ADS131M08

Part: ADS131M08 (ADS131M08IPBSR, 32-pin TQFP) — Texas Instruments

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

Description: 8-channel, simultaneously sampling, 24-bit delta-sigma ADC with data rates up to 32 kSPS, programmable gain up to 128, and 6.0 mW power consumption at 3 V AVDD and DVDD.

Operating Conditions:

• Supply voltage: AVDD 2.7–3.6 V (normal modes), 2.4–3.6 V (standby and current-detect modes); DVDD 2.7–3.6 V (1.65–2 V when DVDD is shorted to CAP, digital LDO bypassed)
• Operating temperature: -40 to 125 °C (ambient)
• External clock (fCLKIN): 0.3–8.4 MHz in high-resolution mode with gain 1 or 2 (0.3–8.2 MHz for gain > 2); 0.3–4.15 MHz in low-power mode; 0.3–2.08 MHz in very-low-power mode
• Reference input voltage (REFIN): 1.1–1.3 V

Absolute Maximum Ratings:

• AVDD to AGND: -0.3 to 3.9 V
• DVDD to DGND: -0.3 to 3.9 V (-0.3 to 2.2 V with CAP tied to DVDD)
• Analog input voltage (AINxP, AINxN): AGND - 1.6 V to AVDD + 0.3 V
• Digital input voltage: DGND - 0.3 V to DVDD + 0.3 V
• Continuous input current, all pins except power-supply pins: ±10 mA
• Junction temperature: 150 °C
• Storage temperature: -60 to 150 °C

Key Specs:

• Resolution: 24-bit, 8 simultaneously sampling differential inputs
• Data rate: programmable up to 32 kSPS
• PGA gain: 1 to 128
• Dynamic range: -102 dB at gain = 1, 4 kSPS; -80 dB at gain = 64, 4 kSPS
• THD: -100 dB
• Channel crosstalk: -120 dB
• Input impedance: 330 kΩ for gains of 1, 2, and 4; ≥ 1 MΩ for gains of 8 to 128
• Power consumption: 6.0 mW at 3 V AVDD and DVDD
• Internal reference: 1.2 V, low drift
• Absolute input range: AGND - 1.3 V to AVDD (gain 1, 2, 4); AGND - 1.3 V to AVDD - 1.8 V (gain ≥ 8)

Features:

• 8 simultaneously sampling differential inputs
• Programmable channel-to-channel phase delay calibration (244-ns resolution at 8.192 MHz fCLKIN)
• Current-detect mode for very low-power tamper detection
• Fast startup: first data within 0.5 ms of supply ramp
• Integrated negative charge pump allows input signals below ground
• Offset and gain calibration registers
• CRC on communications and register map
• Low-drift internal voltage reference

Applications:

• Electricity meters (commercial and residential)
• Circuit breakers
• Protection relays
• Power quality meters
• Battery test equipment
• Battery management systems

Package:

• TQFP-32 (PBS), 5.00 mm × 5.00 mm
• WQFN-32 (RSN), 4.00 mm × 4.00 mm

• 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-kΩ 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 fCLKIN
• Current-detect mode allows for extremely low power tamper detection
• Fast startup: first data within 0.5 ms of supply ramp
• 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 and DVDD
• Packages: 32-pin TQFP or 32-pin WQFN
• Operating temperature range: -40°C to +125°C

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

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

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

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).

See (1)

(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.

over operating ambient temperature range (unless otherwise noted)

This section describes a class 0.1 three-phase energy measurement front-end using the ADS131M08. The ADC samples the outputs of the CTs and voltage dividers to measure the current and voltage (respectively) of each leg of the AC mains. The design can achieve high accuracy across a wide input current range (0.05 A - 100 A) and supports high sampling frequencies necessary for advanced power quality features such as individual harmonic analysis. Using the ADS131M08 to sample the CT output provides designers greater flexibility in the choice of metrology microcontrollers when compared to an integrated system-on-a-chip (SoC) and dedicated application-specific products.

Figure 9-5 shows the front-end for the three-phase energy measurement design.

Figure 9-5. Three-Phase Metrology Design Front-End