MIL-PRF-38534 & 38535 CERTIFIED FACILITY
5979RH
RAD HARD POSITIVE,
0.9A, LDO, SINGLE RESISTOR
ADJ VOLTAGE REGULATOR
FEATURES:
Manufactured using
Space Qualified RH3080 Die
Total Dose Hardened to 300 Krads(Si) (Method 1019.7 Condition A)
Low Dropout to 300mV (VIN - VOUT, with Seperate CTL Supply)
Output Adjustable to Zero Volts
Internal Short Circuit Current Limit
Output Voltage is Adjustable with 1 External Resistor
Output Current Capability to 0.9 Amps
Internal Thermal Overload Protection
Outputs may be Paralleled for Higher Current
Available in 3 Lead Form Options with Ceramic Seals: Straight, Up and Down (TO257)
Contact MSK for MIL-PRF-38534 Qualification Status
DESCRIPTION:
The MSK5979RH offers low dropout down to 300mV and an output voltage range down to zero volts while offering radiation tolerance for space applications. This, combined with the low θJC, allows increased output current while providing
exceptional device efficiency. Because of the increased efficiency, a small hermetic 3 pin package can be used providing
maximum performance while occupying minimal board space. Output voltage is selected by the user through the use of 1
external resistor. Additionally, the regulator offers internal short circuit current and thermal limiting, which allows circuit protection and eliminates the need for external components and excessive derating.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATIONS
PIN-OUT INFORMATION
High Efficiency Linear Regulators
Constant Voltage/Current Regulators
Space System Power Supplies
Switching Power Supply Post Regulators
Very low Voltage Power Supplies
1
2
3
SET
CTL
VIN
CASE VOUT
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ABSOLUTE MAXIMUM RATINGS
VIN
VCTL
PD
IOUT
TJ
Input Voltage 7
Control Voltage 7
Power Dissipation
Output Current 8
Junction Temperature
9
+40V,-0.3V
+40V,-0.3V
Internally Limited
0.9A
+150°C
TST
TLD
TC
Storage Temperature Range
Lead Temperature Range
(10 Seconds)
Case Operating Temperature
MSK5979RH
MSK5979K/H
ESD Rating
-65°C to +150°C
300°C
-40°C to +85°C
-55°C to +125°C
Class 2
ELECTRICAL SPECIFICATIONS
NOTES:
1 Output is decoupled to ground using A 220µF tantalum low ESR capacitor in parallel with 3 pieces of 1.0µF and one 0.1µF ceramic capacitors unless
otherwise specified. (See Figure 1)
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 subgroup 1 unless otherwise specified.
4 Military grade ("H" suffix) and space grade ("K" suffix) devices shall be 100% tested to subgroups 1,2 and 3.
5 Subgroup 1 TA=TC=+25°C
Subgroup 2 TA=TC=+125°C
Subgroup 3 TA=TC=-55°C
6 Minimum load current verified while testing line regulation.
7 Voltage is measured with respect to VOUT.
8 Reference the current limit typical performance curve for input to output voltage differential verses output current capabilities.
9 Continuous operation at or above absolute maximum ratings may adversely effect the device performance and/or life cycle.
10 Pre and Post irradiation limits at 25°C, up to 300 Krads(Si) TID, are identical unless otherwise specified.
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APPLICATION NOTES
OUTPUT VOLTAGE
ADDITIONAL STABILITY
A single resistor (Rset) from the SET pin to ground creates the reference
voltage for the internal Error Amplifier. The MSK5979RH SET pin supplies
a constant current of 10uA that develops the reference voltage. The output
voltage is simply Rset x 10uA. Since the output is internally driven by a
unity-gain amplifier, an alternative to using Rset is to connect a high quality
reference source to the SET pin. With a minimum load requirement of 1mA
on the Output, the Output Voltage can be adjusted to near 0V. To bring
the output voltage to 0V, the load must be connected to a slightly negative
voltage supply to sink the 1mA minimum load current from a 0V output.
A capacitor placed in parallel with the SET pin resistor to ground, will improve the output transient response and filter noise in the system. To reduce
output noise, typically less than 100pF is all that will be required. Capacitors
up to 1µF can be used, however consideration must be given to the effect
the time constant created will have on the startup time.
LOAD REGULATION
The MSK5979RH specified load regulation is Kelvin Sensed, therefore
the parasitic resistance of the system must be considered to design an acceptable load regulation. The overall load regulation includes the specified
MSK5979RH load regulation plus the parasitic resistance multiplied by
the load current as shown in Figure 3. RSO is the series resistance of all
conductors between the MSK5979RH output and the load. It will directly
increase output load regulation error by a voltage drop of ∆Io x Rso. Rss
is the series resistance between the set pin and the load. RSS will have
little effect on load regulation if the set pin trace is connected as close to
the load as possible keeping the load return current on a separate trace as
shown. RSR is the series resistance of all of the conductors between the
load and the input power source return. RSR will not effect load regulation
if the set pin is connected with a Kelvin Sense type connection as shown
in Figure 3, but it will increase the effective dropout voltage by a factor of
IO x RSR. Keeping RSO and RSR as low as possible will ensure minimal
voltage drops and wasted power.
FIGURE 1
OUTPUT CAPACITANCE
For stability purposes, the MSK5979RH requires a minimum output capacitor of 10µF with an ESR of 0.5Ω or less. Tantalum or ceramic capacitors are recommended. A larger capacitance value will improve transient
response for increased load current changes. Consideration must also be
given to temperature characteristics of the capacitors used.
LOW DROPOUT OPERATION
Using separate VIN and Vcontrol power supplies allows for lower dropout
and improved efficiency. Figure 2 shows the MSK5979RH output transistor collector is connected to the VIN pin. The regulator control circuitry is
powered by the Vcontrol input. The dropout of the regulator is determined
by the saturation voltage of the output transistor, typical 300mV at 0.9A
load. The Vcontrol supply must supply the base drive current for the output
transistor. The Vcontrol current minus the 10µA set current is supplied to
the load. See the Typical Performance Characteristics curves for expected
VIN dropout voltage, control pin dropout voltage and current requirements
under various conditions. With separate supplies for VIN and Vcontrol,
power dissipation is reduced and efficiency improves.
FIGURE 3
PARALLELING DEVICES
When currents greater than 0.9A are needed, the MSK5979RH's may
be paralleled to multiply the current capacity. As shown in Figure 4, the Vin
and SET pins must be tied together. The VOUT pins are connected to the
load with consideration to the conductor resistance. The conductor resistance of each MSK5979RH VOUT connection to the load, must be equal
to create equal load sharing. As little as 10mΩ ballast resistance typically
ensures better than 80% equal sharing of load current at full load. Additional
consideration must be given to the effect the additional VOUT conductor
resistance has on load regulation; see paragraph titled "Load Regulation".
FIGURE 4
FIGURE 2
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APPLICATION
NOTES
CONT'D
APPLICATION
NOTES
CONT'D
HEAT SINKING
IMPROVING INITIAL ACCURACY AND
REDUCING TEMPERATURE DRIFT
To determine if a heat sink is required for your application and if so,
what type, refer to the thermal model and governing equation below.
The initial output accuracy of the MSK5979RH due to set pin current
tolerance and set point resistor accuracy can be reduced to 0.2% using the MSK109RH radiation hardened precision reference. Minimal
drift of the MSK109RH from temperature extremes and irradiation
ensure very tight regulation. The circuit can be configured to use
the 2.5V reference to directly set the output at 2.5V or with a slight
variation it can provide any output within the operating range of the
MSK5979RH down to 0V output. Select Rs to maintain between
1mA and 10mA of current through the reference; see Figure 5 below.
Rs may be tied to VIN or another power source. The optional trim
resistor can be used to further trim out initial output and system
error. Reference the MSK109RH data sheet for application circuits
that provide stable output voltages across the full operating range
of the MSK5979RH including down to 0V output and the operating
characteristics of the MSK109RH.
Governing Equation: Tj = Pd x (Rθjc + Rθcs + Rθsa) + Ta
WHERE
Tj = Junction Temperature
Pd = Total Power Dissipation
Rθjc = Junction to Case Thermal Resistance
Rθcs = Case to Heat Sink Thermal Resistance
Rθsa = Heat Sink to Ambient Thermal Resistance
Tc = Case Temperature
Ta = Ambient Temperature
Ts = Heat Sink Temperature
EXAMPLE:
This example demonstrates the thermal calculations for the TO-257
package with the regulator operating at one-half of its maximum
rated output current.
Conditions for MSK5979RH:
VCTL=VIN = +3.0V; Iout = +0.45A VOUT=+1.0V
1.) Assume 45° heat spreading model.
2.) Find regulator power dissipation:
Pd = (VIN - VOUT)(Iout)
Pd = (3-1)(0.45)
= 0.9W
3.) For conservative design, set Tj = +125°C Max.
4.) For this example, worst case Ta = +90°C.
5.) Rθjc = 5.0°C/W from the Electrical Specification Table.
6.) Rθcs= 0.15°C/W for most thermal greases.
7.) Rearrange governing equation to solve for Rθsa:
FIGURE 5
Rθsa= ((Tj - Ta)/Pd) - (Rθjc) - (Rθcs)
= (125°C - 90°C)/0.9W - 5.0°C/W - 0.15°C/W
= 33.7°C/W
ADDING SHUTDOWN
The MSK5979RH can be easily shutdown by either reducing
Rset to 0Ω or connecting a transistor from the set pin to ground.
By connecting two transistors, as shown in Figure 6, a low current
voltage source is all that is required to take the set pin to ground
as well as pull the output voltage to ground. Q2 pulls the output
voltage to ground when no load is present and only needs to sink
10mA. Use a low leakage switching diode between Vout and Set
to avoid overstress during shutdown transitions.
In this case the result is 33.7°C/W. Therefore, a heat sink with a thermal resistance of no more than 33.7°C/W must be used in this application to maintain regulator circuit junction temperature under 125°C.
TOTAL DOSE RADIATION TEST
PERFORMANCE
Radiation performance curves for TID testing have been generated
for all radiation testing performed by MS Kennedy. These curves
show performance trends throughout the TID test process and can
be located in the MSK5977RH radiation test report. The complete
radiation test report is available in the RAD HARD PRODUCTS section
on the MSK website.
ADDITIONAL APPLICATION INFORMATION
For additional applications information, please reference Linear Technology Corporation's® LT3080 and RH3080 data sheets.
DIE GLASSIVATION
For enhanced radiation tolerance the die has a glassivation thickness of 4KA and is not in accordance with MIL-PRF-38534.
FIGURE 6
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TYPICAL PERFORMANCE CURVES
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TYPICAL PERFORMANCE CURVES CONT'D
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MECHANICAL SPECIFICATIONS
ESD TRIANGLE INDICATES PIN 1
WEIGHT=3.2 GRAMS TYPICAL
ALL DIMENSIONS ARE SPECIFIED IN INCHES
ORDERING INFORMATION
MSK5979 K RH U
LEAD CONFIGURATIONS
S= STRAIGHT; U= BENT UP; D= BENT DOWN
RADIATION HARDENED
SCREENING
BLANK= INDUSTRIAL
H=MIL-PRF-38534 CLASS H
K=MIL-PRF-38534 CLASS K
GENERAL PART NUMBER
The above example is an adjustable Class K regulator with leads bent up.
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8548-133 Rev. B 8/15
REVISION HISTORY
MSK
www.anaren.com/msk
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 Class K qualification status.
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