Overview

Part: ADS131M08 from Texas Instruments

Type: 8-Channel, Simultaneously-Sampling, 24-Bit, Delta-Sigma ADC

Key Specs:

Channels: 8 simultaneously sampling differential inputs
Resolution: 24-Bit
Data Rate: up to 32 kSPS
Programmable Gain: up to 128
Dynamic Range: 102

Features

8 simultaneously sampling differential inputs
Programmable data rate up to 32 kSPS
Programmable gain up to 128
Noise performance:
- 102-dB dynamic range at gain = 1, 4 kSPS
- 80-dB dynamic range at gain = 64, 4 kSPS
Total harmonic distortion: -100 dB
High-impedance inputs for direct sensor connection:
- Input impedance 330-k Ω for gains of 1. 2. and 4
- Input impedance ≥ 1-MΩ for gains of 8, 16, 32, 64, and 128
Programmable channel-to-channel phase delay calibration:
- 244-ns resolution, 8.192-MHz f_CLKIN
Current-detect mode allows for extremely low power tamper detection
Fast startup: first data within 0.5 ms of supply
Integrated negative charge pump allows input signals below ground
Crosstalk between channels: -120 dB
Low-drift internal voltage reference
· Cyclic redundancy check (CRC) on communications and register map
2.7-V to 3.6-V analog and digital supplies
Low power consumption: 6.0 mW at 3-V AVDD
Packages: 32-pin TQFP or 32-pin WQFN
Operating temperature range: -40°C to +125°C

Applications

Electricity meters: commercial and residential
Circuit breakers
· Protection relays
· Power quality meters
Battery test equipment
Battery management systems

Pin Configuration

Figure 5-1. PBS Package, 32-Pin TQFP, Top View

Figure 5-2. RSN Package, 32-Pin WQFN, Top View

Table 5-1. Pin Functions

	PIN

NAME	WQFN
AGND	13, 28
AIN0N	30
AIN0P	29
AIN1N	31
AIN1P	32
AIN2N	2
AIN2P	1
AIN3N	3
AIN3P	4
AIN4N	6
AIN4P	5
AIN5N	7
AIN5P	8
AIN6N	10
AIN6P	9
AIN7N	11
AIN7P	12
AVDD	15
CAP	24
CS	17
DGND	25
DIN	21
DOUT	20
DRDY	18
DVDD	26
NC	27
REFIN	14
SCLK	19
SYNC/RESET	16
XTAL1/CLKIN	23
XTAL2	22
Thermal pad

(1) See the Unused Inputs and Outputs section for details on how to connect unused pins.
(2) Do not place any capacitance on REFIN if the current-detect mode is used.
(3) See the Clocking and Power Modes section for more information regarding synchronization and how to implement the clocking scheme for optimized device performance.

Electrical Characteristics

minimum and maximum specifications apply from TA = –40°C to +125°C; typical specifications are at TA = 25°C; all specifications are at AVDD = 3 V, DVDD = 3 V, fCLKIN = 8.192 MHz, data rate = 4 kSPS, gain = 1, all channels enabled, global-chop mode disabled, using internal reference with 100-nF tied to REFIN pin, and internal oscillator disabled (unless otherwise noted).

	PARAMETER	TEST CONDITIONS	MIN	TYP	MAX	UNIT
	ANALOG INPUTS
Zin	Differential input impedance	Gain = 1, 2, or 4		330		kΩ
Ib	Input bias current	Gain = 8, 16, 32, 64, or 128, inputs shorted to ground		±1		μA/V
	ADC CHARACTERISTICS
	Resolution		24			Bits
	Gain settings			1, 2, 4, 8, 16, 32, 64, 128
		High-resolution mode, fCLKIN = 8.192 MHz	250		32k
fDATA	Data rate	Low-power mode, fCLKIN = 4.096 MHz	125		16k	SPS
		Very low-power mode, fCLKIN = 2.048 MHz	62.5		8k
	Startup time	Measured from supplies at 90% to first DRDY falling edge		0.5		ms
	ADC PERFORMANCE
INL	Integral nonlinearity (best fit)			7.5		ppm of FSR
				±240
	Offset error (input referred)	Global-chop mode		±32		μV
				215
	Offset drift Global-chop mode			105		nV/°C
	Gain error			±0.3%
		Excluding voltage reference error, gain = 1		5
	Gain drift	Including internal voltage reference error, gain = 1		10	20	ppm/°C
		Including internal voltage reference error, gain = 32		15
		1000 hours at 85°C, including internal voltage reference error, TQFP package		385
	Long-term gain drift	1000 hours at 85°C, including internal voltage reference error, WQFN package		90		ppm
	Common-mode rejection	At dc		100
CMRR	ratio	fCM = 50 Hz or 60 Hz		94		dB
		AVDD at DC		80
		DVDD at DC		100
PSRR	Power-supply rejection ratio	AVDD supply, fPS = 50 Hz or 60 Hz		78		dB
		DVDD supply, fPS = 50 Hz or 60 Hz		90
				5.4
	Input referred noise	During fast startup		1500		μVRMS
		Gain = 1	99	102
	Dynamic range	Gain = 64		80		dB
		All other gain settings		See Table 7-1
	Crosstalk	fIN = 50 Hz or 60 Hz		–120		dB

Absolute Maximum Ratings

See (1)

		MIN	MAX	UNIT
	AVDD to AGND	–0.3	3.9
	AGND to DGND	–0.3	0.3
Power-supply voltage	DVDD to DGND	–0.3	3.9	V
	DVDD to DGND, CAP tied to DVDD	–0.3	2.2
	CAP to DGND	–0.3	2.2
Analog input voltage	AINxP, AINxN	AGND – 1.6	AVDD + 0.3	V
Reference input voltage	REFIN	AGND – 0.3	AVDD + 0.3	V
Digital input voltage	CS, XTAL1/CLKIN, DIN, SCLK, SYNC/RESET, XTAL2	DGND – 0.3	DVDD + 0.3	V
Input current	Continuous, all pins except power-supply pins	–10	10	mA
	Junction, TJ		150
Temperature	Storage, Tstg	–60	150	°C

⁽¹⁾ Operation outside the Absolute Maximum Ratings may cause permanent device damage. Absolute Maximum Ratings do not imply functional operation of the device at these or any other conditions beyond those listed under Recommended Operating Conditions. If used outside the Recommended Operating Conditions but within the Absolute Maximum Ratings, the device may not be fully functional, and this may affect device reliability, functionality, performance, and shorten the device lifetime.

6.2 ESD Ratings

			VALUE	UNIT
		Human body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)	±2000	V
V(ESD)	Electrostatic discharge	Charged device model (CDM), per JEDEC specification JESD22-C101(2)	±500

6.3 Recommended Operating Conditions

over operating ambient temperature range (unless otherwise noted)

			MIN	NOM	MAX	UNIT
	POWER SUPPLY
		AVDD to AGND, normal operating modes	2.7	3.0	3.6
	Analog power supply	AVDD to AGND, standby and current-detect modes	2.4	3.0	3.6	V
		AGND to DGND	–0.3	0	0.3
		DVDD to DGND	2.7	3.0	3.6
	Digital power supply	DVDD to DGND, DVDD shorted to CAP (digital LDO bypassed)	1.65	1.8	2	V
	ANALOG INPUTS(1)
VAINxP,		Gain = 1, 2, or 4	AGND – 1.3		AVDD
VAINxN	Absolute input voltage	Gains = 8, 16, 32, 64 or 128	AGND – 1.3		AVDD – 1.8	V
VIN	Differential input voltage	Using internal reference, VIN = VAINxP - VAINxN	–VREF / Gain		VREF / Gain
		Using external reference, VIN = VAINxP - VAINxN	– 0.96 × VREF / Gain		0.96 × VREF / Gain	V
	VOLTAGE REFERENCE INPUT
VREFIN	Reference input voltage		1.1	1.25	1.3	V
	EXTERNAL CLOCK SOURCE
		High-resolution mode, Gain = 1 or 2	0.3	8.192	8.4
		High-resolution mode, Gain > 2	0.3	8.192	8.2
fCLKIN	External clock frequency	Low-power mode	0.3	4.096	4.15	MHz
		Very-low-power mode	0.3	2.048	2.08
	Duty cycle		40	50	60	%
	DIGITAL INPUTS
	Input voltage		DGND		DVDD	V
	TEMPERATURE RANGE
TA	Operating ambient temperature		–40		125	°C

⁽¹⁾ The subscript "x" signifies the channel. For example, the positive analog input to channel 0 is named AIN0P. See the Pin Configurations and Functions section for the pin names.

6.4 Thermal Information

			ADS131M08
	THERMAL METRIC(1)	RSN (WQFN)	PBS (TQFP)
		32 PINS	32 PINS
RθJA	Junction-to-ambient thermal resistance	33.7	81.9
RθJC(top)	Junction-to-case (top) thermal resistance	26.5	26.0
RθJB	Junction-to-board thermal resistance	13.4	32.7
ΨJT	Junction-to-top characterization parameter	0.3	1.1
ΨJB	Junction-to-board characterization parameter	13.4	32.5
RθJC(bot)	Junction-to-case (bottom) thermal resistance	4.1	N/A

⁽¹⁾ For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report.

6.5 Electrical Characteristics