UPD78F0138 NEC, UPD78F0138 Datasheet - Page 255

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

Note The time from the rising of the ADCE bit to the falling of the ADCS bit must be 14
Cautions 1. A/D conversion must be stopped before rewriting bits FR0 to FR2 to values other than the
Remark f
Notes 1.
Remark f
the reference voltage.
Note Data of first conversion cannot be used.
Boost reference voltage
2.
ADCS
2. For the sampling time of the A/D converter and the A/D conversion start delay time, see (11)
3. If data is written to ADM, a wait cycle is generated. Do not write data to ADM when the CPU is
X
: X1 input clock oscillation frequency
X
0
0
1
1
Set so that the A/D conversion time is as follows.
• Standard products, (A) grade products: 14
• (A1) grade products:
• (A2) grade products:
A booster circuit is incorporated to realize low-voltage operation. The operation of the circuit that
generates the reference voltage for boosting is controlled by ADCE, and it takes 14
start to operation stabilization. Therefore, when ADCS is set to 1 after 14
from the time ADCE is set to 1, the conversion result at that time has priority over the first conversion
result.
: X1 input clock oscillation frequency
identical data.
in 12.6 Cautions for A/D Converter.
operating on the subsystem clock and the X1 input clock is stopped.
CHAPTER 34 CAUTIONS FOR WAIT.
Figure 12-3. Timing Chart When Boost Reference Voltage Generator Is Used
ADCE
ADCE
ADCS
0
1
0
1
Stop status (DC power consumption path does not exist)
Conversion waiting mode (only reference voltage generator consumes power)
Conversion mode (reference voltage generator operation stopped
Conversion mode (reference voltage generator operates)
Table 12-2. Settings of ADCS and ADCE
Note
Boost reference voltage generator: operating
CHAPTER 12 A/D CONVERTER
Conversion
operation
User’s Manual U16228EJ2V0UD
14
16
Conversion
A/D Conversion Operation
waiting
µ
µ
µ
s or longer but less than 100
s or longer but less than 60
s or longer but less than 48
Conversion
operation
Conversion stopped
µ
µ
µ
s
s
s
µ
Note
µ
s or more has elapsed
s or longer to stabilize
)
µ
For details, see
s from operation
255