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R01UH0823EJ0100 Rev.1.00 Page 1624 of 1823

Jul 31, 2019

RX23W Group 45. 12-Bit D/A Converter (R12DAA)

45.2.5 D/A VREF Control Register (DAVREFCR)

The DAVREFCR register selects the reference voltage of the 12-bit D/A converter.

REF[2:0] Bits (D/A Reference Voltage Select)

The REF[2:0] bits select the reference voltage of the 12-bit D/A converter 0 and 1. When changing the value of these

bits, write 000b to the DAVREFCR.REF[2:0] bits in advance. Read the REF[2:0] bits after changing their value, and

confirm that it has been changed. When selecting the internal reference voltage, set the DADR0 and DADR1 registers to

0000h and discharge the VREF path before switching the voltage. As the path remains discharged after the reset is

released, the internal reference voltage can be selected. For details on discharging, refer to

section 45.3.2, Notes on

Using the Internal Reference Voltage as the Reference Voltage

. Do not rewrite this register during A/D conversion

using the 12-bit A/D converter. If this register is rewritten, the accuracy of A/D conversion is not guaranteed.

When the internal reference voltage is selected, the voltage generation circuit operates and current increases by about

75 μA. This circuit is not automatically turned off even if the MCU enters software standby mode with the internal

reference voltage selected.

Address(es): DA.DAVREFCR 0008 8047h

b7 b6 b5 b4 b3 b2 b1 b0

————— REF[2:0]

Value after reset:

00000000

Bit Symbol Bit Name Description R/W

b2 to b0 REF[2:0] D/A Reference Voltage Select

b2 b0

0 0 0: Not selected

0 0 1: AVCC0/AVSS0

0 1 1: Internal reference voltage/AVSS0

Settings other than above are prohibited.

R/W

b7 to b3 — Reserved These bits are read as 0. The write value should be 0. R/W

Renesas RX Series User Manual

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