Pin descriptions STM6522
10/25 Doc ID 17045 Rev 3
2.5 Adjustable delay of Smart Reset™ (SRC pin)
This pin controls the setup time before the push-button action is validated by the reset
output. It is connected to an external capacitor (C
SRC
), which is tied to ground to provide the
desired value of setup time (t
SRC
).
Selected calculated t
SRC
and C
SRC
examples are given in Ta bl e 2 . Refer also to Table 5.
2.6 Reset output (RST1)
This output is active-low, open-drain with no internal pull-up resistor.
2.7 Reset output (RST2)
This output is active-low, open-drain with no internal pull-up resistor.
Table 2. t
SRC
programmed by an ideal external capacitor
Calculated C
SRC
value [µF]
Setup delay t
SRC
[s]
(1)(2)
1. At 25 ° C. Example calculations based on an ideal capacitor. During application design and component
selection it should be considered that the current flowing into the external t
SRC
programming capacitor
(C
SRC
) is on the order of 100 nA, therefore a low-leakage capacitor (ceramic or film capacitor) should be
used and placed as close as possible to the SRC pin. Also an adequate low-leakage PCB environment
should be ensured to prevent t
SRC
accuracy from being affected. A recommended minimum value of C
SRC
is 0.1 µF.
2. In case of quickly repeated activations of t
SRC
counter, an interval of 10 ms min. is needed between the
activations to fully discharge C
SRC
, so that the next t
SRC
is as specified.
Closest common
C
SRC
value [µF]
Min. Typ. Max.
0.2 2 2.5 3.0 0.22
0.3 3 3.75 4.5 0.33
0.6 6 7.5 9 0.56
1 10 12.5 15 1
