TLD1125EL Datasheet, PDF (18/36 Pages) Infineon Technologies AG – 1 Channel High Side Current Source Basic LED Driver

TLD1125EL
7
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 11 Block Diagram IN_SET pin
7.1
Output Current Adjustment via RSET
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
(8)
The gain factor k (R_SET * output current) is specified in Pos. 11.2.4 and Pos. 11.2.5. 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.
7.2
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 12. This signal can be used to turn off the output stage of the IC. A minimum IN_SET current
of I_{IN_SET(act)} is required to turn on the output stage. This feature is implemented to prevent glimming of LEDs
caused by leakage currents on the IN_SET pin, see Figure 15 for details. In addition, the IN_SET pin offers the
diagnostic feedback information, if the status pin is connected to GND. Another diagnostic possibility is shown in
Figure 13, where the diagnosis information is provided via the ST pin (refer to Chapter 8 and Chapter 10) 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. 10.3.2. Therefore, the device has two voltage domains at the IN_SET-pin, which is shown in
Figure 16.
Data Sheet
18
Rev. 1.0, 2013-08-08