The CMOS bq3285LF is a low-power microprocessor peripheral providing a time-of-day clock and 100-year calendar with alarm features and bat-tery operation. The architecture is based on the bq3285 RTC with added features: century bit, low-voltage operation, 32.768kHz output, 126 additional bytes of CMOS, two shadow registers of last address used, and a day-of-month alarm to be compliant withtheACPIRTCspecification.
A 32.768kHz output is available for sustaining power-management activities. The bq3285LF 32kHz out-put is always on whenever VCC is valid. In VCC standby mode, the 32kHz is active, and the bq3285LF typically draws 100A. Wake-up capability is provided by an alarm interrupt, which is ctive in battery-backup mode. In battery-backup mode, current drain is less than 550nA.
The bq3285LF write-protects the clock, calendar, and storage registers during power failure. A backup battery then maintains data and oper-atestheclockandcalendar.
The bq3285LF is a fully compatible real-time clock for IBM AT-compatible computers and other applications. The only external components are a 32.768kHz crystal and a backupbattery.
The bq3285LF is intended for use in 3V systems; however, it may also operate at 5V and then go into a 3V power-down state, write-protecting asifina3Vsystem.
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ACPI-compliant day-of-month alarm Y2K century bit Direct clock/calendar replace-ment for IBM AT-compatible computers and other applications 2 index shadow registers 2.75.5V operation 240 bytes of general nonvolatile storage Dedicated 32.768kHz output pin System wake-up capability-alarm interrupt output active in battery-backup mode Less than 0.55A load under battery operation Selectable Intel or Motorola bus timing 24-pin plastic SSOP
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| Symbol |
Parameter |
Value |
Unit |
Conditions |
| VCC |
DC voltage applied on VCC relative to VSS |
-0.3 to 7.0 |
V |
|
| VT |
DC voltage applied on any pin excluding VCC
relative to VSS |
-0.3 to 7.0 |
V |
VT VCC + 0.3 |
| TOPR |
Operatingtemperature |
0 to +70 |
°C |
Commercial |
| TSTG |
Storage temperature |
-55 to +125 |
°C |
|
| TBIAS |
Temperature under bias |
-40 to +85 |
°C |
|
| TSOLDER |
Soldering temperature |
260 |
°C |
For 10 seconds |
Post a Buying Lead
Required Field 
