AS3515_08 datasheet(46/67 Pages) AMSCO

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AS3515 V15

austriamicrosystems

Data Sheet, Confidential

www.austriamicrosystems.com

Revision 3.1

- 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

RTC_ON

0: Disable clock for RTC

1: Enables clock for RTC

OSC_ON

0: Disables RTC oscillator

1: Enables RTC oscillator

The register is R/W; default value is 23h

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