MIL-PRF-38534 CERTIFIED FACILITY
M.S.KENNEDY CORP.
5141
1.5A LOW NOISE,
ADJUSTABLE LDO
REGULATOR
4707 Dey Road Liverpool, N.Y. 13088
(315) 701-6751
FEATURES:
Fast Transient Response
Low Dropout Voltage: 340mV @ 1.5A
Low Noise: 40uVrms (10Hz to 100KHz)
1mA Quiescent Current
Adjustable Output from 1.21V to 20V
No Protection Diodes Required
Stable with 10uF Output Capacitor
Contact MSK for MIL-PRF-38534 Qualification Status
DESCRIPTION:
The MSK 5141 adjustable output regulator offers a low 340mV dropout voltage while supplying to 1.5A of output
current. With fast transient response, this regulator has very low output noise. Excellent line and load regulation characteristics ensure accurate performance for multiple applications. A low operating quiescent current of 1mA drops to <1μA at
shutdown. The regulator offers internal short circuit current limit, thermal limiting and reverse current protection which
eliminates the need for external components and excessive derating. The MSK 5141 is available in a hermetically sealed
space efficient 10 pin surface mount ceramic flatpack with built-in metal base.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATIONS
PIN-OUT INFORMATION
1
2
3
4
5
Post Regulator For Switching Power Supplies
Battery Powered Equipment
Microprocessor Power Supplies
Pre-amplifier Power Supplies
1
VOUT
10
VOUT
9
VOUT
8
ADJ
7
GND
6
CASE GND
VIN
VIN
VIN
NC
SHDN
Rev. A 9/11
ABSOLUTE MAXIMUM RATINGS
IN
IOUT
VOUT
VIN
ADJ
SHDN
ADJ
Supply Voltage
Output Current
Pin Voltage
Differential Input to Output Voltage
Pin Voltage
Pin Voltage
Pin Current
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TST
TLD
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TJ
TC
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Storage Temperature Range
-65°C to +150°C
Lead Temperature Range
(10 Seconds)
300°C
Junction Temperature
+150°C
Case Operating Temperature range
MSK 5141H
-55°C to +125°C
MSK 5141
-40°C to +85°C
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20V
1.5A
20V
20V
7V
20V
5mA
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9
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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.
5 Subgroup 1
TC=+25°C
Subgroup 2
TC=+125°C
Subgroup 3
TC=-55°C
6 Adjust pin connected to VOUT pin.
7 Reference current limit typical performance curves for input to output differential limitations.
8 The minimum input voltage requirement must be maintained.
9 Continuous operation at or above absolute maximum ratings may adversely effect the device performance and/or life cycle.
2
Rev. A 9/11
APPLICATION NOTES
OUTPUT ADJUST
REVERSE VOLTAGE PROTECTION
The output voltage range of the MSK 5141 is 1.21V to 20V.
The output voltage is set by the ratio of two external resistors as shown in Figure 1. The device monitors the output to
maintain the voltage at the ADJ pin. The ADJ pin is the input
to the error amplifier. It has a bias current of 3μA which
flows through R2 into the pin. The ADJ pin voltage is 1.21V
referenced to ground. The value of R1 should be less than
4.17K to minimize errors in the output voltage caused by
the ADJ pin bias current. Reference the typical performance
curves for load regulation variation due to the change in the
output voltage.
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.
LOAD REGULATION
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 MSK 5141 ground pin trace must be
designed to carry the ground pin current without significant
voltage drops. See typical performance curves.
INPUT BYPASS CAPACITORS
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.
FIGURE 1
OUTPUT CAPACITOR SELECTION
FIGURE 2
For most applications a 10μF low ESR tantalum capacitor,
as close to the regulators output as possible, is all that is
required for the MSK 5141 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 MSK 5141. 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.
SHUTDOWN MODE
The SHDN pin is used to put the regulator into its low power
state. The output will be off when the SHDN pin is pulled
low. Quiescent current drops from 1mA to less the 1μA in
shutdown mode. The SHDN pin can be driven by 5V logic or
open-collector logic with a pull-up resistor. The typical SHDN
pin current is 3uA. Connect the SHDN pin to VIN if not used.
If the SHDN pin is not connected, the regulator will go into a
low power shutdown state.
OVERLOAD PROTECTION
The MSK 5141 regulator features both current limit and thermal overload protection. Within the safe operating region,
the regulator will current limit above the 1.6 amp 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
regulator will 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.
3
Rev. A 9/11
APPLICATION NOTES CONT'D
MINIMIZING POWER DISSIPATION:
HEAT SINK SELECTION
To maximize the performance and reduce power dissipation
of the MSK 5141 device, 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 MSK 5141, 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 MSK 5141 is connected for VIN=+5V and
VOUT=+3.3V. IOUT is a continuous 1.0A 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=7.6°C/W and RθCS=0.15°C/W for most thermal
greases
Power Dissipation=(5V-3.3V) x (1.0A)
=1.7 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 - 7.6°C/W - 0.15°C/W
1.7W
= 51.1°C/W
In this example, a heat sink with a thermal resistance of no
more than 51.1°C/W must be used to maintain a maximum
junction temperature of no more than 125°C.
4
Rev. A 9/11
TYPICAL PERFORMANCE CURVES
5
Rev. A 9/11
TYPICAL PERFORMANCE CURVES CONT'D
6
Rev. A 9/11
TYPICAL PERFORMANCE CURVES CONT'D
7
Rev. A 9/11
MECHANICAL SPECIFICATIONS
WEIGHT= 0.3 GRAMS TYPICAL
NOTE: ALL DIMENSIONS ARE ±0.010 INCHES UNLESS OTHERWISE LABELED.
ESD Triangle indicates Pin 1.
ORDERING INFORMATION
MSK5141 H
SCREENING
BLANK=INDUSTRIAL
H=MIL-PRF-38534 CLASS H
GENERAL PART NUMBER
The above example is an adjustable Military regulator.
M.S. Kennedy Corp.
4707 Dey Road, Liverpool, New York 13088
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.
8
Rev. A 9/11