XE8000EV120 Semtech, XE8000EV120 Datasheet - Page 57

• Manufacturer Part Number: XE8000EV120
• Description: BOARD EVAL FOR SX8722I070TRLF
• Manufacturer: Semtech
• Series: ZoomingADC™r

Specifications of XE8000EV120

• Number Of Adc's: 1
• Number Of Bits: 16
• Data Interface: I²C
• Inputs Per Adc: 7 Single or 4 Differential
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 125°C
• Utilized Ic / Part: SX8722
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: XM8000EV120; XM8000EV120

PGA3_GAIN:
PGA2_OFFSET:
PGA3_OFFSET:
AMUX(4:0):
VMUX:
(r = read; w = write; rw = read & write)
12.6. Input Multiplexers
The ZoomingADC has eight analog inputs AC_A(0) to AC_A(7) and four reference inputs AC_R(0) to AC_R(3). Let us first
define the differential input voltage VIN and reference voltage VREF respectively as:
As shown in Table 41 the inputs can be configured in two ways: either as 4 differential channels (VIN1 = AC_A(1) -
AC_A(0),..., VIN4 = AC_A(7) - AC_A(6)), or AC_A(0) can be used as a common reference, providing 7 signal paths all
referred to AC_A(0). The control word for the analog input selection is AMUX[4:0]. Notice that the bit AMUX[3] controls the
sign of the input voltage.
ACS - Revision 4.2
©2008 Semtech Corp.
and:
ADVANCED COMMUNICATIONS & SENSING
(RegACCfg5[5:1])
V
(rw) sets the gain of the third stage to PGA3_GAIN[6:0] 1/12.
(rw) sets the offset of the second stage between -1 and +1, with increments of 0.2. The MSB gives the sign (0
positive, 1 negative); amplitude is coded with the bits PGA2_OFFSET[5:0].
(rw) sets the offset of the third stage between -5.25 and +5.25, with increments of 1/12. The MSB gives the sign (0
positive, 1 negative); amplitude is coded with the bits PGA3_OFFSET[5:0].
(rw) AMUX[4] sets the mode (0 ' 4 differential inputs, 1 ' 7 inputs with A(0) = common reference) AMUX(3) sets the sign
(0 ' straight, 1' cross) AMUX[2:0] sets the channel.
(rw) sets the differential reference channel (0 ' R(1) and R(0), 1 ' R(3) and R(2)).
REF
V
AMUX [4:0]
IN
10000
10001
10010
10100
10101
=
00x00
00x01
00x10
00x11
10011
10110
10111
=
(Eq. 3)
V
(Eq. 4)
V
REFP
INP
−
−
V
V
INN
October 2008
REFN
AC_A(1)
AC_A(3)
AC_A(5)
AC_A(7)
AC_A(0)
AC_A(1)
AC_A(2)
AC_A(3)
AC_A(4)
AC_A(5)
AC_A(6)
AC_A(7)
V
INP
Table 41. Analog input selection
AC_A(0)
AC_A(2)
AC_A(4)
AC_A(6)
AC_A(0)
V
INN
V [ ]
V [ ]
Page 57
(RegACCfg5[5:1])
AMUX [4:0]
High gain acquisition for sensor interface
01x00
01x01
01x10
01x11
11000
11001
11010
11011
11100
11101
11110
11111
AC_A(0)
AC_A(2)
AC_A(4)
AC_A(6)
AC_A(0)
V
INP
AC_A(1)
AC_A(3)
AC_A(5)
AC_A(7)
AC_A(0)
AC_A(1)
AC_A(2)
AC_A(3)
AC_A(4)
AC_A(5)
AC_A(6)
AC_A(7)
V
INN
DATASHEET
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SX8722