UPD75238GJ NEC [NEC], UPD75238GJ Datasheet - Page 117

• Manufacturer Part Number: UPD75238GJ
• Description: 4 BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC [NEC]

(6) Notes on the standby mode
Time elapsed before
A/D conversion starts
(Maximum of 2
SA register
Note 40.1 s at 4.19 MHz
The A/D converter operates with the main system clock. So its operation stops in the STOP mode, or when
the subsystem clock is used, in the HALT mode. A current flows through the AV
A/D converter is stopped, so that the current must be stopped to reduce overall system power consump-
tion. Since the P21 pin has a higher drive capability than the other ports, it can supply voltage to the AV
pin directly.
In this case, however, the actual AV
resulting from conversion does not provide precision and can be used only for relative comparison. In
the standby mode, outputting a low on the P21 can reduce power consumption.
In the standby mode, the potential of the AV
Note The drive capability of P-ch is higher than that of other ports.
SOC
EOC
4
/f
X
s)
Previous data
Fig. 4-65 Reducing Power Consumption in the Standby Mode
Fig. 4-64 Timing Chart of A/D Conversion
AV
REF
P21
AV
AV
. .
= V
Sampling time
REF
SS
REF
DD
168/f
voltage does not provide precision. This means that the value
P-ch
X
s (28 s at 6.0 MHz)
A/D conversion
Note
V
DD
DD
pin must be equal to that of the V
PD75238
Undefined
Note
REF
DD
pin even when the
pin.
Result of conversion
PD75238
117
REF