TLF80511EJ_15 Datasheet, PDF (8/20 Pages) Infineon Technologies AG – Low Dropout Linear Fixed Voltage Regulator

TLF80511EJ
Block Description and Electrical Characteristics
5
Block Description and Electrical Characteristics
5.1
Voltage Regulation
The output voltage V_Q is divided by a resistor network. This fractional voltage is compared to an internal voltage
reference and drives the pass transistor accordingly.
The control loop stability depends on the output capacitor C_Q, the load current, the chip temperature and the
internal circuit design. To ensure stable operation, the output capacitor’s capacitance and its equivalent series
resistor ESR requirements given in Table 2 “Functional Range” on Page 7 must be maintained. For details see
the typical performance graph “Stability Region: Equivalent Serial Resistor ESR versus Output Current I_Q
(TLF80511EJV50)” on Page 11. Since the output capacitor is used to buffer load steps, it should be sized
according to the application’s needs.
An input capacitor C_I is not required for stability, but is recommended to compensate line fluctuations. An
additional reverse polarity protection diode and a combination of several capacitors for filtering should be used.
Connect the capacitors close to the regulator terminals.
Whenever the load current exceeds the specified limit, e.g. in case of a short circuit, the output current is limited
and the output voltage decreases.
The overtemperature shutdown circuit prevents the IC from immediate destruction under fault conditions (e.g.
output continuously short-circuited) by switching off the power stage. After the chip has cooled, the regulator
restarts. This oscillatory thermal behaviour causes the junction temperature to exceed the 150° C maximum and
significantly reducing the IC’s life.
Supply
I_I
I
Current
Limitation
CI
VI
ApplicationDiagram.vsd
Temperature
Shutdown
Regulated
Q
I_Q
Output Voltage
Bandgap
Reference
GND
C
ESR
VQ
CQ
LOAD
Figure 3 Block Diagram Voltage Regulation
Data Sheet
8
Rev. 1.0, 2014-11-17