Rainbow Electronics DS1682 User Manual
Note:
Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple
channels. For information about device
ALARM
ALARM
ALARM
ALARM
1
6 3 2
8 4 5 7
DS1682
www.maxim
-
ic.com
FEATURES
§ Records the total time that the event input has
been active and the number of events that
have occurred
§ 32-bit, nonvolatile, elapsed time counter
monitors event duration with quarter-second
resolution and provides 34 years of total t ime
accumulation
§ Programmable elapsed time
§ Nonvolatile 17-bit event counter records the
total number of times an event has occurred
§ Calibrated, temperature-compensated RC
time base accurate to 2% typical
§ 10 bytes of EEPROM user memory
§ Write disable function to prevent the memory
from being changed or erased
§ 2-wire serial communication
§ Wide power-supply range (2.5V to 5.5V)
§ Useful in time-of -use warranty, calibration,
repair, and maintenance applications
output
Total Elapsed Time Recorder
PIN ASSIGNMENT
EVENT
N/C
ALARM
GND
DS1682
DS1682S 8-Pin SO (150mil)
Top View
Package dimension information can be found at:
http://dbserv.maxim-ic.com/products.cfm
PIN DESCRIPTION
EVENT - Event Input
- Alarm Output
GND - Ground
SDA - Serial-Data I/O
SCL - Serial-Clock Input
VCC - Voltage Supply
N/C - No Connect
V
N/C
SDA
with Alarm
CC
SCL
ORDERING INFORMATION
DS1682S 8-Pin SO (150mil) -40°C to +85°C
DESCRIPTION
The DS1682 is an integrated elapsed time recorder containing a factory-calibrated, temperaturecompensated RC time base that eliminates the need for an external crystal. Using EEPROM technology
to maintain data in the absence of power, the DS1682 requires no backup power source. The DS1682
detects and records the number of events on the EVENT pin and the total cumulative event time since the
DS1682 was last reset to 0. The
user-programmed alarm value. The polarity of the open-drain
drive low or to become high impedance upon an alarm condition. The DS1682 is ideal for applications
that monitor the total amount of time that a device has been in operation and/or the number of uses since
inception of service, repair, or the last calibration.
pin alerts the user when the total time accumulated equals the
pin can be programmed to either
revisions of any device may be simultaneously available through various sales
errata, click here: http://dbserv.maxim-ic.com/errata.cfm.
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DS1682
A
OPERATION
The block diagram in Figure 1 shows the relationship between the major functional blocks, the serial
interface, and the EEPROM memory section of the DS1682. Upon power-up, the DS1682 transfers the
contents of the EEPROM into the counters and memory registers where the data can be read and written
through the serial interface. The content of the counters and memory registers are written into the
EEPROM memory when the EVENT pin transitions from a logic high to a logic low.
Figure 1. BLOCK DIAGRAM
SCL
SDA
OSCILLATOR
AND
DIVIDER
V
CC
LARM
EVENT
CONTROL
LOGIC
AND
EVENT
GLITCH
FILTER
The DS1682 uses a calibrated, temperature-compensated RC time base to increment an elapsed time
counter (ETC) while an event is active. When the event becomes active, the contents of the nonvolatile
EEPROM are transferred to the ETC and event counter and the oscillator starts. As the event continues,
the ETC is incremented in quarter-second increments. When the event becomes inactive, the event
counter is incremented and the contents of the ETC and event counter are written to the nonvolatile
EEPROM.
ALARM output can be used to indicate when the ETC has matched the value in the alarm register.
The
The DS1682 can be configured to prevent clearing the alarm and the elapsed time and event counters.
The user memory can be separately write-protected.
SERIAL
INTERFACE
USER, CONTROL, AND
CONFIGURATION
REGISTERS
ELAPSED TIME
COUNTER (ETC)
ALARM REGS
AND
COMPARE LOGIC
EVENT COUNTER
EEPROM ARRAY
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SIGNAL DESCRIPTIONS
V
– VCC is a +2.5V to +5.5V input supply.
CC
DS1682
GND – Ground.
SCL (2-Wire Serial-Clock Input) – The SCL pin is the serial-clock input for the 2-wire synchronous
communications channel. The SCL pin is an input that requires an external pullup resistor.
SDA (2-Wire Input/Output) – The SDA pin is the data input/output signal for the 2-wire synchronous
communications channel. The SDA pin is an open-drain I/O, which requires an external pullup resistor.
EVENT (Event Input) – The EVENT pin is the input the DS1682 monitors to determine when an event
occurs. When the pin is pulled high, the contents of the EEPROM are transferred to the ETC and the
oscillator starts. The ETC will begin to count in quarter-second increments. When the EVENT pin falls to
a logic 0, the event counter increments and the event counter, ETC, and user-memory data are stored in
the EEPROM array. When the EVENT pin changes states, the 2-wire bus is unavailable for
communications for tEW. The EVENT input is also deglitched (tG) to prevent short noise spikes from
triggering an event.
ALARM (Alarm Output) – The DS1682 monitors the values in the ETC for the programmed value in the
alarm register. When the ETC matches the alarm value, the alarm flag (AF) is set. Once set, the alarm
flag cannot be reset. See the operating descriptions for the AOS and AP bits for details about the
operation of the ALARM pin.
N/C (No Connect) – This pin is not connected internally.
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Figure 2. MEMORY MAP
DS1682
ADDR BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FUNCTION
00 0 AF WDF WMDF AOS RE AP ECMSB
Configuration
Register
01 Low Byte
02 Low-Middle Byte
03 High-Middle Byte
Alarm Register
04 High Byte
05 Low Byte
06 Low-Middle Byte
07 High-Middle Byte
08 High Byte
09 Low Byte
0A High Byte
Elapsed
Time
Counter
(ETC)
Event
Counter
0B Byte 1
0C Byte 2
0D Byte 3
0E Byte 4
0F Byte 5
10 Byte 6
User Memory
11 Byte 7
12 Byte 8
13 Byte 9
14 Byte 10
15
16
17
18
19
Not Used (reads 00h) Not Used
1A
1B
1C
1D Reset Command Reset Command
1E Write Disable Write Disable
1F Write Memory Disable Memory Disable
User-modified data are not stored in EEPROM until an event becomes inactive.
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DS1682
EVENT LOGGING
When the DS1682 is powered up, the event time and count values recorded in the EEPROM are
transferred to the ETC and event counter and the device waits for an event. When an event triggers the
input by transitioning the EVENT pin from a low to a high level, the following occurs:
1) The RC oscillator starts.
2) The alarm, ETC, and event counter are transferred from EEPROM to RAM.
Note: Reading the RAM during the transfer will result in invalid data.
3) After tES, the ETC increments. An event greater than tG but less than tES increments the event counter
but not the ETC (zero-length event).
4) The ETC increments every TEI. The ETC holds time in quarter-second resolution.
5) When the EVENT pin goes low, the event counter increments, the oscillator stops, and the ETC and
event counter are transferred to EEPROM. The 2-wire bus is not available for t
See Figure 3 for timing.
The ETC stops counting and does not roll over once FFFFFFFFh, or approximately 34 years, is reached.
Figure 3. EVENT INPUT TIMING
EW
.
DEVICE SETUP
Once installed in a system, the DS1682 can be programmed to record events as required by the
application, and can be tested by generating events and monitoring the results. Afterwards, it can be
“locked” to prevent alteration of the event and alarm registers and the alarm condition.
The following is a typical sequence:
1) Write the configuration register, alarm registers, and user memory to the desired values.
2) Write-protect the alarm, ETC, and event counter registers with the write disable command if needed.
3) Write-protect the user memory with the write-memory disable command, if needed.
4) Issue a reset (described in the Reset Command section).
The alarm, ETC and event counter registers, and user memory, once locked, cannot be changed.
Upon reset, the ETC and event counter registers are cleared. The RE bit is cleared by the device, and the
configuration register becomes read-only. Additional resets are ignored.
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