NEC uPD78P078 - Manual (Page 305)

305
CHAPTER 15 A/D CONVERTER
15.5 A/D Converter Cautions
(1) Current consumption in standby mode
The A/D converter operates on the main system clock. Therefore, its operation stops in STOP mode or in
HALT mode with the subsystem clock. As a current still flows in the AV REF0 pin at this time, this current must
be cut in order to minimize the overall system power dissipation. In Figure 15-9, the power dissipation can
be reduced by outputting a low-level signal to the output port in standby mode. However, there is no precision
to the actual AV
REF0
voltage, and therefore the conversion values themselves lack precision and can only
be used for relative comparison.
Figure 15-9. Example of Method of Reducing Current Consumption in Standby Mode
Series Resistor String
V DD
AV REF0
AV REF0
AV SS
Output Port
.
.
µ PD78078, 78078Y
= V
DD