User's Guide
SNVA421D – January 2010 – Revised April 2013
AN-2022 LMZ1050x Evaluation Board
1
Introduction
The LMZ1050x 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 LMZ1050x 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.
2
Board Specifications
•
•
•
•
•
•
•
•
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VIN = 2.95V to 5.5V
VOUT = 2.5V (default output voltage setting; for other output settings, see Table 2)
±2.5% feedback voltage accuracy at 2.5V output (Including line and load regulation from TJ = -40°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
Evaluation Board Design Concept
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),
see 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.
4
Additional Component Footprints
When the tracking feature of the LMZ1050x 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 LMZ1050x 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. For detailed design implementation, see the Design Guideline and
Operating Description section of the LMZ1050x data sheet.
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 LMZ1050x in
systems with multiple power rails, precision enable and tracking are useful as the main input voltage rail
rises at power-up.
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SNVA421D – January 2010 – Revised April 2013
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AN-2022 LMZ1050x Evaluation Board
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Component Circuit Schematic
5
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Component Circuit Schematic
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
Texas Instruments
LMZ1050xTZ-ADJ
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
Cin5
220 µF, 10V, AL-Elec
E
Panasonic
EEE1AA221AP
1
CO3
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
Ren1
100 kΩ
0805
Vishay Dale
CRCW0805100KFKEA
1
CSS
10 nF, ±5%, C0G, 50V
0805
TDK
C2012C0G1H103J
1
Table 2. Output Voltage Setting (Rfbt = 75 kΩ)
2
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
AN-2022 LMZ1050x Evaluation Board
SNVA421D – January 2010 – Revised April 2013
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Complete Circuit Schematic
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Complete Circuit Schematic
Figure 2. Complete Evaluation Board Schematic
SNVA421D – January 2010 – Revised April 2013
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Connection Diagram
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Connection Diagram
Figure 3. Efficiency Measurement Setup
Oscilloscope
Vo
GND
Co1
Figure 4. Output Voltage Ripple Measurement Setup
4
AN-2022 LMZ1050x Evaluation Board
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Performance Characteristics
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Efficiency
vs.
Load Current
LMZ10504 & LMZ10505, VOUT = 2.5V, TAMB = 25°C
8
Efficiency
vs.
Load Current
LMZ10503, VOUT = 2.5V, TAMB = 25°C
Performance Characteristics
Figure 5. Current Derating vs. Ambient Temperature
LMZ10503, VIN = 5.0V, θJA = 20°C/W
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Performance Characteristics
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Figure 6. Current Derating vs. Ambient Temperature
LMZ10504, VIN = 5.0V, θJA = 20°C/W
Figure 7. Current Derating vs. Ambient Temperature
LMZ10505, VIN = 5.0V, θJA = 20°C/W
Figure 8. Current Derating vs. Ambient Temperature
LMZ10503, VIN = 3.3V, θJA = 20°C/W
6
AN-2022 LMZ1050x Evaluation Board
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Performance Characteristics
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Figure 9. Current Derating vs. Ambient Temperature
LMZ10504, VIN = 3.3V, θJA = 20°C/W
Figure 10. Current Derating vs. Ambient Temperature
LMZ10505, VIN = 3.3V, θJA = 20°C/W
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Performance Characteristics
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Figure 11. Output Voltage Ripple
VIN = 5V, VOUT = 2.5V, IOUT = 3A, 4A, & 5A
LMZ10503 / LMZ10504 / LMZ10505
Figure 12. Load Transient Response
VIN = 5.0V, VOUT = 2.5V
LMZ10503, IOUT = 400 mA to 2.7A, 20 MHz Bandwidth Limit
8
AN-2022 LMZ1050x Evaluation Board
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Performance Characteristics
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Figure 13. Load Transient Response
VIN = 5V, VOUT = 2.5V
LMZ10504, IOUT = 400 mA to 3.6A, 20 MHz Bandwidth Limit
Figure 14. Output Voltage Ripple
VIN = 3.3V, VOUT = 2.5V, IOUT = 3A, 4A, & 5A
LMZ10503 / LMZ10504 / LMZ10505
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Performance Characteristics
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Figure 15. Load Transient Response
VIN = 3.3V, VOUT = 2.5V
LMZ10503, IOUT = 300 mA to 2.7A, 20 MHz Bandwidth Limit
Figure 16. Load Transient Response
VIN = 3.3V, VOUT = 2.5V
LMZ10504, IOUT = 400 mA to 3.6A, 20 MHz Bandwidth Limit
10
AN-2022 LMZ1050x Evaluation Board
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Circuit Example: Complies with EN55022 Class B Radiated Emissions
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Figure 17. Load Transient Response
VIN = 5.0V, VOUT = 2.5V
LMZ10505, IOUT = 500 mA to 4.5A, 20 MHz Bandwidth Limit
Figure 18. Load Transient Response
VIN = 3.3V, VOUT = 2.5V
LMZ10505, IOUT = 500 mA to 4.5A, 20 MHz Bandwidth Limit
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Circuit Example: Complies with EN55022 Class B Radiated Emissions
Figure 19. Component Schematic, VIN = 5V, VOUT = 2.5V, Complies with EN55022 Class B Radiated
Emissions
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Circuit Example: Complies with EN55022 Class B Radiated Emissions
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Table 3. Bill of Materials
Designator
Description
Case Size
Manufacturer
Manufacturer P/N
Quantity
U1
SIMPLE SWITCHER
TO-PMOD-7
Texas Instruments
LMZ10503/4/05TZ-ADJ
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
Figure 20. Radiated Emissions (EN55022, Class B)
VIN = 5V, VOUT = 2.5V, IOUT = 3A
Tested on LMZ10503 Evaluation Board
Figure 21. Radiated Emissions (EN55022, Class B)
VIN = 5V, VOUT = 2.5V, IOUT = 4A
Tested on LMZ10504 Evaluation Board
12
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PCB Layout Diagram
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Figure 22. Radiated Emissions (EN55022, Class B)
VIN = 5V, VOUT = 2.5V, IOUT = 5A
Tested on LMZ10505 Evaluation Board
10
PCB Layout Diagram
Figure 23. Top Layer
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PCB Layout Diagram
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Figure 24. Internal Layer I (Ground)
Figure 25. Internal Layer II (Ground)
14
AN-2022 LMZ1050x Evaluation Board
SNVA421D – January 2010 – Revised April 2013
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PCB Layout Diagram
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Figure 26. Bottom Layer
SNVA421D – January 2010 – Revised April 2013
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