Texas Instruments ADS1254, Руководство пользователя

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The ADS1254
1-2
1.1 The ADS1254
The ADS1254 is a precision 24-bit delta-sigma analog-to-digital converter with
four differential input channels. The delta-sigma architecture employed in the
ADS1254 enables the device to achieve 19 bits of effective resolution (1.8 ppm
RMS noise) at data rates of up to 20 kHz. The part also has a no-missing-codes
characteristic across the full 24 bit range.
The ADS1254 employs an unidirectional two-wire synchronous serial
interface (modified SPI) for communication with the host system. Isolation can
be applied to this interface at minimal cost.
1.2 EVM System Overview
A block diagram of the ADS1254 evaluation module is shown in Figure 1−1.
Figure 1−1. ADS1254EVM Block Diagram
RS-232
Serial Port
MSP430F149
Microcontroller
128 k
×
8
SRAM
Clock
Generator
ADS1254
Reference
Buffer
Serial Data
SPI
Inputs
Reference Inputs
System
Clock
During normal operation, data is read from the ADS1254 into the user’s
computer via the ADS1254EVMs RS-232 port. Once read, the data can be
displayed and analyzed in a variety of ways using the supplied ADS1254EVM
software.
The ADS1254 can supply data much faster than it can be transmitted to the
host PC over the RS-232 connection. Because of this, data read from the
ADS1254 is stored in an onboard RAM, where it is kept until retrieved by the
host system. This process is controlled by the user through the ADS1254EVM
software.