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ISO-9001 CERTIFIED BY DSCC
M.S.KENNEDY CORP. FEATURES:
POSITIVE ADJUSTABLE, LOW DROPOUT SURFACE MOUNT VOLTAGE REGULATORS
5231
(315) 701-6751
4707 Dey Road Liverpool, N.Y. 13088 Hermetic Surface Mount Package Low Dropout Voltage: 1.5V @ 2 Amps Adjustable Output Voltage On Board Thermal Overload Protection Short Circuit Current Limiting Output Current to 3 Amps Second Source for 0M185 Pin Compatible with the OM7628NM
MIL-PRF-38534 QUALIFIED
DESCRIPTION:
The MSK 5231 voltage regulator is a positive adjustable regulator that with proper heatsinking, can provide 3 Amps of output current. Low dropout and impressive thermal characteristics help to improve efficiency and lower power dissipation. An accurate reference voltage allows for precise output adjustment. The MSK 5231 is packaged in a hermetic, space efficient 3 pin power surface mount ceramic package.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATIONS
High Efficiency, High Current Linear Regulators Constant Current Regulators System Power Supplies Switching Power Supply Post Regulators Battery Chargers
1
PIN-OUT INFORMATION
1 VIN 2 Adjust 3 VOUT
Rev. - 7/02
ABSOLUTE MAXIMUM RATINGS

ELECTRICAL SPECIFICATIONS
Parameter Reference Voltage Test Conditions 1 4 (VIN-VOUT)=3V IOUT=10mA 1.5V (VIN-VOUT) 25V 10mA IOUT 2.0A IOUT=2.0A VREF=1% 1.5V (VIN-VOUT) 15V IOUT=10mA 15V (VIN-VOUT) 35V IOUT=10mA VIN-VOUT=3V 10mA IOUT 2.0A Group A Subgroup 1 1 2,3 1 2,3 1 2,3 1 2,3 1 2,3 1 2,3 MSK 5231H/E Min. Typ. Max. 1.238 1.220 1.220 3.2 3.2 0.2 0.2 1.250 1.250 1.250 1.3 1.3 0.02 0.05 0.1 0.2 4.0 4.0 0.5 0.5 1.262 1.270 1.270 1.5 1.5 0.2 0.5 0.8 1.0 2 Min. 1.230 1.215 3.2 0.2 MSK 5231 Typ. Max. 1.250 1.250 1.3 0.02 0.1 4.0 0.5 1.270 1.275 1.5 0.4 1.0 Units V V V V V % % % % A A A A
Dropout Voltage 2
Line Regulation Load Regulation
VIN-VOUT=5.0V Current Limit 2 VIN-VOUT=25V F=120Hz CADJ=25F Ripple Rejection 2 COUT=25F IOUT=2.0A VIN-VOUT=3.0V Adjust Pin Current 1.5V (VIN-VOUT) 25V 10mA IOUT 2.0A
4
60
75
-
60
1 2,3 1 2,3 1 -
-
55 55 5 5 0.004 0.5 0.8
120 120 10 10 0.02 1.5
-
Minimum Load Current 2 Thermal Regulation 2 Temperature Stability Thermal Resistance 2 2
(VIN-VOUT)=24V 30mS pulse TA=25C -55C TJ +125C Junction to Case @ 125C
0.004 0.5 0.8
NOTES:
1 2 3 4 5 6 7 Output decoupled to ground using 20F minimum capacitor unless otherwise specified. This parameter is guaranteed by design but need not be tested. Typical parameters are representative of actual device performance but are for reference only. All output parameters are tested using a low duty cycle pulse to maintain TJ = TC. Industrial grade and "E" suffix devices shall be tested to subgroup 1 unless otherwise specified. Military grade devices ('H' suffix) shall be 100% tested to subgroups 1,2,3. Subgroup 1,4 TA=TC=+25C 2,5 TA=TC=+125C 3,6 TA=TC=-55C
2

PD
TJ
-40C to+85C -55to+125C
75
-
55 5 -
120 10 0.02 1.7
Rev. - 7/02

VIN IOUT
35V Input to Output Voltage Differential 4A Output Current Internally Limited Power Dissipation
TST TLD
Storage Temperature Range Lead Temperature (10 Seconds Soldering) Operating Temperature MSK 5231 MSK 5231H/E
-65C to +150C 300C
dB
A A mA mA %/W % C/W
APPLICATION NOTES
The MSK 5231 features both power and thermal overload protection. When the maximum power dissipation is not exceeded, the regulator will current limit slightly above its 3 amp rating. As the VIN-VOUT voltage increases, however, shutdown occurs in relation to the maximum power dissipation curve. If the device heats enough to exceed its related die junction temperature due to excessive ambient temperature, improper heat sinking etc., the regulator shuts down until an appropriate junction temperature is maintained. It should also be noted that in the case of an extreme overload, such as sustained direct short, the device may not be able to recover. In these instances, the device must be shut off and power reapplied to eliminate the shutdown condition.
OVERLOAD SHUTDOWN
In this case the result is 10.0C/W. Therefore, a heat sink with a thermal resistance of no more than 10.0C/ W must be used in this application to maintain regulator circuit junction temperature under 125C.
STABILITY
For stable operation in most applications it is recommended that a 10f tantalum capacitor be used at the input of the regulator. In addition, if the regulator is not located very close to the power supply filter capacitors, a 4.7f low ESR tantalum capacitor should be added to the regulator's input. Electrolytic capacitors may also be used. When substituting an electrolytic in place of a tantalum the value should be increased by a factor of ten over the tantalum value. The output of the regulator should be bypassed using a minimum 10f tantalum capacitor. To ensure good transient response under heavy load conditions the output capacitor may be increased without limit. Larger capacitance values will further improve stability and transient response.
HEAT SINKING
To determine if a heat sink is required for your application and if so, what type, refer to the thermal model and governing equation below. Governing Equation: Tj=Pd x (Rjc + Rcs +Rsa)+ Ta WHERE Tj = Junction Temperatre Pd = Total Power Dissipation Rjc = Junction to Case Thermal Resistance Rcs = Case to Heat Sink Thermal Resistance Rsa = Heat Sink to Ambient Thermal Resistance Tc = Case Temperature Ta = Ambient Temperature Ts = Heat Sink Temperature EXAMPLE: This example demonstrates an analysis where the regulator is at one-half of its maximum rated power dissipation, which occurs when the output current is at 1.5 amps. VIN=+7.0V VOUT=+5.0V IOUT=1.5A 1.) Assume 45 heat spreading model. 2.) Find power dissipation: Pd=(VIN-VOUT) (IOUT) Pd=(7-5) (1.5) =3.0W 3.) For conservative design, set TJ=+125C Max. 4.) For this example, worst case TA=+90C. 5.) RJC=1.5C/W from the Electrical Specification Table. 6.) RCS=0.15C/W for most thermal greases. 7.) Rearrange governing equation to solve for RSA: RSA= ((TJ - TA)/Pd) - (RJC) - (RCS) = (125C - 90C)/3.0W - 1.5C/W - 0.15C/W = 10.0C/W
3
LOAD REGULATION
Load regulation will be limited by the resistance of the wire connecting the regulator to the load. For example, if 20 gauge wire were used which has a resistance of approximately 0.008 ohms per foot, this would result in a voltage drop of 8mV/ft at 1 amp of load current. Also, best load regulation will be seen when the adjust resistor, R1, is connected directly to the regulator and not to the load. In addition, it is important to follow the capacitor selection guidelines for stability and load regulation performance.
OUTPUT VOLTAGE
The MSK 5231 requires two external resistors to set the output voltage. A 1.25 volt reference voltage is developed between the output and adjust pins. Resistor, R1, is placed between these pins with a second resistor, R2, placed from the adjust pin to ground. A constant current will flow from the output through these two resitors to set the output voltage. The series resistance of R1 & R2 should be selected to provide a minimum load current of 10mA.
Rev. - 7/02
TYPICAL PERFORMANCE CURVES
4
Rev. - 7/02
MECHANICAL SPECIFICATIONS
NOTE: ALL DIMENSIONS ARE 0.010 INCHES UNLESS OTHERWISE LABELED.
ORDERING INFORMATION
MSK5231 H
SCREENING BLANK= INDUSTRIAL; E=EXTENDED RELIABILITY H= MIL-PRF-38534 CLASS H GENERAL PART NUMBER
4707 Dey Road, Liverpool, New York 13088 Phone (315) 701-6751 FAX (315) 701-6752 www.mskennedy.com
M.S. Kennedy Corp.
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.
5
Rev. - 7/02

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