000-0046140-111
Page 58 of 169
SLG46140
9.2 ADC Operation Modes
The ADC has three operating modes:
•
Single-Ended ADC operation using IN+ from PIN 6 or 7, when
ADC_sel
(reg <531>) is “0”
•
Differential ADC operation using IN+ from PIN 6 and IN- from PIN 7, when
ADC_sel
(reg <531>) is “1”
•
Pseudo-Differential ADC operation using IN+ from PIN 6 and IN- from PIN 7, when
ADC_sel
(reg <531>) and
ADC_pseudo-diff_en
(reg <536>) bits are both set to “1”.
9.3 ADC 3-bit Programmable Gain Amplifier (PGA)
The front end of the ADC is a PGA with 3 bits for setting gain. The PGA buffers the ADC in all cases. The PGA gain is set by the
ADC_gain_control (reg<534:532>). See ADC Register Settings Table.
Available gain settings depending on PGA mode selected (when used as ADC front-end):
•
Single-ended: 0.25x, 0.5x, 1x, 2x, 4x, 8x;
•
Differential: 1x, 2x, 4x, 8x, 16x;
•
Pseudo-Differential: 1x, 2x, 4x.
PGA inputs:
•
CH SELECTOR: Single-Ended Mode ADC Selection and Analog Input Mux Control Signal (PIN 11, VDD)
•
IN+: Single-Ended Mode Input (PIN6 or PIN7) and Differential Mode Positive Input (PIN6)
•
IN-: Differential Mode Negative Input (PIN7 or DAC0)
PGA output is connected directly to ADC input. Also, it is possible to connect PIN7 to PGA output (reg<886>), when ADC is not
in use only. The output of PGA has an offset when used as ADC front-end. Please see section
for more details.
9.3.1 PGA 2-Channel Selection
When
ADC_channel_sel
(reg <530>) is set to “1”, the PGA of the ADC will sample either PIN 6 or PIN 7 on the IN+ input, where
the selection is controlled by PIN 11.
•
When PIN 11 is set to “0”, the ADC will sample PIN 7
•
When PIN 11 is set to “1”, the ADC will sample PIN 6
When
ADC_channel_sel
(reg <530>) is set to “0”, the PGA of the ADC will sample PIN 6 on the IN+ input.
Figure 10. ADC 2-Channel Selection
Logic “1”
0
1
0
1
CH Selector (Pin 11)
IN+ CH#1 (Pin 6)
reg <530>
IN+ CH#2 (Pin 7)
IN+
Содержание GreenPAK SLG46140
Страница 102: ...000 0046140 111 Page 101 of 169 SLG46140 14 1 Initial Polarity Operations Figure 54 DFF Polarity Operations ...
Страница 103: ...000 0046140 111 Page 102 of 169 SLG46140 Figure 55 DFF Polarity Operations with nReset ...
Страница 104: ...000 0046140 111 Page 103 of 169 SLG46140 Figure 56 DFF Polarity Operations with nSet ...