Texas Instruments ADS8910B, Руководство пользователя

Страница: 8 / 39

Analog Interface
www.ti.com
8 SBAU268 – July 2016
Submit Documentation Feedback
Copyright © 2016, Texas Instruments Incorporated
ADS8910BEVM-PDK
2.3 Onboard ADC Reference
The EVM does not include a provision for driving the reference input of the ADS8910B from an external
source. The reference input signal path is entirely self-contained on the ADS8910BEVM and consists of
the REF5050, a 5.0-V precision voltage reference. The output of the REF5050 is filtered by a 10-k
Ω and
10-µF low-pass filter. The low-pass filtered output functions as an input to the internal reference buffer of
the ADS8910B ADC. This internal reference driver offers zero-offset, low-noise, and is optimized for a
1-LSB voltage regulation under maximum loading conditions at full device throughput of 1 MSPS.
3 Digital Interfaces
As noted in Section 1 , the EVM interfaces with the PHI that, in turn, communicates with the computer over
USB. There are two devices on the EVM with which the PHI communicates: the ADS8910B ADC (over
SPI or multiSPI) and the EEPROM (over I
2
C). The EEPROM comes pre-programmed with the information
required to configure and initialize the ADS8910BEVM-PDK platform. Once the hardware is initialized, the
EEPROM is no longer used.
3.1 multiSPI
®
for ADC Digital IO
The ADS8910BEVM-PDK supports all the interface modes as detailed in the ADS8910B datasheet
(
SBAS707 ). In addition to the standard SPI modes, (with single-, dual- and quad-SDO lanes), the multiSPI
modes support single- and dual-data output rates and the four possible clock source settings as well. The
PHI is capable of operating at a 3.3-V logic level and is directly connected to the digital I/O lines of the
ADC.