Battery Charger Timer


Quantity Pricing

The following are the unit prices, as you vary the quantity purchased:






All prices are in Canadian dollars. We use the total number purchased (ELM380P + ELM380SM) for the calculation.


The ELM380 is an 8 pin integrated circuit that is used to provide very long time interval outputs. It is typically used for enabling the charge circuit in Nickel Cadmium battery chargers, but can be easily adapted for many other applications.

An express ‘one button’ mode is provided on chip specifically for rechargeable battery circuits. In this mode, pressing the start button once initiates a user selectable 8 or 14 hour timing interval, after which the circuit shuts off. If one prefers, pressing that same button multiple times will allow for user programmable intervals of from 2 to 77 hours.

The circuit requires a 60Hz full-wave rectified signal for its operation. This 120Hz time base is used for all of the timekeeping functions, providing good long term stability and low cost.

Interfacing to the ELM380 is simplified by the provision of internal pull-up resistors so that the mechanical switches can be directly connected without additional components, or simply not used, depending on the application.


  • Ni-Cd battery chargers
  • Yard lighting or watering controls
  • Houseplant grow lamp controllers


  • Low power CMOS design – typically 1mA at 5V
  • Wide supply range – 3.0 to 5.5 volt operation
  • Quick settings of 8 or 14 hours
  • Complementary outputs simplify designs
  • External reset input for system use
  • Internal pullup resistors for switch inputs
  • High current drive outputs – up to 25 mA
  • Line frequency input for accurate timing

Connection Diagram

( PDIP or SOIC, top view )
ELM380 connection diagram

Block Diagram

ELM380 block diagram


The ELM380 data sheet (ver B, 28K):

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