43.19 Sigma-Delta Analog-to-Digital Converter (SDADC) Electrical Specifications

Table 43-26. SDADC Electrical Specifications
AC CHARACTERISTICS			Standard Operating Conditions: VDD and VDDIO 2.7V to 5.5V (unless otherwise stated) Operating temperature: -40°C ≤ TA ≤ +85°C for Industrial
Param. No.	Symbol	Characteristics	Min.	Typical	Max.	Units	Conditions
Device Supply
SDADC_1	VDDANA	ADC Module Supply	2.7V	—	5.5V	V	VDD = VDDIO
Reference Inputs
SDADC_3	VREF⁽²⁾	ADC Reference Voltage	2.7	—	VDDANA	V	V_REF = VDDANA (REFCTRL.REFSEL = 0x3)
SDADC_3	VREF⁽²⁾	ADC Reference Voltage	2.4	—	VDDANA	V	V_REF≤ VDDANA V_REF = INTREF (REFCTRL.REFSEL = 0x0) V_REF = VREFB pin (REFCTRL.REFSEL = 0x1) V_REF = DAC output (REFCTRL.REFSEL = 0x2)
Analog Input Range
SDADC_7	AFS	Full-Scale Analog Input Signal Range (Single-Ended ⁽¹⁾)	GNDANA	—	+VREF	V	V_REF<VDDANA-0.3V, Gaincorr = 0x1
SDADC_8		Full-Scale Analog Input Signal Range (Single-Ended ⁽¹⁾)	GNDANA	—	+0.7 * VREF	V	V_REF> = VDDANA-0.3V, Gaincorr = 0x1
SDADC_9		Full-Scale Analog Input Signal Range (Differential)	-VREF	—	+VREF	V	V_REF<VDDANA-0.3V, Gaincorr = 0x1
SDADC_10		Full-Scale Analog Input Signal Range (Differential)	-0.7*VREF	—	+0.7 * VREF	V	V_REF> = VDDANA-0.3V, Gaincorr = 0x1
SDADC_11	Vcom	Input Common mode voltage	GNDANA	—	AFS(max)	V	Differential mode
Note: This mode corresponds to a differential mode where the selected AINx pin is externally grounded. SDADC functional device operation with either internal or external VREF < 2.4V is functional, but not characterized. SDADC will function, but with degraded accuracy of approximately ~((0.06 * 2n) /VREF). Where "n" = #bits. SDADC accuracy is limited by internal VREF accuracy + drift, MCU generated noise plus users application noise or accuracy on VDDANA, GNDANA.

Table 43-27. SDADC Differential Mode Electrical Specifications
AC CHARACTERISTICS			Standard Operating Conditions: VDD and VDDIO 2.7V to 5.5V (unless otherwise stated) Operating temperature: -40°C ≤ TA ≤ +85°C for Industrial
Param. No.	Symbol	Characteristics	Min.	Typical	Max.	Units	Conditions
DIFFERENTIAL MODE ADC Accuracy
DSDADC_11	Res	Resolution	16			bits	—
DSDADC_13	ENOB ^(1,2,3,5)	Effective Number of bits	13	—	—	bits	FTP(max), REFCTRL.REFSEL = 0x3 = VDDANA V_REF = VDDANA = 5.0V
DSDADC_19	INL^(3,5)	Integral Nonlinearity	-7.9	—	8.7	LSb
DSDADC_25	DNL^(3,5)	Differential Nonlinearity	-1.0	—	3.3	LSb
DSDADC_31	GERR ^(3,5)	Gain Error	-771	—	343	LSb
DSDADC_37	EOFF^(3,5)	Offset Error	-229	—	164	LSb
DIFFERENTIAL MODE ADC Dynamic Performance
DSDADC_49	SINAD ^(1,2,3,5)	Signal to Noise and Distortion	80.1	—	—	dB	FTP(max), REFCTRL.REFSEL = 0x3 = VDDANA V_REF = VDDANA = 5.0V
DSDADC_51	SNR ^(1,2,3,6)	Signal to Noise ratio	85.0	—	—
DSDADC_53	DR^(1,2,3,6)	Dynamic Range	78.0	—	—
DSDADC_55	THD ^(1,2,3,4,5)	Total Harmonic Distortion	—	—	-77.3
Note: Characterized with an analog input sine wave at 500Hz with OSR = 256. Sinewave peak amplitude = -3dB SDADC_ Full Scale amplitude input with 16bit resolution. Spec values collected under the following additional conditions: All registers at reset default value otherwise not mentioned Value taken over 7 harmonics. Differential input mode, OSR = 256, SDADC Clock Period=166.7 ns (6 MHz), Chopper OFF (ANACTRL.ONCHOP = 0).

Table 43-28. SDADC Conversion Timing Requirements
AC CHARACTERISTICS			Standard Operating Conditions: VDD and VDDIO 2.7V to 5.5V (unless otherwise stated) Operating temperature: -40°C ≤ TA ≤ +85°C for Industrial
Param. No.	Symbol	Characteristics	Min.	Typical	Max.	Units	Conditions
SDADC_ Clock Requirements
SDADC_57	TAD	SDADC Clock Period	166.7	—	1000	ns	—
SDADC_58	fGCLK_SDADC	SDADC Module GCLK max input freq	—	—	48	MHz	—
SDADC_60	OSR	Oversampling ratio	64	256	1024	TAD
SDADC Differential Mode Throughput Rates
SDADC_61	FTP	Throughput Rate ⁽¹⁾ Free Running mode	—	—	1/(TAD4OSR)	ksps	CTRLC.FREERUN = 1
SDADC_61	FTP	Throughput Rate ⁽¹⁾ Single Shot mode	—	—	1/(TAD4(N+1)*OSR)	ksps	CTRLC.FREERUN = 0, N = SKPCNT
Note: SDADC Throughput Rate FTP is divided by # of user active analog inputs in use on specific target SDADC module.

Table 43-29. SDADC Sample Timing Requirements
AC CHARACTERISTICS			Standard Operating Conditions: VDD and VDDIO 2.7V to 5.5V (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +85°C for Industrial
Param. No.	Symbol	Characteristics	Min.	Typical	Max.	Units	Conditions
SDADC_63	SKPCNT	skip count ⁽¹⁾	2	—	15	TAD	register bits: CTRLB.SKPCNT[3:0]
SDADC_67	T_CNV	Conversion Time	(1/FTP)/TAD			TAD	—
SDADC_69	C_SAMPLE	Internal Sample Cap	0.425	0.5	0.575	pF	—
SDADC_71	R_SAMPLE	Internal input impedance	1/(Csample1/(4TAD))			kΩ	Differential mode
SDADC_71	R_SAMPLE	Internal input impedance	1/(2 * Csample1/(4TAD))			kΩ	Single-Ended mode
SDADC_72	Rext	Input anti-aliasing filter recommendation⁽²⁾	—	1	—	kΩ	—
SDADC_72	Cext	Input anti-aliasing filter recommendation⁽²⁾	3.3	—	10	nF	—
Note: Number of skip samples before retrieve the first valid sample. The first valid sample starts from the (SKPCNT+1)th sample onward. External anti-alias filter must be placed in front of each SDADC input to ensure high-frequency signals to not alias into measurement bandwidth. Use capacitors of X5R type for DC measurement, or capacitors of COG or NPO type for AC measurement.