NSC CRCW08051K10FKEA Lmz1050xext evaluation board Datasheet

National Semiconductor
Application Note 2074
Yang Zhang
August 16, 2010
Introduction
Evaluation Board Design Concept
The LMZ1050xEXT SIMPLE SWITCHER® power module is
a complete, easy-to-use DC-DC solution capable of driving
up to 3A, 4A, or 5A load with exceptional power conversion
efficiency, output voltage accuracy, line and load regulation.
The LMZ1050xEXT is available in an innovative package that
enhances thermal performance and allows for hand or machine soldering.
The LMZ1050xEXT can accept an input voltage rail between
2.95V and 5.5V and deliver an adjustable and highly accurate
output voltage as low as 0.8V. One megahertz fixed frequency PWM switching provides a predictable EMI characteristic.
Two external compensation components can be adjusted to
set the fastest response time, while allowing the option to use
ceramic and/or electrolytic output capacitors. Externally programmable soft-start capacitor facilitates controlled startup.
The LMZ1050xEXT is a reliable and robust solution with the
following features: lossless cycle-by-cycle peak current limit
to protect for over current or short-circuit fault, thermal shutdown, input under-voltage lock-out, and pre-biased startup.
The evaluation board is designed to demonstrate low conducted noise on the input and output lines, as seen in Figure
11 and Figure 14. Four input capacitors (Cin1 - C in4) and three
output capacitors (Co1 - Co3) are populated for this purpose.
All the input and output filter capacitors are not necessary to
comply with radiation standards. For a circuit example that
passes radiated emissions standards (EN55022, class B)
please refer to Figure 19. Additionally, Cin5 is present to reduce the resonance of the input line produced by the inductance and resistance in the cables connecting the bench
power supply to the evaluation board and the input capacitors.
Board Specifications
•
•
•
•
•
•
•
•
VIN = 2.95V to 5.5V
VOUT = 2.5V (default output voltage setting, refer to Table
2 for other output settings)
±2.5% feedback voltage accuracy at 2.5V output
(Including line and load regulation from TJ = -55°C to
125°C)
±1.63% feedback voltage accuracy over temperature
IOUT = 0A to 3A, 4A, and 5A
θJA = 20°C/W, θJC = 1.9°C/W
Designed on four layers, the top and bottom layers are
1oz. copper and the two inner layers are 1/2 oz. copper
weight
Measures 2.25 in. x 2.25 in. (5.8 cm x 5.8 cm) and is 62mil
(.062”) thick on a FR4 laminate
Additional Component Footprints
LMZ1050xEXT Evaluation Board
LMZ1050xEXT Evaluation
Board
When the tracking feature of the LMZ1050xEXT is used, remove the soft-start capacitor CSS and use a resistor divider
on designators Rtrkb and Rtrkt. The ground and Vtrk post have
been provided for easy connection.
The LMZ1050xEXT eval board incorporates a precision enable circuit which is pulled high by a 100 kΩ pull up resistor
to VIN. This allows the user to pull low on the enable pin to
ground. The top enable resistor is Rent and the bottom enable
resistor is Renb. Refer to the Design Guideline and Operating
Description section of the LMZ1050xEXT data sheet for detailed design implementation.
Select FPGAs specify input inrush currents for particular power-up sequences and others require sequencing rails to avoid
start-up or latch-up problems. To prevent early turn-on of the
LMZ1050xEXT in systems with multiple power rails, precision
enable and tracking are useful as the main input voltage rail
rises at power-up.
AN-2074
© 2010 National Semiconductor Corporation
301280
www.national.com
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Component Circuit Schematic
30128017
FIGURE 1. Component Schematic for Evaluation Board
TABLE 1. Bill of Materials for Evaluation Board, VIN = 3.3V to 5V, VOUT = 2.5V
Designator
Description
Case Size
Manufacturer
Manufacturer P/N
Quantity
U1
SIMPLE SWITCHER®
TO-PMOD-7
National
Semiconductor
LMZ10503/4/5EXTTZ
1
Cin1
1 µF, X7R, 16V
0805
TDK
C2012X7R1C105K
1
Cin2, CO1
4.7 µF, X5R, 6.3V
0805
TDK
C2012X5R0J475K
2
Cin3, CO2
22 µF, X5R, 16V
1210
TDK
C3225X5R1C226M
2
Cin4
47 µF, X5R, 6.3V
1210
TDK
C3225X5R0J476M
1
CO3
100 µF, X5R, 6.3V
1812
TDK
C4532X5R0J107M
1
Rfbt
75 kΩ
0805
Vishay Dale
CRCW080575K0FKEA
1
34.8 kΩ
0805
Vishay Dale
CRCW080534K8FKEA
1
Rcomp
1.1 kΩ
0805
Vishay Dale
CRCW08051K10FKEA
1
Ccomp
180 pF, ±5%, C0G, 50V
0603
TDK
C1608C0G1H181J
1
Ren1
100 kΩ
0805
Vishay Dale
CRCW0805100KFKEA
1
CSS
10 nF, ±5%, C0G, 50V
0805
TDK
C2012C0G1H103J
1
Rfbb
TABLE 2. Output Voltage Setting (Rfbt = 75 kΩ)
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VOUT
Rfbb
3.3 V
23.7 kΩ
2.5 V
34.8 kΩ
1.8 V
59 kΩ
1.5 V
84.5 kΩ
1.2 V
150 kΩ
0.9 V
590 kΩ
2
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Complete Circuit Schematic
30128024
FIGURE 2. Complete Evaluation Board Schematic
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Connection Diagram
30128015
FIGURE 3. Efficiency Measurement Setup
30128016
FIGURE 4. Output Voltage Ripple Measurement Setup
Efficiency vs. Load Current
LMZ10504EXT & LMZ10505EXT, VOUT = 2.5V, TAMB = 25°C
Efficiency vs. Load Current
LMZ10503EXT, VOUT = 2.5V, TAMB = 25°C
30128028
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30128031
4
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Performance Characteristics
30128029
30128030
FIGURE 5. Current Derating vs. Ambient Temperature
LMZ10503EXT, VIN = 5.0V, θJA = 20°C/W
FIGURE 8. Current Derating vs. Ambient Temperature
LMZ10503EXT, VIN = 3.3V, θJA = 20°C/W
30128022
30128023
FIGURE 6. Current Derating vs. Ambient Temperature
LMZ10504EXT, VIN = 5.0V, θJA = 20°C/W
FIGURE 9. Current Derating vs. Ambient Temperature
LMZ10504EXT, VIN = 3.3V, θJA = 20°C/W
30128032
30128033
FIGURE 7. Current Derating vs. Ambient Temperature
LMZ10505EXT, VIN = 5.0V, θJA = 20°C/W
FIGURE 10. Current Derating vs. Ambient Temperature
LMZ10505EXT, VIN = 3.3V, θJA = 20°C/W
5
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30128018
30128020
FIGURE 11. Output Voltage Ripple
VIN = 5V, VOUT = 2.5V, IOUT = 3A, 4A, & 5A
LMZ10503EXT / LMZ10504EXT / LMZ10505EXT
FIGURE 14. Output Voltage Ripple
VIN = 3.3V, VOUT = 2.5V, IOUT = 3A, 4A, & 5A
LMZ10503EXT / LMZ10504EXT / LMZ10505EXT
30128037
30128036
FIGURE 12. Load Transient Response
VIN = 5.0V, VOUT = 2.5V
LMZ10503EXT, IOUT = 400 mA to 2.7A, 20 MHz Bandwidth
Limit
FIGURE 15. Load Transient Response
VIN = 3.3V, VOUT = 2.5V
LMZ10503EXT, IOUT = 300 mA to 2.7A, 20 MHz Bandwidth
Limit
30128019
30128021
FIGURE 13. Load Transient Response
VIN = 5V, VOUT = 2.5V
LMZ10504EXT, IOUT = 400 mA to 3.6A, 20 MHz Bandwidth
Limit
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FIGURE 16. Load Transient Response
VIN = 3.3V, VOUT = 2.5V
LMZ10504EXT, IOUT = 400 mA to 3.6A, 20 MHz Bandwidth
Limit
6
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30128034
30128035
FIGURE 18. Load Transient Response
VIN = 3.3V, VOUT = 2.5V
LMZ10505EXT, IOUT = 500 mA to 4.5A, 20 MHz Bandwidth
Limit
FIGURE 17. Load Transient Response
VIN = 5.0V, VOUT = 2.5V
LMZ10505EXT, IOUT = 500 mA to 4.5A, 20 MHz Bandwidth
Limit
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Circuit Example: Complies with EN55022 Class B Radiated Emissions
30128025
FIGURE 19. Component Schematic, VIN = 5V, VOUT = 2.5V, Complies with EN55022 Class B Radiated Emissions
TABLE 3. Bill of Materials
Designator
Description
Case Size
Manufacturer
Manufacturer P/N
Quantity
U1
SIMPLE SWITCHER®
TO-PMOD-7
National
Semiconductor
LMZ10503/4/5EXTTZ
1
Cin1
1 µF, X7R, 16V
0805
TDK
C2012X7R1C105K
1
Cin2
4.7 µF, X5R, 6.3V
0805
TDK
C2012X5R0J475K
1
Cin3
47 µF, X5R, 6.3V
1210
TDK
C3225X5R0J476M
1
CO1
100 µF, X5R, 6.3V
1812
TDK
C4532X5R0J107M
1
Rfbt
75 kΩ
0805
Vishay Dale
CRCW080575K0FKEA
1
Rfbb
34.8 kΩ
0805
Vishay Dale
CRCW080534K8FKEA
1
Rcomp
1.1 kΩ
0805
Vishay Dale
CRCW08051K10FKEA
1
Ccomp
180 pF, ±5%, C0G, 50V
0603
TDK
C1608C0G1H181J
1
CSS
10 nF, ±5%, C0G, 50V
0805
TDK
C2012C0G1H103J
1
30128038
30128026
FIGURE 20. Radiated Emissions (EN55022, Class B)
VIN = 5V, VOUT = 2.5V, IOUT = 3A
Tested on LMZ10503EXT Evaluation Board
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FIGURE 21. Radiated Emissions (EN55022, Class B)
VIN = 5V, VOUT = 2.5V, IOUT = 4A
Tested on LMZ10504EXT Evaluation Board
8
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30128027
FIGURE 22. Radiated Emissions (EN55022, Class B)
VIN = 5V, VOUT = 2.5V, IOUT = 5A
Tested on LMZ10505EXT Evaluation Board
9
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PCB Layout Diagram
30128007
FIGURE 23. Top Layer
30128008
FIGURE 24. Internal Layer I (Ground)
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10
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30128011
FIGURE 25. Internal Layer II (Ground)
30128013
FIGURE 26. Bottom Layer
11
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