TLD1311EL_15 Datasheet, PDF (27/33 Pages) Infineon Technologies AG – 3 Channel High Side Current Source

TLD1311EL
Power Stage
10
Power Stage
The output stages are realized as high side current sources with a current of 120 mA. During off state the leakage
current at the output stage is minimized in order to prevent a slightly glowing LED.
The maximum current of each channel is limited by the power dissipation and used PCB cooling areas (which
results in the applications R_thJA).
For an operating current control loop the supply and output voltages according to the following parameters have
to be considered:
• Required supply voltage for current control V_S(CC), Pos. 6.1.10
• Voltage drop over output stage during current control V_PS(CC), Pos. 10.2.6
• Required output voltage for current control V_OUTx(CC), Pos. 10.2.7
10.1
Protection
The device provides embedded protective functions, which are designed to prevent IC destruction under fault
conditions described in this data sheet. Fault conditions are considered as “outside” normal operating range.
Protective functions are neither designed for continuous nor for repetitive operation.
10.1.1 Over Load Behavior
An over load detection circuit is integrated in the LITIX^TM Basic IC. It is realized by a temperature monitoring of the
output stages (OUTx).
As soon as the junction temperature exceeds the current reduction temperature threshold T_j(CRT) the output current
will be reduced by the device by reducing the IN_SET reference voltage V_{IN_SET(ref)}. This feature avoids LED’s
flickering during static output overload conditions. Furthermore, it protects LEDs against over temperature, which
are mounted thermally close to the device. If the device temperature still increases, the three output currents
decrease close to 0 A. As soon as the device cools down the output currents rise again.
IOU T
VIN_ SET
T_{j (CR T)}
T_j
Figure 20 Output current reduction at high temperature
Note: This high temperature output current reduction is realized by reducing the IN_SET reference voltage voltage
(Pos. 9.3.1). In case of very high power loss applied to the device and very high junction temperature the
output current may drop down to I_OUTx = 0 mA, after a slight cooling down the current increases again.
10.1.2 Reverse Battery Protection
The TLD1311EL has an integrated reverse battery protection feature. This feature protects the driver IC itself, but
also connected LEDs. The output reverse current is limited to I_OUTx(rev) by the reverse battery protection.
Data Sheet
27
Rev. 1.1, 2015-03-19