CDP68HC68T1

CMOS Serial Real-Time Clock With RAM and Power Sense/Control

Product Status: Mass Production

OVERVIEW

The CDP68HC68T1 Real-Time Clock provides a time/calendar function, a 32 byte static RAM, and a 3 wire Serial Peripheral Interface (SPI Bus). The primary function of the clock is to divide down a frequency input that can be supplied by the on-board oscillator in conjunction with an external crystal or by an external clock source. The internal oscillator can operate with a 32kHz, 1MHz, 2MHz, or 4MHz crystal. An external clock source with a 32kHz, 1MHz, 2MHz, 4MHz, 50Hz or 60Hz frequency can be used to drive the CDP68HC68T1. The time registers hold seconds, minutes, and hours, while the calendar registers hold day-of-week, date, month, and year information. The data is stored in BCD format. In addition, 12 or 24 hour operation can be selected. In 12 hour mode, an AM/PM indicator is provided. The T1 has a programmable output which can provide one of seven outputs for use elsewhere in the system.

Computer handshaking is controlled with a "wired-OR" interrupt output. The interrupt can be programmed to provide a signal as the result of:
  1. An alarm programmed to occur at a predetermined combination of seconds, minutes, and hours.
  2. One of 15 periodic interrupts ranging from sub-second to once per day frequency.
  3. A power fail detect. The PSE output and the VSYS input are used for external power control. The CPUR output is available to reset the processor under power-down conditions. CPUR is enabled under software control and can also be activated via the CDP68HC68T1's watchdog. If enabled, the watchdog requires a periodic toggle of the CE pin without a serial transfer.

KEY FEATURES

  • SPI (Serial Peripheral Interface)
  • Full Clock Features
  • Seconds, Minutes, Hours (12/24, AM/PM), Day of Week, Date, Month, Year (0 to 99), Automatic Leap Year
  • 32 Wordx8-Bit RAM
  • Seconds, Minutes, Hours Alarm
  • Automatic Power Loss Detection
  • Low Minimum Standby (Timekeeping) Voltage 2.2V
  • Selectable Crystal or 50/60Hz Line Input
  • Buffered Clock Output
  • Battery Input Pin that Powers Oscillator and also Connects to VDD Pin When Power Fails
  • Three Independent Interrupt Modes
  • Alarm
  • Periodic
  • Power-Down Sense
  • Pb-Free Available (RoHS Compliant)

BLOCK DIAGRAM

 Block Diagram

PARAMETRICS

Parameters
CDP68HC68T1
Basic Information
Production Status
Mass Production
Oscillator Type
CRYSTAL or EXT CLK
Frequency Range (MHz)
32k to 4M
IS
80 µA
Supply Voltage Vcc Range (V)
3 to 6
Qualification Level
Standard
Temperature Range
-40 to +85

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