TLC5930PWPR Datasheet, PDF (28/40 Pages) Texas Instruments – 12-CHANNEL LED DRIVER

TLC5930
SLLS528 – MARCH 2002
PRINCIPLES OF OPERATION
failure monitor information read
Using this packet, information is ORed when all outputs for OVM detection results, error flags for HEF, GEF,
TEF, and AWC flag can be read out. For individual IDs, each flag is information for each device, and for common
IDs, the information is ORed for devices connected in series. Although defective devices cannot be detected,
problems can be detected only by sending this packet periodically. Data other than AWC sent from controller
should be 0 as a dummy except ID and CMD. When the failure monitor information is 0, the input data (except
AWC) passes through. OVMFA and TEF are sent when this packet is sent. However, HEF and GEF are sent
when the HSYNC packet before this packet has been sent.
Table 13. Packet Configuration (24-bit)
ID (Bin) CMD (Bin)
xxxxxxxx 01100000
MSB
RESERVED
DATA
LSB
OVMFA HEF GEF TEF AWC
(xx6000h.PACKET SENT FROM CONTROLLER)
UDG–02041
The default value for all the information is 1, so, note that 1 may be read out until normal lighting-ON starts after
the reset packet is sent.
OVMFA
The information ORed with detection results for all constant-current output in OVM function appears in this flag.
Although defective constant-current output cannot be identified by reading this flag, the OVM function detects
output errors.
HEF function (HSYNC Error Flag)
This function is to set 0 to HEF flag if the input number of gray-scale clock per 1 HSYNC cycle is more than 1024,
and 1 if less than 1025, at the time when the next HSYNC packet is sent. For example, when, despite the normal
gray-scale clock, the sending period of the HSYNC packet is shortened for any reason and the number of
gray-scale clock in 1 HSYNC cycle is less than 1025, that is, when the HSYNC packet is entered with the number
of gray-scale clock than 1025, HEF is set to 1. In other words, by using this function, one can know failure in
the HSYNC cycle. This function is assumed to use the TLC5930 for 1024 gray scale, and if use it less than 1025
such as 256 gray scale, this flag should be neglected even though it is always set to 1.
Regarding the number of the gray-scale clock needed for lighting-ON, a gray-scale clock total of 1025,
equivalent to 1024 plus 1, is needed to complete lighting on with 1024 gray-scale clock, since lighting on starts
with second rising edge of gray-scale clock after LSB input of the HSYNC packet.
GEF function (GCLK Error Flag)
This function is to set 0 to GEF flag if the number of gray-scale clock meet the requied number of gray-scale
per 1 HSYNC cycle, and 1 if not, at the time when the next HSYNC packet is sent. For example, when the
gray-scale data for given constant-current output is 100, and the gray-scale clock is entered between 2 and 100
for each HSYNC cycle, the correcponding constant-current output remains in an on–state until the next HSYNC
packet is sent. When the clock is less than 2, the output is not turned on. In this case, if lighting-ON for the number
of gray-scale clock is not done, GEF is set to 1 assumed as failure. In other words, by using this function, one
can know whether the gray scale clock is normally sent or 1 HSYNC cycle meet the lighting-ON time desired.
Notes that this flag is set to 1 independent of the status of the gray-scale clock during one HSYNC cycle after
all outputs are forced on.
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