LMZ23605 Datasheet, PDF (1/10 Pages) National Semiconductor (TI) – Evaluation Board to be an easy-to-use platform to evaluate

LMZ23605/03, LMZ22005/03
Evaluation Board
National Semiconductor
Application Note 2085
Alan Martin
March 27, 2011
Introduction
The LMZ23605/03, LMZ22005/03 evaluation boards are de-
signed to be an easy-to-use platform to evaluate the full
capabilities of this family of SIMPLE SWITCHER® power
modules. The PCB construction has excellent thermal per-
formance and includes extra locations for optional compo-
nents that may not be required in the end application.
The LMZ23605/03 can accept an input voltage rail between
6V and 36V and the LMZ22005/03 can accept an input volt-
age rail between 6V and 20V. The devices can deliver an
adjustable and highly accurate output voltage as low as 0.8V
and as high as 6V. The control architecture is constant fre-
quency PWM with emulated current mode sensing. The con-
trol loop operates well with low ESR output capacitors such
as ceramics or specialty polymer. The precision enable input
allows for programmable UVLO on the input supply or flexi-
bility in sequencing. The external soft-start capacitor facili-
tates controlled output rise time at startup. The module family
is a reliable and robust solution with cycle-by-cycle valley cur-
rent limit to protect for over current or short-circuit faults.
Additionally there is thermal shutdown protection, and they
will start up into a pre-biased output. The free-running switch-
ing frequency is 812 kHz (typ) and a 650 kHz to 950 kHz
synchronization range is supported.
Board Specifications
• V_IN = 6V to 36V (LMZ22005/03 limited to 20V)
• Enable UVLO = 5.7V
• V_OUT = 3.3V
• I_OUT = 0 to 5A (LMZ23603 and LMZ22003 limited to 3A)
• θ_JA = 12°C / W, θ_JC = 1.9°C/W
• PCB designed on four layers; Inner are 2 oz; Outer are 3
oz.
• Measures 3.5 in. x 3.5 in. (8.9 cm x 8.9 cm) and is 62mil
(.062”) thick of FR4 laminate material
• Max ambient temp of 70°C at full 5A load (12 Vin)
For additional circuit considerations refer to the Applications
Section of the LMZ23605/03 or LMZ22005/03 data sheets.
For negative output voltage connections follow the method
shown in AN-2027.
FIGURE 1. Evaluation Board Simplified Schematic
30131601
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