-60
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
0
0.25
0.5
0.75
1
F/Fs
Gain (dB)
SDHS Functional Operation
576
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
Sigma-Delta High Speed (SDHS)
Figure 22-12. SDHS Filter Frequency Response within f
s
, SDHSCTL1.OSR = 160
22.2.3.4 Filter Output Data Formats
SDHS filter output can be configured as offset binary format (SDHSCTL0.DFMSEL = 1) or 2s complement
format (SDHSCTL0.DFMSEL = 0 ). The output values range is between 0 to FS when offset binary format
is selected, between –f
s
/2 and +f
s
/2 when 2s complement format is selected. See
for the data
range based on the configuration of SDHSCTL0.DFMSEL, SDHSCTL0.DALGN, and SDHSCTL0.OBR
bits.
Table 22-1. Data Format
Format
(SDHSCTL0.DF
MSEL Bit)
Alignment
(SDHSCTL0.DAL
GN Bit)
Analog
Input
Data Output
(SDHSCTL0.OBR = 0):
12 Bit
Data Output
(SDHSCTL0.OBR = 1):
13 Bit
Data Output
(SDHSCTL0.OBR = 2):
14 Bit
2s Complement
(0)
Right Aligned (0)
+f
s
/2
0x7FF
0xFFF
0x1FFF
0
0
0
0
–f
s
/2
0x800
0x1000
0x2000
Offset Binary (1)
Right Aligned (0)
+f
s
/2
0xFFF
0x1FFF
0x3FFF
0
0x800
0x1000
0x2000
–f
s
/2
0
0
0
The effective number of bits in the output data format is determined by SDHSCTL0.OBR and
SDHSCTL0.SHIFT bits.
shows bits selection from the filter output to the SDHSDT register
with left alignment mode (SDHSCTL0.DALGN = 0).
shows bits selection from the filter output
to the SDHSDT register with right alignment mode (SDHSCTL0.DALGN = 1). Increasing the
SDHSCTL0.SHIFT value is equivalent of multiplying the output data by 2 at every shift. Take care when
using SDHSCTL0.SHIFT bits and ensure that signal overflow never happens after shifting.