ADS1294 - 4-Channel 24-Bit ADC With Integrated ECG Front End

The ADS1294, ADS1296, ADS1298 (ADS129x) and ADS1294R, ADS1296R ADS1298R (ADS129xR) are a family of multichannel, simultaneous sampling, 24-bit, delta-sigma (ΔΣ) analog-to-digital converters (ADCs) with built-in programmable gain amplifiers (PGAs), internal reference, and an onboard oscillator. The ADS129x and ADS129xR incorporate all of the features that are commonly required in medical electrocardiogram (ECG) and electroencephalogram (EEG) applications. With high levels of integration and exceptional performance, the ADS129x and ADS129xR enables the development of scalable medical instrumentation systems at significantly reduced size, power, and overall cost.

The ADS129x and ADS129xR have a flexible input multiplexer (mux) per channel that can be independently connected to the internally-generated signals for test, temperature, and lead-off detection. Additionally, any configuration of input channels can be selected for derivation of the right leg drive (RLD) output signal. The ADS129x and ADS129xR operate at data rates as high as 32 kSPS, thereby allowing the implementation of software pace detection. Lead-off detection can be implemented internal to the device, either with a pullup or pulldown resistor, or an excitation current sink or source. Three integrated amplifiers generate the Wilson central terminal (WCT) and the Goldberger central terminals (GCT) required for a standard 12-lead ECG. The ADS129xR versions include a fully integrated, respiration impedance measurement function. Multiple ADS129x and ADS129xR devices can be cascaded in high channel count systems in a daisy-chain configuration.

Package options include a tiny 8-mm × 8-mm, 64-ball BGA, and a TQFP-64. The ADS129x BGA version is specified over the commercial temperature range of 0°C to 70°C. The ADS129xR BGA and ADS129x TQFP versions are specified over the industrial temperature range of –40°C to +85°C.

• Eight Low-Noise PGAs and Eight High-Resolution ADCs (ADS1298, ADS1298R)
• Low Power: 0.75 mW/channel
• Input-Referred Noise: 4 μV_PP (150 Hz BW, G = 6)
• Input Bias Current: 200 pA
• Data Rate: 250 SPS to 32 kSPS
• CMRR: –115 dB
• Programmable Gain: 1, 2, 3, 4, 6, 8, or 12
• Supports systems meeting AAMI EC11, EC13, IEC60601-1, IEC60601-2-27, and IEC60601-2-51 Standards
• Unipolar or Bipolar Supplies:
  • AVDD = 2.7 V to 5.25 V
  • DVDD = 1.65 V to 3.6 V
• Built-In Right Leg Drive Amplifier, Lead-Off Detection, Wilson Center Terminal, Pace Detection, Test Signals
• Integrated Respiration Impedance Measurement
• Digital Pace Detection Capability
• Built-In Oscillator and Reference
• SPI™-Compatible Serial Interface