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M.S. KENNEDY CORPORATION
By Bob Abel & Paul Musil, MS Kennedy Corp.; 02/2011
Introduction
The MSK 5059RH is a radiation hardened 500 kHz switching regulator controller
capable of delivering up to 4.5A of current to the load. A fixed 500 kHz 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 MSK 5059RH 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.
The evaluation board provides a platform from which to evaluate new designs with ample
real estate to make changes and evaluate results. Evaluation early in the design phase
reduces the likelihood of excess ripple, instability, or other issues, from becoming a
problem at the application PCB level.
This application note is intended to be used in conjunction with the MSK5059RH data
sheet and the LT1959 data sheet. Reference those documents for additional application
information and specifications.
Setup
Use the standard turret terminals to connect to your power supply and test equipment.
Connect a power supply across the Vin and GND
output load between the VOUT and GND
to connect input and output monitoring equipment. When measuring output ripple voltage
with an oscilloscope probe, the wire from the probe to the ground clip will act as an
4707 DEY ROAD LIVERPOOL, NY 13088
PHONE: (315) 701-6751 | FAX: (315) 701-6752
MSK Web Site:
MSK5059RH
Evaluation Board
User's Guide
terminals (see note 1). Connect the
1
terminals. Use separate or Kelvin connections
2
http://www.mskennedy.com/
Page 1 of 9
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Summary of Contents for MSK MSK5059RH
- Page 1 PCB level. This application note is intended to be used in conjunction with the MSK5059RH data sheet and the LT1959 data sheet. Reference those documents for additional application information and specifications.
- Page 2 12V. When configured for an output voltage of 2.5V or greater the MSK5059RH will function normally with input voltages up to the maximum rating of 15V. If operating the MSK5059RH at less than the minimum on time is required greater than typical compensation can reduce the irregular switching.
- Page 3 Loop Stability The compensation for MSK5059RH evaluation board is a 1000pF capacitor in parallel with a series RC consisting of a 1500pF capacitor and a 10k resistor. This compensation was selected for use with the default components on this evaluation board.
- Page 4 and plot the loop’s gain and phase response between 1 kHz and 1 MHz. This provides a full picture of the situation on both sides of the unity gain frequency (20 kHz in this case). Figure 2 illustrates typical results for the default configuration. The phase margin is the phase value at the unity gain frequency, or about 68 Deg.
- Page 5 Figures 4-A and B illustrate typical results for a step load function between 500ma and 2.0A. Notice that the ringing in Figure 4-B is evident for the design intentionally modified to be less stable versus the critically damped response in Figure 4-A. Figure 4-A (Typical Response) Figure 4-B (Modified Response) Current Sharing and Synchronization...
- Page 6 converter is high, typically I /2. Tantalum capacitors become resistive at higher frequencies, requiring careful ripple-rating selection to prevent excessive heating. Measure the capacitor case rise above ambient in the worst case thermal environment of the application, and if it exceeds 10°C, increase the voltage rating or lower the ESR rating.
- Page 7 Current Limitations Peak current for a buck converter is limited by the maximum switch current rating. This current rating is 4.5A up to 50% duty cycle (DC), decreasing to 3.7A at 80% duty cycle for the MSK5059. Figure 5 This is shown graphically in Figure 5, and can be calculated using the formula below: = 4.5A for DC <...
- Page 8 MSK5059 Evaluation Board Schematic Typical Performance Parameter Conditions Units Typical Output Voltage = 5.0V, I = 2.0A 1.8V (Factory Default) Switching Frequency = 5.0V, I = 2.0A Output Ripple Voltage = 5.0V, I = 2.0A mVp-p Line Regulation 4.3V ≤ V ≤...
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Page 9: Bill Of Materials
Bill Of Materials Ref Des Description Manufacturer Part Number Switching Regulator MS Kennedy Corp. MSK5059RHG 1210 Ceramic cap 1.0uF 12103C105KAT 1210 Ceramic cap 1.0uF 12103C105KAT 8050 Ceramic Cap .33uF 08053C334KAT 8050 Ceramic Cap 1000pF 08053A102JAT 8050 Ceramic Cap 1500pF 08053A152FAT 220 uF Low ESR tantalum TAZH227K010L (CWR29FC227K) 220 uF Low ESR tantalum TAZH227K010L (CWR29FC227K) 220 uF Low ESR tantalum TAZH227K010L (CWR29FC227K) 1210 Ceramic cap 1.0uF 12103C105KAT 8050 Ceramic cap 0.1uF 08053C104KAT 47 uF Low ESR tantalum TAZH476K020L (CWR29JC476K) 47 uF Low ESR tantalum TAZH476K020L (CWR29JC476K) Resistor 1.21K, 1/8W Resistor 2.49K, 1/8W Resistor 10.0K, 1/8W Resistor 20Ω, 1/8W Fairchild Fairchild FYD0504SATM 1N4148 or 1N914 1N4148 or 1N914...
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