DS1602

DS1602 DALLAS | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 10

Technical content

FEATURES

§ Two 32–bit counters keep track of real time and elapsed time § Counters keep track of seconds for over 125 years § Battery powered counter counts seconds from the time battery is attached until VBAT is less than 2.5 volts § VCC powered counter counts seconds while VCC is above 4.25 volts and retains the count in the absence of VCC under battery backup power § Clear function resets selected counter to 0 § Read/Write serial port affords low pin count § Maximum current drain of less than 1 µA from VBAT pin when serial port is disabled § One byte protocol defines read/write, counter address and software clear function § 8–pin DIP or optional 8–pin SOIC § Operating temperature range of –40°C to +85°C § Reduced performance operation down to VCC = 2.5V PIN ASSIGNMENT PIN DESCRIPTION RST - Reset CLK - Clock DQ - Data Input/Output GND - Ground X1, X2 - Crystal Inputs VBAT - + Battery Input VCC - +5 Volts

DESCRIPTION

The DS1602 is a real time clock/elapsed time counter designed to count seconds when V CC power is applied and continually count seconds under battery backup power with an additional counter regardless of the condition of VCC. The continuous counter can be used to derive time of day, week, month, and year by using a software algorithm. The V CC powered counter will automatically record the amount of time that V CC power is applied. This function is particularly useful in determining the operational time of equipment in which the DS1602 is used. Alternatively, this counter can also be used under software control to record real time events. Communication to and from the DS1602 takes place via a 3–wire serial port. A 1-byte protocol selects read/ write functions, counter clear functions and oscillator trim. A low cost 32.768 kHz crystal attaches directly to the X1 and X2 pins. If battery powered-only operation is desired, the VBAT pin must be grounded and the VCC pin must be connected to the battery. DS1602 8-Pin SOIC (200-mil) DS1602 8-Pin DIP (300-mil) DS1602 Elapsed Time Counter www.dalsemi.com VCC VBAT RST DQ CLK GND RST DQ CLK GND VCC VBAT

elapsed time counter occur over a 3–wire serial port. The port is activated by driving RST to a high state. powered operation down to 2.5V is possible with reduced speed performance on the serial port. Table 1. Each data transfer to the protocol register designates what action is to occur. As defined, the 32 clock cycles should always follow the protocol. RST turns on the serial port logic which allows access to the protocol register for the protocol data entry.

goes to a high impedance state. RST should only be transitioned low while the clock is high to avoid disturbing the last bit of data. All data transfers must consist of 8 bits when transferring protocol only or 8 + 32 bits when reading or writing either counter. Data transfer is illustrated in Figure 3. DATA INPUT Following the 8–bit protocol that inputs write mode, 32 bits of data are written to the selected counter on the rising edge of the next 32 CLK cycles. After 32 bits have been entered any additional CLK cycles will be ignored until RST is transitioned low to end data transfer, and then high again to begin new data transfer. DATA OUTPUT Following the eight CLK cycles that input read mode protocol, 32 bits of data will be output from the selected counter on the next 32 CLK cycles. The first data bit to be transmitted from the selected 32–bit counter occurs on the falling edge after the last bit of protocol is written. When transmitting data from the selected 32–bit counter, RST must remain at high level as a transition to low level will terminate data transfer. Data is driven out the DQ pin as long as CLK is low. When CLK is high the DQ pin is tristated. CRYSTAL SELECTION A standard 32.768 kHz quartz crystal can be directly connected to the DS1602 via pins 1 and 2 (X1, X2). The crystal selected for use should have a specified load capacitance (C L) of 6 pF. For more information on crystal selection and crystal layout considerations, please consult Application Note 58, “Crystal Considerations with Dallas Real Time Clocks.” BATTERY SELECTION The battery selected for use with the DS1602 should have an output voltage between 2.5 and 3.5 volts. A lithium battery of 35 mAh or greater will run the elapsed time counter for over 10 years in the absence of power. Small lithium coin cell batteries produce both the proper output voltage and have the capacity to supply the DS1602 for the useable lifetime of the equipment where they are installed. DS1602 ELAPSED TIME COUNTER BLOCK DIAGRAM Figure 1

ACC AVC OSC2 OSC1 OSC0 CCC CVC RD

ACTION ACC AVC OSC2 OSC1 OSC0 CCC CVC RD DESCRIPTION Read Continuous Counter 1 0 X X X X X 1 Output continuous counter on the 32 clocks following protocol. Oscillator trim register is not updated. Counters are not reset. Write Continuous Counter 1 0 X X X X X 0 Input data to continuous counter on the 32 clocks following protocol. Oscillator trim register is not updated. Counters are not reset. Read VCC Active Counter 0 1 X X X X X 1 Output VCC active counter on the 32 clocks following protocol, oscillator trim register is not updated. Counters are not reset. Write VCC Active Counter 0 1 X X X X X 0 Input data to continuous counter on the 32 clocks following protocol. Oscillator trim register is not updated. Counters are not reset. Clear Continuous Counter 0 0 X X X 1 X X Resets the continuous counter to all zeroes at the end of protocol. Oscillator trim register is not updated. Clear VCC Active Counter 0 0 X X X X 1 X Resets the VCC active counter to all zeroes at the end of protocol. Oscillator trim register is not updated. Set Oscillator Trim Bits 1 1 A B C X X 0 Sets the oscillator trim register to a value of ABC. Counters are unaffected. X = Don’t Care

TIMING DIAGRAM: READ/WRITE DATA TRANSFER NOTE: tCL, tCH, tR, and tF apply to both read and write data transfer.

ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground –0.3V to +7.0V Operating Temperature –4 0°C to +85°C Storage Temperature –55 °C to +125°C Soldering Temperature 260°C for 10 seconds * This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. RECOMMENDED DC OPERATING CONDITIONS (-40°C to +85°C) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Supply Voltage VCC 4.5 5.0 5.5 V 1 Battery Supply Voltage VBAT 2.5 3.0 3.5 V 1 Logic 1 Input VIH 2.0 VCC+0.3 V 1 Logic 0 Input VIL -0.3 0.8 V 1 DC ELECTRICAL CHARACTERISTICS (-40°C to +85°C; VCC = 5V ±10%) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Input Leakage ILI -1 +1 µA I/O Leakage ILO -1 +1 µA Logic 1 Output VOH 2.4 V 2 Logic 0 Output VOL 0.4 V 3 Active Supply Current ICC 1 mA 4 Timekeeping Current ICC1 50 µA 5 Timekeeping Current IBAT 400 nA 6 Leakage Current IBATL 100 nA 11 CAPACITANCE (tA = 25°C) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Input Capacitance CI 5 pF I/O Capacitance CI/O 10 pF Crystal Capacitance CX 6 pF 10

AC ELECTRICAL CHARACTERISTICS (VCC = +5V ±10%; -40°C to 85°C) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Data to CLK Setup tDC 50 ns 7 CLK to Data Hold tCDH 60 ns 7 CLK to Data Delay tCDD 200 ns 7, 8, 9 CLK Low Time tCL 250 ns 7 CLK High Time tCH 250 ns 7 CLK Frequency fCLK DC 2.0 MHz 7 CLK Rise & Fall tF, tR 500 ns RST to CLK Setup tCC 100 ns 7 CLK to RST Hold tCCH 60 ns 7 RST Inactive Time tCWH 1 µs 7 RST Low to I/O High Z tRDZ 70 ns 7 CLK High to I/O High Z tCDZ 20 ns 7 NOTES: 1. All voltages are reference to ground. 2. Logic 1 voltages are specified at a source current of 1 mA. 3. Logic 0 voltages are specified at a sink current of 4 mA. 4. ICC is specified with the DQ pin open. 5. ICC1 is specified with V CC at 5.0V and RST = GND. 6. IBAT is specified with V CC < VBAT and VBAT within DC recommended operating conditions. 7. Measured at VIH = 2.0V or VIL = 0.8V. 8. Measured at VOH = 2.4V or VOL = 0.4V. 9. Load capacitance = 50 pF. 10. Specified as the load capacitance for which the crystal frequency is guaranteed (see crystal manufacturer’s data sheet). 11. Leakage current is the amount of current consumed from the battery when V CC is not present and the oscillator is turned off.

A IN. MM 0.360 9.14 0.400 10.16 B IN. MM 0.240 6.10 0.260 6.60 C IN. MM 0.120 3.05 0.140 3.56 D IN. MM 0.300 7.62 0.325 8.26 E IN. MM 0.015 0.38 0.040 1.02 F IN. MM 0.120 3.04 0.140 3.56 G IN. MM 0.090 2.29 0.110 2.79 H IN. MM 0.320 8.13 0.370 9.4 J IN. MM 0.008 0.20 0.012 0.30 K IN. MM 0.015 0.38 0.021 0.53

A IN. MM 0.203 5.16 0.213 5.41 B IN. MM 0.203 5.16 0.213 5.41 C IN. MM 0.070 1.78 0.074 1.88 E IN. MM 0.004 0.102 0.007 0.254 F IN. MM 0.074 1.88 0.084 2.13 G IN. MM

0.050 BSC

1.27 BSC

H IN. MM 0.302 7.67 0.318 8.07 J IN. MM 0.006 0.152 0.010 0.254 K IN. MM 0.013 0.33 0.020 0.508 L IN. MM 0.019 4.38 0.030 0.762