PGA
V
OUT
PVSS
PLL
USSXT
PVCC
PPG
MOD
Filter
USSXTIN USSXTOUT
DTC
RAM
(Shared with LEA)
UUPS
PHY
ASQ
PLL_CLK
USS Module
PVSS
CH0_OUT
CH1_OUT
CH0_IN
CH1_IN
OSC
USSXT_BOUT
SDHS
SAPH
HSPLL
MSP430FRxxxx
Copyright © 2017, Texas Instruments Incorporated
Introduction
569
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
Sigma-Delta High Speed (SDHS)
22.1 Introduction
The Sigma-Delta High Speed (SDHS) is a high-performance high-speed 12-bit analog-to-digital converter
(ADC). The SDHS is one of the submodules in the Ultrasonic Sensing Solution (USS) module. The USS
module is designed for ADC-based ultrasonic sensing technology in various measurement applications.
shows the block diagram of the USS module.
Figure 22-1. USS Block Diagram
The SDHS module consists of three blocks: the programmable gain amplifier (PGA), the sigma-delta high
speed (SDHS), and the data transfer controller (DTC) (see
•
PGA block: Applies a gain to the input signal before the SDHS.
•
SDHS block: ADC converts that converts the input signal to digital data at the programmed sampling
rate.
•
DTC block: Transfers the output data from the SDHS to the LEA RAM for data processing.
NOTE:
Naming convention for register names and bit fields:
•
SDHS registers: RegisterName or RegisterName.BitField
•
Other module registers: ModuleNameRegisterName or
ModuleNameRegisterName.BitField
22.2 SDHS Functional Operation
The SDHS is a high-performance high-speed ADC that supports output data rates up to 8 Msps.
shows the SDHS block diagram. The converter consists of a third-order sigma-delta modulator
and digital decimation filters. The decimation filters are CIC filters with selectable oversampling ratios of
10, 20, 40, 80, or 160.
Features of the SDHS include:
•
Third-order sigma-delta architecture
•
High-speed data conversion rate up to 8 Msps
•
Low-pass filter with selectable oversampling ratios of 10, 20, 40, 80, or 160