Datasheet

Electrical characteristics STM32F103x8, STM32F103xB
68/105 DocID13587 Rev 16
Figure 30. I/O AC characteristics definition
5.3.14 NRST pin characteristics
The NRST pin input driver uses CMOS technology. It is connected to a permanent pull-up
resistor, R
PU
(see Table 35).
Unless otherwise specified, the parameters given in Table 38 are derived from tests
performed under the ambient temperature and V
DD
supply voltage conditions summarized
in Table 9.
ai14131c
10%
90%
50%
t
r(IO)out
OUTPUT
EXTERNAL
ON 50pF
Maximum frequency is achieved if (t
r
+ t
f
) ≤ 2/3)T and if the duty cycle is (45-55%)
10%
50%
90%
when loaded by 50pF
T
t
f(IO)out
Table 38. NRST pin characteristics
Symbol Parameter Conditions Min Typ Max Unit
V
IL(NRST)
(1)
1. Guaranteed by design, not tested in production.
NRST Input low level voltage –0.5 - 0.8
V
V
IH(NRST)
(1)
NRST Input high level voltage 2 - V
DD
+0.5
V
hys(NRST)
NRST Schmitt trigger voltage
hysteresis
- 200 - mV
R
PU
Weak pull-up equivalent resistor
(2)
2. The pull-up is designed with a true resistance in series with a switchable PMOS. This PMOS contribution
to the series resistance must be minimum (~10% order).
V
IN
V
SS
30 40 50 k
V
F(NRST)
(1)
NRST Input filtered pulse - - 100 ns
V
NF(NRST)
(1)
NRST Input not filtered pulse 300 - - ns