BG
LED
ISET
2560 V
LED(n) _ current[11: 0]
I
(n) =
R
4095
u
u
Using the LP8863EVM
25
SNVU558 – February 2017
Copyright © 2017, Texas Instruments Incorporated
The LP8863EVM Evaluation Module
10.5 Setting the LED String Current
R57 between ISET and GND sets LED string current. The value can be calculated from
. The
default LED string current setting is 120 mA (25.8 k
Ω
).
where
•
V
BG
= 1.2 V
(1)
10.6 LED String Configuration
LED string configuration of LP8863-Q1 is automatically detected at VDD POR. Any LED out pins (LED0 to
LED5) connected to GND are disabled and removed from adaptive loop control. Pin 2 of J21 to J26 can
be used to connect LED out pins to GND.
11
LED Load Board
The LED board is intended to be used as the load for LED drivers and can use up to 6 strings and up to
20 LEDs in the string (number of LEDs in use are defined by jumpers). Cree Xlamp ML-B LEDs with
maximum current 175 mA and maximum forward voltage 3.5 V at 80 mA (3.3 V typical) are used on the
board.
NOTE:
The LED board is not included with the EVM -- contact your local TI sales representative if
board is needed.
Figure 15. LED Load Board (Top View)
