Catalog
Timer control peripheral (TCP)
Key Features
• Full function real time clock/calendar12/24 hour mode timekeepingDay of week and day of years countersFour selectable oscillator frequenciesParallel Resonant OscillatorTwo 16-bit timers10 MHz external clock frequencyProgrammable multi-function outputFlexible re-trigger facilitiesPower fail featuresInternal power supply switch to external batteryPower Supply Bus glitch protectionAutomatic log of time into RAM at power failureOn-chip interrupt structurePeriodic, alarm, timer and power fail interruptsUp to 44 bytes of CMOS RAMINTR/MFO/T1 pins programmable High/Low and push-pull or open drainTRI-STATE® is a registered trademark of National Semiconductor Corporation.(size: 390486)WebDIRECT™ SearchWebDIRECT™is a trademark ofCoris, Inc.,a wholly-owned subsidiary ofR.R. Donnelley & Sons Company.How to download and view our Data SheetsOur Data Sheets and other documents are available for downloading in the Portable Document Format (PDF). You can view and print these documents using the Adobe Acrobat Reader. If you do not already have Adobe Acrobat Reader installed and configured on your system, thenclick here.Copyright © 1995National Semiconductor CorporationLearn About and Influence The SiteFull function real time clock/calendar12/24 hour mode timekeepingDay of week and day of years countersFour selectable oscillator frequenciesParallel Resonant OscillatorTwo 16-bit timers10 MHz external clock frequencyProgrammable multi-function outputFlexible re-trigger facilitiesPower fail featuresInternal power supply switch to external batteryPower Supply Bus glitch protectionAutomatic log of time into RAM at power failureOn-chip interrupt structurePeriodic, alarm, timer and power fail interruptsUp to 44 bytes of CMOS RAMINTR/MFO/T1 pins programmable High/Low and push-pull or open drainTRI-STATE® is a registered trademark of National Semiconductor Corporation.(size: 390486)WebDIRECT™ SearchWebDIRECT™is a trademark ofCoris, Inc.,a wholly-owned subsidiary ofR.R. Donnelley & Sons Company.How to download and view our Data SheetsOur Data Sheets and other documents are available for downloading in the Portable Document Format (PDF). You can view and print these documents using the Adobe Acrobat Reader. If you do not already have Adobe Acrobat Reader installed and configured on your system, thenclick here.Copyright © 1995National Semiconductor CorporationLearn About and Influence The Site
Description
AI
The DP8570A is intended for use in microprocessor based systems where information is required for multi-tasking, data logging or general time of day/date information. This device is implemented in low voltage silicon gate microCMOS technology to provide low standby power in battery back-up environments. The circuit's architecture is such that it looks like a contiguous block of memory or I/O ports. The address space is organized as 2 software selectable pages of 32 bytes. This includes the Control Registers, the Clock Counters, the Alarm Compare RAM, the Timers and their data RAM, and the Time Save RAM. Any of the RAM locations that are not being used for their intended purpose may be used as general purpose CMOS RAM.
Time and date are maintained from 1/100 of a second to year and leap year in a BCD format, 12 or 24 hour modes. Day of week, day of month and day of year counters are provided. Time is controlled by an on-chip crystal oscillator requiring only the addition of the crystal and two capacitors. The choice of crystal frequency is program selectable.
Two independent multifunction 10 MHz 16-bit timers are provided. These timers operate in four modes. Each has its own prescaler and can select any of 8 possible clock inputs. Thus, by programming the input clocks and the timer counter values a very wide range of timing durations can be achieved. The range is from about 400 ns (4.915 MHz oscillator) to 65,535 seconds (18 hrs., 12 min.).
Power failure logic and control functions have been integrated on chip. This logic is used by the TCP to issue a power fail
interrupt, and lock out the µp interface. The time power fails may be logged into RAM automatically when VBB> VCC. Additionally, two supply pins are provided. When VBB> VCC, internal circuitry will automatically switch from the main supply to the battery supply. Status bits are provided to indicate initial application of battery power, system power, and low battery detect.
The DP8570A is intended for use in microprocessor based systems where information is required for multi-tasking, data logging or general time of day/date information. This device is implemented in low voltage silicon gate microCMOS technology to provide low standby power in battery back-up environments. The circuit's architecture is such that it looks like a contiguous block of memory or I/O ports. The address space is organized as 2 software selectable pages of 32 bytes. This includes the Control Registers, the Clock Counters, the Alarm Compare RAM, the Timers and their data RAM, and the Time Save RAM. Any of the RAM locations that are not being used for their intended purpose may be used as general purpose CMOS RAM.
Time and date are maintained from 1/100 of a second to year and leap year in a BCD format, 12 or 24 hour modes. Day of week, day of month and day of year counters are provided. Time is controlled by an on-chip crystal oscillator requiring only the addition of the crystal and two capacitors. The choice of crystal frequency is program selectable.
Two independent multifunction 10 MHz 16-bit timers are provided. These timers operate in four modes. Each has its own prescaler and can select any of 8 possible clock inputs. Thus, by programming the input clocks and the timer counter values a very wide range of timing durations can be achieved. The range is from about 400 ns (4.915 MHz oscillator) to 65,535 seconds (18 hrs., 12 min.).
Power failure logic and control functions have been integrated on chip. This logic is used by the TCP to issue a power fail
interrupt, and lock out the µp interface. The time power fails may be logged into RAM automatically when VBB> VCC. Additionally, two supply pins are provided. When VBB> VCC, internal circuitry will automatically switch from the main supply to the battery supply. Status bits are provided to indicate initial application of battery power, system power, and low battery detect.
