MIL-PRF-38534 AND 38535 CERTIFIED FACILITY
M.S.KENNEDY CORP.
RAD HARD ULTRA LOW
VOLTAGE ADJUSTABLE
POSITIVE LINEAR REGULATOR
5950RH
FEATURES:
Manufactured using
Space Qualified RH1009 and RH1573 Die
Total Dose Hardened to 300 Krads(Si) (Method 1019.7 Condition A)
Output Adjustable Down to Near Zero
External Shutdown/Reset Function
Latching Overload Protection
Adjustable Output Using External Resistors
Output Current Limit
Surface Mount Package Available with Lead Forming
Low Input Voltage for Maximum Efficiency
Up to 5A Output Current
Contact MSK for MIL-PRF-38534 Qualification Status
DESCRIPTION:
The MSK5950RH is a radiation hardened adjustable linear regulator capable of delivering 5.0 amps of output current.
The typical dropout is only 0.11 volts at 1 amp. An external shutdown/reset function is ideal for power supply sequencing.
This device also has latching overload protection that requires no external current sense resistor. The MSK5950RH is
radiation hardened and specifically designed for many space/satellite applications. The device is packaged in a hermetically
sealed 20 pin flatpack that can be lead formed for surface mount applications.
EQUIVALENT SCHEMATIC
TYPICAL
APPLICATIONS
TYPICAL APPLICATIONS
PIN-OUT INFORMATION
Satellite System Power Supplies
Switching Power Supply Post Regulators
Constant Voltage/Current Regulators
Microprocessor Power Supplies
1
2
3
4
5
6
7
8
9
10
VINA
VINB
VINC
VIND
VINE
VBIAS
GND1
GND1
Latch
Shutdown
20
19
18
17
16
15
14
13
12
11
VOUTE
VOUTD
VOUTC
VOUTB
VOUTA
VREF
GND2
GND2
GND2
FB
CASE=ISOLATED
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8548-18 Rev. J 6/14
8
ABSOLUTE MAXIMUM RATINGS
+VBIAS
+VIN
VSD
IVREF
IOUT
TC
Bias Supply Voltage
10V
Supply Voltage
10V
Shutdown Voltage
10V
Reference Sink Current
20mA
Output Current 7
5A
Case Operating Temperature Range
MSK5950K/H RH
-55°C to +125°C
MSK5950RH
-40°C to +85°C
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TST
TLD
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PD
TC
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Storage Temperature Range
Lead Temperature Range
(10 Seconds)
Power Dissipation
Junction Temperature
ESD Rating
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10
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-65°C to +150°C
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300°C
See SOA Curve
150°C
Class 1C
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ELECTRICAL SPECIFICATIONS
NOTES:
1
2
3
4
5
6
7
8
9
10
Unless otherwise specified, VBIAS=VIN=5.0V, R1=1.62K, RREF=249W (see figure 2), VSHUTDOWN=0V and IOUT=10mA.
Guaranteed by design but not tested. Typical parameters are representative of actual device performance but are for reference only.
Industrial grade devices shall be tested to subgroups 1 and 4 unless otherwise requested.
Military grade devices ("H" suffix) shall be 100% tested to subgroups 1,2,3 and 4.
Subgroup 5 and 6 testing available upon request.
Subgroup 1,4 TC=+25°C
Subgroup 2,5 TC=+125°C
Subgroup 3,6 TA=-55°C
Output current limit is tested with a low duty cycle pulse to minimize junction heating and is dependent on the values of VIN, VOUT and case
temperature. See Typical Performance Curves.
Continuous operation at or above absolute maximum ratings may adversely effect the device performance and/or life cycle.
Pre and post irradiation limits @25°C, up to 300 Krad TID, are identical unless otherwise specified.
Internal solder reflow temperature is 180°C, do not exceed.
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8548-18 Rev. J 6/14
APPLICATION NOTES
PIN FUNCTIONS
VIN A,B,C,D,E - These pins provide the input power connection to the
MSK5950RH. This is the supply that will be regulated to the output.
All five pins must be connected for proper operation.
LATCH - The MSK5950RH LATCH pin is used for both current limit
and thermal limit. A capacitor between the LATCH pin and ground
sets a time out delay in the event of an over current or short circuit
condition. The capacitor is charged to approximately 1.6V from a
7.2μA (nominal) current source. Exceeding the thermal limit will
charge the latch capacitor from a larger current source for a near
instant shutdown. Once the latch capacitor is charged the device
latches off until the latch is reset. Momentarily pull the LATCH pin
low, toggle the shutdown pin high then low or cycle the power to
reset the latch. Toggling the shutdown pin or cycling the bias power
both disable the device during the reset operation (see SHUTDOWN
pin description). Pulling the LATCH pin low immediately enables the
device for as long as the LATCH pin is held low plus the time delay
to re-charge the latch capacitor whether or not the fault has been
corrected. Disable the latch feature by tying the LATCH pin low.
With the LATCH pin held low the thermal limit feature is disabled
and the current limit feature will force the output voltage to droop
but remain active if excessive current is drawn.
VBIAS - This pin provides power to all internal circuitry including bias,
start-up, thermal limit and overcurrent latch. VBIAS voltage range is
2.9V to 7.5V. VBIAS should be kept greater than or equal to VIN.
VREF - Internal general purpose 2.5V shunt regulator that will operate
over a wide current range while maintaining good stability. This reference voltage is used along with the feedback voltage to configure the
desired output voltage. The reference will maintain good regulation as
long as 0.4<ISHUNT<10mA. The shunt current is derived from a resistor tied to VIN or VBIAS. The resistor must supply both the minimum shunt current of 400μA (1mA recommended) and the current
required by the output voltage feedback divider network, between 2
and 2.5mA total is typically sufficient. A constant current diode (CCR)
may be used in place of the resistor to minimize variations in ISHUNT
due to line voltage variations.
SHUTDOWN - There are two functions to the SHUTDOWN pin. It
may be used to disable the output voltage or to reset the LATCH pin.
To activate the shutdown/reset functions the user must apply a
voltage greater than 1.3V to the SHUTDOWN pin. The voltage applied to the SHUTDOWN pin can be greater than the input voltage.
The output voltage will turn on when the SHUTDOWN pin is pulled
below the threshold voltage. If the SHUTDOWN pin is not used, it
should be connected to ground.
Resistor calculation example:
VBIAS=3.3V±10%
VOUT=0.9V
First determine the required current by selecting R2 in the feed back
divider, typically between 1.0 and 1.2KΩ; see the output voltage selection paragraph. Using standard value 0.1% tolerance resistors, the
nominal output will be 0.9V with R2=1.07K and R1=316Ω. The
current in the divider will be equal to (VREF-VFDBK)/R2 or 1.154mA
nominal and 1.2mA worst-case in this example.
FB - The FB pin is the inverting input of the internal error amplifier.
The non-inverting input is connected to an internal 1.265V reference. This error amplifier controls the drive to the output transistor
to force the FB pin to 1.265V. An external resistor divider is connected to the output, FB pin, VREF and VIN to set the output voltage.
The total current required is the sum of the worst-case divider current
plus the VREF shunt current. The minimum shunt current is 400μA but
1mA is recommended. Using the recommended 1mA the minimum
current required in RREF is 2.2mA.
POWER SUPPLY BYPASSING
The maximum resistor value to source the required current is equal to
(VBIAS min-VREF)/2.2mA or 218Ω for this example. The maximum
current in the reference must not exceed 10mA, the absolute maximum allowable bias voltage is
10mA*RREF+VREF(min) or 4.67V for this application.
To maximize transient response and minimize power supply transients it is recommended that a 33μF minimum tantalum capacitor
is connected between VIN and ground. A 0.1μF ceramic capacitor
should also be used for high frequency bypassing.
The designer must also consider that the feedback divider will provide
a resistive connection from the source (VIN or VBIAS) to the output
even when the regulator is disabled. A minimum load resistor can be
used to draw the voltage down in the event this poses a problem. A
90Ω resistor will sink 10mA during operation and pull the output well
below 200mV when the regulator is disabled in this application.
Low ESR output capacitors are required to maintain regulation and
stability. Four CWR29FB227 (AVX PN TAZH227K010L) tantalum
capacitors in parallel with ceramic decoupling capacitors (0.1μF typical) provides sufficient gain and phase margin for most applications.
The maximum ESR specification for the CWR29FB227 capacitor is
180mΩ at 100kHz and is sufficient for many applications. MSK has
found through full WCCA on the MSK5820RH-1.5 that screening for
a maximum ESR of 57mΩ ensures EOL stability criteria to be met
for many applications with the most stringent requirements. Analysis of the final design is recommended to ensure stability requirements are met.
OUTPUT CAPACITOR SELECTION
VREF can be used as a precision 2.5V reference for other parts of the
circuit as long as circuit loading, shunt current and parasitics are
carefully considered.
GND1 - SIGNAL GROUND - Internally connected to the reference ground,
these pins should be connected externally by the user to the circuit
ground and the GND2 pins.
THERMAL LIMITING
The MSK5950RH control circuitry has a thermal shutdown temperature of approximately 150°C. This thermal shutdown can be used
as a protection feature, but for continuous operation, the junction
temperature of the pass transistor must be maintained below 150°C.
Proper heat sink selection is essential to maintain these conditions.
Exceeding the thermal limit activates the latch feature of the
MSK5950RH. See LATCH pin description for instructions to reset
the latch or disable the latch feature.
VOUT A,B,C,D,E - These are the output pins for the device. All five
pins must be connected for proper operation.
GND2 - POWER GROUND - Internally connected to the pass element
drive circuitry, these pins should be connected externally by the user
to the circuit ground and the GND1 pins.
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8548-18 Rev. J 6/14
APPLICATION NOTES CONT.
Governing Equation:
START UP OPTIONS
TJ = PD X (RθJC + RθCS + RθSA) + TA
The MSK5950RH starts up and begins regulating immediately
when VBIAS and VIN are applied simultaneously. Applying VBIAS
before VIN starts the MSK5950RH up in a disabled or latched
state. When starting in a latched state the device output can be
enabled either by pulling the latch pin low to drain the latch capacitor or pulsing the shutdown pin high. The shutdown pulse duration is partially dependent upon the size of the latch capacitor and
should be characterized for each application; 30uS is typically adequate for a 1uF latch capacitor at 25°C. A momentary high pulse
on the shutdown pin can be achieved using the RC circuit below if
VIN rises rapidly. The resistor and capacitor must be selected based
on the required pulse duration, the rise characteristic of VIN and
the shutdown pin threshold (see shutdown pin threshold and current curves).
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).
The shutdown pin can be held high and pulled low after VIN comes
up or the latch pin held low and released after VIN comes up to
ensure automatic startup when applying VBIAS before VIN. Either
of the basic circuits below can be adapted to a variety of applications for automatic start up when VBIAS rises before VIN.
Example:
An MSK5950RH is connected for VIN=+3.3V and
VOUT=+1.2V. IOUT is a continuous 1A DC level. The ambient temperature is +25°C. The maximum desired junction
temperature is +125°C.
RθJC=8.4°C/W and RθCS=0.15°C/W for most thermal
greases
Power Dissipation=(3.3V-1.2V) x (1A)
=2.1Watts
Solve for RθSA:
RθSA=
125°C - 25°C
2.1W
-8.4°C/W - 0.15°C/W
= 39°C/W
In this example, a heat sink with a thermal resistance of no
more than 39°C/W must be used to maintain a junction temperature of no more than 125°C.
START UP CURRENT
OVERCURRENT LATCH-OFF/LATCH PIN
CAPACITOR SELECTION
The MSK5950RH sinks increased current during startup to
bring up the output voltage. Reference the "Saturated Drive
Current vs. Input Voltage" graph in the typical performance
curves of this data sheet and the "Understanding Startup Surge
Current With MS Kennedy's RH1573 Based Rad Hard LDO
Regulators" application note in the application notes section
of the MS Kennedy Web site for more information.
As previously mentioned, the LATCH pin provides over current/
output short circuit protection with a timed latch-off circuit. Reference the LATCH pin description note. The latch off time out is
determined with an external capacitor connected from the LATCH
pin to ground. The time-out period is equal to the time it takes to
charge this external capacitor from 0V to 1.6V. The latch charging
current is provided by an internal current source. This current is a
function of bias voltage and temperature (see latch charging current curve). For instance, at 25°C, the latch charging current is
7.2μA at VBIAS=3V and 8μA at VBIAS=7V.
In the latch-off mode, some additional current will be drawn from
the bias supply. This additional latching current is also a function
of bias voltage and temperature (see typical performance curves).
The MSK5950RH current limit function is directly affected by
the input and output voltages. Custom current limit is available;
contact the factory for more information.
http://www.mskennedy.com/
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 are located in the MSK5950RH radiation test report.
The complete radiation test report is available in the RAD HARD
PRODUCTS section on the MSK website.
HEAT SINK SELECTION
To select a heat sink for the MSK5950RH, the following formula
for convective heat flow may be used.
http://www.mskennedy.com/store.asp?pid=9951&catid=19680
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8548-18 Rev. J 6/14
APPLICATION NOTES CONT.
TYPICAL APPLICATIONS CIRCUIT
For output voltages above the feedback voltage the unit should
be configured as shown in Figure 2.
FIGURE 1
OUTPUT VOLTAGE SELECTION
The MSK5950RH output voltage can be adjusted from 0 to 5V.
Three different resistor network schemes are used depending on
the required output voltage level.
For output voltages below the minimum feedback voltage tolerance of 1.225V, R3 as shown in Figure 1 can be omitted. Output voltage can be calculated as follows:
Given:
VFB=1.265V
VREF=2.5V
FIGURE 2
VOUT=1.265(1+R1/R2)
As noted in the above typical applications circuit, the formula for
output voltage selection is:
VOUT=1.265(1+(R1/R2))
VOUT=VFB-((VREF-VFB)/R2)R1
For convenience Table 1 below provides standard 0.1% tolerance resistor values required to achieve several output voltages
based on nominal feedback voltage, R3 is ommitted.
A good starting point for this output voltage selection is set to
R2=1K. By rearranging the formula it is simple to calculate the
final R1 value.
R1=R2((VOUT/1.265)-1)
Table 3 below lists some of the most probable resistor combinations based on industry standard usage, R3 is ommitted.
For output voltages close to the feedback voltage tolerance of
1.225V-1.305V, a three resistor network may be used to improve adjustment capabilities and trim out initial feedback voltage tolerances. Reference Figure 1.
VREFcan be used as a precision 2.5V reference as long as circuit
loading and shunt current are carefully considered. If VREF is not
used the pin should be pulled to ground.
VOUT= (R2R3VFB+R1R3(VFB-VREF)+R1R2VFB)/(R2R3)
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8548-18 Rev. J 6/14
TYPICAL PERFORMANCE CURVES
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8548-18 Rev. J 6/14
MECHANICAL SPECIFICATIONS
ESD TRIANGLE INDICATES PIN 1
WEIGHT=3.5 GRAMS TYPICAL
ALL DIMENSIONS ARE SPECIFIED IN INCHES
ORDERING INFORMATION
PART NUMBER
SCREENING LEVEL
MSK5950RH
INDUSTRIAL
MSK5950HRH
MIL-PRF-38534 CLASS H
MSK5950KRH
MIL-PRF-38534 CLASS K
7
LEADS
STRAIGHT
8548-18 Rev. J 6/14
MECHANICAL SPECIFICATIONS CONTINUED
ESD TRIANGLE INDICATES PIN 1
WEIGHT=3.3 GRAMS TYPICAL
ALL DIMENSIONS ARE SPECIFIED IN INCHES
ORDERING INFORMATION
PART NUMBER
SCREENING LEVEL
MSK5950RHG
INDUSTRIAL
MSK5950HRHG
MIL-PRF-38534 CLASS H
MSK5950KRHG
MIL-PRF-38534 CLASS K
8
LEADS
GULL
WING
8548-18 Rev. J 6/14
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 Class H, Class K status.
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8548-18 Rev. J 6/14