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TEF: THERMAL ERROR FLAG

LOD: LED OPEN DETECTION

DELAY BETWEEN OUTPUTS

OUTPUT ENABLE

SETTING MAXIMUM CHANNEL CURRENT

Imax +

V

(IREF)

R

(IREF)

31.5

(1)

TLC5941

SLVS589 – JULY 2005

The TLC5941 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), the TEF circuit trips and pulls XERR

to ground. TEF status can also be read out from the TLC5941 status register.

The TLC5941 provides an LED open-detection circuit (LOD). This circuit reports an error if any one of the 16

LEDs is open or disconnected from the circuit. The LOD circuit trips when the following two conditions are met

simultaneously:

1. BLANK is set to LOW

1

µs after being turned on.)

The LOD circuit also pulls XERR to GND when tripped. The LOD status of each channel can also be read out

from the TLC5941 status information data (SID) in GS data input cycle.

The TLC5941 has graduated delay circuits between outputs. These circuits can be found in the constant-current

driver block of the device (see functional block diagram). The fixed-delay time is 20 ns (typical), OUT0 has no

delay, OUT1 has 20 ns delay, and OUT2 has 40 ns delay, etc. The maximum delay is 300 ns from OUT0 to

OUT15. The delay works by switch on and switch off of each output channel. This means that the on/off time of

each channel is the same regardless of delay. These delays prevent large inrush currents and switching noise

which reduces the bypass capacitors when the outputs turn on.

All OUTn channels of TLC5941 can be switched off with one signal. When BLANK is set to high, all OUTn

channels are disabled, regardless of logic operations of the device. The grayscale counter is also reset. When

BLANK is set to low, all OUTn channels work under normal conditions.

Table 2. BLANK Signal Truth Table

BLANK

OUT0 - OUT15

LOW

Normal condition

HIGH

Disabled

where:

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