Datasheet

ADuC7033
Rev. B | Page 64 of 140
Low Power Plus Mode
In summary, the simplified ADC transfer function can be
described as
The PGA gain is set to 512 and the K factor is 8.
NOM
REF
IN
OUT
ADCGN
ADCGN
ADCOF
V
PGAV
ADC ×−
×
=
⎥
⎦
⎤
⎢
⎣
⎡
In low power and low power plus modes, the K factor doubles if
(REG_AVDD)/2 is used as the reference.
ADC DIAGNOSTICS
This equation is valid for the voltage/temperature channel ADC.
The ADuC7033 features diagnostic capability on both ADCs. For the current channel ADC,
Current ADC Diagnostics
NOM
REF
IN
OUT
ADCGN
ADCGN
ADCOFK
V
PGAV
ADC ××−
×
=
⎥
⎦
⎤
⎢
⎣
⎡
The ADuC7033 features the capability to detect open-circuit
conditions on the application board. This is accomplished using
the two current sources on IIN+ and IIN−; these are controlled
via ADC0CON[14:13].
where K is dependent on the PGA gain setting and ADC mode.
Normal Mode
Note that these current sources have a tolerance of ±30%. A
PGA gain ≥ 2 (ADC0CON[3:0] ≥ 0001) must be used when
current sources are enabled.
For PGA gains of 1, 4, 8, 16, 32, and 64, the K factor is 1. For
PGA gains of 2 and 128, the K factor is 2. For a PGA gain of
256, the K factor is 4. For a PGA gain of 512, the K factor is 8.
Temperature ADC Diagnostics
Low Power Mode
The ADuC7033 features the capability to detect open-circuit
conditions on the temperature channel inputs. This is
accomplished using the two current sources on VTEMP and
GND_SW, controlled via ADC1CON[14:13].
The PGA gain is set to 128 and the K factor is 32.