TLC5926 Datasheet, PDF (18/29 Pages) Texas Instruments – 16-CHANNEL CONSTANT-CURRENT LED SINK DRIVERS

TLC5926, TLC5927
SLVS677 – JULY 2008 ....................................................................................................................................................................................................... www.ti.com
Open-Circuit Detection Principle
The LED Open-Circuit Detection compares the effective current level I_OUT with the open load detection threshold
current I_OUT,Th. If I_OUT is below the I_OUT,Th threshold, the TLC5926/TLC5927 detects an open-load condition. This
error status can be read as an error status code in the Special mode. For open-circuit error detection, a channel
must be on.
STATE OF OUTPUT PORT
Off
On
(1) I_OUT,Th = 0.5 × I_OUT,target (typical)
Table 1. Open-Circuit Detection
CONDITION OF
OUTPUT CURRENT
I_OUT = 0 mA
I_OUT < I_OUT,Th ⁽¹⁾
I_OUT ≥ I_OUT,Th ⁽¹⁾
ERROR STATUS CODE
0
0
Channel n error status bit 1
MEANING
Detection not possible
Open circuit
Normal
Short-Circuit Detection Principle (TLC5927 Only)
The LED short-circuit detection compares the effective voltage level V_OUT with the shorted-load detection
threshold voltages V_OUT,TTh and V_OUT,RTh. If V_OUT is above the V_OUT,TTh threshold, the TLC5927 detects an
shorted-load condition. If the V_OUT is below V_OUT,RTh threshold, no error is detected and the error bit is reset. This
error status can be read as an error status code in the Special mode. For short-circuit error detection, a channel
must be on.
STATE OF OUTPUT PORT
Off
On
(1) I_OUT,Th = 0.5 × I_OUT,target (typical)
Table 2. Short-Circuit Detection
CONDITION OF
OUTPUT VOLTAGE
I_OUT = 0 mA
V_OUT < V_OUT,TTh ⁽¹⁾
V_OUT < V_OUT,RTh ⁽¹⁾
ERROR STATUS CODE
0
0
Channel n error status bit 1
MEANING
Detection not possible
Short circuit
Normal
Overtemperature Detection and Shutdown
The TLC5926/TLC5927 is equipped with a global overtemperature sensor and 16 individual, channel-specific
overtemperature sensors.
• When the global sensor reaches the trip temperature, all output channels are shutdown, and the error status
is stored in the internal Error Status register of every channel. After shutdown, the channels automatically
restart after cooling down, if the control signal (output latch) remains on. The stored error status is not reset
after cooling down and can be read out as the error status code in the Special mode.
• When one of the channel-specific sensors reaches trip temperature, only the affected output channel is shut
down, and the error status is stored only in the internal Error Status register of the affected channel. After
shutdown, the channel automatically restarts after cooling down, if the control signal (output latch) remains
on. The stored error status is not reset after cooling down and can be read out as error status code in the
Special mode.
For channel-specific overtemperature error detection, a channel must be on.
The error status code is reset when the TLC5926/TLC5927 returns to Normal mode.
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