STM32F722IC datasheet(133/229 Pages) STMICROELECTRONICS

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DS11853 Rev 6

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STM32F722xx STM32F723xx

Electrical characteristics

201

Figure 38. Low-speed external clock source AC timing diagram

High-speed external clock generated from a crystal/ceramic resonator

The high-speed external (HSE) clock can be supplied with a 4 to 26 MHz crystal/ceramic

resonator oscillator. All the information given in this paragraph are based on

characterization results obtained with typical external components specified in Table 40. In

the application, the resonator and the load capacitors have to be placed as close as

possible to the oscillator pins in order to minimize output distortion and startup stabilization

time. Refer to the crystal resonator manufacturer for more details on the resonator

characteristics (frequency, package, accuracy).

Table 40. HSE 4-26 MHz oscillator characteristics(1)

1. Guaranteed by design.

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

fOSC_IN

Oscillator frequency

MHz

Feedback resistor

200

IDD

HSE current consumption

VDD=3.3 V,

ESR= 30 Ω,

CL=5 pF@25 MHz

450

µA

VDD=3.3 V,

ESR= 30 Ω,

CL=10 pF@25 MHz

530

ACCHSE(2)

2. This parameter depends on the crystal used in the application. The minimum and maximum values must

be respected to comply with USB standard specifications.

HSE accuracy

− 500

500

ppm

Gm_crit_max Maximum critical crystal gm

Startup

mA/V

tSU(HSE(3)

3. tSU(HSE) is the startup time measured from the moment it is enabled (by software) to a stabilized 8 MHz

oscillation is reached. This value is based on characterization results. It is measured for a standard crystal

resonator and it can vary significantly with the crystal manufacturer.

Startup time

VDD is stabilized

ai17529

OSC32_IN

External

STM32F

clock source

VLSEH

tf(LSE)

tW(LSE)

90%

10 %

TLSE

tr(LSE)

tW(LSE)

fLSE_ext

VLSEL

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