ADS1299-X

Part: ADS1299-x (ADS1299, ADS1299-4, ADS1299-6) — Texas Instruments

Type: 24-Bit Simultaneous-Sampling Delta-Sigma ADC with PGA (EEG/Biopotential Analog Front End)

Description: Low-noise 4-, 6-, or 8-channel 24-bit simultaneous-sampling ΔΣ ADC with programmable gain (1–24), data rates of 250 SPS to 16 kSPS, 5 V analog supply, 1.8–3.6 V digital supply and SPI interface, for EEG and ECG measurements.

Operating Conditions:

• Analog supply (AVDD to AVSS): 4.75–5.25 V
• Digital supply (DVDD to DGND): 1.8–3.6 V
• Operating temperature: -40 to +85 °C
• External clock frequency (CLKSEL = 0): 1.5–2.25 MHz (2.048 MHz nominal)
• Reference input voltage: 4.5 V

Absolute Maximum Ratings:

• AVDD to AVSS: -0.3 to 5.5 V
• DVDD to DGND: -0.3 to 3.9 V
• Analog input: AVSS - 0.3 V to AVDD + 0.3 V
• Digital input: DGND - 0.3 V to DVDD + 0.3 V
• Input current, continuous, any pin except power supply pins: ±10 mA
• Junction temperature: 150 °C
• Storage temperature: -60 to 150 °C

Key Specs:

• Resolution: 24-bit, up to eight simultaneous-sampling channels
• Input-referred noise: 1 μVPP (70 Hz bandwidth)
• Input bias current: 300 pA
• CMRR: -110 dB
• Data rate: 250 SPS to 16 kSPS
• Programmable gain: 1, 2, 4, 6, 8, 12, or 24
• Full-scale differential input: ±VREF / gain

Features:

• Up to eight low-noise PGAs and eight high-resolution simultaneous-sampling ADCs
• Unipolar or bipolar supplies
• Built-in bias drive amplifier, lead-off detection, and test signals
• Built-in oscillator
• Internal or external reference
• Flexible power-down and standby modes
• Flexible per-channel input multiplexer (test, temperature, lead-off signals)
• Optional SRB pins for referential montage
• Daisy-chain cascading of multiple devices
• Pin-compatible with the ADS129x
• SPI-compatible serial interface

Applications:

• Medical instrumentation
• Electroencephalogram (EEG) study
• Fetal electrocardiography (ECG)
• Sleep study monitor
• Bispectral index (BIS)
• Evoked audio potential (EAP)

Package:

• TQFP-64 (10.00 mm × 10.00 mm body)

• 1 · Up to Eight Low-Noise PGAs and Eight HighResolution Simultaneous-Sampling ADCs
• Input-Referred Noise: 1 μ

VPP (70-Hz BW)

• Input Bias Current: 300 pA
• Data Rate: 250 SPS to 16 kSPS
• CMRR: -110 dB
• Programmable Gain: 1, 2, 4, 6, 8, 12, or 24
• Unipolar or Bipolar Supplies:
• -Analog: 4.75 V to 5.25 V
• -Digital: 1.8 V to 3.6 V
• Built-In Bias Drive Amplifier, Lead-Off Detection, Test Signals
• Built-In Oscillator
• Internal or External Reference
• Flexible Power-Down, Standby Mode
• Pin-Compatible with the ADS129x
• SPI-Compatible Serial Interface
• Operating Temperature Range: -40°C to +85°C

• Medical Instrumentation Including:
• -Electroencephalogram (EEG) Study
• -Fetal Electrocardiography (ECG)
• -Sleep Study Monitor
• -Bispectral Index (BIS)
• -Evoked Audio Potential (EAP)

Minimum and maximum specifications apply from TA = -40°C to 85°C. Typical specifications are at TA = +25°C. All specifications are at AVDD - AVSS = 5 V, DVDD = 3.3 V, VREF = 4.5 V, external f CLK = 2.048 MHz, data rate = 250 SPS, and gain = 12 (unless otherwise noted)

over operating ambient temperature range (unless otherwise noted)

The biopotential signals that are measured in electroencephalography (EEG) are small when compared to other types of biopotential signals. The ADS1299 is equipped to measure such small signals due to its extremely low input-referred noise from its high performance internal PGA. Figure 72 and Figure 73 are examples of how the ADS1299 may be configured in typical EEG measurement setups. Figure 72 shows how to measure electrode potentials in a sequential montage, whereas Figure 73 illustrates referential montage measurement connections.

Figure 72. Example Schematic Using the ADS1299 in an EEG Data Acquisition Application, Sequential Montage