MIL-PRF-38534 AND 38535 CERTIFIED FACILITY
5045
HIGH EFFICIENCY, HIGH VOLTAGE
4 AMP SURFACE MOUNT
SWITCHING REGULATORS
SERIES
FEATURES:
•
•
•
•
•
•
•
•
•
•
•
•
Up To 88% Efficiency For 5V Version
4 Amp Output Current
1.2 x VOUT to 80V Input Range with Separate Bias
12V to 80V Input Range with UVLO (VBIAS=VIN)
Preset 2.5V, 3.3V or 5.0V Output Versions
300KHz Switching Frequency @ 1 Amp
User Programmable Soft-Start
User Programmable Current Limit
Hermetic Package
-55°C to +125°C Operating Temperature Range
Available with Gull Wing Leads
Contact MSK for MIL-PRF-38534 Qualification Status
DESCRIPTION:
The MSK5045 series are high efficiency, 4 amp, surface mount switching regulators. The output voltage is configured
for 2.5V, 3.3V or 5.0V internally with a tolerance of 1% at 1.5 amps. The operating frequency of the MSK5045 is 300KHz.
An external "soft start" capacitor allows the user to control how quickly the output comes up to regulation voltage after the
application of an input. A low quiescent current and greater than 85% operating efficiency keep the total internal power
dissipation of the MSK5045 down to an absolute minimum. The input circuitry has been designed to withstand a very wide
range of voltages from less than 12V to as high as 80V. The device is packaged in a hermetic kovar flatpack for high reliability
applications and is available screened to MIL-PRF-38534 Class H.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATIONS
• Step-down Switching Regulator
• Microprocessor Power Source
• High Efficiency Low Voltage
• Subsystem Power Supply
PIN-OUT INFORMATION
1
1
CASE
2
Sense High
3
Sense Low
4
NC
5
RFB
6
NC
7
PWR SAVE
8
CTON
9
NC
10
ENABLE
11
VBIAS
12-22
VIN
23-33
GROUND
34-44
VOUT
8548-158 Rev. K 3/18
ABSOLUTE MAXIMUM RATINGS
11
Input Voltage ...................................................................................................................... -0.3V, +80V
ENABLE ............................................................................................................................ -0.3V, 10.5V
PWR SAVE ........................................................................................................................ -0.3V, 5.5V
Output Current .................................................................................................................. 4.0 Amps
Sense Pin Voltage ............................................................................................................. -0.3V, +7V
Thermal Resistance (@ 125°C)
(Each MOSFET) ................................................................................................................ 15°C/W
TST
Storage Temperature Range .... 12 ................................................................................... -65°C to +150°C
TLD
Lead Temperature Range
(10 Seconds) ..................................................................................................................... 300°C
TC
Case Operating Temperature Range
MSK5045 Series ............................................................................................................ -40°C to +85°C
MSK5045H Series .......................................................................................................... -55°C to +125°C
TJ
Junction Temperature ........................................................................................................ +150°C
2
8548-158 Rev. K 3/18
ELECTRICAL SPECIFICATIONS
Parameter
Test Conditions
1
VIN Input Supply Range 10
VBias Input Supply Range
2
9
VBias Current
VIN = 1.5 x (VOUT)
Under Voltage Lockout
VBIAS = 15V
2
Enable Input Current
2
PWR SAVE Input Voltage
2
PWR SAVE Input Current
2
Disabled Quiescent Current
2
2
80
V
28
80
V
19
21
mA
10.0
12.0
V
Input Falling
1
7.0
9.7
11.7
6.9
9.7
11.7
V
IOUT = 1.5A
Enable Input Voltage
28
12
12
0.75A ≤ IOUT ≤ 2.5A
7
Note 10
7.3
1
2.47
2.5
2.55
2.45
2.5
25.55
V
2, 3
2.38
2.5
2.63
-
-
-
V
1
3.27
3.3
3.33
3.23
3.3
3.37
V
2, 3
3.14
3.3
3.47
-
-
-
V
1
4.95
5.0
5.05
4.9
5.0
5.1
V
2, 3
4.75
5.0
5.25
-
-
-
V
1
4.0
4.2
-
4.0
4.2
-
A
Within SOA
2
80
21
IOUT = 1.5A
Line Regulation
80
28
12.0
8
Load Regulation
28
19
Output Voltage 5045-5.0
IOUT = 2A
Max.
10.0
IOUT = 1.5A
Efficiency
12
Units
Typ.
12
8
Cton Current
Note 10
1, 2, 3
Min.
7.4
Output Voltage 5045-3.3
Current Limit Threshold
1, 2, 3
MSK5045 SERIES
Max.
1
IOUT = 1.5A
Oscillator Frequency
Typ.
1
8
2
Min.
Input Rising
Output Voltage 5045-2.5
Output Current
MSK5045H SERIES
Group A
Subgroup
12V ≤ VIN ≤ 40V
1
-
0.5
1.5
-
0.5
2.0
%
2, 3
-
0.5
2.5
-
-
-
%
1
-
0.5
1.5
-
0.5
2.0
%
2, 3
-
0.5
2.5
-
-
-
%
IOUT ≥ 1.5A
4
270
300
330
270
300
330
KHz
Open Circuit Voltage
1, 2, 3
9.6
12.8
15.5
9.6
12.8
15.5
V
Low
1, 2, 3
-
-
0.5
-
-
0.5
V
VEN = 0V
1
-
120
200
-
120
200
uA
Open Circuit Voltage
1, 2, 3
3.0
3.4
5.5
3.0
3.4
5.5
V
Low
1, 2, 3
-
-
0.5
-
-
0.5
V
V PWR SAVE = 0V
1
-
100
200
-
100
200
uA
VEN = 0V
1
-
1
2.5
-
1
2.5
mA
Positive
1
80
100
120
75
100
125
mV
Negative
1
-50
-100
160
-45
-100
-165
mV
Source
1
2.5
4.0
6.5
2.5
4.0
6.5
uA
Fault Sink
1
2.0
-
-
2.0
-
-
mA
5045-2.5
VIN = 16V
IOUT = 1.5A
-
-
83
-
-
83
-
%
5045-3.3
VIN = 16V
IOUT = 1.5A
-
-
85
-
-
85
-
%
5045-5.0
VIN = 16V
IOUT = 1.5A
-
-
87
-
-
87
-
%
NOTES:
1
VIN = VBIAS = 28V, 5mV ≤ (sense high-sense low) ≤ 75mV, IL = 0A, ENABLE = NC, PWR SAVE = NC COUT = 6 x 220µF, CIN = 1 x 250µF + 4 x 10µF,
CTON = 0.01µF unless otherwise specified.
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 devices shall be tested to subgroup 1 unless otherwise specified.
5
Military grade devices ('H' suffix) shall be 100% tested to subgroups 1, 2 and 3.
6
Subgroup 1
2
3
TA = TC = +25°C
TA = TC = +125°C
TA = TC = -55°C
7
Actual switching frequency is load dependent if output current is low and sense resistor is large or zero. Refer to typical performance curves.
8
Alternate output voltages are available. Please contact the factory.
9
The device can withstand input voltages as high as 80V, but efficiency is best at lower inputs.
10
With VBIAS (pin 11) connected to a separate source, VIN Min. is VOUT + VDROPOUT; see dropout curves.
11
Continuous operation at or above absolute maximum ratings may adversely effect the device performance and/or life cycle.
12
Internal solder reflow temperature is 180°C, do not exceed.
3
8548-158 Rev. K 3/18
APPLICATION NOTES
INPUT BIAS AND UVLO:
SOFT START/CTON:
Pin 11 of the MSK5045 provides bias to an internal linear regulator
that powers the control circuitry. The VBIAS pin can be connected
directly to the input bus for 12V to 80V operation or it can be biased
separately with a 12V to 15V source to extend the input range of the
device and improve efficiency at high line; refer to the paragraph titled
"INPUT VOLTAGE RANGE". VBIAS must be applied simultaneous
with or prior to the input voltage. The MSK5045's built in under
voltage lockout feature prevents damage to downstream devices
in the event of a drop in bias voltage. Under voltage lockout occurs
at bias voltages of approximately 10V rising and 9.7V falling. When
separating the bias voltage from VIN to extend the input range below
the VBIAS UVLO set point, a simple open collector circuit can disable
the device at any desired set point for VIN if UVLO is required. The
internal bias draws approximately 30mA under normal operation and
less than 10mA in Power Save mode with a light load on the output.
The internal soft-start circuitry allows a gradual increase of the
internal current-limit level at start-up for the purpose of reducing
input surge currents, and possibly for power-supply sequencing.
In Disable mode, the soft-start circuit holds the Cton capacitor
discharged to ground. When ENABLE goes high, a 4µA current
source charges the Cton capacitor up to 3.2V. The resulting
linear ramp causes the internal current-limit threshold to increase
proportionally from 20mV to 100mV. The output capacitors charge
up relatively slowly, depending on the CTON capacitor value. The
exact time of the output rise depends on output capacitance and load
current and is typically 1mS per nanofarad of soft-start capacitance.
With no capacitor connected, maximum current limit is reached
typically within 10µS.
INPUT VOLTAGE RANGE
In high current applications, it is very important to ensure that both
MOSFETS are within their maximum junction temperature at high
ambient temperatures. Temperature rise can be calculated based
on package thermal resistance and worst case dissipation for each
MOSFET. These worst case dissipations occur at minimum voltage
for the high side MOSFET and at maximum voltage for the low side
MOSFET.
POWER DISSIPATION:
The MSK5045's wide input range of 12V to 80V can be further
extended down to VOUT + VDROPOUT by using a separate bias
supply; refer to the paragraph titled "LOW VOLTAGE OPERATION".
In this configuration very efficient low V to low V conversion can be
achieved. At high line voltages the internal linear regulator dissipates
more power than at low line. This loss in efficiency can be eliminated
with a separate bias supply pushing the high line efficiency up close
to the low line performance. Output ripple changes with line voltage;
refer to the paragraph titled "OUTPUT INDUCTOR (OPTIONAL)"
for more information.
Calculate power dissipation using the following formulas:
Pd (upper FET) = ILOAD² x 0.090Ω x DUTY
+ VIN x ILOAD x f x
SELECTING RS:
VIN x CRSS + 25ns
IGATE
Pd (lower FET) = ILOAD² x 0.090Ω x (1 - DUTY)
The MSK5045 monitors the inductor current and the average load
current by sensing the voltage across RS. Cycle-by-cycle current
limiting is controlled with an upper threshold of 100mV ±20mV; the
high side MOSFET switch is gated off whenever the upper threshold
is exceeded. Pulse skipping occurs in power save mode when the
signal falls below the 30% current threshold of 30mV. The sychronous rectifier is disabled when the signal falls below 0V indicating
discontinuous inductor current. Selection of RS must take all of these
features into consideration.
DUTY =
(VOUT + VQ2)
(VIN - VQ1)
Where: VQ1 or VQ2 (on state voltage drop) = ILOAD x 0.090Ω
CRSS = 65pF
IGATE = 2A
During output short circuit, Q2, the synchronous-rectifier MOSFET,
will have an increased duty factor and will see additional stress.
This can be calculated by:
When operated in the continuous conduction mode peak to peak
inductor current is approximated by the equation
Q2 DUTY = 1 -
VQ2
VIN (MAX) - VQ1
Where: VQ1 or VQ2 = (120MV/RSENSE) x 0.090
(VIN - VOUT) • VOUT
f • L • VIN
INPUT CAPACITOR SELECTION:
where f=300KHz and L=6.4µH. (If optional output inductance is
used L=6.4uH + optional L). The device will operate in continuous
conduction as long as IOUT ≥ ½ Ip-p. The maximum and minimum
current peaks are equal to IOUT±½ Ip-p. RS translates the current
levels into the control signal. Once the current levels are established
the designer can size RS for specific applications. Care must be
taken when selecting RS because under a short circuit condition the
output current will approach the cycle-by-cycle current limit.
The MSK5045 should have an external high frequency ceramic
capacitor (0.1uF) between VIN and GND. Connect a low-ESR bulk
capacitor directly to the input pin of the MSK5045. Select the bulk
input filter capacitor according to input ripple-current requirements
and voltage rating, rather than capacitor value. Electrolytic capacitors
that have low enough ESR to meet the ripple-current requirement
invariably have more than adequate capacitance values. Aluminumelectrolytic capacitors are preferred over tantalum types, which could
cause power-up surge-current failure when connecting to robust
AC adapters or low-impedance batteries. RMS input ripple current
is determined by the input voltage and load current, with the worst
possible case occuring at VIN = 2 x VOUT:
For most applications, it may be useful to wire the sense inputs
with a twisted pair instead of PCB traces. Low inductance current
sense resistors, such as metal film surface mount styles are best.
IRMS = ILOAD x √ VOUT(VIN-VOUT)
VIN
4
8548-158 Rev. K 3/18
APPLICATION NOTES CONT'D
OUTPUT CAPACITOR SELECTION:
CURRENT LIMITING:
The output capacitor values are generally determined by the
ESR and voltage rating requirements rather than capacitance
requirements for stability. Low ESR capacitors that meet the ESR
requirement usually have more output capacitance than required for
stability. Only specialized low-ESR capacitors intended for switchingregulator applications, such as AVX TPS, Sprague 595D, Sanyo
OS-CON, Nichicon PL series or Kemet T510 series should be used.
The capacitor must meet minimum capacitance and maximum ESR
values as given in the following equations:
Current limiting the MSK5045 is achieved by setting the
cycle-by-cycle current limit as described in the section titled
SELECTING RS. The designer must set the peak current limit such
that the average output current will not exceed the application limits.
In a short circuit condition the average output current will approach
the peak current limit. RS should be selected such that the average
output current will not exceed 4.0 Amps. RS must be small enough
to allow for the required load current plus the peak ripple current;
80mV/RS=IOUT+½Ip-p. Load components should be sized to
withstand a maximum current of 120mV/RS
CF >
2.5V(1 + VOUT/VIN(MIN))
VOUT x RSENSE x f
OUTPUT INDUCTOR (OPTIONAL):
RSENSE x VOUT
RESR <
2.5V
Placing an output inductor between the package and the sense
resistor will reduce output ripple and noise. Output ripple and noise
increase as the input to output voltage differential increases. Ouput
ripple is also higher when the MSK5045 is operated in power save
mode. Optional inductance will directly add to the internal inductance
of the device and should be included in peak to peak current
calculations (see SELECTING RS). Since additional inductance
will affect the output response of the regulator, the inductance value
must be carefully selected for each application.
These equations provide 45 degrees of phase margin to ensure
jitter-free fixed-frequency operation and provide a damped output
response for zero to full-load step changes. Lower quality capacitors
can be used if the load lacks large step changes. Bench testing
over temperature is recommended to verify acceptable noise and
transient response. As phase margin is reduced, the first symptom is
timing jitter, which shows up in the switching waveforms. Technically
speaking, this typically harmless jitter is unstable operation, since
the switching frequency is non-constant. As the capacitor ESR is
increased, the jitter becomes worse. Eventually, the load-transient
waveform has enough ringing on it that the peak noise levels exceed
the output voltage tolerance. With zero phase margin and instability
present, the output voltage noise never gets much worse than IPEAK
x RESR (under constant loads). Designers of industrial temperature
range digital systems can usually multiply the calculated ESR value
by a factor of 1.5 without hurting stability or transient response.
RFB:
It is very important that the DC voltage returned to the RFB pin
from the output be as noise and oscillation free as possible. This
voltage helps to determine the final output and therefore must be a
clean voltage. Excessive noise or oscillation can cause the device to
have an incorrect output voltage. Proper PC board layout techniques
can help to achieve a noise free voltage at the RFB pin.
The output ripple is usually dominated by the ESR of the filter
capacitors and can be approximated as IRIPPLE x RESR. Including
the capacitive term, the full equation for ripple in the continuous mode
is VNOISE(p-p)=IRIPPLE x (RESR + 1/(2πfC)). In pulse skipping
mode, the inductor current becomes discontinuous with high peaks
and widely spaced pulses, so the noise can actually be higher at
light load compared to full load. In pulse skipping mode, the output
ripple can be calculated as follows:
VNOISE(p-p)=
POWER SAVE MODE:
Power save mode is enabled by applying a logic low to the
PWR SAVE pin and disabled by applying a logic high or leaving it
open. The MSK5045 will skip switching pulses to save gate drive
current in Q1 and Q2 when operated under light load with power
save enabled. MSK5045 senses the voltage across RS and skips
most switching pulses when the voltage falls below 30mV indicating a
light load condition. The oscillator is gated off because the minimum
current comparator resets the high side latch at the start of each cycle
until the voltage feedback signal falls below the output voltage set
point. Under heavy loads the voltage across RS does not fall below
30mV and the MSK5045 operates in full PWM mode at 300 KHz.
0.02 x RESR + 0.0003 x 6.4µH x [1/VOUT+1/(VIN-VOUT)]
RSENSE
(RSENSE)² x C
ENABLE FUNCTION:
The MSK5045 is enabled by applying a logic level high to the
ENABLE pin or leaving it open. A logic level low will disable the
device and quiescent input current will reduce to approximately
1mA. The ENABLE threshold voltage is 1V. If automatic start up is
required, simply make no connection. Maximum ENABLE voltage is
+10.5V. The ENABLE pin has an internal pull up resistor to 10.5V.
Disabling the power save mode sets the PWM to 300KHz constant
switching frequency for low noise mode operation. Maximum input
voltage on the PWR SAVE pin is 5.5V. The PWR SAVE pin has
an internal pull-up resistor to 5V. RS should not be eliminated
when power save is disabled because it provides cycle-by-cycle
current limiting and synchronous rectifier control as described in
the SEQUENCE OF OPERATION paragraph. Refer to table 1 for
power save mode operational characteristics.
5
8548-158 Rev. K 3/18
APPLICATION NOTES CONT'D
LOW VOLTAGE OPERATION:
The MSK5045 is capable of low voltage to low voltage conversion with up to 90% efficiency. A 5V bus can be stepped down to
3.3V or 2.5V with greater efficiency than linear conversion. Using an external bias supply the input voltage can be as low as VOUT plus
VDROPOUT; consult the dropout curves for typical dropout voltages. Low line regulation error is easily trimmed with a low value feedback
resistor in series with the RFB pin (5). Since the input current of the pin is approximately 250uA the output will increase by approximately
25mV per 100 ohms of resistance. The resistor should be selected such that the output voltage does not exceed the nominal output by
more than 0.25V under the high input condition. Placing the feedback resistor as close to the device pin as possible helps to maintain
noise immunity.
SEQUENCE OF OPERATION:
Each pulse from the oscillator sets the internal PWM latch that turns on the high-side MOSFET. As the high-switch turns off, the
synchronous rectifier latch is set. 60ns later the low-side MOSFET turns on until the start of the next clock cycle or until the inductor
current crosses zero. Under fault conditions the current exceeds the ±100mV current-limit threshold and the high-side switch turns off.
Under light load conditions the synchronous rectifier is gated off as the inductor current falls through zero.
TABLE 1
OPERATIONAL CHARACTERISTICS
PWR SAVE
ENABLE
LOAD
DESCRIPTION
x
0
x
DEVICE DISABLED
0
1
LOW < 10%
PULSE SKIPPING MODE DISCONTINUOUS INDUCTOR CURRENT
0
1
MED < 30%
PULSE SKIPPING MODE CONTINUOUS INDUCTOR CURRENT
0
1
HIGH > 30%
CONSTANT FREQ. PWM MODE CONTINUOUS INDUCTOR CURRENT
1
1
x
LOW NOISE CONSTANT FREQ. MODE
6
8548-158 Rev. K 3/18
TYPICAL 2.5V APPLICATION CIRCUIT
TYPICAL PERFORMANCE CURVES
7
8548-158 Rev. K 3/18
TYPICAL PERFORMANCE CURVES CONT'D
8
8548-158 Rev. K 3/18
MECHANICAL SPECIFICATIONS
ESD TRIANGLE INDICATES PIN 1
WEIGHT=17 GRAMS TYPICAL
MSK5045-3.3 H G
ALL DIMENSIONS ARE SPECIFIED IN INCHES
ORDERING INFORMATION
LEAD FORM OPTIONS
BLANK=STRAIGHT;G=GULL WING
SCREENING
BLANK= INDUSTRIAL; H= MIL-PRF-38534 CLASS H
OUTPUT VOLTAGE
2.5=+2.5V; 3.3=+3.3V; 5.0=+5.0V
GENERAL PART NUMBER
The above example is a +3.3V, Military regulator with gull wing leads.
9
8548-158 Rev. K 3/18
MECHANICAL SPECIFICATIONS
ESD TRIANGLE INDICATES PIN 1
WEIGHT=17 GRAMS TYPICAL
MSK5045-3.3 H
ALL DIMENSIONS ARE SPECIFIED IN INCHES
ORDERING INFORMATION
LEAD FORM OPTIONS
BLANK=STRAIGHT;G=GULL WING
SCREENING
BLANK= INDUSTRIAL; H= MIL-PRF-38534 CLASS H
OUTPUT VOLTAGE
2.5=+2.5V; 3.3=+3.3V; 5.0=+5.0V
GENERAL PART NUMBER
The above example is a +3.3V, Military regulator.
10
8548-158 Rev. K 3/18
REVISION HISTORY
REV
J
K
STATUS
Released
Released
DATE
10/15
03/18
DESCRIPTION
Add internal note and clarify mechanical specifications
MAX BIAS current from 35mA to 21mA
ANAREN, MSK Products
www.anaren.com/msk
The information contained herein is believed to be accurate at the time of printing. Anaren, MSK Products 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 Anaren, MSK Products for MIL-PRF-38534 quailfication status.
11
8548-158 Rev. K 3/18