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TLC5940-EP Datasheet, PDF (15/33 Pages) Texas Instruments – 16-CHANNEL LED DRIVER WITH DOT CORRECTION AND GRAYSCALE PWM CONTROL
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TLC5940-EP
SLVSA51D – MARCH 2010 – REVISED MAY 2010
VPRG
XLAT
DCb
SIN(a) MSB
DCa
LSB
GSb1
MSB
SCLK 1
SOUT(b)
BLANK
192
96X2
-
DCb
MSB
1
-
-
GSa1
LSB
384
192X2
GSb1
MSB
GSb2
MSB
385
1
SIDb1 SIDb1
MSB MSB-1
GSa2
LSB
384
SIDa1 GSb2
LSB MSB
GSb3
MSB
385
1
SIDb2 SIDb2
MSB MSB-1
GSCLK
OUT0
(current)
OUT1
(current)
OUT15
(current)
XERR
1
4096
1
Figure 14. Timing Chart for Two Cascaded TLC5940 Devices
ERROR INFORMATION OUTPUT
The open-drain output XERR is used to report both of the TLC5940 error flags, TEF and LOD. During normal
operating conditions, the internal transistor connected to the XERR pin is turned off. The voltage on XERR is
pulled up to VCC through an external pullup resistor. If TEF or LOD is detected, the internal transistor is turned
on, and XERR is pulled to GND. Since XERR is an open-drain output, multiple ICs can be OR'ed together and
pulled up to VCC with a single pullup resistor. This reduces the number of signals needed to report a system error
(see Figure 23).
To differentiate LOD and TEF signal from XERR pin, LOD can be masked out with BLANK = HIGH.
Table 2. XERR Truth Table
ERROR CONDITION
TEMPERATURE
OUTn VOLTAGE
TJ < T(TEF)
TJ > T(TEF)
TJ < T(TEF)
TJ > T(TEF)
Don't Care
Don't Care
OUTn > V(LED)
OUTn < V(LED)
OUTn > V(LED)
OUTn < V(LED)
ERROR INFORMATION
TEF
LOD
L
X
H
X
L
L
L
H
H
L
H
H
SIGNALS
BLANK
XERR
H
H
L
H
L
L
L
L
TEF: THERMAL ERROR FLAG
The TLC5940 provides a temperature error flag (TEF) circuit to indicate an overtemperature condition of the IC. If
the junction temperature exceeds the threshold temperature (160°C typical), TEF becomes H and XERR pin
goes to low level. When the junction temperature becomes lower than the threshold temperature, TEF becomes
L and XERR pin becomes high impedance. TEF status can also be read out from the TLC5940 status register.
Copyright © 2010, Texas Instruments Incorporated
Product Folder Link(s): TLC5940-EP
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