LX8384-15CP-TR [MICROSEMI]
Fixed Positive LDO Regulator, 1.5V, 1.5V Dropout, PSFM3, ROHS COMPLIANT, PLASTIC, TO-220, 3 PIN;
| 型号： | LX8384-15CP-TR |
| 厂家： | 
Microsemi |
| 描述： | Fixed Positive LDO Regulator, 1.5V, 1.5V Dropout, PSFM3, ROHS COMPLIANT, PLASTIC, TO-220, 3 PIN 局域网 输出元件 调节器 |
| 文件： | 总11页 (文件大小：283K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
KEY FEATURES
DESCRIPTION
available and specified in the Available
Options table below.
Three-Terminal Adjustable Or
Fixed Output
Guaranteed < 1.3V Headroom a
5A (LX8384A)
Guaranteed 2.0% Max.
Reference Tolerance (LX8384A)
Guaranteed 1.0% Max.
Reference Tolerance (LX8384B)
0.015% Line Regulation
0.15% Load Regulation
The LX8384/84A/84B Series ICs are
positive regulators designed to provide 5A
output current. These regulators yield
higher efficiency than currently available
devices with all internal circuitry designed
to operate down to a 1V input-to-output
differential. In each of these products, the
dropout voltage is fully specified as a
function of load current. Dropout is
guaranteed at a maximum of 1.3V (8384A)
and 1.5V (8384) at maximum output
current, decreasing at lower load currents.
In addition, on-chip trimming adjusts the
reference voltage tolerance to 1% maximum
at room temperature and 2% maximum over
the 0 to 125°C range for the LX8384A,
making this ideal for the Pentium P54C-
VRE specification. The LX8384B offers
0.8% tolerance at room temperature and
1.0% maximum over line, load and
The LX8384/84A/84B Series devices are
pin-compatible with earlier 3-terminal
regulators, such as the 117 series products,
but they do require input and output
capacitors. A minimum 10µF capacitor is
required on the input and a 15µF or greater
on the output of these new devices for
stability. Although, these capacitors are
generally included in most regulator
designs.
The LX8384/84A/84B Series quiescent
current flows into the load, thereby
increasing efficiency. This feature contrasts
with PNP regulators where up to 10% of the
output current is wasted as quiescent
current. The LX8384-xxI is specified over
the industrial temperature range of -25°C to
125°C, while the LX8384-xxC/84A-
xxC/84B-xxC is specified over the
commercial range of 0°C to 125°C.
APPLICATIONS
Pentium® Processor VRE
Application
High Efficiency Linear
Regulators
Power Regulators For Switching
Power Supplies
Battery Chargers
Constant Current Regulators
Cyrix® 6x86™
temperature.
Fixed versions are also
AMD-K5™
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
PRODUCT HIGHLIGHT
IN
OUT
OUTPUT
PART #
3.5V
at 5A
5V
LX8384A
VOLTAGE
+
121Ω
0.1%
*1500µF
6MV1500GX
Sanyo
LX8384/84A/84B-00
LX8384/84A/84B-15
LX8384/84A/84B-33
Adjustable
1.5V
ADJ
+
1500µF
5x 6MV1500GX
Sanyo
218Ω
0.1%
3.3V
Table 1 - Available Options
* Capacitors must have < 20mΩ
Total ESR for the VRE Specification
An Application of the LX8384A for the Pentium P54C Processors Meeting VRE Specification.
PACKAGE ORDER INFO
Plastic TO-220
Plastic TO-263
3-Pin
Plastic TO-252
(D-Pak) 3-Pin
Max Ref Max Dropout DT
P
DD
3-Pin
TA (°C)
Accuracy
Voltage
RoHS Compliant
RoHS Compliant
RoHS Compliant
Transition DC: 0532
Transition DC: 0543
LX8384-xxCP
LX8384A-xxCP
LX8384B-xxCP
LX8384-xxIP
Transition DC: 0535
2.0%
2.0%
1.0%
1.5V
1.3V
1.3V
1.5V
LX8384-xxCDT
LX8384A-xxCDT
LX8384B-xxCDT
LX8384-xxIDT
LX8384-xxCDD
LX8384A-xxCDD
LX8384B-xxCDD
LX8384-xxIDD
0 to 125
-25 to 125 2.0%
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX8384-xxCP-TR)
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Integrated Products Division
Page 1
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
ABSOLUTE MAXIMUM RATINGS(NOTE 1)
PACKAGE PIN OUT
Power Dissipation................................................................................... Internally Limited
Input Voltage ................................................................................................................ 10V
Input to Output Voltage Differential............................................................................. 10V
Operating Junction Temperature................................................................................150°C
Storage Temperature Range....................................................................... -65°C to 150 °C
Peak Package Solder Reflow Temp. (40 seconds max. exposure) .................260°C (+0,-5)
TAB is VOUT
3
VIN
2
1
VOUT
ADJ /
GND*
Note 1: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal.
DD PACKAGE (3-PIN)
(Top View)
TAB is VOUT
VIN
3
2
1
VOUT
THERMAL DATA
ADJ/
GND
*
Plastic TO-263 3-Pin
DD
DT PACKAGE (3-PIN)
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA
THERMAL RESISTANCE-JUNCTION TO TAB, θJT
60°C/W
2.7°C/W
(Top View)
TAB is VOUT
Plastic TO-220 3-Pin
P
3
VIN
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA
THERMAL RESISTANCE-JUNCTION TO TAB, θJT
60°C/W
2.7°C/W
2
VOUT
ADJ
1
GND
Plastic TO-252 3-Pin
DT
P PACKAGE (3-PIN)
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA
THERMAL RESISTANCE-JUNCTION TO TAB, θJT
60°C/W
2.7°C/W
(Top View)
*Pin 1 is GND for fixed voltage versions
RoHS 100% Matte Tin Lead Finish
Junction Temperature Calculation: TJ = TA + (PD x θJT).
The θJA & θJT numbers are guidelines for the thermal performance of the device/pc-board
system. All of the above assume no ambient airflow.
BLOCK DIAGRAM
VIN
Bias Circuit
Thermal
Limit Circuit
Bandgap
Circuit
Control
Circuit
Output
Circuit
VOUT
SOA
Protection
Circuit
ADJ or
GND*
Current
Limit Circuit
*Pin 1 is GND for fixed voltage versions
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Page 2
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, the following specifications apply over the operating ambient temperature for the LX8384x-xxC with
0°C ≤ TA ≤ 125°C and the LX8384-xxI with -25°C ≤ TA ≤ 125°C except where otherwise noted. Test conditions: VIN -VOUT = 3V;
IOUT = 5A. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient
temperature.
LX8384x-xx
Parameter
Symbol
Test Conditions
Units
Min
Typ
Max
LX8384-00 / 8384A-00 / 8384B-00 (ADJUSTABLE)
`
IOUT = 10mA, TA = 25°C
1.238
1.225
1.240
1.238
1.250
1.250
1.250
1.250
1.262
1.270
1.260
1.262
V
V
V
V
Reference Voltage
(Note 4)
LX8384/84A-00
LX8384B-00
10mA < IOUT < 5A, 1.5V < (VIN -VOUT),
VIN < 10V, P < PMAX
VREF
IOUT = 10mA, TA = 25°C
10mA < IOUT < 5A, 1.5V < (VIN -VOUT),
VIN < 10V, P < PMAX
1.3V < (VIN -VOUT), VIN < 7V, IOUT = 10mA
1.3V < (VIN -VOUT), VIN < 10V, IOUT = 10mA
0.015
0.035
0.2
0.3
%
%
Δ VREF
(VIN)
Line Regulation (Note 2)
Δ VREF
VOUT > VREF, VIN - VOUT = 3V,
10mA < IOUT < 5A
Load Regulation (Note 2)
Thermal Regulation
0.15
0.01
83
0.5
%
% / W
dB
(IOUT
)
ΔVOUT
(Pwr)
TA = 25°C, 20ms pulse
0.02
VOUT = 5V, f= 120Hz, COUT = 100µF Tantalum,
VIN = 6.5V, CADJ = 10µF, IOUT = 5A
Ripple Rejection (Note 3)
65
20
Adjust Pin Current
IADJ
55
0.2
1.2
1.1
2
100
5
µA
µA
V
Adjust Pin Current Change (Note 4)
ΔIADJ
10mA < IOUT < IOUT(MAX), 1.3V < (VIN -VOUT), VIN<10V
ΔVREF = 1%, IOUT = 5A
ΔVREF = 1%, IOUT = 5A
VIN < 10V
1.5
1.3
10
Dropout Voltage
LX8384-00
ΔV
LX8384A/84B-00
V
Minimum Load Current
IOUT(MIN)
IOUT(MAX)
mA
A
(VIN - VOUT) < 7V
5
3
6
Maximum Output Current
(VIN - VOUT) < 10V
4
A
Long Term Stability (Note 3)
Temperature Stability (Note 3)
ΔVOUT(t) TA = 125°C, 1000 hours
ΔVOUT(T)
0.3
0.25
1
%
%
RMS Output Noise (% of VOUT
(Note 3)
)
ΔVOUT(RMS) TA = 25°C, 10Hz < f < 10kHz
0.003
%
LX8384-15 / 8384A-15 / 8384B-15 (1.5V FIXED)
`
VIN = 5V, IOUT = 0mA, TA = 25°C
4.75V < VIN < 10V, 0mA < IOUT < 5A, P < PMAX
VIN = 5V, IOUT = 0mA, TA = 25°C
4.75V < VIN < 10V, 0A < IOUT < 5A, P < PMAX
4.75V < VIN < 7V
1.485
1.470
1.488
1.485
1.50
1.50
1.50
1.50
1
1.515
1.530
1.512
1.515
3
V
V
Output Voltage
(Note 4)
LX8384/84A-15
LX8384B-15
VOUT
V
V
mV
mV
ΔVOUT
(VIN)
Line Regulation (note 2)
4.75V < VIN < 10V
1
5
ΔVOUT
Load Regulation (note 2)
Thermal Regulation
VIN = 5V, 0mA < IOUT < IOUT(MAX)
TA = 25°C, 20ms pulse
2.5
7
mV
(IOUT
)
ΔVOUT
(Pwr)
0.01
0.02
% / W
Ripple Rejection (note 3)
Quiescent Current
COUT = 100µF (Tantalum), IOUT = 5A
0mA < IOUT < IOUT(MAX), 4.75V < V < 10V
ΔVOUT = 1%, IOUT < IOUT(MAX)
60
83
4
dB
mA
V
IQ
10
1.5
1.3
1.2
1
Dropout Voltage
LX8384-15
LX8384A/84B-15
ΔV
ΔVOUT = 1%, IOUT < IOUT(MAX)
V
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Page 3
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
ELECTRICAL CHARACTERISTICS (CONTINUED)
Unless otherwise specified, the following specifications apply over the operating ambient temperature for the LX8384x-xxC with
0°C ≤ TA ≤ 125°C and the LX8384-xxI with -25°C ≤ TA ≤ 125°C except where otherwise noted. Test conditions: VIN -VOUT = 3V;
IOUT = 5A. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient
temperature.
LX8384x-xx
Parameter
Symbol
Test Conditions
Units
Min
Typ
Max
LX8384-15 / 8384A-15 / 8384B-15 (1.5V FIXED)(CONTINUED)
`
`
Maximum Output Current
IOUT(MAX)
VIN < 7V
5
6
A
%
%
Temperature Stability (Note 3)
Long Term Stability (Note 3)
ΔVOUT(T)
0.25
0.3
ΔVOUT (t) TA=125°C, 1000 hours
1
RMS Output Noise (% of VOUT
(Note 3)
)
VOUT (RMS) TA=25°C, 10Hz < f < 10kHz
0.003
%
LX8384-33 / 8384A-33 / 8384B-33 (3.3V FIXED)
VIN=5V, IOUT=0mA, TA=25°C
4.75V < VIN < 10V, 0mA < IOUT < 5A, P < PMAX
VIN=5V, IOUT=0mA, TA=25°C
4.75V < VIN < 10V, 0mA < IOUT < 5A, P < PMAX
4.75V < VIN < 7V
3.267
3.235
3.274
3.267
3.30
3.30
3.30
3.30
1
3.333
3.365
3.326
3.333
6
V
V
Output Voltage
(Note 4)
LX8384/84A-33
LX8384B-33
VOUT
V
V
mV
mV
Line Regulation (Note 2)
ΔVOUT(VIN)
ΔVOUT
4.75V < VIN < 10V
2
10
Load Regulation (Note 2)
Thermal Regulation
VIN=5V, 0mA < IOUT < IOUT(MAX)
TA=25°C, 20ms pulse
5
15
mV
(IOUT
)
ΔVOUT
(Pwr)
0.01
0.02
% / W
Ripple Rejection (Note 3)
Quiescent Current
COUT=100µF (Tantalum), IOUT=5A
0mA < IOUT < IOUT(MAX), 4.75V < VIN < 10V
ΔVOUT=1%, IOUT < IOUT(MAX)
60
83
4
dB
mA
V
IQ
10
1.5
1.3
1.2
1
Dropout Voltage
LX8384-33
LX8384A/84B-33
ΔV
ΔVOUT=1%, IOUT < IOUT(MAX)
V
Maximum Output Current
IOUT(MAX) VIN < 7V
ΔVOUT (T)
5
6
A
Temperature Stability (Note 3)
Long Term Stability (Note 3)
0.25
0.3
%
%
ΔVOUT (t) TA=125°C, 1000 hours
1
RMS Output Noise (% of VOUT
(Note 3)
)
VOUT (RMS) TA=25°C, 10Hz < f < 10kHz
0.003
%
Note 2
Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output
voltage due to heating effects are covered under the specification for thermal regulation.
These parameters, although guaranteed are not tested in production.
Note 3
Note 4
See Maximum Output Current Section
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Page 4
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
APPLICATION NOTES
Power
Supply
Minimum Load
(Larger resistor)
The LX8384/84A/84B Series ICs are easy to use Low-
Dropout (LDO) voltage regulators. They have all of the standard
self-protection features expected of a voltage regulator: short
circuit protection, safe operating area protection and automatic
thermal shutdown if the device temperature rises above
approximately 165°C.
Use of an output capacitor is REQUIRED with the
LX8384/84A/84B series. Please see the table below for
recommended minimum capacitor values.
IN
OUT
LX8384x
Full Load
(Smaller
resistor)
ADJ
RDSON << RL
10ms
Star Ground
1 sec
These regulators offer a more tightly controlled reference
voltage tolerance and superior reference stability when measured
against the older pin-compatible regulator types that they replace.
FIGURE 1 - DYNAMIC INPUT AND OUTPUT TEST
STABILITY
OVERLOAD RECOVERY
The output capacitor is part of the regulator’s frequency
compensation system. Many types of capacitors are available,
with different capacitance value tolerances, capacitance
temperature coefficients, and equivalent series impedances. For
all operating conditions, connection of a 220µF aluminum
electrolytic capacitor or a 47µF (<400mΩ ESR) solid tantalum
capacitor between the output terminal and ground will guarantee
stable operation.
If a bypass capacitor is connected between the output voltage
adjust (ADJ) pin and ground, ripple rejection will be improved
(please see the section entitled “RIPPLE REJECTION”). When
ADJ pin bypassing is used, the required output capacitor value
increases. Output capacitor values of 220µF (aluminum) or 47µF
(tantalum) provide for all cases of bypassing the ADJ pin. If an
ADJ pin bypass capacitor is not used, smaller output capacitor
values are adequate. The table below shows recommended
minimum capacitance values for operation.
Like almost all IC power regulators, the LX8384/84A/84B
regulators are equipped with Safe Operating Area (SOA)
protection. The SOA circuit limits the regulator's maximum
output current to progressively lower values as the input-to-output
voltage difference increases. By limiting the maximum output
current, the SOA circuit keeps the amount of power that is
dissipated in the regulator itself within safe limits for all values of
input-to-output voltage within the operating range of the
regulator. The LX8384/84A/84B SOA protection system is
designed to be able to supply some output current for all values of
input-to-output voltage, up to the device breakdown voltage.
Under some conditions, a correctly operating SOA circuit may
prevent a power supply system from returning to regulated opera-
tion after removal of an intermittent short circuit at the output of
the regulator. This is a normal mode of operation, which can be
seen, in most similar products, including older devices such as
7800 series regulators. It is most likely to occur when the power
system input voltage is relatively high and the load impedance is
relatively low.
Minimum Capacitor Values
INPUT
10µ
10µ
OUTPUT
15µF Tantalum, 100µF Aluminum
47µF Tantalum, 220µF Aluminum
ADJ
None
15µF
When the power system is started “cold”, both the input and
output voltages are very close to zero. The output voltage closely
follows the rising input voltage, and the input-to-output voltage
difference is small. The SOA circuit therefore permits the
regulator to supply large amounts of current as needed to develop
the designed voltage level at the regulator output.
To ensure good transient response from the power supply
system under rapidly changing current load conditions, designers
generally use several output capacitors connected in parallel.
Such an arrangement serves to minimize the effects of the
parasitic resistance (ESR) and inductance (ESL) that are present
in all capacitors. Cost-effective solutions that sufficiently limit
ESR and ESL effects generally result in total capacitance values
in the range of hundreds to thousands of microfarads, which is
more than adequate to meet regulator output capacitor
specifications. Output capacitance values may be increased
without limit.
The circuit shown in Figure 1 can be used to observe the
transient response characteristics of the regulator in a power
system under changing loads. The effects of different capacitor
types and values on transient response parameters, such as
overshoot and under-shoot, can be compared quickly in order to
develop an optimum solution.
Now consider the case where the regulator is supplying
regulated voltage to a resistive load under steady state conditions.
A moderate input-to-output voltage appears across the regulator
but the voltage difference is small enough that the SOA circuitry
allows sufficient current to flow through the regulator to develop
the designed output voltage across the load resistance. If the
output resistor is short-circuited to ground, the input-to-output
voltage difference across the regulator suddenly becomes larger
by the amount of voltage that had appeared across the load
resistor. The SOA circuit reads the increased input-to-output
voltage, and cuts back the amount of current that it will permit the
regulator to supply to its output terminal. When the short circuit
across the output resistor is removed, all the regulator output
current will again flow through the output resistor. The maximum
current that the regulator can supply to the resistor will be limited
by the SOA circuit, based on the large input-to-output
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Page 5
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
APPLICATION NOTES (CONTINUED)
OVERLOAD RECOVERY (continued)
IN
OUT
voltage across the regulator at the time the short circuit is
removed from the output. If this limited current is not sufficient
to develop the designed voltage across the output resistor, the
voltage will stabilize at some lower value, and will never reach
the designed value. Under these circumstances, it may be
necessary to cycle the input voltage down to zero in order to
make the regulator output voltage return to regulation.
VOUT
VIN
LX8384x
VREF
R1
R2
ADJ
IADJ
50µA
⎛
R2
R1
⎞
⎟
RIPPLE REJECTION
VOUT =VREF ⎜1+
+ IADJ R2
⎜
⎠
⎝
Ripple rejection can be improved by connecting a capacitor
between the ADJ pin and ground. The value of the capacitor
should be chosen so that the impedance of the capacitor is equal
in magnitude to the resistance of R1 at the ripple frequency. The
capacitor value can be determined by using this equation:
FIGURE 2 - BASIC ADJUSTABLE REGULATOR
LOAD REGULATION
Because the LX8384/84A/84B regulators are three-terminal
devices, it is not possible to provide true remote load sensing.
Load regulation will be limited by the resistance of the wire
connecting the regulator to the load. The data sheet specification
for load regulation is measured at the bottom of the package.
Negative side sensing is a true Kelvin connection, with the
bottom of the output divider returned to the negative side of the
load. Although it may not be immediately obvious, best load
regulation is obtained when the top of the resistor divider, (R1), is
connected directly to the case of the regulator, not to the load.
This is illustrated in Figure 3. If R1 were connected to the load,
the effective resistance between the regulator and the load would
be:
1
C =
(
6.28× FR × R1
)
where:
C
≡
the value of the capacitor in Farads; select
an equal or larger standard value.
the ripple frequency in Hz
FR
R1
≡
≡
the value of resistor R1 in ohms
At a Ripple frequency of 120Hz, with R1= 100Ω:
1
C =
=13.3μF
(
6.28×120Hz×100Ω
)
The closest equal or larger standard value should be used, in
this case, 15µF. When an ADJ pin bypass capacitor is used,
output ripple amplitude will be essentially independent of the
output voltage. If an ADJ pin bypass capacitor is not used, output
ripple will be proportional to the ratio of the output voltage to the
reference voltage:
R2 + R1
R1
⎛
⎜
⎞
⎟
RPeff = R ×
P
⎝
⎠
where:
RP
≡
Actual parasitic line resistance.
When the circuit is connected as shown in Figure 3, the
parasitic resistance appears as its actual value, rather than the
VOUT
M =
higher RPeff
.
VREF
RP Parasitic Line
Resistance
where:
M
≡
a multiplier for the ripple seen when the
ADJ pin is optimally bypassed.
1.25V
OUT
IN
LX8384x
VIN
VREF
=
For example, if VOUT = 2.5V the output ripple will be:
2.5V
Connect R1 to
Case of Regulator
R1
R2
ADJ
M =
= 2
RL
1.25V
Connect R2 to
Load
Output ripple will be twice as bad as it would be if the ADJ
pin were to be bypassed to ground with a properly selected
capacitor.
OUTPUT VOLTAGE
The LX8384/84A/84B ICs develop a 1.25V reference voltage
between the output and the adjust terminal (See Figure 2). By
placing a resistor, R1, between these two terminals, a constant
current is caused to flow through R1 and down through R2 to set
the overall output voltage. Normally this current is the specified
minimum load current of 10mA. Because IADJ is very small and
constant when compared with the current through R1, it
represents a small error and can usually be ignored.
FIGURE 3 - CONNECTIONS FOR BEST LOAD REGULATION
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Page 6
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
APPLICATION NOTES (CONTINUED)
Example
LOAD REGULATION (continued)
Given: VIN
VOUT
=
=
=
=
=
5V
2.8V
5.0A
50°C
Even when the circuit is configured optimally, parasitic
resistance can be a significant source of error. A 100 mil. 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.
IOUT
TA
RθJT
2.7°C/W for TO-220
300 ft/min airflow available
Find:
Proper Heat Sink to keep IC’s junction temperature
below 125°C.**
Solution: The junction temperature is:
TJ = PD (RθJT + RθCS + RθSA ) + TA
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.
where: PD
RθJT
≡
≡
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 at 6 in-lbs mounting screw
torque).
Thermal resistance from the mounting
surface to ambient (thermal resistance
of the heat sink).
RθCS
≡
RθSA
≡
≡
TS
Heat Sink Temperature.
TJ
TC
RθJT RθCS RθSA
First, find the maximum allowable thermal resistance of the
TS
TA
VΙΝ(ΜΙΝ) = VOUT + VDROPOUT(MAX)
where: VIN(MIN)
≡ the lowest allowable instantaneous
voltage at the input pin.
heat sink:
VOUT
≡ the designed output voltage for the
power supply system.
TJ − TA
RθSA
=
−
(
RθJT + RθCS
)
VDROPOUT(MAX) ≡ the specified dropout voltage for the
PD
installed regulator.
P = (VIN(MAX)− VOUT )IOUT = (5.0V −2.8V)×5.0A
D
THERMAL CONSIDERATIONS
The LX8384/84A/84B 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.
P =11.0W
D
125°C−50°C
(5.0V − 2.8V)*5.0A
RθSA = 3.1°C/W
RθSA
=
−(2.7°C/W +1.0°C/W)
Next, select a suitable heat sink. The selected heat sink must
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.
have RθSA < 3.1°C/W. Thermalloy heatsink 6296B has RθSA
3.0°C/W with 300ft/min air flow.
Finally, verify that junction temperature remains within speci-
fication using the selected heat sink:
=
TJ =11W(2.7°C/W +1.0°C/W +3.0°C/W)+50°C
TJ =124°C
** 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.
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Page 7
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
TYPICAL APPLICATIONS
IN
OUT
(Note A)
VIN
VOUT**
LX8384x
+
IN
OUT
C1*
10µF
R1
121Ω 1%
VIN
(Note A)
VOUT
LX8384x
C2
+
100µF
ADJ
+
R1
10µF
121Ω 1%
ADJ
150µF
R2
1k
C1
10µF*
+
R2
365Ω 1%
* C1 improves ripple rejection.
≈
XC should be R1 at ripple
frequency.
* Needed if device is far from filter capacitors.
R2
⎛
⎞
⎟
⎠
* *VOUT = 1.25V 1+
FIGURE 4 - IMPROVING RIPPLE REJECTION
⎜
R1
⎝
FIGURE 5 - 1.2V - 8V ADJUSTABLE REGULATOR
IN
OUT
VIN
5V
LX8384x
(Note A)
+
121Ω
1%
10µF
ADJ
+
1k
100µF
2N3904
1k
365Ω
1%
TTL
Output
FIGURE 6 - 5V REGULATOR WITH SHUTDOWN
IN
OUT
3.3V
VIN
LX8384x
Min. 15µF Tantalum or
10µF Tantalum or
100µF Aluminum
100µF Aluminum capacitor. May
be increased without limit. ESR
must be less than <400mΩ.
ADJ
FIGURE 7 - FIXED 3.3V OUTPUT REGULATOR
Not e A: VIN(MIN) = (Intended VOUT ) + VDROPOUT(MAX)
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Page 8
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
PACKAGE DIMENSIONS
3-Pin Plastic TO-220
P
B
S
MILLIMETERS
INCHES
Dim
F
T
MIN
14.22
9.65
3.56
0.51
3.53
MAX
15.88
10.67
4.83
1.14
4.09
MIN
MAX
0.625
0.420
0.190
0.045
0.161
Q
A
B
C
D
F
0.560
0.380
0.140
0.020
0.139
U
A
C
G
2.54 BSC
0.100 BSC
1
2
3
H
6.35
1.14
14.73
0.250
0.045
0.580
0.050
R
H
J
K
L
0.30
12.70
1.14
0.012
0.500
0.045
1.27
5.08 TYP
K
N
0.200 TYP
D
Q
R
S
T
U
2.54
2.03
1.14
5.84
0.508
3.05
2.92
1.40
6.86
1.14
0.100
0.080
0.045
0.230
0.020
0.120
0.115
0.055
0.270
0.045
L
J
G
N
3-Pin Plastic TO-263
DD
I
A
MILLIMETERS
INCHES
D
Dim
MIN
10.03
8.51
4.19
1.14
0.330
1.19
2.41
2.29
–
MAX
10.67
9.17
4.59
1.40
0.51
1.34
2.66
2.79
1.65
0.25
15.87
MIN
0.395
0.335
0.165
0.045
0.013
0.047
0.095
0.090
–
MAX
0.420
0.361
0.181
0.055
0.020
0.053
0.104
0.110
0.065
0.010
0.625
C
A
B
C
D
E
F
G
H
I
B
K
M
N
H
E
F
G
J
0
0
K
M
N
14.60
0.575
7°
3°
7°
3°
0° -8°
J
Seating Plane
Note: Dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm(.006”) on any side. Lead dimension shall
not include solder coverage.
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Integrated Products Division
Page 9
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
PACKAGE DIMENSIONS
3-Pin Plastic TO-252
DT
P
L1
MILLIMETERS
INCHES
Dim
MIN
2.16
0
MAX
2.42
0.13
0.89
5.46
0.64
0.94
6.23
5.80
6.73
2.42
10.41
1.40
2.74
1.27
1.02
4.67
1.70
-
MIN
MAX
0.095
0.005
0.035
0.215
0.025
0.037
0.245
0.228
0.265
0.095
0.410
0.055
0.108
0.050
0.040
0.184
0.067
-
A
A1
b
b3
c
c2
D
D1
E
e
0.085
0
e
L4
W
E
b3
0.63
5.20
0.38
0.68
5.97
5.21
6.35
2.16
9.40
1.02
2.44
0.89
0.51
4.19
1.00
6°
0.025
0.205
0.015
0.027
0.235
0.205
0.250
0.085
0.370
0.040
0.096
0.035
0.020
0.165
0.039
6°
b
D1
H
L
L1
L3
L4
P
W
Θ1
Θ1
C2
A
c
D
L
A1
L3
H
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Page 10
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8384x-xx
®
TM
5A Low Dropout Positive Regulators
PRODUCTION DATA SHEET
NOTES
Pentium is a registered trademark of Intel Corporation. Cyrix is a registered trademark
and 6x86 is a trademark of the Cyrix Corporation. K5 is a registered trademark of AMD.
PRODUCTION DATA – Information contained in this document is proprietary to
LinFinity and is current as of publication date. This document may not be modified in any
way without the express written consent of LinFinity. Product processing does not
necessarily include testing of all parameters. LinFinity reserves the right to change the
configuration and performance of the product and to discontinue product at any time.
Copyright © 2000
Rev. 2.1f, 2006-01-20
Microsemi Inc.
Integrated Products Division
Page 11
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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