TLC5945 Datasheet, PDF (12/29 Pages) Texas Instruments – 16-CHANNEL LED DRIVER WITH DOT CORRECTION AND GRAYSCALE PWM CONTROL

TLC5945
SLVS755 – MARCH 2007
PRINCIPLES OF OPERATION (continued)
MODE
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
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GSb3
MSB
385
1
SIDb2 SIDb2
MSB MSB-1
GSCLK
OUT0
(current)
OUT1
(current)
OUT15
(current)
XERR
1
4096
1
Figure 8. Timing Chart for Two Cascaded TLC5945 Devices
ERROR INFORMATION OUTPUT
The open-drain output XERR is used to report both of the TLC5945 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 V_CC through an external pullup resistor. If TEF or LOD is detected, the internal transistor is turned
on, and XERR is pulled to GND. Because XERR is an open-drain output, multiple ICs can be ORed together
and pulled up to V_CC with a single pullup resistor. This reduces the number of signals needed to report a system
error (see Figure 16).
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
T_J < T_(TEF)
T_J > T_(TEF)
T_J < T_(TEF)
T_J > 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
12
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