TLC5973 Datasheet, PDF (22/34 Pages) Texas Instruments – TLC5973 3-Channel, 12-Bit, PWM Constant-Current LED Driver with Single-Wire Interface (EasySet)

TLC5973
SBVS225B – MARCH 2013 – REVISED MAY 2014
www.ti.com
9 Applications and Implementation
9.1 Application Information
The device is a constant sink current LED driver. This device is typically used to minimize wiring cost in
applications and also provides no restrictions of cascading multiple devices in series. Furthermore, the device
maximum data transfer rate is 3 Mbps and can contribute high-frequency display data change rates. The
following design procedures can be used to maximize application design with minimal wiring cost. The device is
also a good choice for higher VCC power-supply voltage applications because of the internal shunt regulator
included in the device.
9.2 Typical Applications
9.2.1 No Internal Shunt Regulator Mode 1
This application does not use the shunt regulator. However, the device VCC and LED lamp anode voltage can
be supplied from the same power supply because only one LED lamp is connected in series.
Power
Supply
(5 V)
VCC
GND
Controller
R_IREF
GND
IREF
Device
SDI
VCC
OUT0
OUT1
OUT2
SDO
R_IREF
GND
IREF
Device
SDI
VCC
OUT0
OUT1
OUT2
SDO
Figure 22. No Internal Shunt Regulator Mode 1 Typical Application Circuit
9.2.1.1 Design Requirements
DESIGN PARAMETER
Input voltage range for VCC
SDI voltage range
SDI data transfer rate
Table 4. Design Parameters
EXAMPLE VALUE
3.0 V or LED forward voltage (V_F) + 1 V to 5.5 V
Low level = GND, high level = VCC
100 kbps to 3 Mbps
9.2.1.2 Detailed Design Procedure
The OUTn (n = 0 to 2) constant output current is set by an external resistor connected between the device IREF
and GND pins. Use Equation 1 to calculate the requirements for R_IREF.
22
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