
AS3515 V15
austriamicrosystems
Data Sheet, Confidential
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Revision 3.1
45
- 66
6.17 Real Time Clock
6.17.1 General
The real time clock block is an independent block, which is still working even the AS3515, is shut down. 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.
6.17.2 RTC supply
The internal RTC is supplied via the RTCSUP 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 RTCSUP pin rises, the whole AS3515 gets powered up.
6.17.3 Register Description
A RTCSUP low condition can be signalled by an interrupt request, if the corresponding bit in the IRQ_ENRD0 register (0x25h) is set. To
get a second or minute interrupt the enable bit in IRQ_ENRD2 register (0x27h) All other RTC functions can be controlled and accessed
via the following registers.
RTCV Register (28h)
Table 47 RTCV Register
Bit
Name
Description
7..4
VRTC<3..0>
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
Reserved
For testing purpose only, must be set to 0h
1
RTC_ON
0: Disable clock for RTC
1: Enables clock for RTC
0
OSC_ON
0: Disables RTC oscillator
1: Enables RTC oscillator
The register is R/W; default value is 23h
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