MIL-PRF-38534 CERTIFIED
M.S.KENNEDY CORP.
RAD TOLERANT ULTRA LOW
DROPOUT ADJUSTABLE
POSITIVE LINEAR REGULATOR
5921RH
(315) 701-6751
4707 Dey Road Liverpool, N.Y. 13088
FEATURES:
Total Dose Tested to 300K RAD
Ultra Low Dropout for Reduced Power Consumption
External Shutdown
Latching Overload Protection
Adjustable Output Using Two External Resistors
Output Current Limit
Available in 3 Lead Form Options: Straight, Up and Down
Available to DSCC SMD # 5962-05220
DESCRIPTION:
The MSK 5921RH is a rad tolerant adjustable linear regulator typically capable of delivering 5.0 amps of output
current. The typical dropout is only 0.30 volts with a 3.0A load. An external shutdown function is ideal for power
supply sequencing. This device also has latching overload protection that requires no external current sense resistor.
The MSK 5921RH is radiation tolerant and specifically designed for space/satellite applications. The device is pack-
aged in a hermetically sealed space efficient 5 pin SIP that is electrically isolated from the internal circuitry allowing for
direct heat sinking.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATIONS
TYPICAL APPLICATIONS
Satellite System Power Supplies
Switching Power Supply Post Regulators
Constant Voltage/Current Regulators
Microprocessor Power Supplies
PIN-OUT INFORMATION
1
2
3
4
5
VIN
GND
VOUT
SHUTDOWN
ADJUST
1
Rev. C
1/06
ABSOLUTE MAXIMUM RATINGS
+V
IN
I
OUT
T
C
8
ELECTRICAL SPECIFICATIONS
Parameter
Input Voltage Range
2
Test Conditions
1
11
10mA
≤
I
OUT
≤
1.0A
Group A
Subgroup
1
2,3
Feedback Voltage
I
OUT
=3.0A R1=187Ω
1
2,3
Feedback Pin Current
2
Quiescent Current
V
FB
=1.265V 10mA
≤
I
OUT
≤
3.0A
V
IN
=6.5V
Not Including I
OUT
Line Regulation
9
I
OUT
=50mA
V
OUT
+0.4V
≤
V
IN
≤
I
OUT
+1.3V
Load Regulation
9
10mA
≤
I
OUT
≤
3.0A
1,2,3
1
2,3
1
2,3
1
2,3
Dropout Voltage
10
Delta FB=1% I
OUT
=2.5A
1
2,3
Minimum Output Current
2
2.8V
≤
V
IN
≤
6.5V
R1=187Ω
Output Voltage Range
2
Output Current Limit
7
MSK5921K/H/E
Min.
2.9
2.9
1.225
1.225
0
-
-
-
-
-
-
-
-
-
-
1.5
3.0
3.0
1.0
1.0
65
65
30
10
-
-
Typ.
-
-
1.265
-
-
14
14
Max.
6.5
6.5
Min.
2.9
-
MSK5921
Typ.
-
-
1.265
-
-
14
-
0.01
-
0.06
-
0.22
-
8
-
-
4.0
-
1.3
-
-
-
70
18
-
2.2
Max.
6.5
-
1.328
-
5.0
20
-
1.305 1.202
1.305
5.0
20
20
-
0
-
-
-
-
-
-
-
-
-
-
1.5
3.0
-
1.0
-
65
-
30
10
-
-
±0.01 ±0.50
-
±0.50
±0.60 %V
OUT
-
%V
OUT
±0.06 ±0.80
-
0.22
0.26
8
9
-
4.0
4.0
1.3
1.3
-
-
70
18
-
2.2
±0.80
0.40
0.40
10
10
6.0
5.0
5.0
1.6
1.6
-
-
-
-
50
4.0
±1.0 %V
OUT
-
0.45
-
10
-
6.0
5.0
-
1.6
-
-
-
-
-
50
4.0
%V
OUT
V
V
mA
mA
V
A
A
V
V
dB
dB
degrees
dB
µV
RMS
°C/W
1
2,3
-
1
2,3
V
IN
=6.5V
V
IN
=3.5V V
OUT
=2.5V
Shutdown Threshold
V
OUT
≤
0.2V (OFF)
V
OUT
=Nominal (ON)
1
2,3
4
5,6
4,5,6
4,5,6
Ripple Rejection
2
f=120Hz
I
OUT
=50mA
Phase Margin
2
Gain Margin
2
Equivalent Noise Voltage
2
Thermal Resistance
2
Referred to Feedback Pin
Junction to Case @ 125°C Output Device
4,5,6
-
NOTES:
1
2
3
4
5
6
Unless otherwise specified, V
IN
=5.0V, R1=1.62K, V
SHUTDOWN
=0V and I
OUT
=10mA. See Figure 2.
Guaranteed by design but not tested. Typical parameters are representative of actual device performance but are for reference only.
Industrial grade and "E" suffix 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 T
C
=+25°C
Subgroup 2,5 T
C
=+125°C
Subgroup 3,6 T
A
=-55°C
Output current limit is dependent upon the values of V
IN
and V
OUT
. See Figure 1 and typical performance curves.
Continuous operation at or above absolute maximum ratings may adversely effect the device performance and/or life cycle.
V
IN
shall be as specified or V
IN
Min, whichever is greater.
Not applicable when V
OUT
<V
IN
Min - dropout voltage maximum.
Consult factory for post radiation limits.
7
8
9
10
11
2
Rev. C
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○
○
P
D
T
C
○
○
○
○
○
○
○
○
○
Supply Voltage
+10V
7
Output Current
5A
Case Operating Temperature Range
MSK5921K/H/E RH
-55°C to +125°C
MSK5921RH
-40°C to +85°C
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○
○
○
○
○
○
○
○
○
○
○
T
ST
T
LD
Storage Temperature Range -65°C to +150°C
Lead Temperature Range
300°C
(10 Seconds)
Power Dissipation
See SOA Curve
Junction Temperature
150°C
Units
V
V
V
V
µA
mA
mA
1/06
APPLICATION NOTES
PIN FUNCTIONS
VIN -
This pin provides power to all internal circuitry
including bias, start-up, thermal limit and overcurrent
latch. Input voltage range is 2.9V to 6.5V.
GND -
Internally connected to ground, this pin should be
connected externally by the user to the circuit ground.
SHUTDOWN -
There are two functions to the SHUT-
DOWN pin. It may be used to disable the output voltage
or to reset a current latch condition. To activate the shut-
down/reset functions the user must apply a voltage
greater than 1.6V to the SHUTDOWN pin. 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. It should be
noted that with the shutdown pin tied to ground, a cur-
rent latch condition can only be reset by cycling power
off, then on.
VOUT -
This is the output pin for the device.
ADJUST -
The ADJUST pin is the inverting input of the
internal error amplifier. The non-inverting input is con-
nected to an internal 1.265V reference. This error ampli-
fier controls the drive to the output transistor to force
the ADJUST pin to 1.265V. An external resistor divider
is connected to the output, ADJUST pin and ground to
set the output voltage.
OUTPUT CAPACITOR SELECTION
Output capacitors are required to maintain regulation
and stability. A 220µF surface mount tantalum capacitor
in parallel with a 1.0µF ceramic capacitor from the out-
put to ground should suffice under most conditions. If
the user finds that tighter voltage regulation is needed
during output transients, more capacitance may be added.
If more capacitance is added to the output, the band-
width may suffer. ESR of the output capacitors should
be maintained at 0.1Ω to 1Ω.
OVERCURRENT LATCH
Overcurrent protection is provided by the MSK5921RH
series through the use of a timed latch off circuit. The
internal latch timeout is triggered by an overcurrent con-
dition. To allow for start up surge currents, the timeout
is approximately 5.5mS at 25°C. If the overcurrent con-
dition remains at the end of the timeout cycle, the regu-
lator will latch off until the latch is reset. The latch con-
dition can be reset by pulling the shutdown pin high or
cycling VIN off then back on. A thermal limit condition
will trigger the latch with no time out delay.
FIGURE 1
CURRENT LIMIT AND SOA
The MSK 5921RH current limit function is directly af-
fected by the input and output voltages. Figure 1 illus-
trates the relationship between VIN and ICL for various
output voltages. It is very important for the user to con-
sult the SOA curve when using input voltages which
result in current limit conditions beyond 4.5 Amps. When
using input voltages which result in current limit above
4.5 Amps, the user must maintain output current within
the SOA curve to avoid damage to the device. Note that
5 Amp maximum is due to current carrying capability of
the internal wirebonds.
INPUT POWER SUPPLY BYPASSING
To maximize transient response and minimize power
supply transients it is recommended that a 100µF tanta-
lum capacitor is connected between VIN and ground. A
0.1µF ceramic capacitor should also be used for high
frequency bypassing.
3
Rev. C
1/06
APPLICATION NOTES CONT.
THERMAL LIMITING
The MSK 5921RH control circuitry has a thermal shut-
down temperature of approximately 150°C. This ther-
mal 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 condi-
tions.
TYPICAL APPLICATIONS CIRCUIT
HEAT SINK SELECTION
To select a heat sink for the MSK 5921RH, the follow-
ing formula for convective heat flow may be used.
Governing Equation:
T
J
=
P
D
X (R
θJC
+ R
θCS
+ R
θSA
) + T
A
Where
T
J
P
D
R
θJC
R
θCS
R
θSA
T
A
=
=
=
=
=
=
Junction Temperature
Total Power Dissipation
Junction to Case Thermal Resistance
Case to Heat Sink Thermal Resistance
Heat Sink to Ambient Thermal Resistance
Ambient Temperature
OUTPUT VOLTAGE SELECTION
As noted in the above typical applications circuit, the
formula for output voltage selection is
R1
V
OUT
=1.265 1+
R2
A good starting point for this output voltage selection is
to set R2=1K. By rearranging the formula it is simple to
calculate the final R1 value.
R1=R2
V
OUT
-1
1.265
Power Dissipation=(V
IN
-V
OUT
) x I
OUT
Next, the user must select a maximum junction tem-
perature. The absolute maximum allowable junction tem-
perature is 150°C. The equation may now be rearranged
to solve for the required heat sink to ambient thermal
resistance (R
θSA
).
Example:
An MSK 5921RH is connected for V
IN
=+3.3V and
V
OUT
=+2.5V. I
OUT
is a continuous 3A DC level. The am-
bient temperature is +25°C. The maximum desired junc-
tion temperature is +125°C.
R
θJC
=4.0°C/W and R
θCS
=0.15°C/W for most thermal
greases
Power Dissipation=(3.3V-2.5V) x (3A)
=2.4Watts
Solve for R
θSA:
R
θSA
= 125°C - 25°C -4.0°C/W - 0.15°C/W
2.4W
= 36.5°C/W
In this example, a heat sink with a thermal resistance
of no more than 36.5°C/W must be used to maintain a
junction temperature of no more than 125°C.
Table 1 below lists some of the most probable resistor
combinations based on industry standard usage.
TABLE 1
OUTPUT
VOLTAGE
(V)
1.5
1.8
2.0
2.5
2.8
3.3
4.0
5.0
R2
(Ω)
Ω
1K
1K
1K
1K
1K
1K
1K
1K
R1 (nearest 1%)
(Ω)
Ω
187
422
576
976
1.21K
1.62K
2.15K
2.94K
4
Rev. C
1/06
TYPICAL PERFORMANCE CURVES
5
Rev. C
1/06
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