MIL-PRF-38534 & 38535 CERTIFIED FACILITY
RAD HARD 4.5A,
500KHz STEP DOWN
SWITCHING REGULATOR
CONTROLLER
5059RH
FEATURES:
Manufactured using
Rad Hard RH1959MILDICE
Radiation Hardened to 100 Krad(Si) (Method 1019.7 Condition A)
Low Dose Rate Hardened to 50 Krad(Si) (Method 1019.7 Condition D)
500KHz Constant Switching Frequency:Synchronizable to 1MHz
4.5A Integrated Switch
Internal Slope Compensation
Input Voltage Range from 4.3V to 16V
Cycle by Cycle Current Limit
Output Voltages Down to 1.21V
Available to DSCC SMD 5962R11234
Single Event Effect Tested
Equivalent Non Rad Hard Device MSK5032
DESCRIPTION:
The MSK5059RH is a radiation hardened 500KHz switching regulator controller capable of delivering up to 4.5A of current
to the load. A fixed 500KHz switching frequency allows the use of smaller inductors reducing required board space for a
given design. The 4.5A integrated switch leaves only a few application specific components to be selected by the designer.
The MSK5059RH simplifies design of high efficiency radiation hardened switching regulators that use a minimum amount of
board space. The device is packaged in a hermetically sealed 16 pin flatpack and is available with straight or gull wing leads.
EQUIVALENT SCHEMATIC
PIN-OUT INFORMATION
TYPICAL APPLICATIONS
POL Applications
Satellite System Power Supply
Step Down Switching Regulator
Microprocessor, FPGA Power Source
High Efficiency Low Voltage Subsystem Power Supply
1
2
3
4
5
6
7
8
VINA
VINB
VINC
VIND
VINE
BOOST
FB
GND
16
15
14
13
12
11
10
9
SWA
SWB
SWC
SWD
SWE
SYNC
SHDN
VC
CASE=ISOLATED
1
8548-31 Rev. K 12/14
ABSOLUTE MAXIMUM RATINGS
VIN
IOUT
FB
Input Voltage (VIN)
Output Current 8
BOOST Voltage
BOOST Above Input Voltage
SHDN Pin Voltage
FB Pin Voltage
FB Pin Current
7
16V
4.5A
30V
15V
7V
3.5V
1mA
PD
TJ
TST
TLD
TC
ELECTRICAL SPECIFICATIONS
Power Dissipation
Junction Temperature
Storage Temperature Range 11
Lead Temperature Range 9
(10 Seconds)
Case Operating Temperature
MSK5059RH
MSK5059(K/H)RH
ESD Rating
14W
+150°C
-65°C to +150°C
300°C
-40°C to +85°C
-55°C to +125°C
3A
NOTES:
1
2
3
4
5
6
7
8
9
10
11
12
Unless otherwise specified VIN=5V, VC=1.5V, BOOST=VIN+5V.
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 subgroup 1 unless otherwise specified.
Military grade devices ("H" and "K" suffix) shall be 100% tested to subgroups 1,2,3 and 4.
Subgroup 5 & 6 testing available on request.
Subgroup 1,4,7 TC =+25°C
Subgroup 2,5 TC =+125°C
Subgroup 3,6 TC =-55°C
Continuous operation at or above absolute maximum ratings may adversely effect the device performance and/or life cycle.
The absolute maximum current of 4.5A applies for duty cycles of 0.75 or lower.
De-rate linearly from 4.5A at D=0.75 to 3.375A at D=100.
The internal case temperature must not exceed 175°C under any conditions.
Pre and Post irradiation limits at 25°C, up to 100 Krad(Si) TID (Condition A) and 50 Krad(Si) TID (Condition D), are identical unless otherwise specified.
Internal solder reflow temperature is 180°C, do not exceed.
Reference DSCC SMD 5962R11234 for electrical specification for devices purchased as such.
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8548-31 Rev. K 12/14
APPLICATION NOTES
PIN FUNCTIONS
SETTING THE OUTPUT VOLTAGE
VIN - The VIN pins connect to the collector of the internal power
switch and provide power to the internal control circuitry and internal regulator. Very high di/dt is seen at these pins during switch
on and off transitions. High frequency decoupling capacitors are
recommended to minimize voltage spikes. All five VIN pins should
be connected to a low impedence source for best operation.
The output voltage of the MSK5059RH is set with a simple resistor
divider network: see Figure 1 (Typical Application Circuit). Select
the resistor values to divide the desired output down to equal VFB
(1.21V nominal) at the FB pin. Use a 2.5K or lower value resistor for
R2 to keep output error due to FB pin bias current less than 0.1%.
VOUT=VFB*(1+R1/R2)
SW - The SW pins are connected to the emitter of the internal power transistor. These pins rise up to the input voltage during the on
time of the switch and are driven negative when the power switch
turns off. The negative voltage is clamped by the catch diode and
must not go more negative than -0.8V. All five SW pins must be
connected for maximum performance.
R1=R2*(VOUT/VFB-1)
SELECTING THE INDUCTOR
The inductor is used to filter the square pulses at the SW pin to an
acceptable linear ripple. The inductance value will limit the maximum available current at different input and output voltages. See
"Maximum Load Current" in the typical performance curves section
of this data sheet. Use the curves to make the initial value selection.
Determine the peak inductor current as follows:
BOOST - The BOOST pin provides drive voltage greater that VIN to
the base of the power transistor. Using a voltage greater than VIN
ensures hard saturation of the power switch significantly improving
overall efficiency. Connect a capacitor between BOOST and SW to
store charge. Connect a diode between VIN and BOOST to charge
the capacitor during the off time of the power switch.
IPK=IOUT+VOUT*(VIN-VOUT)/(2*f*L*VIN)
FB - The FB (feedback) pin's primary function is to set the output
voltage. Use a resistive divider from VOUT to GND to set the voltage at the feedback pin to 1.21V when the output voltage is at the
desired level. The FB pin provdes two additional functions. If the
voltage at the FB pin drops below 0.8V the switch current limit is
reduced. When the voltage at the FB pin drops below 0.7V the
switching frequency is reduced and sync is disabled. The switching
frequency reduces to approximately 100KHz at VFB<=0.4V.
Where:
f=the switching frequency in Hz
L=inductor value in Henries
GND - The GND pin provides a return path for all internal control
current and acts as a reference to the error amplifier. It is important
that it is at the same voltage potential as the load return to ensure
proper regulation. Keep current on the ground between the load
and the MSK5059RH to a minimum and use heavy copper traces
to minimize voltage drops and regulation error.
Nearly all of the current ripple will be seen by the output capacitance.
See selecting the output capacitor.
Select an inductor what will not saturate at worst case peak current.
Calculate the peak to peak inductor current ripple as follows:
IP-P=VOUT*(VIN-VOUT)/(f*L*VIN)
SELECTING THE OUTPUT CAPACITOR
The output capacitor filters the ripple current from the inductor to
an acceptable ripple voltage seen by the load. The primary factor in
determining voltage ripple is the ESR of the output capacitor. The
voltage ripple can be approximated as follows:
VC - The VC pin is the output of the error amplifier and the input of
the peak current comparator. This pin is typically used for frequency
compensation but can also be used as a current clamp or as an
override to the internal error amplifier control. The pin voltage is
typically around 1V at light load and 2V at heavy load. Driving the
pin low will shut down the regulator. Driving it high will increase the
output current. The current into the VC pin must be limited to 4mA
when driving it high.
VP-P=IP-P*ESR
The typical ESR range for an MSK5059RH application is between
0.05 and 0.20 ohm. Capacitors within these ESR ranges typically
have enough capacitance value to make the capacitive tern of the
ripple equation insignificant. The capacitive term of the output voltage
ripple lags the ESR term by 90° and can be calculated as follows:
SHDN - The SHDN (shutdown) pin has two shutdown functions. The
first function disables switching when the voltage on the pin drops
below 2.38V (nominal). The second forces a complete shutdown
minimizing power consumption when the voltage drops below 0.4V
(nominal). Pull this pin high or leave open for normal operation. The
2.38V threshold can be used for UVLO functions by configuring a
resistive divider to VIN and GND that holds the pin voltage below
2.38V until VIN rises to the minimum desired voltage.
VP-P(CAP)=IP-P/(8*f*C)
Where:
C=output capacitance in Farads
Select a capacitor or combination of capacitors that can tolerate the
worst-case ripple current with sufficient de-rating. When using multiple capacitors in parallel to achieve ESR and/or total capacitance
sharing of ripple current between capacitors will be approximately
equal if all of the capacitors are the same type and preferably from
the same lot. Low ESR tantalum capacitors are recommended over
aluminum electrolytic. The zero created by the ESR of the capacitor
is necessary for loop stabilty. A small amount of ceramic capacitance
close to the load to decouple high frequency is acceptable but it
should not cancel the ESR zero.
SYNC - The SYNC pin is used to synchronize the oscillator to
an external clock. It is logic compatible and can be driven to any
frequency between the free run frequency (500KHz nominal) and
1MHz. The duty cycle of the input signal must be between 10%
and 90% to ensure proper synchronization. Tie the SYNC pin to
GND if it is not used.
3
8548-31 Rev. K 12/14
APPLICATION NOTES CONT'D
SELECTING THE CATCH DIODE
TYPICAL EFFICIENCY FOR 3.3V APPLICATION
Schottky diodes work best in the catch diode position because they
switch very quickly and have low forward voltage. The diode should
be rated for well above the maximum input voltage to account for
the full input voltage, transients at the switch node and de-rating
requirements. Transients at the switch node can be minimized with
careful attention to switching current paths during board layout. The
diode must be rated for the worst-case peak voltage and the average
current plus any de-rating requirements. The average current can
be approximated as follows:
ID=IOUT*(VIN-VOUT)/VIN
PROVIDING BOOST DRIVE
The BOOST pin provides drive greater than VIN for the power transistor. The boost capacitor is charged through a switching diode to
the input voltage when the power switch is off, see Figure 1. When
the power switch turns on the SW node rises to VIN and the boost
capacitor supplies current to drive the power transistor. Typically a
0.27µF capacitor will provide sufficient charge but smaller capacitors
may be used. The following equation gives an approximation for the
absolute minimum value but should be used with caution as it does
not take all worst case and secondary factors into consideration.
CMIN=(IOUT/50)*(VOUT/VIN)/f*(VOUT-2.8V)
COMPENSATING THE LOOP
The current mode power stage from the VC node to the SW node
can be modeled as a transconductance of gm=5.3A/V. The DC
output gain will be the product of the transconductance times the
load resistance. As frequency increases the output capacitance rolls
off the gain until the ESR zero is reached. The error amplifier can
be modeled as a transconductance of 1000µMho with an output
impedance of 2KΩ in parallel with 12pF. Typically a single 1000 to
2000pF capacitor is all that is needed to compensate the loop but
more complex compensation schemes are readily achieved.
TYPICAL APPLICATION CIRCUIT
TOTAL DOSE, LOW DOSE RATE, AND SEE RADIATION TEST PERFORMANCE
Radiation performance curves for TID and Low Dose Rate testing
have been generated for all radiation testing performed by MS
Kennedy. These curves show performance trends throughout the
radiation test process and are located in the MSK5059RH radiation
test report. The complete radiation test report is available in the RAD
HARD PRODUCTS section on the MSK website. Contact MSK for
SEE test results.
http://www.mskennedy.com/store.asp?pid=9951&-
ADDITIONAL APPLICATION INFORMATION
For additional applications information, please reference Linear
Technology Corporation's LT1959 data sheet.
FIGURE 1
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8548-31 Rev. K 12/14
TYPICAL PERFORMANCE CURVES
5
8548-31 Rev. K 12/14
TYPICAL PERFORMANCE CURVES CONT'D
6
8548-31 Rev. K 12 /14
MECHANICAL SPECIFICATIONS
ESD TRIANGLE INDICATES PIN 1
WEIGHT=1.5 GRAMS TYPICAL
ALL DIMENSIONS ARE SPECIFIED IN INCHES
ORDERING INFORMATION
PART NUMBER
SCREENING LEVEL
MSK5059RH
INDUSTRIAL
MSK5059HRH
MIL-PRF-38534 CLASS H
MSK5059KRH
MIL-PRF-38534 CLASS K
5962R11234
DSCC SMD
7
LEADS
STRAIGHT
8548-31 Rev. K 12/14
MECHANICAL SPECIFICATIONS
ESD TRIANGLE INDICATES PIN 1
WEIGHT=1.5 GRAMS TYPICAL
ALL DIMENSIONS ARE SPECIFIED IN INCHES
ORDERING INFORMATION
PART NUMBER
MSK5059RHG
SCREENING LEVEL
LEADS
INDUSTRIAL
MSK5059HRHG
MIL-PRF-38534 CLASS H
MSK5059KRHG
MIL-PRF-38534 CLASS K
5962R11234
DSCC SMD
8
GULL
WING
8548-31 Rev. K 12 /14
REVISION HISTORY
MSK
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.
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8548-31 Rev. K 12/14