STM32U385CG datasheet(129/224 Pages) STMICROELECTRONICS

129 / 224 page

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 the output distortion and startup stabilization time. Refer to the crystal resonator

manufacturer for more details on the resonator characteristics (frequency, package, accuracy).

Table 73. HSE oscillator characteristics

Specified by design and not tested in production.

Symbol

Parameter

Conditions(1)

Min

Typ

Max

Unit

fOSC_IN

Oscillator frequency

MHz

Feedback resistor

200

kΩ

IDD(HSE)

HSE current consumption

During startup(2)

μA

VDD = 3 V, Rm = 30 Ω, CL = 10 pF @ 4 MHz

790

VDD = 3 V, Rm = 30 Ω, CL = 10 pF @ 8 MHz

910

VDD = 3 V, Rm = 45 Ω, CL = 10 pF @ 8 MHz

930

VDD = 3 V, Rm = 30 Ω, CL = 5 pF @ 48 MHz

1430

VDD = 3 V, Rm = 30 Ω, CL = 10 pF @ 48 MHz

1960

VDD = 3 V, Rm = 30 Ω, CL = 20 pF @ 48 MHz

3000

Gmcritmax Maximum critical crystal transconductance Gm

Startup

1.5

mA/V

tsu(HSE)(3) Startup time

VDD stabilized

1. Resonator characteristics given by the crystal/ceramic resonator manufacturer.

2. This consumption level occurs during the first 2/3 of the tSU(HSE) startup time.

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

measured for a standard crystal resonator and it can vary significantly with the crystal manufacturer.

Note:

For information on selecting the crystal, refer to the application note 'Oscillator design guide for STM8AF/AL/S,

STM32 MCUs and MPUs' (AN2867).

Figure 32. Typical application with a 8 MHz crystal

(1)

OSC_IN

OSC_OUT

Bias

controlled

gain

fHSE

REXT

8 MHz

resonator

Resonator with integrated

capacitors

CL1

CL2

(1): REXT value depends on the crystal characteristics.

STM32U385xx

Electrical characteristics

DS14830 - Rev 2

page 129/224

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