-state voltage at 160 C of 112 mV. Using a
15
–
SUPPLY
12 V
Rev. 03 — 5 November 2002
=
7W
I
O
CC
shutdown
=
fails as a result of a fault in the auxiliary supply, this will
-----------------------------------------
V
T
ON
TFL
SUPPLY
5 V
–
R
T
th j a
amb
–
2.2
k
=
1
k
-------------------------
0.112 15
VI
160 55
V CC
TFL
–
© Koninklijke Philips Electronics N.V. 2002. All rights reserved.
GND
VRS
VO
=
OR-ing Intelligent Switch
62.5 A
LOAD
03ah74
PIP401
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