TLE4284_07 Datasheet, PDF (21/25 Pages) Infineon Technologies AG – Voltage Regulator

TLE 4284
Application Hints
Adjustable Version
At the fixed voltage TLE 4284 devices, the output voltage is divided internally and
compared to an internal reference of 1.25 V typical. The regulation loop controls the
output voltage to achieve the output voltage of 5 V, 3.3 V, 2.6 V, 1.8V or 1.5V. The
variable version compares the voltage difference between the adjust pin ADJ and the
output pin Q to the internal reference of typically 1.25 V. The output voltage is adjusted
by an external voltage divider between Q, ADJ and GND and calculates:
V_Q = V_REF × _1 + ^RR----²¹-_ + I_ADJ × R₂
For the variable regulator TLE 4284 DV, a minimum load current of 5 mA is necessary
in order to keep the output voltage regulated. If the application does not assure this
minimum load requirement, the output voltage divider should be dimensioned sufficiently
low-ohmic: R₁ ≤ 240 Ω.
For the variable voltage type an additional decoupling a capacitor C_ADJ at the adjust pin
improves the ripple rejection ratios. Placing C_ADJ requires an increased output
capacitance of C_Q ≥ 22 µF.
Output
The output current limitation is reduced as a function of the input voltage for high input
voltages above 25 V.
The TLE 4284 requires a 10 µF output capacitor with 0.1 Ω ≤ ESR ≤ 10 Ω for the stability
of the regulation loop.
At the input of the regulator a capacitor is necessary for compensation of line influences.
A serial diode should be used to eliminate negative voltages from the input. As a
minimum, a 100 nF ceramic input capacitor should be used. If the regulator is used in an
environment with long input lines, an input capacitance of 10 µF is recommended.
Data Sheet
21
Rev. 2.1, 2007-03-20