Datasheet Real-Time Clock (RTC) series 2 I C BUS Serial Interface RTC with High-precision Oscillation Adjustment BU9873 Outline Important Characteristics The BU9873 is a CMOS real-time clock, which has a Time Keeping Voltage 1.45V to 5.5V built-in interrupt generation function. This product is Time Keeping Current 1 0.4A (Typ) 2 connected to the CPU via I C interface, and configured to (V =3V, Ta=+25C) DD perform serial transmission of time and calendar data to Time Keeping Current 2 1.0A (Max) the CPU. A high-precision oscillation adjustment circuit is (V =3V, Ta=-40C to +85C) DD also integrated, which is capable of adjusting time counts Power Supply Voltage 1.8V to 5.5V with digital method, and correcting deviations in the Access Frequency 1 100kHz (Max) oscillation frequency of the crystal oscillator. (VDD=1.8V to 2.5V) Access Frequency 2 400kHz (Max) (VDD=2.5V to 5.5V) Features Package W (Typ) x D (Typ) x H (Max) 2 Connected to the CPU via I C Interface Time (Hour Minute Second, Selectable 12-Hour and 24-Hour Mode Setting) Calendar (Year Month DayWeek) Periodic Interrupt Function SOP8 MSOP8 (Output from INTRB, Ranging from 1 Second to 1 5.00mm x 6.20mm x 1.71mm 2.90mm x 4.00mm x 0.90mm Month) Alarm Interrupt Function (Day-of-Week Hour Minute in Setting Format, Output from INTRB) Oscillation Halt Sensing Function SOP- J8 VSON008X2030 32.768 kHz Clock Output 4.90mm x 6.00mm x 1.65mm 2.00mm x 3.00mm x 0.60mm (Output from 32KOUT with Control Register) 30 Second Adjustment Function Automatic Leap Year Recognition up to the Year 2099 TSSOP-B8 Built-in Oscillation Stabilizing Capacitors (CG, CD) 3.00mm x 6.40mm x 1.20mm High-Precision Oscillation Adjustment Circuit Product structure: Silicon monolithic integrated circuit This product has no designed protection against radioactive rays w ww.rohm.com TSZ02201-0919AGZ00010-1-2 2013 ROHM Co., Ltd. All rights reserved. 1/37 TSZ2211114001 26.Jan.2018 Rev.002 BU9873 Typical Application Circuit R 10k PU R 1k S 32KOUT VDD Primary C C 1 2 Battery SCL OSCIN CPU C GOUT SDA OSCOUT C DOUT VSS INTRB Quartz crystal: 32.768 kHz (C =6pF, R =20k) L 1 C = C = 0 pF GOUT DOUT Figure 1. Typical application circuit (with primary battery) R 10k PU R 1k S 32KOUT VDD Secondary C C 1 2 Battery SCL OSCIN CPU C GOUT SDA OSCOUT C DOUT VSS INTRB Quartz crystal: 32.768 kHz (C =6pF, R =20k) L 1 C = C = 0 pF GOUT DOUT Figure 2. Typical application circuit (with secondary battery) The above circuits do not guarantee operation. Set the circuits and constants after performing sufficient evaluation using the actual application. And please arrange the circuits to keep Notes during Power On. If it is necessary, please use the discharge circuits of battery to keep it. www.rohm.com TSZ02201-0919AGZ00010-1-2 2013 ROHM Co., Ltd. All rights reserved. 2/37 TSZ2211115001 26.Jan.2018 Rev.002