Electrical characteristics
Figure 24. I/O AC characteristics definition
STM32F103x8, STM32F103xB
90%
10 %
50%
50%
90%
10%
t
EXTERNAL
OUTPUT
ON 50pF
t
r(IO)out
r(IO)out
T
Maximum frequency is achieved if (t + t ) 2/3)T and if the duty cycle is (45-55%)
r
f
when loaded by 50pF
ai14131
5.3.13
NRST pin characteristics
The NRST pin input driver uses CMOS technology. It is connected to a permanent pull-up
resistor, R (see Table 34).
PU
Unless otherwise specified, the parameters given in Table 37 are derived from tests
performed under the ambient temperature and V supply voltage conditions summarized
DD
in Table 9.
Table 37. NRST pin characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
(1)
VIL(NRST)
NRST Input low level voltage
NRST Input high level voltage
–0.5
2
0.8
V
(1)
VIH(NRST)
Vhys(NRST)
RPU
VDD+0.5
NRST Schmitt trigger voltage
hysteresis
200
40
mV
Weak pull-up equivalent resistor(2)
VIN VSS
30
50
k
ns
ns
(1)
VF(NRST)
NRST Input filtered pulse
100
(1)
VNF(NRST)
NRST Input not filtered pulse
300
1. Guaranteed by design, not tested in production.
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).
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STMICROELECTRONICS [ ST ]
