STM32F401XB Datasheet, PDF (74/135 Pages) STMicroelectronics – ARM Cortex-M4 32b MCU+FPU, 105 DMIPS, 256KB Flash/64KB RAM, 11 TIMs, 1 ADC, 11 comm. interfaces

STM32F401xB STM32F401xC
Electrical characteristics
6.3.8
External clock source characteristics
High-speed external user clock generated from an external source
In bypass mode the HSE oscillator is switched off and the input pin is a standard I/O. The
external clock signal has to respect the Table 54. However, the recommended clock input
waveform is shown in Figure 22.
The characteristics given in Table 35 result from tests performed using an high-speed
external clock source, and under ambient temperature and supply voltage conditions
summarized in Table 14.
Table 35. High-speed external user clock characteristics
Symbol
Parameter
Conditions
Min Typ Max Unit
f_{HSE_ext}
External user clock source
frequency⁽¹⁾
1
-
50 MHz
V_HSEH
V_HSEL
OSC_IN input pin high level voltage
OSC_IN input pin low level voltage
0.7V_DD -
V_DD
V
V_SS
- 0.3V_DD
t_w(HSE)
t_w(HSE)
t_r(HSE)
t_f(HSE)
C_in(HSE)
OSC_IN high or low time⁽¹⁾
OSC_IN rise or fall time⁽¹⁾
OSC_IN input capacitance⁽¹⁾
5
-
-
ns
-
-
10
-
5
-
pF
DuCy_(HSE) Duty cycle
45
-
55
%
I_L
OSC_IN Input leakage current
V_SS ≤V_IN ≤V_DD
-
-
±1 µA
1. Guaranteed by design.
Low-speed external user clock generated from an external source
In bypass mode the LSE oscillator is switched off and the input pin is a standard I/O. The
external clock signal has to respect the Table 54. However, the recommended clock input
waveform is shown in Figure 23.
The characteristics given in Table 36 result from tests performed using an low-speed
external clock source, and under ambient temperature and supply voltage conditions
summarized in Table 14.
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