UPD78F1502AGK-GAK-AX Datasheet, PDF (452/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 13 VOLTAGE REFERENCE (μ PD78F150xA only)
Figure 13-3. Format of Analog Reference Voltage Control Register (ADVRC)
Address: FFF36H After reset: 00H
Symbol
7
6
ADVRC ADREF
0
R/W
5
0
4
3
2
0
VRSEL
0
1
VRGV
0
VRON
ADREF
0
1
Negative reference voltage supply of A/D converter selection
AVSS
AVREFM (external voltage reference input)
VRSEL
VRGV
VRON
0
0
0
0
1
0
1
0
0
1
0
1
1
1
0
1
1
1
Other than the above
Positive reference
voltage supplies
selection of A/D
and D/A
converters
Operation
control of
voltage
reference
Output
voltage
selection
of voltage
reference
Operation
control of
input gate
voltage
boost
circuit for
A/D
converter
Relationship with
the conversion
mode used
AVREFP
(external voltage
reference input)
Stops
operation
(Hi-Z)
2.5 V
2.0 V
Stops
Can be set in
operation normal mode 1.
Enables
operation
Can be set in
normal mode 2
or low voltage
mode.
VREFOUT
Stops
2.5 V
Stops
−
(voltage reference operation
operation
output)
(pull-down
output)
Enables
operation
2.5 V
Enables
operation
Can be set in
normal mode 2
or low voltage
mode.
Stops
2.0 V
−
operation
(pull-down
output)
Enables
operation
2.0 V
Can be set in
normal mode 2
or low voltage
mode.
Setting prohibited
Cautions 1. During voltage reference operation, be sure to connect a tantalum capacitor (capacitance: 10
μF±30 %, ESR: 2 Ω (max.), ESL: 10 nH (max.)) and a ceramic capacitor (capacitance: 0.1 μF±30 %,
ESR: 2 Ω (max.), ESL: 10 nH (max.)) to the VREFOUT/AVREFP pin for stabilizing the reference voltage.
Furthermore, do not apply a voltage from the VREFOUT/AVREFP pin during voltage reference
operation.
2. To use voltage reference output (VREFOUT) to the positive reference voltage of the A/D converter
(ADREFP) and the positive reference voltage of the D/A converter (DAREFP), be sure to set VRON to
1 after setting VRSEL to 1.
R01UH0004EJ0501 Rev.5.01
436
Jun 20, 2011