tle42754 Infineon Technologies Corporation, tle42754 Datasheet - Page 15

• Manufacturer Part Number: tle42754
• Description: Low Dropout Linear Fixed Voltage Regulator
• Manufacturer: Infineon Technologies Corporation

5.3
The reset function provides several features:
Output Undervoltage Reset:
An output undervoltage condition is indicated by setting the Reset Output RO to “low”. This signal might be used
to reset a microcontroller during low supply voltage.
Power-On Reset Delay Time:
The power-on reset delay time
from exceeding the reset switching threshold
“low” to “high”. The power-on reset delay time
charged by the delay capacitor charge current
If the application needs a power-on reset delay time
capacitor’s value can be derived from the specified values in
with
•
•
•
For a precise calculation also take the delay capacitor’s tolerance into consideration.
Reset Reaction Time:
The reset reaction time avoids that short undervoltage spikes trigger an unwanted reset “low” signal. The reset
reaction rime
capacitor
with
•
•
•
Reset Output Pull-Up Resistor
The Reset Output RO is an open collector output requiring an external pull-up resistor to a voltage
Table “Electrical Characteristics Reset Function” on Page 18
is given for the case it is connected to
voltage
Data Sheet
C
t
t
t
t
t
rd,new
rr
rr,int
rd
rr,d
D
: reset reaction time
: power-on reset delay time specified in this datasheet
: capacitance of the delay capacitor to be chosen
: reset discharge
: internal reset reaction time
V
: desired power-on reset delay time
IO
R
C
C
t
RO
D
D
rr
>
Reset Function
(see typical performance graph for details). Hence, the total reset reaction time becomes:
=
t
V
=
=
rr
Q
t
----------------
t
rd new
considers the internal reaction time
, use the following formula:
5kΩ
---------- -
rd int
V
t
,
rd
,
Q
×
+
×
V
t
47nF
rr d ,
IO
t
rd
allows a microcontoller and oscillator to start up. This delay time is the time frame
R
RO
:
V
Q
or to a voltage
V
RT
t
I
rd
D,ch
until the reset is released by switching the reset output “RO” from
is defined by an external delay capacitor
starting from
t
rr,int
t
15
rd
and the discharge time
different from the value given in
V
IO
Block Description and Electrical Characteristics
Item 5.3.6
<
V
V
Q
D
. If the pull-up resistor shall be connected to a
a minimum value for the external resistor
= 0 V.
and the desired power-on delay time:
t
rr,d
defined by the external delay
C
Rev. 1.0, 2008-05-29
Item
D
connected to pin D
5.3.6, the delay
V
IO
TLE42754
, e.g.
V
Q
R
. In
RO