1 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

– 1.5μA input current typical, mid-speed mode

• Input range: ±VREF or ±2VREF

• Internal or external clock operation

• Conversion latency (low-latency filter): 3μs

• Functional Safety-Capable

– Documentation available to aid functional safety

system design

2 Applications

• Test and measurement:

– Data acquisition (DAQ)

– Digital multimeter

• Factory automation and control:

– Vibration, condition monitoring

• Medical:

– Doppler ultrasound

• Grid infrastructure:

– Power quality analyzer

3 Description

The ADS127L21B is a high-precision, 24-bit,

delta-sigma (ΔΣ), analog-to-digital converter (ADC)

featuring programmable digital filters. This digital filter

has data rates up to 512kSPS using the wideband

filter and up to 1365kSPS using the low-latency

filter. The device offers an excellent combination of

ac performance and dc precision with low power

consumption.

The low-drift modulator achieves excellent dc

precision with maximum 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 data rate, resolution,

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 A-weighting compensation and frequency

notch filters. The wideband or low-latency filter option

optimize ac-signal performance or data throughput of

dc signals, all in one device.

The serial interface features daisy-chain capability to

reduce the number of signal lines over an isolation

barrier. SPI input data and register memory contents

are validated by cyclic-redundancy check (CRC) to

enhance operational reliability.

The small 3mm × 3mm WQFN package is designed

for space-limited applications. The device is fully

specified for operation over the –40°C to +125°C

temperature range and is pin-to-pin compatible to the

ADS127L21.