Astronomical Timer

Energy Management from Dusk to Dawn - Automatically.

Renesas ASSP device TIMR-IS1 is a digital IC integrating the astronomical calculator. The configuration input parameters for the astronomical function are configured via the input pins.

Built-in Astro function takes geographic location inputs from the provided switch inputs and calculates the Sunrise and Sunset timings for the entire Indian & sub-continents with 1204 cities.

System Block Diagram


  • Allows energy saving via Programming of time and geographical area of installation
  • Random On Time Delay (up to 59sec) for street light mode
  • Daily automatic regulation of sunrise and sunset time.
  • Suitable to program the coordinates of the city through easy interface via dip switches
    1. Latitude and longitude information is stored for 1204 cities – DIP switch 1
    2. City can be selectable through dip switch – DIP switch 2
    3. Off time can be programmable through dip switch- DIP switch3 enabling energy management
  • Separate (RTC) clock battery is present can be programmable through UART
  • Manual on/off is present
  • Enabling energy management

Technical Specifications:

  • Supply Voltage (1 Phase): 110 to 240 VAC
  • Power Consumption (Max.): 4VA
  • Battery Backup : Minimum 6 years running reserve
  • LED Indication: Red LED for Relay Status
  • Contact Arrangement : 1 C/O (SPDT)
  • Contact Rating: 16A (NO) and 5A (NC) @240VAC/ 24VDC
  • Incandescent Lamps: 1000 W
  • Inductive Load (Cos o = 0.6): 6A @ 250VAC
  • Clock Accuracy: Features RTC with built-in 32.768KHz
  • DTCXO, High Stability (UB ± 5.0 x 10-6 / -40oC to +85oC (Equivalent to 13secs per month deviation)


  • Domestic applications: Gate Lights, Outside lights, Parking, Home Automation
  • Commercial Applications: Street Illuminations, Road Sign Illuminations, Shopping Center Illuminations (Luminous Signboards), Park/ Garden Illuminations, Parking Illuminations
  • Others: Home Illuminations, Other illumination applications
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