Rtc(32.768Khz Crystal) - LG 410G Service Manual

3. H/W Circuit Description

3.4 RTC(32.768KHz Crystal)

R16
OSC32KIN
T16
OSC32KOUT
P16
CLK32KOUT
C16
LED_A
E17
LED_B
F17
LED_C
U12
VIBDR
H12
CKEN
G12
REGEN
F16
HSDET
M8
BM_SEL
B16
BM_PRECH
The integrated Real Time Clock (RTC) is able to provide programmable alarm functions and external
interrupts. Due to its extreme low power consumption the RTC can be supplied from a small backup
battery. This allows the generation of external interrupts, even when the main Locosto supply voltage
is switched off. For this purpose the RTC is powered by own voltage supply pins VDD_RTC and
VSS_RTC.
The RTC shall be driven by a 32.768 kHz (32k) clock which needs to be applied via the Triton(ABB)
OSC32KIN and OSC32KOUT pins. The clock can be fed from either an external clock source or use
the on chip 32 KHz oscillator module.
The low clock frequency and the optimized low power design give the possibility to run the chip with a
minimum of power dissipation. For example, for this specific application the 26 MHz reference
oscillator can be switched off during system standby and a low- power time reference can be kept
when the 32k clock is provided to the RTC.
The RTC consists of an Locosto specific RTC shell, containing the RTC macro, as well as the 32 kHz
oscillator, as described in the following sections. The module RTC Shell solely performs level
translation of the 32KHz clock to the VDD_LD1 power supply domain, and is not functionally
associated with the RTC.
LGE Internal Use Only
CLK32K
MLED1
MLED2
MOTOR_P
CKEN
JACK_DETECT
Figure. 3-4 Locosto RTC Interface
-18-
- 22 -
C104
15p
4
R103
1
220K
C105 C106
10p 15p
V_RTC
Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
X100
MC-146_7pF
3
2
32.768KHz