DS1672 Datasheet | Dallas Semiconductor

FEATURES 32-bit counter 2-wire serial interface Automatic power-fail detect and switch circuitry Power-fail reset output Low-voltage oscillator operation (1.3V min.) Trickle charge capability PIN ASSIGNMENT X1 X2 VBACKUP GND 1 2 3 4 8 7 6 5 VCC RST SCL SDA PIN DESCRIPTION ORDERING INFORMATION DS1672X-X 2 2.0V operation 3 3.0V operation 33 3.3V operation blank S VCC, VBACKUP GND X1, X2 SCL SDA - Power Supply Inputs - Ground - 32.768 k Hz crystal pins - Serial clock - Serial data - Reset output 8-pin DIP 8-pin SOIC 8-pin µSOP DESCRIPTION The DS1672 incorporates a 32-bit counter and power monitoring functions. The 32-bit counter is designed to count seconds and can be used to derive time of day, week, month, month, and year by using a software algorithm. A precision temperature-pensated reference and parator circuit monitors the status of VCC. When an out-of-tolerance condition occurs, an internal power-fail signal is generated which forces the reset to the active state. When VCC returns to an in-tolerance condition, the reset signal is kept in the active state for 250 ms to allow the power supply and processor to stabilize. OPERATION The block diagram in Figure 1 shows the main elements of the DS1672. As shown, munications to and from the DS1672 occur serially over a 2-wire bi-directional bus. The DS1672 operates as a slave device on the serial bus. Access is obtained by implementing a START condition and providing a device identification code followed by a register address. Subsequent registers can be accessed sequentially until a STOP condition is executed. 1 of 13 .. DS1672 BLOCK DIAGRAM Figure 1 X1 X2 32-BIT COUNTER (4 BYTES) CONTROL TRICKLE CHARGER OSCILLATOR AND DIVIDER VCC VBACKUP GND RST POWER CONTROL CONTROL LOGIC SERIAL BUS INTERFACE ADDRESS REGISTER ADDRESS MAP The counter is accessed by reading or writing the first 4 bytes of the DS1672 (00h - 03h). The control register and trickle charger are accessed by...