EVALED2000P STMicroelectronics, EVALED2000P Datasheet - Page 26

• Manufacturer Part Number: EVALED2000P
• Description: LED Lighting Development Tools LED2000 3A 850KHz 3.0V to 18V Eval BRD
• Manufacturer: STMicroelectronics

Specifications of EVALED2000P

• Product Category: LED Lighting Development Tools
• Rohs: yes
• Product: Evaluation Boards
• Operating Supply Voltage: 3 V to 18 V
• For Use With: LED2000

Application information
7.2
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Layout considerations
The layout of switching DC-DC converters is very important to minimize noise and
interference. Power-generating portions of the layout are the main cause of noise and so
high switching current loop areas should be kept as small as possible and lead lengths as
short as possible.
High impedance paths (in particular the feedback connections) are susceptible to
interference, so they should be as far as possible from the high current paths. A layout
example is provided in
The input and output loops are minimized to avoid radiation and high frequency resonance
problems. The feedback pin to the sensing resistor path must be designed as short as
possible to avoid pick-up noise. Another important issue is the ground plane of the board. As
the package has an exposed pad, it is very important to connect it to an extended ground
plane in order to reduce the thermal resistance junction-to-ambient.
To increase the design noise immunity, different signal and power ground should be
implemented in the layout (see
the small signal components, the device analog ground pin, the exposed pad and a small
filtering capacitor connected to the VCC pin. The power ground serves the device ground
pin and the input filter. The different grounds are connected underneath the output
capacitor. Neglecting the current ripple contribution, the current flowing through this
component is constant during the switching activity and so this is the cleanest ground point
of the buck application circuit.
Figure 16. Layout example
Figure
Doc ID 023432 Rev 3
16.
Section 7.5: Application
circuit). The signal ground serves
LED2000