Texas Instruments TLC5929, User Manual

Page: 5 / 19

R =
IREF
I
OLCMax
V
IREF
´
54.8
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Connector and Test Point Descriptions
4.2 I
REF
Jumpers (J7)
The 2 × 5 header, J7, selects the desired maximum output current. The currents available for the
TLC5929 are 10, 20, 30, 40, and 50 mA per channel.
NOTE: The LEDs connected to J3 do not turn on if there is no jumper set at J7.
(1)
Where:
V
IREF
= the internal reference voltage on the IREF pin (typically 1.205 V)
I
OLCMax
= 1 mA to 40 mA for V
CC
≤
3.6 V, or 1 mA to 50 mA for V
CC
> 3.6 V with BC = 7Fh
4.3 Test Point Descriptions
Table 3. Test Point Description
Test Points Name Type Description
TP1 LAT Input Level-triggered latch. The data is held when LAT is low. The data is transferred to the on/off
data latch when LAT is high.
TP2 SCLK Input Serial data shift clock input
TP3 SIN Input Serial data input for the shift register
TP4 BLANK Input Output enable for all channels. Outputs are disabled when BLANK is high.
TP5 VCC Power Supply for TLC5929 (3–5.5 V).
TP6 SOUT Output Serial data output
TP7 I
REF
I/O Constant-current set resistor
TP8 V
LED
Power Power supply for LED lamps (up to 17 V)
TP9, TP10 GND Power Power ground
4.3.1 Input Voltage Monitoring (TP5, TP8, TP9, TP10)
The TLC5929 EVM provides test points for measuring the voltage applied to the IC and the LEDs. This
allows measurement of the actual supply voltages without losses from input cables and connectors.
The V
CC
voltage measurements are made between TP5 and TP10. The V
LED
voltage measurements are
made between TP8 and TP9. Use these test points by connecting a voltmeter positive terminal to TP5/8
and negative terminal to TP9/10.
4.3.2 Serial Interface Connection (TP1, TP2, TP3, TP4, TP6)
Evaluate this EVM by preparing a signal pattern generator like an FPGA, CPLD, MCU or some equipment
like DG2020 for the input signals BLANK (TP4), SIN (TP3), SCLK (TP2) and LAT (TP1).
Use TP6 for observing the signal SOUT sends to a second EVM (not included).
4.3.3 Constant Sink Current (TP7)
Measure the voltage present at the I
REF
pin of the TLC5929 with TP7.
5 SLVU756 – August 2012 Using the TLC5929, 16-Channel LED Driver with 7-Bit Global Brightness
Control, Power-Save Mode, and Full Self-Diagnosis for LEDs
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