Texas Instruments ADS127L21B Wideband Delta-Sigma ADC
Texas Instruments ADS127L21B Wideband Delta-Sigma Analog-to-Digital Converter (ADC) is a high-precision, 24-bit, delta-sigma (ΔΣ) ADC featuring programmable digital filters. The digital filter has data rates up to 512kSPS using the wideband filter and up to 1365kSPS using the low-latency filter. The device offers excellent AC performance and DC precision with low power consumption. The low-drift modulator achieves excellent DC precision with a maximum of 0.8ppm INL (0°C to 70°C) and outstanding AC performance with low wideband noise. The power-scalable architecture features four-speed modes to optimize resolution, data rate, and power consumption. Signal and reference input buffers reduce driver loading for increased accuracy.
Programmable infinite and finite impulse response (IIR and FIR) digital filters allow custom filter profiles, such as frequency notch filters and A-weighting compensation. The wideband or low-latency filter option optimizes one device's data throughput or AC-signal performance of DC signals. The serial interface features a daisy-chain capability to reduce the number of signal lines over an isolation barrier. Register memory and SPI input data contents are validated by cyclic-redundancy check (CRC) to enhance operational reliability. This device is designed for space-limited applications with the small 3mm × 3mm WQFN package. The Texas Instruments ADS127L21B is fully pin-to-pin compatible with the ADS127L21 and is specified for operation over the –40°C to +125°C temperature range.
Features
- AC performance with DC precision
- Dynamic range (200kSPS): 111.5dB (typical)
- INL: 0.2ppm of FSR (typical)
- THD: –125dB (typical)
- Offset drift: 50nV/°C (typical)
- Gain drift: 0.5ppm/°C (typical)
- Power-scalable speed modes
- Max speed: 512kSPS (33mW typical)
- High speed: 400kSPS (26mW typical)
- Mid speed: 200kSPS (14mW typical)
- Low speed: 50kSPS (4.3mW typical)
- Wideband or low-latency filter modes
- Programmable data rates
- Wideband filter mode: 512kSPS
- Low-latency filter mode: 1.365MSPS
- Programmable IIR and FIR digital filters
- Buffered inputs of 1.5µA input current typical, mid-speed mode
- ±VREF or ±2VREF input range
- Internal or external clock operation
- 3µs conversion latency (low-latency filter)
- Functional Safety-Capable with documentation available to aid functional safety system design
Applications
- Test and measurement
- Data acquisition (DAQ)
- Digital multimeter
- Medical - doppler ultrasound
- Factory automation and control - vibration, condition monitoring
- Grid infrastructure - power quality analyzer
Functional Block Diagram
