LX8584B-33CP Microsemi Analog Mixed Signal Group, LX8584B-33CP Datasheet - Page 6

• Manufacturer Part Number: LX8584B-33CP
• Description: IC REG LDO POS 7A 3.3V TO220
• Manufacturer: Microsemi Analog Mixed Signal Group

Specifications of LX8584B-33CP

• Regulator Topology: Positive Fixed
• Voltage - Output: 3.3V
• Voltage - Input: Up to 10V
• Number Of Regulators: 1
• Current - Output: 7A (Min)
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: TO-220
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Dropout (typical): -
• Current - Limit (min): -

Copyright © 1997
Rev. 1.3, 2005-11-11
LOAD REGULATION (continued)
resistance can be a significant source of error. A 100 mil (2.54
mm) wide PC trace built from 1 oz. copper-clad circuit board
material has a parasitic resistance of about 5 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 5 amps of current, a 50 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 2.45
volts, which is a 2% 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.
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.
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.
THERMAL CONSIDERATIONS
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
Even when the circuit is optimally configured, parasitic
The minimum specified output capacitance for the regulator
To maintain good load regulation, wide traces should be used
The LX8584/84A/84B regulators have internal power and
Where:
V
IN(MIN)
V
TM
DROPOUT(MAX)
=
V
V
V
IN(MIN)
OUT
OUT
+
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
≡
≡
≡
V
DROPOUT(MA
the lowest allowable instantaneous
voltage at the input pin.
the designed output voltage for the
power supply system.
the specified dropout voltage for the
installed regulator.
X)
A P P L I C A T I O N N O T E
Integrated Products Division
®
Microsemi
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.
Examples
Given: V
Find: Proper Heat Sink to keep IC’s junction temperature below
Solution: The junction temperature is:
Where: P
First, find the maximum allowable thermal resistance of the heat
sink:
have R
3.0°C/W with 300ft/min air flow.
specification using the selected heat sink:
recommended for long term reliability to keep the junction
temperature below 125°C whenever possible.
T
T
R
P
R
T
7A Low Dropout Positive Regualtors
D
J
J
J
Θ
Θ
Next, select a suitable heat sink. The selected heat sink must
Finally, verify that junction temperature remains within
** Although the device can operate up to150°C junction, it is
SA
SA
=
=
=
R
11W(2.7
P
(
=
=
V
D
ΘSA
V
Ambient Temp., T
R
125°C.**
R
R
R
TS
IN
JT
T
5 (
(R
D
ΘJT
ΘJT
ΘCS
ΘSA
IN
OUT
J
(
0 .
P
MAX
T
−
125
< 3.1°C/W. Thermalloy heatsink 6296B has R
ΘJT
D
V
C
T
P
R
−
A
°
°
=
=
=
≡
≡
≡
≡
≡
)
RODUCTION
C/W
C
+
2
−
−
8 .
CS
R
V
−
(
V
R
OUT
50
5V
2.8V, I
2.7°C/W 300 ft/min airflow available
ΘCS
Dissipated power
Thermal resistance from the junction to the
mounting tab of the package
Thermal resistance through the interface
between the IC and the surface on which it is
mounted. (1.0°C/W @ 6 in-lbs mounting
screw torque).
Thermal resistance from the mounting
surface to ambient (thermal resistance of the
head sink).
Heat sink temperature.
T
Θ
* )
+
S
JT
°
1.0
C
R
)
5
I
0 .
+
+
OUT
°
A
A
R
SA
R
C/W
OUT
= 50°C
Θ
−
ΘSA
CS
=
2 (
D
= 5.0A
T
)
5 (
+
7 .
ATA
)
A
0 .
°
3.0
+
C
V
T
/
°
A
−
W
C/W)
S
2
HEET
8 .
+
V
1
0 .
* )
+
°
C
50
5
LX8584x-xx
0 .
/
°
W
C
A
)
=
=
=
11
124
3
0 .
1 .
W
°
°
C
C
ΘSA
/
W
=
Page 6