XE8802MI000 SEMTECH [Semtech Corporation], XE8802MI000 Datasheet - Page 119

• Manufacturer Part Number: XE8802MI000
• Description: Sensing Machine Data Acquisition MCU
• Manufacturer: SEMTECH [Semtech Corporation]

17.4.3
The ADC can be operated in two distinct modes: "continuous-time" and "on-request" modes (selected using the bit
CONT).
In "continuous-time" mode, the input signal is repeatedly converted into digital. After a conversion is finished, a new
one is automatically initiated. The new value is then written in the result register, and the corresponding internal
trigger pulse is generated. This operation is sketched in Figure 17-3. The conversion time in this case is defined as
T
In the "on-request" mode, the internal behavior of the converter is the same as in the "continuous-time" mode, but
the conversion is initiated on user request (with the START bit). As shown in Figure 17-4, the conversion time is
also T
17.5 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 V
and:
As shown in Table 17-11 the inputs can be configured in two ways: either as 4 differential channels (V
AC_A(1) - AC_A(0),..., V
7 signal paths all referenced 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.
© Semtech 2006
CONV
.
CONV
V
V
IN
REF
.
Continuous-Time vs. On-Request
=
V
=
INP
V
REFP
−
V
INN
−
V
REFN
IN4
= AC_A(7) - AC_A(6)), or AC_A(0) can be used as a common reference, providing
(V)
(V)
RegACOut[15:0]
RegACOut[15:0]
Figure 17-3. ADC "continuous-time" operation
Internal Trig
Ouput Code
Ouput Code
Internal Trig
Figure 17-4. ADC "on-request" operation
Request
START
BUSY
BUSY
IRQ
IRQ
XE8802 Sensing Machine Data Acquisition MCU
17-7
IN
and reference voltage V
with ZoomingADC™ and LCD driver
T
T
CONV
CONV
(Eq. 3)
(Eq. 4)
REF
respectively as:
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IN1
=