SPC582BX datasheet(42/115 Pages) STMICROELECTRONICS

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Electrical characteristics

SPC582Bx

42/115

DS11597 Rev 4

4.11.2

RC oscillator 16 MHz

VHYS

Comparator Hysteresis

TJ = –40 °C to 150 °C

0.1

1.0

IXTAL

XTAL current(8),(9)

TJ = –40 °C to 150 °C

—

1. The range is selectable by UTEST miscellaneous DCF client XOSC_FREQ_SEL.

2. The XTAL frequency, if used to feed the PPL0 (or PLL1), shall obey the minimum input frequency limit set for PLL0 (or

PLL1).

3. This value is determined by the crystal manufacturer and board design, and it can potentially be higher than the maximum

provided.

4. Proper PC board layout procedures must be followed to achieve specifications.

5. Crystal recovery time is the time for the oscillator to settle to the correct frequency after adjustment of the integrated load

capacitor value.

6. Applies to an external clock input and not to crystal mode.

7. See crystal manufacturer’s specification for recommended load capacitor (CL) values. The external oscillator requires

external load capacitors when operating from 8 MHz to 16 MHz. Account for on-chip stray capacitance (CS_EXTAL/CS_XTAL)

and PCB capacitance when selecting a load capacitor value. When operating at 20 MHz/40 MHz, the integrated load

capacitor value is selected via S/W to match the crystal manufacturer’s specification, while accounting for on-chip and PCB

capacitance.

8. Amplitude on the EXTAL pin after startup is determined by the ALC block, that is the Automatic Level Control Circuit. The

function of the ALC is to provide high drive current during oscillator startup, but reduce current after oscillation in order to

reduce power, distortion, and RFI, and to avoid over driving the crystal. The operating point of the ALC is dependent on the

crystal value and loading conditions.

9. IXTAL is the oscillator bias current out of the XTAL pin with both EXTAL and XTAL pins grounded. This is the maximum

current during startup of the oscillator.

Table 21. External 40 MHz oscillator electrical specifications (continued)

Symbol

Parameter

Conditions

Value

Unit

Min

Max

Table 22. Internal RC oscillator electrical specifications

Symbol

Parameter

Conditions

Value

Unit

Min

Typ

Max

fTarget

IRC target frequency

—

MHz

δfvar_noT

IRC frequency variation

without temperature

compensation

T < 150 °C

–5

—

δfvar_T

IRC frequency variation

with temperature

compensation

T < 150 °C

–3

—

δfvar_SW

IRC software trimming

accuracy

Trimming

temperature

–0.5

+0.3

0.5

Tstart_noT

T Startup time to reach within

fvar_noT

Factory

trimming

already

applied

——

µs

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