UPD70F3793GC-UEU-AX Datasheet, PDF (862/1113 Pages) Renesas Technology Corp – RENESAS MCU V850ES/Jx3-L Microcontrollers

V850ES/JG3-L
CHAPTER 23 STANDBY FUNCTION
(2) Subclock low-power operation control register (SOSCAMCTL)
The SOSCAMCTL register is used to select the low-power control method of the subclock (fXT) to perform
even lower power operations in the RTC backup mode.. This register is a special register that can only be
written in a specific sequence (see 3.4.7 Special registers).
This register can be read or written in 8-bit or 1-bit units.
This register is cleared to 00H when a power-on reset operation is executed for RVDD.
After Reset: Note R/W Address: FFFFFB03H
7
6
5
4
3
2
1
<0>
SOSCAMCTL
0
0
0
0
0
0
0
AMPHS
AMPHS
Subclock (fXT) oscillator mode select
0 Normal oscillation
1 Ultra low consumption oscillation
Note
RVDD power-on reset : 00H
Other kind of reset : Previous value retained
Caution Be sure to set bits 7 to 1 to “0”.
Remark When the subclock (fXT) is oscillating in the ultra low consumption mode, the effects of noise can more
easily cause the incorrect number of oscillation cycle counting. Before deciding to use this mode,
thoroughly evaluate the effects of noise.
23.9.2 RTC backup mode setting conditions
The RTC backup mode can be entered by stopping power supplies other than the RTC backup power
supply (RVDD) after the settings for the pre-RTC backup mode have been specified. The procedures for
setting and exiting pre-RTC backup mode are described below.
(1) Conditions for setting pre-RTC backup mode
If the following conditions are satisfied, the pre-RTC backup mode is set.
<1> RTCBUMCTL0.RBMEN = 1 (Using RTC backup mode is enabled.)
<2> SOSCAMCTL.AMPHS = 1 (This setting is necessary for subclock (fXT) oscillation in the ultra low
consumption mode, but the setting is not necessary for the RTC backup
mode.)
<3> RTCBUMCTL0.RBMSET = 1 (Pre-RTC backup mode setting.)
(2) Conditions for exiting pre-RTC backup mode
If the following conditions are satisfied, the pre-RTC backup mode is exited.
<1> SOSCAMCTL.AMPHS = 0 (the normal oscillation of the subclock.)
<2> RTCBUMCTL0.RBMSET = 0 (Pre-RTC backup mode exiting.)
R01UH0165EJ0700 Rev.7.00
Sep 22, 2011
Page 862 of 1113