Datasheet

ADuC7033
Rev. B | Page 46 of 140
ADC GROUND SWITCH
The ADuC7033 features an integrated ground switch pin,
GND_SW, Pin15. This switch allows the user to dynamically
disconnect ground from external devices. It allows either a
direct connection to ground, or a connection to ground using a
20 kΩ resistor. This additional resistor can be used to reduce the
number of external components required for an NTC circuit.
The ground switch feature can be used for reducing power
consumption on application specific boards.
An example application is shown in Figure 19.
R
REF
REG_AVDD
VTEMP
NTC
20kΩ
REG_AVDD
VTEMP
GND_SW
GND_SW
NTC
06847-017
Figure 19. Example External Temperature Sensor Circuits
This diagram shows an external NTC used in two modes, one
using the internal 20 kΩ resistor, and the second showing a
direct connection to ground, via the GND_SW.
ADCCFG[7] controls the connection of the ground switch to
ground and
ADCMDE[6]
controls the GND_SW resistance as
shown in Figure 20.
20kΩ
GND_SW
ADCMDE[6]
ADCCFG[7]
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Figure 20. Internal Ground Switch Configuration
The possible combinations are shown in Table 31.
Table 31. GND_SW Configuration
ADCCFG[7]
ADCMDE[6]
GND_SW
0 0 Floating
0 1 Floating
1 0 Direct connection to ground
1 1
Connected to ground via 20 kΩ
resistor