STM32WL55JC datasheet(99/147 Pages) STMICROELECTRONICS

99 / 147 page

DS13293 Rev 2

99/147

STM32WL55/54xx

Electrical characteristics

137

5.3.9

External clock source characteristics

High-speed external user clock generated from an external source

The high-speed external (HSE32) clock can be supplied with a 32 MHz crystal oscillator or

by a TCXO (temperature controlled crystal oscillator).

Crystal oscillator

The devices include internal programmable capacitances that can be used to tune the

crystal frequency in order to compensate the PCB parasitic one.

Characteristics in the tables below, are measured over recommended operating conditions,

unless otherwise specified. Typical values are referred to TA = 25 °C and VDD = 3 V.

Table 58. Regulator modes transition times(1)

Symbol

Parameter

Conditions

Typ

Max

Unit

tWULPRUN

Transition time from LPRun to Run

mode(2)

Code run with MSI = 2 MHz

19.6

µs

tVOST

Regulator transition time from Range 2 to

Range 1(3)

Code run with HSI16

21.9

32.2

Regulator transition time from Range 1 to

Range 2(3)

23.1

33.9

1. Guaranteed by characterization results (VDD = 3 V, T = 25 °C).

2. Time until REGLPF flag is cleared in PWR_SR2.

3. Time until VOSF flag is cleared in PWR_SR2.

Table 59. HSE32 crystal requirements(1)

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

fnom

Oscillator frequency

MHz

fTOL

Frequency accuracy(2)

Initial(3)

±10

ppm

Over temperature(4)

±30

Aging over 10 years

±10

CLoad

Load capacitance(5)

-9.5

10.5

CShunt

Crystal shunt capacitance

0.3

0.6

Cmotion Crystal motional capacitance

1.3

1.89

2.5

ESR

Crystal equivalent series

resistance

Ω

Drive level

100

µW

Oscillator transconductance

Startup

11.3

mA/V

1. 32 MHz XTAL is specified for two specific references: NX2016SA and NX1612SA.

2. Crystal frequency accuracy can also be further restricted by the protocols support by the application.

3. Initial accuracy can be compensated by initial calibration. See the application note AN5646.

4. Frequency over temperature can be partially compensated by firmware.

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