Oscillators and Clocks

Operating conditions:

V_DD = 3V, unless otherwise specified
Oscillator frequencies above speed specification must be divided so the CPU clock is always within specification.

Table 1. 20 MHz Internal Oscillator (OSC20M) Characteristics
Symbol	Description	Condition		Min.	Typ.	Max.	Unit
f_OSC20M	Factory calibration frequency	FREQSEL = `0x01`	T_A = 25°C, 3.0V		16		MHz
f_OSC20M	Factory calibration frequency	FREQSEL = `0x02`	T_A = 25°C, 3.0V		20		MHz
f_CAL	Frequency calibration range	OSC20M FREQSEL = `0x01`		14.5		17.5	MHz
f_CAL	Frequency calibration range	OSC20M FREQSEL = `0x02`		18.5		21.5	MHz
E_TOTAL	Total error with 16 MHz and 20 MHz frequency selection	From target frequency	T_A = 25°C, 3.0V	-1.5		1.5	%
			T_A = [0, 70]°C, V_DD = [1.8, 3.6]V	-2.0		2.0	%
			Full operation range	-4.0		4.0	%
E_DRIFT	Accuracy with 16 MHz and 20 MHz frequency selection relative to the factory-stored frequency value	Factory calibrated V_DD = 3V⁽¹⁾	T_A = [0, 70]°C, V_DD = [1.8, 5.5]V	-1.8		1.8	%
Δf_OSC20M	Calibration step size			-	0.75	-	%
D_OSC20M	Duty cycle			-	50	-	%
t_startup	Start-up time	Within 2% accuracy		-	12	-	µs

Note:

1.See also the description of OSC20M on calibration.

Table 2. 32.768 kHz Internal Oscillator (OSCULP32K) Characteristics
Symbol	Description	Condition	Min.	Typ.	Max.	Unit
f_OSCULP32K	Factory calibration frequency			32.768		kHz
	Factory calibration accuracy	T_A = 25°C, 3.0V	-3		3	%
E_TOTAL	Total error from target frequency	T_A = [0, 70]°C, V_DD = [1.8, 3.6]V	-10		+10	%
E_TOTAL	Total error from target frequency	Full operation range	-20		+20	%
D_OSCULP32K	Duty cycle			50		%
t_startup	Start-up time		-	250	-	µs

Table 3. 32.768 kHz External Crystal Oscillator (XOSC32K) Characteristics
Symbol	Description	Condition	Min.	Typ.	Max.	Unit
f_out	Frequency		-	32.768	-	kHz
t_startup	Start-up time	C_L = 7.5 pF	-	300	-	ms
C_L	Crystal load capacitance		7.5⁽¹⁾	-	12.5⁽¹⁾	pF
ESR	Equivalent Series Resistance - Safety Factor=3	C_L = 7.5 pF	-	-	80⁽¹⁾	kΩ
ESR	Equivalent Series Resistance - Safety Factor=3	C_L = 12.5 pF	-	-	40⁽¹⁾	kΩ

Note:

1.This parameter is for design guidance only. Not production tested.

Figure 1. External Clock Waveform Characteristics

Table 4. External Clock Characteristics
Symbol	Description	Condition	V_DD=[1.8, 5.5]V		V_DD=[2.7, 5.5]V		V_DD=[4.5, 5.5]V		Unit
Symbol	Description	Condition	Min.	Max.	Min.	Max.	Min.	Max.	Unit
f_CLCL	Frequency		0	5.0	0.0	10.0	0.0	20.0	MHz
t_CLCL	Clock Period		200	-	100	-	50	-	ns
t_CHCX⁽¹⁾	High Time		80	-	40	-	20	-	ns
t_CLCX⁽¹⁾	Low Time		80	-	40	-	20	-	ns
t_CLCH⁽¹⁾	Rise Time (for maximum frequency)		-	40	-	20	-	10	ns
t_CHCL⁽¹⁾	Fall Time (for maximum frequency)		-	40	-	20	-	10	ns
Δt_CLCL⁽¹⁾	Change in period from one clock cycle to the next		-	20	-	20	-	20	%

Note:

1.This parameter is for design guidance only. Not production tested.