TLD1314EL_15 Datasheet, PDF (13/29 Pages) Marl International Limited – Basic LED Driver

TLD1314EL
6
IN_SET Pin
The IN_SET pin is a multiple function pin for output current definition, input and diagnostics:
IN_SET Pin
Logic
IN_SET
IIN_SET
high impedance
VIN_SET
VIN_SET(OL /SC)
GND
Figure 6 Block Diagram IN_SET pin
6.1
Output Current Adjustment via RSET
The output current for all three channels can only be adjusted simultaneously. The current adjustment can be done
by placing a low power resistor (R_SET) at the IN_SET pin to ground. The dimensioning of the resistor can be done
using the formula below:
R_SET
=
-----^k------
I_OUT
(2)
The gain factor k (R_SET * output current) is specified in Pos. 9.2.4 and Pos. 9.2.5. The current through the R_SET is
defined by the resistor itself and the reference voltage V_{IN_SET(ref)}, which is applied to the IN_SET during supplied
device.
6.2
Smart Input Pin
The IN_SET pin can be connected via R_SET to the open-drain output of a µC or to an external NMOS transistor as
described in Figure 7 This signal can be used to turn off the output stages of the IC. A minimum IN_SET current
of I_{IN_SET(act)} is required to turn on the output stages. This feature is implemented to prevent glimming of LEDs
caused by leakage currents on the IN_SET pin, see Figure 10 for details. In addition, the IN_SET pin offers the
diagnostic feedback information, if the status pin is connected to GND and V_DEN > V_DEN(act) (refer to Chapter 5).
Another diagnostic possibility is shown in Figure 8, where the diagnosis information is provided via the ST pin
(refer to Chapter 7 and Chapter 8) to a micro controller In case of a fault event with the ST pin connected to GND
the IN_SET voltage is increased to V_{IN_SET(OL/SC)} Pos. 8.3.2. Therefore, the device has two voltage domains at the
IN_SET-pin, which is shown in Figure 11.
Data Sheet
13
Rev. 1.1, 2015-03-24