DS-72-34 Datasheet, PDF (13/18 Pages) Cymbet Corporation – I2C Real-Time Clock/Calendar with Integrated Backup Power

Preliminary
CBC34803 EnerChip™ RTC
Typical CBC34803 EnerChip RTC Connection to Microcontroller
Figure 5 illustrates how the CBC34803 is typically connected to a microcontroller (MCU) in a system. For
simplicity, only the MCU lines routed to/from the CBC34803 are shown. The I/O line from the MCU to the EN pin
of the CBC34803 is optional for reducing power consumption of the CBC34803. The EN pin can be forced low by
the MCU when the integrated EnerChip does not need to be charged. If EN is not connected to the MCU or
otherwise controlled externally, it must be tied to VDD to ensure the EnerChip is charged when VDD is valid.
VDD
U2
VDD
I/O
MCU
INT
SDA
VSS ^SCL
Y1
32.768KHz
VDD
R3
10K
VDD
C1
0.1uF
VDD
U1
OSCI EN RESET VDD
1 _OSCO
FOUT/IRQ ¹²
2 _VOUT
3 _IRQ2
CBC34803
AF ¹¹
SCL ¹⁰
4 _nc
nc ⁹
VSS VCHG VEC SDA
VDD
R1
10K
FOUT
C3
47pF
R2
10K
Figure 5: Typical Application Schematic Showing MCU Connections to CBC34803
©2014-2015 Cymbet Corporation • Tel: [phone] • www.cymbet.com
DS-72-34 V.20

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