Document
SHANGHAI BELLING
BL5372 Low Power Real-Time Clock (RTC)
GENERAL DESCRIPTION
The BL5372 is a CMOS type real-time clock, which is connected to the CPU via two wires and capable of serial transmission of clock to the CPU. The BL5372 can generate various periodic interrupt clock pulses lasting for long period (one month), and alarm interrupt can be made by two incorporated systems. Since an oscillation circuit is driven at a constant voltage, it undergoes fluctuations of few voltage and consequently offers low current consumption (TYP. 400nA @ 5V)
It also provides an oscillator halt sensing function applicable for data validation at power-on and other occasions. The product also incorporates a time trimming circuit that adjusts the clock with higher precision by adjusting any errors in crystal oscillator frequencies based on signals from the CPU. The crystal oscillator may be selected from 32KHz or 32.768KHz types. It adopts 8-pin SOP or TSSOP package.
FEATURES
Lowest supply current: 400nA TYP. @ 5V Connected to the CPU via only 2-wires
(MAX. 100KHz) A clock counter (counting hours, minutes,
and seconds) and a calendar counter (counting leap years, years, months, days, and days of the week) in BCD codes Two systems output providing interrupt to the CPU output (period of one month to one second, interrupt halt function) Two systems output of alarm functions Oscillation halt sensing to judge internal data validity Clock output of 32.768KHz (32KHz) (output controllable via a register) Second digit adjustment by ±30 seconds Automatic leap year recognition up to the year 2099 12-hour or 24-hour time display selectable High precision time trimming circuit Oscillator of 32.768KHz or 32KHz may be used CMOS logic Package: 8pin SOP or TSSOP
BL5372 Data Sheet
1
Shanghai Belling
ORDERING INFORMATION
Type number
BL5372 BL5372T
Name SOP8
TSSOP8
Package
Description plastic small outline package;8 pins; body width 3.9mm plastic thin shrink small outline package; 8 pins; body width 4.3mm
BLOCK DIAGRAM
PIN CONFIGURATION 8pin SOP
INTRB 1 SCL 2 SDA 3 GND 4
8 VDD 7 OSCIN 6 OSCOUT 5 INTRA
BL5372 BL5372T
8pin TSSOP
INTRB 1 SCL 2 SDA 3 GND 4
8 VDD IN 7 OSCOUT 6 OSCRA 5 INT
PIN DEFINITION
Pin No.
Symbol
1 INTRB 2 SCL 3 SDA 4 GND 5 INTRA 6 OSCOUT 7 OSCIN 8 VDD
Definition
Interrupt Output B Serial Clock Line Serial Data Line
Ground Power Interrupt Output A Oscillator Circuit Output Oscillator Circuit Input
Supply Voltage
Value
0~12V 0~5.5V 0~5.5V
0V 0~12V 0~1.5V 0~1.5V 1.8V~5.5V
IN/OUT
OUT IN
IN/OUT POWER
OUT OUT
IN POWER
2
BL5372 Data Sheet
Shanghai Belling
VDD and GND
BL5372
VDD
C1
GND
VDD
0.1u +
C2 GND
Bypass Capacitance
The VDD pin is connected to the positive power supply and GND to the ground. To prevent the possibility of noise, when rapidly changing signal took place on BL5372 pin, we have to place a capacitance beside the BL5372. One possibility is to place a bypass capacitance as close as to the BL5372. T.