UPD78F9500MA-CAC-A Datasheet, PDF (177/342 Pages) Renesas Technology Corp – 8-Bit Single-Chip Microcontrollers

CHAPTER 9 A/D CONVERTER (μPD78F920x ONLY)
(8) Conversion results just after A/D conversion start
The first A/D conversion value immediately after A/D conversion starts may not fall within the rating range if the
ADCS bit is set to 1 within 1 μs after the ADCE bit was set to 1, or if the ADCS bit is set to 1 with the ADCE bit =
0. Take measures such as polling the A/D conversion end interrupt request (INTAD) and removing the first
conversion result.
(9) A/D conversion result register (ADCR, ADCRH) read operation
When a write operation is performed to the A/D converter mode register (ADM) and analog input channel
specification register (ADS), the contents of ADCR and ADCRH may become undefined. Read the conversion
result following conversion completion before writing to ADM and ADS. Using a timing other than the above may
cause an incorrect conversion result to be read.
(10) The operating current at the conversion waiting mode
The DC characteristic of the operating current at the STOP mode is not satisfied at the conversion waiting mode
(when A/D converter mode register (ADM) is set up with bit 7(ADCS) =0 and bit 0 (ADCE) =1) (only comparator
consumes power).
(11) Internal equivalent circuit
The equivalent circuit of the analog input block is shown below.
Figure 9-21. Internal Equivalent Circuit of ANIn Pin
ANIn
ROUT
RIN
COUT
CIN
LSI internal
Table 9-3. Resistance and Capacitance Values (Reference Values) of Equivalent Circuit
VDD
ROUT
RIN
COUT
CIN
4.5 V ≤ VDD ≤ 5.5 V
1 kΩ
3 kΩ
8 pF
15 pF
2.7 V ≤ VDD < 4.5 V
1 kΩ
60 kΩ
8 pF
15 pF
Remarks 1. The resistance and capacitance values shown in Table 9-3 are not guaranteed
values.
2. n = 0 to 3
3. ROUT: Allowable signal source impedance
RIN: Analog input equivalent resistance
COUT: Internal pin capacitance
CIN: Analog Input equivalent capacitance
User’s Manual U18172EJ3V0UD
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