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User's Guide
SNVA450B–July 2010–Revised April 2013
AN-2074 LMZ1050xEXT Evaluation Board
1 Introduction
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.
2 Board Specifications
• V
IN
= 2.95V to 5.5V
• V
OUT
= 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 T
J
= -55°C to
125°C)
• ±1.63% feedback voltage accuracy over temperature
• I
OUT
= 0A to 3A, 4A, and 5A
• θ
JA
= 20°C/W, θ
JC
= 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
3 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 (C
in1
- C
in4
) and three output capacitors (C
o1
- C
o3
)
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, C
in5
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.
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SNVA450B–July 2010–Revised April 2013 AN-2074 LMZ1050xEXT Evaluation Board
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