AS3525-A/-B C22O22
Data Sheet, Confidential
7.4.19
Real Time Clock
7.4.19.1 General
The real time clock block is an independent block, which is still working even when the chip is shut down. The only condition for this operation is
that BVDD has a voltage of above 1.0V. The block uses a standard 32kHz crystal that is connected to a low power oscillator. An internal 32bit
second register stores the current time.
The RTC block has special functions for trimming the time base and generating interrupts every second or minute.
7.4.19.2 RTC supply
The internal RTC is supplied via the BVDD pin. The block has an internal LDO to generate the RTC supply voltage on RVDD pin. This voltage can
be programmed via the RTCV register (0x28h). If the internal RTC is not used, RVDD can be used to supply an external RTC block.
If the supply voltage on BVDD pin rises, the whole chip gets powered up. See also power-up conditions in chapter 7.4.1.2.
7.4.19.3 Register Description
Table 148 RTC Related Register
Name
Base
Offset
Description
IRQ_ENRD_0
IRQ_ENRD_2
I2C audio master
I2C audio master
0x25
0x27
Interrupt settings for RVDD under-voltage detection
Interrupt settings for getting a second or minute interrupt
Table 149 RTCV Register
Name
RTCV
Base
Default
0x23
I2C audio master
RTC Voltage Register
This register is reset at a RVDD-POR. (DVDD_POR for C21O20)
Offset: 0x28
Bit
Bit Name
VRTC<3..0>
Default
Access
Bit Description
7:4
0010
R/W
Sets the RTC supply voltage, 16 steps @ 0.1V, default is 1.2V
0000: 1V
0001: 1.1V
0010: 1.2V
…
1110: 2.4V
1111: 2.5V
3:2
1
-
00
1
n/a
R/W
do not change
RTC_ON
RTC clock control:
0: Disable clock for RTC
1: Enables clock for RTC
RTC oscillator control:
0: Disables RTC oscillator
1: Enables RTC oscillator
0
OSC_ON
1
R/W
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