4524_M Datasheet, PDF (219/310 Pages) Renesas Technology Corp – 4-BIT CISC SINGLE-CHIP MICROCOMPUTER 720 FAMILY / 4500 SERIES

4524 Group
APPLICATION
2.4 A/D converter
(5) A/D converter is used at the comparator mode
The analog input voltage is higher than the comparison voltage as a result of comparison, the
contents of ADF flag retains “0,” not set to “1.”
In this case, the A/D interrupt does not occur even when the usage of the A/D interrupt is enabled.
Accordingly, consider the time until the comparator operation is completed, and examine the state
of ADF flag by software. The comparator operation is completed after 8 machine cycles.
(6) Analog input pins
When P20/AIN0–P23/AIN3, P30/AIN4–P33/AIN7 are set to pins for analog input, they cannot be used as
I/O ports P2 and P3.
(7) TALA instruction
When the TALA instruction is executed, the low-order 2 bits of register AD is transferred to the high-
order 2 bits of register A, and simultaneously, the low-order 2 bits of register A is “0.”
(8) Recommended operating conditions when using A/D converter
The recommended operating conditions of supply voltage and system clock frequency when using A/
D converter are different from those when not using A/D converter.
Table 2.4.5 shows the recommended operating conditions when using A/D converter.
Table 2.4.5 Recommended operating conditions (when using A/D converter)
Parameter
Condition
Limits
Unit
Min. Typ. Max.
System clock frequency VDD = 4.0 to 5.5 V (through mode)
0.1
6.0 MHz
(at ceramic resonance) VDD = 2.7 to 5.5 V (through mode)
0.1
4.4
(Note 2)
VDD = 2.7 to 5.5 V (Frequency/2 mode)
0.1
3.0
VDD = 2.7 to 5.5 V (Frequency/4 mode)
0.1
1.5
VDD = 2.7 to 5.5 V (Frequency/8 mode)
0.1
0.7
System clock frequency VDD = 2.7 to 5.5 V (through mode)
0.1
4.4 MHz
(at RC oscillation)
VDD = 2.7 to 5.5 V (Frequency/2 mode)
0.1
2.2
(Note 2)
VDD = 2.7 to 5.5 V (Frequency/4 mode)
0.1
1.1
VDD = 2.7 to 5.5 V (Frequency/8 mode)
0.1
0.5
System clock frequency VDD = 4.0 to 5.5 V (through mode)
0.1
4.8 MHz
( c e r a m i c r e s o n a n c e VDD = 2.7 to 5.5 V (through mode)
0.1
3.2
selected, at external VDD = 2.7 to 5.5 V (Frequency/2 mode)
0.1
2.4
clock input)
VDD = 2.7 to 5.5 V (Frequency/4 mode)
0.1
1.2
VDD = 2.7 to 5.5 V (Frequency/8 mode)
0.1
0.6
Note: The frequency at RC oscillation is affected by a capacitor, a resistor and a microcomputer. So, set
the constants within the range of the frequency limits.
Rev.2.00 Aug, 06 2004
REJ09B0107-0200Z
2-55