MIL-PRF-38534 AND 38535 CERTIFIED FACILITY
M.S.KENNEDY CORP.
FEATURES:
RAD HARD
1.5A, NEGATIVE
ADJUSTABLE
LINEAR REGULATOR
5973RH
(315) 701-6751
4707 Dey Road Liverpool, N.Y. 13088
Manufactured using
Space Qualified RH 137 Die
Radiation Hardened to 100 Krads(Si) (Method 1019.7 Condition A)
Output Current Limit
Internal Thermal Overload Protection
Output Current to 1.5 Amps
Adjustable Output using two External Resistors
Available in 3 Lead Form Options: Straight, Up and Down (TO-257)
Available to DSCC SMD 5962R09214
Equivalent Non Rad Hard Device MSK 5173
SMD-1
3 PAD
CERAMIC
TO-257
DESCRIPTION:
The MSK 5973RH is a radiation hardened 3-terminal negative adjustable regulator capable of supplying up to 1.5A of
current. The output is adjustable using external resistors for a range of Vref to -27V. Excellent line and load regulation
characteristics ensure accurate performance. The MSK 5973RH has full protection with current and thermal limiting. The
MSK 5973RH is packaged in two space saving packages, the 3 pin power surface mount ceramic SMD-1 or the TO-257
package with 3 lead form options: straight, up and down.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATIONS
Satellite System Power Supplies
Switching Power Supply Post Regulators
Constant Voltage/Current Regulators
High Efficiency Linear Regulators
PIN-OUT INFORMATION
TO-257
1 ADJ
2 VIN
3 VOUT
SMD-1
1 ADJ
2 VOUT
3 VIN
CASE=ISOLATED
8548-84 Rev. G 10/12
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ABSOLUTE MAXIMUM RATINGS
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8
-40°C to +85°C
-55°C to +125°C
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ELECTRICAL SPECIFICATIONS
NOTES:
1 Output is decoupled to ground using 10μF low ESR tantalum capacitors and 0.1μF ceramic.
2 Guaranteed by design but not tested. Typical parameters are representative of actual device
performance but are for reference only.
3 All output parameters are tested using a low duty cycle pulse to maintain TJ = TC.
4 Industrial grade and devices shall be tested to subgroup 1 unless otherwise specified.
5 Military grade devices ("H" and "K" suffix) shall be 100% tested to subgroups 1,2 and 3.
6 Subgroup 1
TA=TC=+25°C
Subgroup 2
TA=TC=+125°C
Subgroup 3
TA=TC=-55°C
7 The output current limit function provides protection from transient overloads but it may exceed the maximum continuous rating.
Continuous operation in current limit may damage the device.
8 Continuous operation at or above absolute maximum ratings may adversely effect the device performance and/or life cycle.
9 Pre and Post irradiation limits at 25°C, up to 100 Krad TID, are identical unless otherwise specified.
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8548-84 Rev. G 10/12
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V
IN
P
D
I
OUT
T
J
Input Voltage (V
IN
-V
OUT
)
Power Dissipation
Output Current
Junction Temperature
30V
DC
Internally Limited
1.5A
+150°C
T
ST
Storage Temperature Range
T
LD
Lead Temperature Range
(10 Seconds)
T
C
Case Operating Temperature
MSK 5973RH
MSK 5973(K/H)RH
-65°C to +150°C
300°C
APPLICATION NOTES
OUTPUT VOLTAGE
The MSK 5973RH develops a nominal -1.25V reference volt-
age between the output and adjustment terminal. With a con-
stant reference voltage drop across program resistor R1, a con-
stant current flows through the output set resistor R2. Since the
current from the adjustment terminal represents an error in the
programmed output voltage, the MSK 5973RH was designed
to minimize I
ADJ
and make it very constant with line and load
changes. To do this, all quiescent operating current is returned
to the output establishing a minimum load current requirement.
If there is insufficient load on the output, the output will rise.
Figure 1 shows the output voltage calculations.
LOAD REGULATION
The MSK 5973RH is capable of providing extremely good load
regulation but a few precautions are needed to obtain maximum
performance. The current set resistor connected between the
adjustment terminal and the output terminal should be tied di-
rectly to the output pin as close to the case of the regulator as
possible rather than near the load. This eliminates package pin
and trace drops from appearing effectively in series with the
reference and degrading regulation. For example, if the regulator
is set to -5V with 0.05Ω resistance between the regulator and
the current set resistor, the output will droop 225mV at 1A due
to package pin and trace resistance. The amount of droop can be
calculated as follows: (Vout at 5mA) - (1.250-
(0.05Ω*IL))*(1+R2/R1). The ground of R2 can be returned
near the ground of the load to provide remote ground sensing
and improve load regulation. Figure 2A shows the effect of re-
sistance between the regulator and 240Ω set resistor.
FIGURE 1
INPUT VOLTAGE
The minimum required input voltage for proper operation is
Vout+ Dropout voltage. See typical performance curves for
dropout performance.
FIGURE 2A
(Degraded Regulation)
EXTERNAL CAPACITORS
Input bypassing with a 1uF tantalum in parallel with a 0.1uF
ceramic on the input is suitable in most applications. To maxi-
mize transient response and minimize input supply transients
more input capacitance can be added. The adjustment terminal
can be bypassed to ground on the MSK 5973RH to improve
ripple rejection. This bypass capacitor prevents ripple from be-
ing amplified at higher output voltages. The impedance of the
adjust pin capacitor at the ripple frequency should be less than
the value of R1. For most application a 10μF bypass capacitor
will provide sufficient ripple rejection at any output level. In-
creases over 10μF do not appreciably improve the ripple rejec-
tion at frequencies above 120Hz. Output bypassing with 10μF
low ESR tantalum in parallel with a 0.1μF ceramic attached as
close to the regulator's output as possible is best. This will ef-
fectively lower the regulator output impedance, increase tran-
sient response and eliminate any oscillations. Any increase of
the load capacitance larger than 10μF will merely improve the
loop stability and output impedance. See Figure 3 for typical
application schematic.
FIGURE 2B
(Best Case Regulation)
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8548-84 Rev. G 10/12
APPLICATION NOTES CONT'D
PROTECTION DIODES
When external capacitors are used with any IC regulator it is
sometimes necessary to add protection diodes to prevent the
capacitors from discharging through low current points into the
regulator. Most 10μF capacitors have low enough internal se-
ries resistance to deliver 20A spikes when shorted. Although
the surge is short, there is enough energy to stress MSK 5973RH.
When an output capacitor is connected to a regulator and the
input is shorted or crowbarred, the output capacitor will dis-
charge into the output of the regulator. The discharge current
depends on the value of the capacitor, the output voltage of the
regulator, and the rate of decrease of VIN. Figure 3 shows an
MSK 5973RH with protection diodes included. D2 is only re-
quired if the adjust pin has external capacitance tied to it .
HEAT SINKING
To determine if a heat sink is required for your application
and if so, what type, refer to the thermal model and govern-
ing equation below.
Governing Equation: Tj = Pd x (R
θ
jc + R
θ
cs + R
θ
sa) + Ta
WHERE
Tj = Junction Temperature
Pd = Total Power Dissipation
R
θ
jc= Junction to Case Thermal Resistance
R
θ
cs= Case to Heat Sink Thermal Resistance
R
θ
sa = Heat Sink to Ambient Thermal Resistance
Tc = Case Temperature
Ta = Ambient Temperature
Ts = Heat Sink Temperature
EXAMPLE:
This example demonstrates an analysis with the output set
to -10V, where the output current is at 0.5 amp and the
input is -15V.
Conditions for MSK 5973RH:
Vin = -15V; Iout = 0.5A
1.) Assume 45° heat spreading model.
2.) Find regulator power dissipation:
Pd = (Vin - Vout)(Iout)
Pd = (15V-10V)(0.5A)
Pd = 2.5W
FIGURE 3
TOTAL DOSE RADIATION TEST
PERFORMANCE
Radiation performance curves for TID testing have been gen-
erated for all radiation testing performed by MS Kennedy.
These curves show performance trends throughout the TID
test process and is located in the MSK 5973RH radiation
test report. The complete radiation test report is available in
the RAD HARD PRODUCTS section on the MSK website.
3.) For conservative design, set Tj = +125°C Max.
4.) For this example, worst case Ta= +90°C.
5.) R
θ
jc = 4.8°C/W from the Electrical Specification Table.
6.) R
θ
cs= 0.15°C/W for most thermal greases.
7.) Rearrange governing equation to solve for R
θ
sa:
R
θ
sa=((Tj - Ta)/Pd) - (R
θ
jc) - (R
θ
cs)
= (125°C-90°C)/2.5W - 4.8°C/W - 0.15°C/
= 9.0°C/W
In this case the result is 9.0°C/W. Therefore, a heat sink
with a thermal resistance of no more than 9.0°C/W must be
used in this application to maintain regulator circuit junction
temperature under 125°C.
http://www.mskennedy.com/store.asp?pid=9951&catid=19680
4
8548-84 Rev. G 10/12
TYPICAL PERFORMANCE CURVES
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8548-84 Rev. G 10/12
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