MIL-PRF-38534 AND 38535 CERTIFIED FACILITY
M.S.KENNEDY CORP.
5142
3A LOW NOISE,
FIXED OUTPUT LDO
REGULATOR
SERIES
FEATURES:
Fast Transient Response
Low Dropout Voltage: 340mV @ 3A
Low Noise: 40uVrms (10Hz to 100KHz)
1mA Quiescent Current
Fixed Output Voltages: 1.5V, 1.7V, 1.8V, 1.9V, 2.0V, 2.5V, 3.3V
No Protection Diodes Required
Stable with 10uF Output Capacitor
Available with Top Tab or Tabless Package
Available in Four Lead Configurations
Contact MSK for MIL-PRF-38534 Qualification Status
NO TAB
TOP TAB
DESCRIPTION:
The MSK5142 series regulators offer a low 340mV dropout voltage while supplying to 3A of output current. With fast
transient response, these regulators have very low output noise. Excellent line and load regulation characteristics ensure
accurate performance for multiple applications with a low operating quiescent current of 1mA. These regulators offer
internal short circuit current limit, thermal limiting and reverse current protection which eliminates the need for external
components and excessive derating. The MSK5142 series regulators are available in a hermetically sealed space efficient
TO-257 package with multiple lead form options.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATIONS
PIN-OUT INFORMATION
1 GND
2 VOUT
3 VIN
Post Regulator For Switching Power Supplies
Battery Powered Equipment
Microprocessor Power Supplies
Pre-amplifier Power Supplies
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8548-105 Rev. C 8/14
ABSOLUTE MAXIMUM RATINGS
IN
IOUT
VIN
TC
7
Supply Voltage
20V
Output Current
3A
Differential Input Voltage
20V
Case Operating Temperature range
MSK5142H
-55°C to +125°C
MSK5142
-40°C to +85°C
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TST
TLD
Storage Temperature Range
Lead Temperature Range
(10 Seconds)
Junction Temperature
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TJ
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-65°C to +150°C
300°C
+150°C
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ELECTRICAL SPECIFICATIONS
NOTES:
1 The output is decoupled to ground using a 100μF low ESR tantalum capacitor in parallel with a 1μF ceramic capacitor. See figure 1 for
typical circuit.
2 Guaranteed by design but not tested. Typical parameters are representative of actual device performance but are for reference only.
3 Industrial grade devices shall be tested to subgroups 1 unless otherwise requested.
4 Military grade devices ("H" suffix) shall be 100% tested to subgroups 1,2 and 3.
TA=+25°C
5 Subgroup 1
Subgroup 2
TA=+125°C
Subgroup 3
TA=-55°C
6 Not applicable to versions where VIN + VDROPOUT < VIN min. The minimum input voltage requirement must be maintained.
7 Reference current limit typical performance curves for input to output differential limitations.
8 Continuous operation at or above absolute maximum ratings may adversely effect the device performance and/or life cycle.
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8548-105 Rev. C 8/14
APPLICATION NOTES
INPUT BYPASS CAPACITORS
LOAD REGULATION
Unless the regulator is located very close to the main input
filter capacitor, a 1μF to 10μF low ESR tantalum capacitor
should be added to the regulator's input to maximize transient response and minimize power supply transients. A
0.1μF ceramic capacitor should also be used for high frequency bypassing.
In voltage regulator applications where very large load currents are present, the load connection is very important.
The path connecting the output of the regulator to the load
must be extremely low impedance to avoid affecting the
load regulation specifications. As shown in figure 2, any
impedance (Rs) in this path will form a voltage divider with
the load. For best results the ground pin should be connected
directly to the load as shown in figure 2. The direct connection eliminates the effect the potential voltage drop in the
power ground path can have on the internal ground sensing,
thus improving load regulation. The MSK5142 ground pin
trace must be designed to carry the ground pin current without significant voltage drops. See typical performance curves.
FIGURE 1
OUTPUT CAPACITOR SELECTION
For most applications a 10μF low ESR tantalum capacitor,
as close to the regulators output as possible, is all that is
required for the MSK5142 to be stable. When using a 10μF
capacitor on the lower output voltage devices, a minimum
ESR is required of the capacitor. This requirement decreases
from 20mΩ on the 1.5V output regulator to 5mΩ on the
3.3V output regulator. With an increase in capacitance, the
minimum ESR requirement decreases. At 100μF, the minimum ESR requirement decreases to 5mΩ for all versions of
the MSK5142. To reduce ringing and improve transient response, capacitors with slightly larger ESR in the range of
20mΩ to 50mΩ provides improved damping. Capacitors
with higher ESR can be combined in parallel with low ESR
ceramic capacitors for good high frequency response and
settling time. The maximum ESR value must be less than
3Ω. Care must be taken when selecting a ceramic type.
The X5R and X7R are the best choice for output stability
when considering response due to applied voltage and temperature.
FIGURE 2
OVERLOAD PROTECTION
The MSK5142 series regulators feature both current limit
and thermal overload protection. Within the safe operating
region, the regulators will current limit above their 1.6amp
rating. As the input to output voltage increases, however,
the current limit decreases to keep the output transistor
within its power dissipation limitation. See the Current Limit
Typical Curves for conditional performance detail. If the device heats enough to exceed its rated die junction temperature due to excessive ambient temperature, improper heat
sinking etc., the regulators also shutdown until an appropriate junction temperature is maintained. To bring the regulator out of shutdown, the device input may need to be cycled
to zero and power reapplied to eliminate the shutdown condition.
REVERSE VOLTAGE PROTECTION
The regulators are protected against reverse input and output voltages. Reverse input voltages up to 20V will be
blocked from the input while current flow is limited to less
than 1mA. The reverse voltage on the input is also prevented from appearing on the output and the load. When
the input voltage is pulled down to ground and the output is
held up by a second source, the current flow between them
is limited to typically 600μA. See the electrical specifications table.
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8548-105 Rev. C 8/14
APPLICATION NOTES CONT'D
MINIMIZING POWER DISSIPATION:
HEAT SINK SELECTION
To maximize the performance and reduce power dissipation
of the MSK5142 series devices, VIN should be maintained
as close to dropout or at VIN minimum when possible. See
Input Supply Voltage requirements. A series resistor can be
used to lower VIN close to the dropout specification, lowering the input to output voltage differential. In turn, this will
decrease the power that the device is required to dissipate.
Knowing peak current requirements and worst case voltages, a resistor can be selected that will drop a portion of
the excess voltage and help to distribute the heating. The
circuit below illustrates this method.
To select a heat sink for the MSK5142, the following formula for convective heat flow may be used.
Governing Equation:
TJ = PD X (RθJC + RθCS + RθSA) + TA
Where
TJ
PD
RθJC
RθCS
RθSA
TA
=
=
=
=
=
=
Junction Temperature
Total Power Dissipation
Junction to Case Thermal Resistance
Case to Heat Sink Thermal Resistance
Heat Sink to Ambient Thermal Resistance
Ambient Temperature
Power Dissipation=(VIN-VOUT) x IOUT
Next, the user must select a maximum junction temperature. The absolute maximum allowable junction temperature
is 150°C. The equation may now be rearranged to solve for
the required heat sink to ambient thermal resistance (RθSA).
Example:
The maximum resistor value can be calculated from the
following:
An MSK5142 is connected for VIN=+5V and
VOUT=+3.3V. IOUT is a continuous 2A DC level. The ambient temperature is +25°C. The maximum desired junction temperature is +125°C.
R1 max = VIN min - (VOUT max + VDROP)
IOUT peak + GND Pin Current
Where:
RθJC=5.6°C/W and RθCS=0.15°C/W for most thermal
greases
Power Dissipation=(5V-3.3V) x (2A)
=3.4 Watts
Solve for RθSA:
VIN min=Minimum input voltage
VOUT max=Maximum output voltage across the full
temperature range
VDROP=Worst case dropout voltage (Typically 430mV)
IOUT peak=Maximum load current
GND Pin Current=Max. GND Pin Current at IOUT peak
RθSA= 125°C - 25°C - 3.8°C/W - 0.15°C/W
3.4W
= 25.5°C/W
In this example, a heat sink with a thermal resistance of no
more than 25.5°C/W must be used to maintain a maximum
junction temperature of no more than 125°C.
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8548-105 Rev. C 8/14
TYPICAL PERFORMANCE CURVES
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8548-105 Rev. C 8/14
TYPICAL PERFORMANCE CURVES CONT'D
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8548-105 Rev. C 8/14
MECHANICAL SPECIFICATIONS
ESD TRIANGLE INDICATES PIN 1
WEIGHT=2.9 GRAMS TYPICAL
ALL DIMENSIONS ARE SPECIFIED IN INCHES
ORDERING INFORMATION
MSK5142-1.8 H T D
LEAD CONFIGURATIONS
(GULL WING NOT AVAILABLE WITH TOP TAB VERSION)
S= STRAIGHT; U= BENT UP; D= BENT DOWN
PACKAGE STYLE
T=TOP TAB; BLANK=NO TAB
SCREENING
BLANK= INDUSTRIAL
H= MIL-PRF-38534 CLASS H
OUTPUT VOLTAGE
1.5=+1.5V; 1.7=+1.7V; 1.8=+1.8V; 1.9=+1.9V;
2.0=+2.0V; 2.5=+2.5V; 3.3=+3.3V
GENERAL PART NUMBER
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8548-105 Rev. C 8/14
MECHANICAL SPECIFICATIONS
ESD TRIANGLE INDICATES PIN 1
WEIGHT=2.9 GRAMS TYPICAL
ALL DIMENSIONS ARE SPECIFIED IN INCHES
ORDERING INFORMATION
MSK5142-1.8 H
G
LEAD CONFIGURATIONS
(GULL WING NOT AVAILABLE WITH TOP TAB VERSION)
S= STRAIGHT; U= BENT UP; D= BENT DOWN; G=GULL WING
PACKAGE STYLE
T=TOP TAB; BLANK=NO TAB
SCREENING
BLANK= INDUSTRIAL
H= MIL-PRF-38534 CLASS H
OUTPUT VOLTAGE
1.5=+1.5V; 1.7=+1.7V; 1.8=+1.8V; 1.9=+1.9V;
2.0=+2.0V; 2.5=+2.5V; 3.3=+3.3V
GENERAL PART NUMBER
The above example is a +1.8V, Military regulator with gull wing leads and no tab.
8548-105 Rev. C 8/14
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REVISION HISTORY
M.S. Kennedy Corp.
Phone (315) 701-6751
FAX (315) 701-6752
www.mskennedy.com
The information contained herein is believed to be accurate at the time of printing. MSK reserves the right to make
changes to its products or specifications without notice, however, and assumes no liability for the use of its products.
Please visit our website for the most recent revision of this datasheet.
Contact MSK for MIL-PRF-38534 qualification status.
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8548-105 Rev. C 8/14