TLE4675 Datasheet, PDF (17/25 Pages) Infineon Technologies AG – Low Drop Out Linear Voltage Regulator 5V Fixed Output Voltage

TLE4675
Reset Function
Reset Reaction Time
In case the output voltage of the regulator drops below the output undervoltage lower reset threshold V_RT,lo, the
delay capacitor CD is discharged rapidly. Once the delay capacitor’s voltage has reached the lower delay
switching threshold V_DST,lo, the reset output RO will be set to “low”.
Additionally to the delay capacitor discharge time t_rr,d an internal time t_rr,int applies. Hence the total reset reaction
time t_rr,total becomes:
t_rr,total = t_rr,int + t_rr,d
with
• t_rr,total: total reset reaction time
• t_rr,int: Internal reset reaction time; see Item 7.2.16
• t_rr,d: Delay capacitor discharge time. For a capacitor C_D different from the value specified in Item 7.2.17, see
typical performance graphs.
Reset Output Pull-Up Resistor R_RO:
The Reset Output RO is an open collector output requiring an external pull-up resistor to a voltage V_IO, e.g. V_Q. In
Item 7.2.7 a minimum value for the external resistor R_RO is given for the case it is connected to V_Q.
For applications, where the external pull-up resistor R_RO has to be connected to a different voltage rail V_IO than
V_Q, the minimum pull-up resistor R_RO can be calculated out of the minimum sink current capability given in
Item 7.2.6:
:
R_RO = ^V-----I--^O-I--_R-^–--_O---V-_,--_m-^R---_aO--_x--^,-^l-^o--^w--
with
• R_RO: Reset pull up resistor
• V_IO: Voltage rail, where the pull up resistor is connected
• V_RO,low: Maximum allowed voltage level for a logic “Low” signal inside the application
Please be aware, that V_IO should not exceed the ratings for the RO pin given in Item 4.1.3.
Reset Output “RO” Low for V_Q ≥ 1 V
In case of an undervoltage reset condition reset output “RO” is held “low” for V_Q ≥ 1 V, even if the input voltage V_I
is 0 V. This is achieved by supplying the reset circuit from the output capacitor.
Data Sheet
17
Rev. 1.0, 2008-09-30