EVALED2000P STMicroelectronics, EVALED2000P Datasheet - Page 22

• 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
7.1
7.1.1
7.1.2
22/40
The software calculates external components according to the internal database. It is also
possible to define new components and ask the software to use them.
Bode plots, estimated efficiency and thermal performance are provided.
Finally, the user can save the design and print all the information including the bill of material
of the board.
Application information
Component selection
Sensing resistor
In closed loop operation the LED2000 feedback pin voltage is 100 mV, so the sensing
resistor calculation is expressed as:
Equation 22
Since the main loop (see
average current is regulated into the LEDs. The integration period is at minimum 5*T
since the system bandwidth can be dimensioned up to f
The system performs the output current regulation over a period which is at least five times
longer than the switching frequency. The output current regulation neglects the ripple
current contribution and its reliance on external parameters like input voltage and output
voltage variations (line transient and LED forward voltage spread). This performance can
not be achieved with simpler regulation loops such as a hysteretic control.
For the same reason, the switching frequency is constant over the application conditions,
which helps to tune the EMI filtering and to guarantee the maximum LED current ripple
specification in the application range. This performance can not be achieved using constant
ON/OFF-time architecture.
Inductor and output capacitor selection
The output capacitor filters the inductor current ripple that, given the application condition,
depends on the inductor value. As a consequence, the LED current ripple, that is the main
specification for a switching current source, depends on the inductor and output capacitor
selection.
R
S
=
100 mV
------------------- -
I
LED
Section
Doc ID 023432 Rev 3
6.1) regulates the sensing resistor voltage drop, the
SW
/5 at maximum.
LED2000
SW