ap2191d Diodes, Inc., ap2191d Datasheet - Page 11

• Manufacturer Part Number: ap2191d
• Description: 1.5a Single Channel Current-limited Power Switch With Output Discharge
• Manufacturer: Diodes, Inc.

Application Note
Power Dissipation and Junction Temperature
The low on-resistance of the internal MOSFET allows the small surface-mount packages to pass large current.
Using the maximum operating ambient temperature (T
Finally, calculate the junction temperature:
Where:
Generic Hot-Plug Applications
In many applications it may be necessary to remove modules or pc boards while the main unit is still operating.
These are considered hot-plug applications. Such implementations require the control of current surges seen by
the main power supply and the card being inserted. The most effective way to control these surges is to limit and
slowly ramp the current and voltage being applied to the card, similar to the way in which a power supply normally
turns on. Due to the controlled rise times and fall times of the AP2181D/AP2191D, these devices can be used to
provide a softer start-up to devices being hot-plugged into a powered system. The UVLO feature of the
AP2181D/AP2191D also ensures that the switch is off after the card has been removed, and that the switch is off
during the next insertion.
By placing the AP2181D/AP2191D between the V
these devices first after insertion. The typical rise time of the switch is approximately 1ms, providing a slow
voltage ramp at the output of the device. This implementation controls system surge current and provides a hot-
plugging mechanism for any device.
AP2181D/2191D
Document number: DS32251 Rev. 1 - 2
P
T
T
R
P
D
J
A
D
θJA
= Ambient temperature °C
= P
= R
= Total power dissipation
= Thermal resistance
D
DS(ON)
x R
θJA
× I
+ T
2
(Continued)
A
1.5A SINGLE CHANNEL CURRENT-LIMITED POWER
www.diodes.com
CC
input and the rest of the circuitry, the input power reaches
A
11 of 18
) and R
DS(ON)
SWITCH WITH OUTPUT DISCHARGE
, the power dissipation can be calculated by:
AP2181D/AP2191D
© Diodes Incorporated
June 2010