TI ADS8484 1.25MSPS微功耗模数转换方案

TI公司的ADS8484 是取样速率1.25MSPS的微功耗18位模数转换器,集成了4.096V基准电压和假双极全差分输入,18位基于电容的SAR ADC和取样与保持电路. ADS8484的工作电压从2.7V到5.25V,SNR为99dB,THD为-117dB,SFDR为120dB,在取样1.25MSPS时的功耗为235mW,有高速并行接口,可用在医疗设备,光网络,传感器接口,高精度数据采集系统和磁力计.本文介绍了ADS8484的主要特性,方框图, 应用电路, 单端输入差分输出配置图和差分输入差分输出配置图,以及评估板ADS848xEVM的主要特性,详细电路图和材料清单(BOM).

ADS8484:18-BIT,1.25-MSPS,PSEUDO-BIPOLAR,FULLY DIFFERENTIAL INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE,REFERENCE

The ADS8484 is an 18-bit, 1.25-MSPS A/C converter with an internal 4.096-V reference and a pseudo-bipolar, fully differential input. The device includes a 18-bit capacitor-based SAR A/D converter with inherent sample and hold. The ADS8484 offers a full 18-bit interface, a 16-bit option where data is read using two read cycles, or an 8-bit bus option using three read cycles.

The ADS8484 is available in a 48-lead 7x7 QFN package and is characterized over the industrial -40℃ to 85℃ temperature range.

ADS8484主要特性:

1.25-MHz Sample Rate

±1.5 LSB Typ, ±2.5 LSB Max INL

+0.8/-0.6 LSB Typ, +1.5/-1 LSB Max DNL

18-Bit NMC Ensured Over Temperature

±0.5-mV Offset Error

TBD-PPM/℃ Offset Error Drift

±0.1 %FSR Gain Error

±TBD-PPM/℃ Gain Error Drift

99dB SNR, -117db THD, 120dB SFDR

Zero Latency

Low Power: 235 mW Typ at 1.25 MSPS

Pseudo-Bipolar Fully Differential Input Range: V_ref to -Vref

Onboard Reference with TBD PPM/℃ Drift

Onboard Reference Buffer

High-Speed Parallel Interface

Wide Digital Supply 2.7 V to 5.25 V

8-/16-/18-Bit Bus Transfer

48-Pin 7x7 QFN Package

ADS8484应用:

Medical Instruments

Optical Networking

Transducer Interface

High Accuracy Data Acquisition Systems

Magnetometers

图1. ADS8484方框图


图2.ADS8484应用电路

图3.ADS8484单端输入差分输出配置图

图4.ADS8484差分输入差分输出配置图

ADS8484评估板ADS848xEVM

The ADS848xEVM is an evaluation and demonstration platform for the ADS848x ADC. The EVM board is a flexible design that allows the user to choose among many different analog signal conditioning, reference, and interface modes.

ADS848xEVM主要特性:

Full-featured evaluation board for the high-speed, 18-bit ADS8482 and ADS8484 1-MSPS/1.25-MSPS,single-channel, parallel interface, SAR-type analog-to-digital converters

Onboard signal conditioning

Onboard reference

Input and output digital buffers

Onboard decoding for stacking multiple EVMs


图5. 评估板ADS848xEVM电路图(1)

图6. 评估板ADS848xEVM电路图(2)


图7. 评估板ADS848xEVM电路图(3)

评估板ADS848xEVM材料清单(BOM):