Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.COM

X  

LX8385B-XXCP Datasheet(PDF) 7 Page - Microsemi Corporation

Part # LX8385B-XXCP
Description  3A Low Dropout Positive Regulators
Download  11 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  MICROSEMI [Microsemi Corporation]
Direct Link  http://www.microsemi.com
Logo MICROSEMI - Microsemi Corporation

LX8385B-XXCP Datasheet(HTML) 7 Page - Microsemi Corporation

Back Button LX8385B-XXCP Datasheet HTML 3Page - Microsemi Corporation LX8385B-XXCP Datasheet HTML 4Page - Microsemi Corporation LX8385B-XXCP Datasheet HTML 5Page - Microsemi Corporation LX8385B-XXCP Datasheet HTML 6Page - Microsemi Corporation LX8385B-XXCP Datasheet HTML 7Page - Microsemi Corporation LX8385B-XXCP Datasheet HTML 8Page - Microsemi Corporation LX8385B-XXCP Datasheet HTML 9Page - Microsemi Corporation LX8385B-XXCP Datasheet HTML 10Page - Microsemi Corporation LX8385B-XXCP Datasheet HTML 11Page - Microsemi Corporation  
Zoom Inzoom in Zoom Outzoom out
 7 / 11 page
background image
PRODUCTION DATA SHEET
Microsemi Inc.
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 7
Copyright
© 2000
Rev. 2.0b, 2005-10-25
LX8385x-xx
3A Low Dropout Positive Regulators
TM
®
APPLICATION NOTES ( C ONTIN UE D)
LOAD REGULATION (continued)
Even when the circuit is configured optimally, parasitic
resistance can be a significant source of error. A 20 mil. wide PC
trace built from 1 oz. copper-clad circuit board material has a
parasitic resistance of about 25 milliohms per inch of its length at
room temperature. If a 3-terminal regulator used to supply 2.50
volts is connected by 2 inches of this trace to a load which draws
1.5 amps of current, a 75 millivolt drop will appear between the
regulator and the load. Even when the regulator output voltage is
precisely 2.50 volts, the load will only see 2.43 volts, which is a
3% error. It is important to keep the connection between the
regulator output pin and the load as short as possible, and to use
wide traces or heavy-gauge wire.
The minimum specified output capacitance for the regulator
should be located near the regulator package. If several capacitors
are used in parallel to construct the power system output
capacitance, any capacitors beyond the minimum needed to meet
the specified requirements of the regulator should be located near
the sections of the load that require rapidly-changing amounts of
current. Placing capacitors near the sources of load transients will
help ensure that power system transient response is not impaired
by the effects of trace impedance.
To maintain good load regulation, wide traces should be used
on the input side of the regulator, especially between the input
capacitors and the regulator. Input capacitor ESR must be small
enough that the voltage at the input pin does not drop below
VIN(MIN) during transients.
X)
DROPOUT(MA
OUT
ΙΝ(ΜΙΝ)
V
V
V
+
=
where: VIN(MIN)
≡ the lowest allowable instantaneous
voltage at the input pin.
VOUT
≡ the designed output voltage for the
power supply system.
VDROPOUT(MAX)≡ the specified dropout voltage for the
installed regulator.
THERMAL CONSIDERATIONS
The LX8385/85A/85B regulators have internal power and
thermal limiting circuitry designed to protect each device under
overload conditions. For continuous normal load conditions,
however, maximum junction temperature ratings must not be
exceeded. It is important to give careful consideration to all
sources of thermal resistance from junction to ambient. This
includes junction to case, case to heat sink interface, and heat
sink thermal resistance itself.
Junction-to-case thermal resistance is specified from the IC
junction to the back surface of the case directly opposite the die.
This is the lowest resistance path for heat flow. Proper mounting
is required to ensure the best possible thermal flow from this area
of the package to the heat sink. Thermal compound at the case to
heat sink interface is strongly recommended. If the case of the
device must be electrically isolated, a thermally conductive
spacer can be used, as long as its added contribution to thermal
resistance is considered. Note that the case of all devices in this
series is electrically connected to the output.
Example
Given:
VIN
=
5V
VOUT =
2.5V
IOUT
=
1.5A
TA
=
50°C
RθJT
=
2.7°C/W for TO-220
Find:
Proper Heat Sink to keep IC’s junction temperature
below 125°C.**
Solution: The junction temperature is:
A
θSA
θCS
θJT
J
T
)
R
R
(R
T
+
+
+
=
D
P
where: P
D
Dissipated power.
RθJT
Thermal resistance from the junction to
the mounting tab of the package.
RθCS
Thermal resistance through the
interface between the IC and the
surface on which it is mounted.
(1.0°C/W at 6 in-lbs mounting screw
torque).
RθSA
Thermal resistance from the mounting
surface to ambient (thermal resistance
of the heat sink).
TS
Heat Sink Temperature.
T
J
T
C
T
S
T
A
R
θ JT
R
θCS
R
θSA
First, find the maximum allowable thermal resistance of the
heat sink:
()
CS
θ
θJT
D
A
J
SA
θ
R
R
P
T
T
R
+
=
3.75W
1.5A
2.5V
5.0V
=
×
=
=
D
D
P
P
)
(
I
)
V
(V
OUT
OUT
IN(MAX)
C/W
C/W)
1.0
C/W
(2.7
1.5A
*
2.5V)
(5.0V
C
50
C
125
°
=
°
+
°
°
°
=
3
.
16
R
R
θSA
θSA
Next, select a suitable heat sink. The selected heat sink must
have RθSA < 3.1°C/W. Thermalloy heatsink 6230B has RθSA =
12°C/W.
Finally, verify that junction temperature remains within speci-
fication using the selected heat sink:
C
109
C
50
C/W)
12.0
C/W
1.0
C/W
3.75W(2.7
°
=
°
+
°
+
°
+
°
=
J
J
T
T
** Although the device can operate up to 150°C junction, it is recommended for long
term reliability to keep the junction temperature below 125°C whenever possible.


Similar Part No. - LX8385B-XXCP

ManufacturerPart #DatasheetDescription
logo
Microsemi Corporation
LX8385B-XXCP MICROSEMI-LX8385B-XXCP Datasheet
272Kb / 11P
   3A Low Dropout Positive Regulators
More results

Similar Description - LX8385B-XXCP

ManufacturerPart #DatasheetDescription
logo
Microsemi Corporation
LX8587-XX MICROSEMI-LX8587-XX Datasheet
211Kb / 8P
   3A LOW DROPOUT POSITIVE REGULATORS
logo
List of Unclassifed Man...
LA8385 ETC1-LA8385 Datasheet
233Kb / 8P
   3A LOW DROPOUT POSITIVE REGULATORS
logo
Microsemi Corporation
LX8385-00CDD MICROSEMI-LX8385-00CDD Datasheet
285Kb / 11P
   3A Low Dropout Positive Regulators
LX8587X MICROSEMI-LX8587X Datasheet
283Kb / 11P
   3A Low Dropout Positive Regulators
logo
National Semiconductor ...
LM1085 NSC-LM1085 Datasheet
744Kb / 13P
   3A Low Dropout Positive Regulators
logo
Microsemi Corporation
LX8385A-00CDD MICROSEMI-LX8385A-00CDD Datasheet
272Kb / 11P
   3A Low Dropout Positive Regulators
LX8385-00IDD MICROSEMI-LX8385-00IDD Datasheet
272Kb / 11P
   3A Low Dropout Positive Regulators
LX8587X-XX MICROSEMI-LX8587X-XX Datasheet
289Kb / 11P
   3A Low Dropout Positive Regulators
logo
Texas Instruments
LM1085IT-5.0 TI1-LM1085IT-5.0 Datasheet
2Mb / 22P
[Old version datasheet]   LM1085 3A Low Dropout Positive Regulators
logo
Linear Technology
LT1083 LINER-LT1083_05 Datasheet
203Kb / 16P
   7.5A, 5A, 3A Low Dropout Positive Adjustable Regulators
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11


Datasheet Download

Go To PDF Page


Link URL




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

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   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
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com