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CD00253742 Datasheet, PDF (89/120 Pages) STMicroelectronics – XL-density performance line ARM-based 32-bit MCU
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STM32F103xF, STM32F103xG
Electrical characteristics
5.3.15
Figure 44. I/O AC characteristics definition
90%
50%
10%
10%
50%
90%
EXT ERNAL
O UTP UT
ON 50pF
tr(I O)out
tr(I O)out
T
Maximum fr equency is achieved if (tr + tf) £ 2/3) T and if the duty cycle is (45-55%)
when loaded by 50pF
ai14131
NRST pin characteristics
The NRST pin input driver uses CMOS technology. It is connected to a permanent pull-up
resistor, RPU (see Table 49).
Unless otherwise specified, the parameters given in Table 52 are derived from tests
performed under ambient temperature and VDD supply voltage conditions summarized in
Table 10.
Table 52. NRST pin characteristics
Symbol
Parameter
Conditions Min Typ Max Unit
VIL(NRST)(1) NRST Input low level voltage
VIH(NRST)(1) NRST Input high level voltage
–0.5
2
-
0.8
V
- VDD+0.5
Vhys(NRST)
NRST Schmitt trigger voltage
hysteresis
- 200
-
mV
RPU
Weak pull-up equivalent resistor(2)
VF(NRST)(1) NRST Input filtered pulse
VNF(NRST)(1) NRST Input not filtered pulse
VIN = VSS
30 40
-
-
300 -
50
kΩ
100 ns
-
ns
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)
Figure 45. Recommended NRST pin protection
External
reset circuit(1)
VDD
NRST(2)
RPU
0.1 µF
Internal Reset
Filter
STM32F10xxx
ai14132d
1. The reset network protects the device against parasitic resets.
2. The user must ensure that the level on the NRST pin can go below the VIL(NRST) max level specified in
Table 52. Otherwise the reset will not be taken into account by the device.
Doc ID 16554 Rev 3
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