STM32F105xx, STM32F107xx
Figure 22. I/O AC characteristics definition
Electrical characteristics
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
5.3.14
NRST pin characteristics
The NRST pin input driver uses CMOS technology. It is connected to a permanent pull-up
resistor, R (see Table 36).
PU
Unless otherwise specified, the parameters given in Table 39 are derived from tests
performed under the ambient temperature and V supply voltage conditions summarized
DD
in Table 9.
Table 39. 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
kΩ
ns
ns
(1)
VF(NRST)
NRST Input filtered pulse
100
(1)
VNF(NRST)
NRST Input not filtered pulse
VDD > 2.7 V
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).
Doc ID 15274 Rev 6
61/104
STMICROELECTRONICS [ ST ]
