Electronic Components Datasheet Search
  English  ▼

Delete All
ON OFF
ALLDATASHEET.COM

X  

Preview PDF Download HTML

AP2146 Datasheet(PDF) 14 Page - Diodes Incorporated

Part No. AP2146
Description  0.5A DUAL CHANNEL CURRENT-LIMITED POWER SWITCH
Download  17 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Maker  DIODES [Diodes Incorporated]
Homepage  http://www.diodes.com
Logo 

AP2146 Datasheet(HTML) 14 Page - Diodes Incorporated

 
Zoom Inzoom in Zoom Outzoom out
 14 / 17 page
background image
AP2146/AP2156
0.5A DUAL CHANNEL CURRENT-LIMITED POWER
SWITCH
AP2146/AP2156 Rev 1
14 of 17
APRIL 2009
www.diodes.com
© Diodes Incorporated
Application Note
(Continued)
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 (TA) and RDS(ON), the power dissipation can be
calculated by:
PD = RDS(ON)× I
2
Finally, calculate the junction temperature:
TJ = PD x RθJA + TA
Where:
TA= Ambient temperature
°C
RθJA = Thermal resistance
PD = Total power dissipation
Thermal Protection
Thermal protection prevents the IC from damage when heavy-overload or short-circuit faults are present for
extended periods of time. The AP2146/AP2156 implements a thermal sensing to monitor the operating
junction temperature of the power distribution switch. Once the die temperature rises to approximately 140°C
due to excessive power dissipation in an over-current or short-circuit condition the internal thermal sense
circuitry turns the power switch off, thus preventing the power switch from damage. Hysteresis is built into
the thermal sense circuit allowing the device to cool down approximately 25°C before the switch turns back
on. The switch continues to cycle in this manner until the load fault or input power is removed. The FLG
open-drain output is asserted when an over-temperature shutdown or over-current occurs with 7-ms deglitch.
Under-voltage Lockout (UVLO)
Under-voltage lockout function (UVLO) keeps the internal power switch from being turned on until the power
supply has reached at least 1.9V, even if the switch is enabled. Whenever the input voltage falls below
approximately 1.9V, the power switch is quickly turned off. This facilitates the design of hot-insertion systems
where it is not possible to turn off the power switch before input power is removed.
Host/Self-Powered HUBs
Hosts and self-powered hubs (SPH) have a local power supply that powers the embedded functions and the
downstream ports (see Figure 2). This power supply must provide from 5.25V to 4.75V to the board side of
the downstream connection under both full-load and no-load conditions. Hosts and SPHs are required to
have current-limit protection and must report over-current conditions to the USB controller. Typical SPHs are
desktop PCs, monitors, printers, and stand-alone hubs.
3.3V
IN
GND
EN2
Power Supply
USB
Controller
FLG2
OUT1
68uF
0.1uF
4
3
7
8
6
5V
Downstream
USB Ports
D+
D-
VBUS
GND
AP2146
0.1uF
EN1
FLG1
1
2
OUT2
68uF
0.1uF
5
D+
D-
VBUS
GND
Figure 2. Typical Two-Port USB Host / Self-Powered Hub


Html Pages

1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17 


Datasheet Download




Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ]  

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Alldatasheet API   |   Link Exchange   |   Manufacturer List
All Rights Reserved© Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn