TLC5940_15 Datasheet, PDF (25/38 Pages) Texas Instruments – 16-Channel LED Driver

www.ti.com
TLC5940
SLVS515D – DECEMBER 2004 – REVISED NOVEMBER 2015
10 Power Supply Recommendations
The V_CC power supply voltage should be decoupled by placing a 0.1uF ceramic capacitor close to VCC pin and
GND plane. Depending on panel size, several electrolytic capacitors must be placed on board equally distributed
to get a well regulated LED supply voltage (VLED). VLED voltage ripple should be less than 5% of its nominal
value. Furthermore, the VLED should be set to the voltage calculated by equation:
VLED > VF + 0.4V ( 10mA constant current example) where Vf = maximum forward voltage of all LEDs.
11 Layout
11.1 Layout Guidelines
1. Place the decoupling capacitor near the VCC pin and GND plane.
2. Place the current programming resistor Riref close to IREF pin and IREFGND pin.
3. Route the GND pattern as widely as possible for large GND currents.
4. Routing wire between the LED cathode side and the device OUTn pin should be as short and straight as
possible to reduce wire inductance.
5. When several ICs are chained, symmetric placements are recommended.
11.2 Layout Example
GND
VCC
GND
GND
BLANK
XLAT
SCLK
SIN
VPRG
OUT0
OUT1
OUT2
OUT3
OUT4
OUT5
OUT6
OUT7
1
28
2
27
3
26
4
25
5
24
6
Thermal
23
Pad
7
22
8
21
9
20
10
Via to
Heatsink
19
Layer
11
18
12
17
13
16
14
15
VCC
IREF
DCPRG
GSCLK
SOUT
XERR
OUT15
OUT14
OUT13
OUT12
OUT11
OUT10
OUT9
OUT8
Figure 24. Layout Recommendation
Copyright © 2004–2015, Texas Instruments Incorporated
Product Folder Links: TLC5940
Submit Documentation Feedback
25