• Superior safety

Poly carbonmonofluoride lithium batteries do not employ any harmful or corrosive liquids or gases for the active materials, assuring a construction that provides for exceptional safety. This superior safety level has been confirmed by repeated testing. Result: Panasonic lithium batteries have been recognized as meeting the UL safety standard (UL1642).

(1) The increase in battery temperature when continu-ously shorted is shown by the following graph.



(2) Destruction of the charge-preventive diode.

  It is anticipated that the power supply voltage is directly applied to the batteries. In this case, a large current will flow to the battery initially, but the current will diminish rapidly, with no fear of safety trouble. (Coin type)
However, disintegration of the electrolyte, etc. may occur in the battery, causing an increase in impedan-ce, resulting in the significant deterioration of battery performance. Therefore, consideration should be given to the circuit design for preventing primary batteries from being charged

• Reliable terminal welding

(1) Terminal welding with laser.
  The company employs a laser for welding the termi-nals of the batteries that can be mounted on the printed board by soldering. Whereas the tensile welding strength obtained from the conventional resistance welding method is 20 to 50 N (approx. 2 to 5 kgf), laser welding increases the strength to about 10 kg and reduces the variation to about a half. It also makes it possible to perform terminal welding to a battery as thin as 1.6mm. With the laser, a highly reliable terminal welding method has been established, providing wide applicability with-out the need for reinforcement.

(2) Pre-solder-coated terminal tips.

  Terminal tips are pre-solder-coated to increase the soldering reliability



(1) Battery selection

  When selecting a battery, give consideration to such factors as current consumption of the equipment to be used, expected life of the battery, and environmental temperatures. At low environmental temperatures, current consumption of the IC becomes smaller but the discharge voltage of batteries also decreases. At high environmental temperatures, the capacity deterioration of batteries in long-term use becomes significant. The relationship between current consumption and duration years of the battery used in normal temperature environment is shown on the graphs in pages 28 and 51.

(2) Backup voltage condition

  A typical memory backup circuit is illustrated below. Memory holding voltage is expressed as:
(H8 - VF- I F X R) is greater than (Memory holding voltage of IC).

(3) Inverse current blocking diode

  Since lithium primary batteries are not rechargeable, use of an inverse current blocking diode and a protective resistor in series is required where there is the possibility of charging in the equipment circuit. (Refer to UL recognition on page 70.) Use a silicone diode or schottky diode of small inverse current for preventing inverse current. To maintain the characteristics of coin type lithium batteries, the total charging amount of a battery during its total usage period must be no greater than 3% of the nominal capacity of said battery. For example, assuming the use of CR2477 (l000mAh) in a memory backup power supply for 5 years, charging by a leakage current of the inverse current blocking diode should be no greater than 30mAh (=3% of l000mAh), thus:

  30mAh / Total usage period (5 years x 365 days x 24 hours) = 0.7 μA; that is, an inverse current blocking diode of which the inverse current is not greater than 0.7 μA should be selected.
  Allowable total charging capacity:


For coin type batteries: Within 3 %
For cylindrical type batteries: Within 1 %

Note that the inverse current of inverse current blocking diodes varies with temperature.

(4) Protective resistor

  For UL Standard applied products, a resistor must be used in series with the battery to limit the charge current which will flow to the battery in case of destruction in continuity of the inverse current blocking diode. The maximum allowable current is specified for each battery size, and the resistance value of resistors is determined as:
R is greater than V / I (I = Maximum allowable charge current specified by UL) This circuit is also recommended for non-UL applied devices.

(5) Battery terminal soldering

  When mounting batteries onto circuits, do not directly solder to the batteries; use batteries with terminals. Observe the following instructions for soldering batteries with terminals.
  • Never use reflow soldering
    • In reflow soldering, the battery body is directly heated to a high temperature, causing solution
      leakage; deterioration of battery characteristics; or danger of rupture or ignition.

  • Soldering with a soldering iron
    • Take care not to touch the battery directly with the soldering iron. Maintain an iron tip temperature at 350°C; perform soldering quickly (within 5 seconds).

  • Automatic dip soldering
    • Do not allow the temperature of the battery body to exceed 85°C. Be alert to possible temperature rise of the battery body after dipping due to ambient heat in the dipping device. The basic conditions should be: Solder dipping bath temperature of up to 260°C, dipping time of within 5 seconds, a maximum of two times.


(6) Cleaning and drying

  Make sure to use a non-conductive cleaning solu-tion. In a conductive solution, batteries may dis-charge, causing a deterioration of battery perfor-mance such as voltage drop. Dry batteries at a temperature below 85°C. If the temperature of the battery body exceeds 85°C, the gasket may be deformed by heat, causing solution leakage or deterioration of battery performance.