米6体育平台手机版

SLASEB7D June 2017 – December 2020

PRODUCTION DATA

8.13.3.2 High-Frequency Crystal Oscillator, HFXT

over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted)⁽¹⁾

PARAMETER		TEST CONDITIONS	V_CC	MIN	TYP	MAX	UNIT
I_DVCC.HFXT	HFXT oscillator crystal current HF mode at typical ESR	f_OSC = 4 MHz, HFXTBYPASS = 0, HFXTDRIVE = 0, HFFREQ = 1⁽²⁾, T_A = 25°C, C_L,eff = 18 pF, typical ESR, C_shunt	3.0 V		75		μA
		f_OSC = 8 MHz, HFXTBYPASS = 0, HFXTDRIVE = 1, HFFREQ = 1, T_A = 25°C, C_L,eff = 18 pF, typical ESR, C_shunt			120
		f_OSC = 16 MHz, HFXTBYPASS = 0, HFXTDRIVE = 2, HFFREQ = 2, T_A = 25°C, C_L,eff = 18 pF, typical ESR, C_shunt			190
		f_OSC = 24 MHz HFXTBYPASS = 0, HFXTDRIVE = 3, HFFREQ = 3, T_A = 25°C, C_L,eff = 18 pF, typical ESR, C_shunt			250
f_HFXT	HFXT oscillator crystal frequency, crystal mode	HFXTBYPASS = 0, HFFREQ = 1⁽²⁾ ⁽³⁾		4		8	MHz
		HFXTBYPASS = 0, HFFREQ = 2⁽³⁾		8.01		16
		HFXTBYPASS = 0, HFFREQ = 3⁽³⁾		16.01		24
DC_HFXT	HFXT oscillator duty cycle	Measured at SMCLK, f_HFXT = 16 MHz		40%	50%	60%
f_HFXT,SW	HFXT oscillator logic-level square-wave input frequency, bypass mode	HFXTBYPASS = 1, HFFREQ = 0⁽⁴⁾ ⁽³⁾		0.9		4	MHz
		HFXTBYPASS = 1, HFFREQ = 1⁽⁴⁾ ⁽³⁾		4.01		8
		HFXTBYPASS = 1, HFFREQ = 2⁽⁴⁾ ⁽³⁾		8.01		16
		HFXTBYPASS = 1, HFFREQ = 3⁽⁴⁾ ⁽³⁾		16.01		24
DC_{HFXT, SW}	HFXT oscillator logic-level square-wave input duty cycle	HFXTBYPASS = 1		40%		60%
OA_HFXT	Oscillation allowance for HFXT crystals⁽⁵⁾	HFXTBYPASS = 0, HFXTDRIVE = 0, HFFREQ = 1⁽²⁾, f_HFXT,HF = 4 MHz, C_L,eff = 16 pF			450		Ω
		HFXTBYPASS = 0, HFXTDRIVE = 1, HFFREQ = 1, f_HFXT,HF = 8 MHz, C_L,eff = 16 pF			320
		HFXTBYPASS = 0, HFXTDRIVE = 2, HFFREQ = 2, f_HFXT,HF = 16 MHz, C_L,eff = 16 pF			200
		HFXTBYPASS = 0, HFXTDRIVE = 3, HFFREQ = 3, f_HFXT,HF = 24 MHz, C_L,eff = 16 pF			200
t_START,HFXT	Start-up time⁽⁶⁾	f_OSC = 4 MHz, HFXTBYPASS = 0, HFXTDRIVE = 0, HFFREQ = 1, T_A = 25°C, C_L,eff = 16 pF	3.0 V		1.6		ms
t_START,HFXT	Start-up time⁽⁶⁾	f_OSC = 24 MHz, HFXTBYPASS = 0, HFXTDRIVE = 3, HFFREQ = 3, T_A = 25°C, C_L,eff = 16 pF	3.0 V		0.6		ms
C_HFXIN	Integrated load capacitance at HFXIN terminaI⁽⁷⁾ ⁽⁸⁾				2		pF
C_HFXOUT	Integrated load capacitance at HFXOUT terminaI⁽⁷⁾ ⁽⁸⁾				2		pF
f_Fault,HFXT	Oscillator fault frequency⁽⁹⁾ ⁽¹⁰⁾			0		800	kHz

(1) To improve EMI on the HFXT oscillator the following guidelines should be observed.

Keep the traces between the device and the crystal as short as possible.
Design a good ground plane around the oscillator pins.
Prevent crosstalk from other clock or data lines into oscillator pins HFXIN and HFXOUT.
Avoid running PCB traces underneath or adjacent to the HFXIN and HFXOUT pins.
Use assembly materials and processes that avoid any parasitic load on the oscillator LFXIN and LFXOUT pins.
If conformal coating is used, ensure that it does not induce capacitive or resistive leakage between the oscillator pins.

(2) HFFREQ = {0} is not supported for HFXT crystal mode of operation.

(3) Maximum frequency of operation of the entire device cannot be exceeded.

(4) When HFXTBYPASS is set, HFXT circuits are automatically powered down. Input signal is a digital square wave with parametrics defined in the Schmitt-trigger Inputs section of this datasheet. Duty cycle requirements are defined by DC_{HFXT, SW}.

(5) Oscillation allowance is based on a safety factor of 5 for recommended crystals.

(6) Includes start-up counter of 1024 clock cycles.

(7) This represents all the parasitic capacitance present at the HFXIN and HFXOUT terminals, respectively, including parasitic bond and package capacitance. The effective load capacitance, C_L,eff can be computed as C_IN × C_OUT / (C_IN + C_OUT), where C_IN and C_OUT is the total capacitance at the HFXIN and HFXOUT terminals, respectively.

(8) Requires external capacitors at both terminals to meet the effective load capacitance specified by crystal manufacturers. Recommended effective load capacitance values supported are 14 pF, 16 pF, and 18 pF. Maximum shunt capacitance of 7 pF. The PCB adds additional capacitance, so it must also be considered in the overall capacitance. Verify that the recommended effective load capacitance of the selected crystal is met.

(9) Frequencies above the MAX specification do not set the fault flag. Frequencies between the MIN and MAX specifications might set the flag. A static condition or stuck at fault condition will set the flag.

(10) Measured with logic-level input frequency but also applies to operation with crystals.