RT5035A/B
CH9 : Keep Alive LDO and RTC Related Function Block
The RT5035A/B provides a 3.1V output LDO for all IC control circuits and real time clock. The LDO features low
quiescent current (3A) and high output voltage accuracy. This LDO is always on, even when the system is shut
down. For better stability, it is recommended to connect a 1F to the VDDM pin. The RTCPWR switch avoids back
charging from the RTCPWR node into the input node VDDM.
To ASIC Power
Sequencer
VM
VM
-
3.1V
CL = 40mA (min)
VDDM = 3.1V ±3%
+
BAT
RTCPWR
+
Backup
Battery
VM
1μF
VM
-
BAT
RTCPWR
VDDM
UVLO
+
-
2.6V/2.4V
falling
delay 4ms
+
VREF
UVLO
Low BAT
discharge
2.4V/2.2V
/RESET
To ASIC Power
Sequencer
RTCPWR
Rbias
RTCPWR
-
RTCPWR
32768Hz
RTCPWR
RTCPWR
/EN
/R
Count
YY/MM/DD, Week,
hh : mm : ss
With leap year
correction
1Hz
clock
Freq divider
RTC
UVLO
/R
RTCGND
+
1.9V
N = 0 to 63
R1
XOUT
C1
XIN
Internal bus
C2
VDDM
C32K
To ASIC Power
Sequencer
CH10 : Synchronous Step-Down DC-DC Converter
CH10 is suitable for memory power in DSC system. The converter operates in fixed frequency PWM mode or PFM
mode with integrated internal MOSFETs, FB resistors and compensation network. The CH10 step-down converter
can be operated at 100% maximum duty cycle to extend battery operating voltage range. The output voltage of
CH10 is adjustable by the I2C interface in the range of 1.2V to 1.52V or set by external feedback resistors, as
expressed in the following equation :
VOUT_CH10 = (1 + R1 / R2) x VFB10
Where VFB10 is 0.8V typically and suggested value for R1 is 100k to 600k.
RTC_C32K
The Frequency Divider from 32768Hz to 1Hz would generate the below 1Hz wave that with a little jitter but the 1Hz
average frequency can be finely tuned.
RTCPWR
RTCPWR
C32K
1Hz
clock
Freq divider
N = 0 to 127
Rbias
R1
C1
32767 CLKo
32767 CLKo
...
32767 CLKo
N CLKo
1Hz clock
C2
1
2
60
1
60sec
Fine tune 1Hz by digital divider can create
tuning range = (-60 to 67) / (32768Hz x 60s) = -30 to 33 ppm
each tune step size = 0.5 ppm.
But the 1Hz would include jitter and the C32K still is not tuned.
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is a registered trademark of Richtek Technology Corporation.
www.richtek.com
22
DS5035A/B-03 February 2020
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
