TLF80511EJ_15 Datasheet, PDF (15/20 Pages) Infineon Technologies AG – Low Dropout Linear Fixed Voltage Regulator

6
Application Information
6.1
Application Diagram
TLF80511EJ
Application Information
Supply
DI1
D I2
<45 V
CI2
10µF
CI1
100nF
I
Current
Limitation
Temperature
Shutdown
GND
Bandgap
Reference
Q ^{Regulated Output Voltage}
Load
e. g.
Micro
Controller
CQ
XC22xx
1µF
(ESR<5 Ω)
GND
Figure 4 Application Diagram
6.2
Selection of External Components
6.2.1 Input Pin
The typical input circuitry for a linear voltage regulator is shown in the application diagram above.
A ceramic capacitor at the input, in the range of 100nF to 470nF, is recommended to filter out the high frequency
disturbances imposed by the line e.g. ISO pulses 3a/b. This capacitor must be placed very close to the input pin
of the linear voltage regulator on the PCB.
An aluminum electrolytic capacitor in the range of 10µF to 470µF is recommended as an input buffer to smooth
out high energy pulses, such as ISO pulse 2a. This capacitor should be placed close to the input pin of the linear
voltage regulator on the PCB.
An overvoltage suppressor diode can be used to further suppress any high voltage beyond the maximum rating
of the linear voltage regulator and protect the device against any damage due to over-voltage above 45 V.
The external components at the input are not mandatory for the operation of the voltage regulator, but they are
recommended in order to protect the voltage regulator against external disturbances and damages.
6.2.2 Output Pin
An output capacitor is mandatory for the stability of linear voltage regulators.
The requirement to the output capacitor is given in “Functional Range” on Page 7. The graph “Stability Region:
Equivalent Serial Resistor ESR versus Output Current I_Q (TLF80511EJV50)” on Page 11 shows the stable
operation range of the device.
TLF80511EJ is designed to be stable with extremely low ESR capacitors. According to the automotive
requirements, ceramic capacitors with X5R or X7R dielectrics are recommended.
The output capacitor should be placed as close as possible to the regulator’s output and GND pins and on the
same side of the PCB as the regulator itself.
Data Sheet
15
Rev. 1.0, 2014-11-17