Chapter 1 Overview Chapter 1 Overview INDEX Introduction ..........................................2 Model Number .......................................7 General Features ...................................3 Selecting a Battery.................................7 Coin Type Rechargeable Lithium Batteries .....5 Battery Selector Chart ............................8 Comparison Table of Lithium Battery Types .....5 General Safety Precautions for Using, Handling and Designing 11 Comparison Between BR and CR ............5 Design for Memory Back-up Use ...........14 Applications .........................................6 Chapter 1 3-1 2006 Chapter 1 Introduction Lithium & Micro Batteries :Types and Features Overview Ever since Panasonic became the first company in the world to develop and commence the mass production of lithium batteries for consumer products in 1971, Panasonic has launched a series of lithium batteries in many shapes and sizes including cylindrical types, coin types and pin types. Panasonic has also successfully introduced coin type rechargeable lithium batteries to the market for applications such as memory back-up or watches. Today, lithium batteries have a proven track record of opening up a host of new fields where conventional batteries cannot be used. Applications range from high-current discharge applications typified by 35 mm cameras to ultra-lowcurrent discharge applications in such products as electronic watches or applications as power supplies for IC memory backup which require long-term reliability. Panasonic has conducted repeated tests on the various safety and performance characteristics, plus the effects of environmental factors such as temperature. We have accumulated a wealth of corroborative data on the performance of our batteries which cannot be pinpointed by short-term accelerated tests. As a result, Panasonic batteries have won approval under the UL safety standards in the United States and wide recognition throughout the world for their high reliability and safety. Types of Lithium & Micro Batteries Poly-carbonmonofluoride Lithium Batteries (BR series) Cylindrical Type Manganese Dioxide Lithium Batteries (CR series) Primary Lithium Batteries (non-rechargeable) Poly-carbonmonofluoride Lithium Batteries (BR series) Coin Type Manganese Dioxide Lithium Batteries (CR series) Pin Type Poly-carbonmonofluoride Lithium Batteries (BR series) Lithium & Micro Batteries Vanadium Rechargeable Lithium Batteries (VL series) Rechargeable Lithium Batteries Manganese Rechargeable Lithium Batteries (ML series) Coin Type Niobium Rechargeable Lithium Batteries (NBL series) Titanium Lithium Ion Batteries (MT series) Chapter 1 3-2 2006 Chapter 1 General Features ■ High voltage The high energy density of lithium batteries and their high voltage of 3V (there are 1.5V and 2V lineups also) Voltage(V) A single lithium battery can replace two, three or more conventional batteries. The figure on the right shows the 2.0 Voltage maintaining the data of C-MOS IC 1.0 3V 1.55V 1.5V 1.2V 0 number of cells required to provide the C-MOS IC data holding voltage for each type of battery. Lithium Silver Manganese Ni-Cd ■ Low self-degradation rate and superior storability Poly-carbonmonofluoride, CR series:Manganese dioxide),if preservation conditions are proper, 90% of capacity remains even after ten years storage. BR-C (Cylindrical type) Capacity retentions(%) Since the substance that is chemically very stable is used for plus terminal as an active material (BR series: storage temp: room temp 100 90 BR2325 (Coin type) 80 0 5 10 Storage period(Y) ■ Long-term discharge BR2325 Long-term discharge has been verified at all operating temperatures under low-load discharge conditions. 3.5 load:2.2M (1.3µA) 45˚C 3.0 Voltage(V) 2.5 20˚C -10˚C 2.0 1.5 1.0 0.5 0 0 0 500 1 1000 2 1500 2500 2000 4 3 5 6 7 3000 (days) 8 (years) Duration BR-C 45˚C 20˚C load : 30k 0˚C ( 97µA) Voltage(V) 3.0 2.5 2.0 1.5 1.0 0 1000 500 1 2 3 1500 4 2500 2000 5 6 (days) 7 (years) Duration The data in this document are for descriptive purposes only and are not intended to make or imply any guarantee or warranty. Chapter 1 3-3 2006 Overview make them ideally suited for use in all kinds of products where the trend is to achieve increasing miniaturization. 3.0 Leakage resistance evaluation items Test conditions High-temperature storage 60 ˚C High-temperature High-humidity storage 45 ˚C / 90%RH 60 ˚C / 90%RH Lithium batteries employ organic electrolytes with minimum creeping so they are vastly superior in terms of leakage 60˚C Temperature cycle The batteries achieve stable characteristics under high temperature and humidity conditions (45°C / 90%RH, 60°C / 90 1h 1h 1h 1cycle -10˚C 1h 60˚C %RH), and even under heat shock which constitutes the severest challenge for batteries. Heat shock -10˚C 1h 1h 1cycle Leakage resistance test results Conditions Stor age Model 60˚C/90% 45˚C/90% 60˚C 1 month 3 months 1 month 3 months 1 month Temp. cycle 60 cycles 3 months Heat shock 120 cycles BR2325 BR-2/3A ■ Wide operating temperature range BR2325 Operating voltage under high-resistance discharge tive materials and a structural design that assures safety 20˚C 0˚C 45˚C 60˚C 1.5 1.0 ~ ~ 0 1000 2000 3000 4000 5000 Duration(h) BR-2/3A Current drain vs. operation voltage 3.2 Voltage at 50% Discharge duration 85 3.0 60 2.8 45 2.6 2.4 20 2.2 0 2.0 -20 1.8 and, as such, their superior safety has been verified from the results of repeatedly subjecting them to a number of different safety tests. As a result, Panasonic's lithium batteries have been approved under the safety standard (UL1642) of UL (Underwriters Laboratories Inc.). -10˚C 1.6 10µA 100µA 1mA -40 10mA 100mA Discharge current BR2325 Charge resistance characteristics (10V consistent-voltage charge) Battery surface temperature when short-circuited Current(mA) 12 Battery voltage 10 200 150 BR-2/3A 8 6 Temperature(˚C) Lithium batteries feature stable substances for the ac- -30˚C 2.0 Operating voltage(V) ■ Superior safety (1.3µA) 2.5 cells use a special engineering plastic as the material for the gasket and separator instead of the conventional polyolefin resin but its operating temperature range has also been significantly increased by employing an electrolyte with a high boiling point. load : 2.2M 80˚C 3.0 Voltage(V) Due to the use of organic electrolytes with a solidifying point that is much lower than the aqueous solution electrolytes used in other types of batteries, lithium batteries are capable of operation in a wide range of temperatures. Not only do the high operating temperature BR series Voltage(V) Overview resistance under environmental changes compared to other types of batteries that employ aqueous solution electrolytes. Battery temperature(˚C) Chapter 1 ■ Outstanding electrolyte leakage resistance 300 40 Battery temperature 4 200 30 100 20 2 Current 0 100 0 0 1 2 3 4 5 6 7 0 Duration(h) 50 BR2325 0 0 2 4 6 Time(min) Chapter 1 3-4 2006 8 10 The data in this document are for descriptive purposes only and are not intended to make or imply any guarantee or warranty. ■ Rechargeable lithium batteries come with excellent characteristics and high reliability. Long-term reliability High capacity Overview Low self-discharge rate Resistance to continuous discharge Resistance to over discharge Comparison Table of Lithium Battery Types Item Type Model Primary battery Rechargeable battery BR CR VL cylindrical : -40 to +85 coin : -30 to +80 high operating temperature coin : -40 to +125 pin : -30 to +80 cylindrical : -40 to +70 coin : -30 to +60 ML NBL MT + electrode Material - electrode Nominal voltage Operating temperature range(˚C) Cylindrical type Coin type Average discharge voltage(V) Charge voltage(V) Cut-off voltage(V) Self-discharge (per year) under standard conditions Charge-discharge cycles 1000 1000 1000 500 charge/discharge partly (charge/discharge for 10% of discharge depth) charge/discharge partly (charge/discharge for 10% of discharge depth) charge/discharge partly (charge/discharge for 10% of discharge depth) charge/discharge up to 1V or discharge limit voltage (charge/discharge for 100% of discharge depth) Comparison Between BR and CR B Discharge capacity Voltage during discharging Flatness of discharge voltage Performance Load characteristics Storage properties (self-discharge) Chapter 1 Coin Type Rechargeable Lithium Batteries R C R (Higher) (Flatter) (Superior) (Less self-discharge) (Less self-discharge & stable) Notes: In terms of their characteristics, the CR series provides a slightly higher voltage during discharge than the BR series. BR batteries, compared with CR batteries, show more stable characteristics with less discharge voltage variations. These characteristics should be taken into consideration when selecting a battery for each application. Chapter 1 3-5 2006 Chapter 1 Applications Recommended applications Potential applications Type of Battery (See the below for a description of items 1~10) Coin type Cylindrical type Pin type Primary type Rechargeable type Primary type Overview Usage 1 2 3 4 5 Analog Digital Clocks Watches Rechargeable watches Calculators AE cameras Flashes Digital cameras Portable game players Games Memory back up Small card devices IC tags IC cards Memory back up Medical equipment Electronics thermometers Keyless entry Car equipment Memory back up Meters Electronic organizers Shaver Household use Lights Solar remote control Communication equipment Business use Test equipment Cameras Electronic float with lightning diode Fishing equipment Light for a pole Lighted lures 1 : Poly-carbonmonofluoride Lithium Battery (BR series) 2 : High operating temperature Poly-carbonmonofluoride Lithium Battery (BR"A" series) 3 : Manganese Dioxide Lithium Battery (CR series) 4 : Vanadium Rechargeable Lithium Battery (VL series) 5 : Manganese Rechargeable Lithium Battery (ML series) 6 : Niobium Rechargeable Lithium Battery (NBL series) 7 : Titanium Lithium Ion Battery (MT series) 8 : Poly-carbonmonofluoride Lithium Battery (BR series) 9 : Manganese Dioxide Lithium Battery (CR series) 10 : Poly-carbonmonofluoride Lithium Battery (BR series) Chapter 1 3-6 2006 6 7 8 9 10 ■ How to interpret the model numbers generally used for coin type lithium batteries The model numbers are normally indicated using two upper-case English letters and a figure consisting of three or more digits as shown in the example below. Overview Example B R 2 3 2 5 Battery type Round Diameter Height Figures to first decimal place with decimal point omitted(ex.2.5mm) Integers omitting fractions(ex.23mm Dia.) In accordance with JIS and IEC standards The above numbering system is supported by the Japan International Standard Committee of Clocks and Watches and is also an established practice in Japan. Selecting a Battery ■ Selecting batteries The steps for selecting the batteries for the power supplies of specific equipment are summarized below. ● Preparation of required specifications (draft) The required specifications (draft) are studied by checking the requirements for the batteries to be used as the power supplies of the specific equipment and their conditions against the battery selection standards. The technical requirements for battery selection are shown in the table below for reference purposes. ● Selection of a battery Select several candidate batteries by referring to the catalogs and data sheets of batteries which are currently manufactured and marketed. From this short list, select the battery which will best meet the ideal level of the requirements. In actual practice, however, the "perfect" battery is seldom found by this method, instead, the basic procedure followed should be to examine the possibility of finding a compromise or partial compromise with the required specifications (draft) and then make a selection under the revised requirements from the batteries currently manufactured and marketed. Such a procedure enables batteries to be selected more economically. Questions and queries arising at this stage should be directed to our battery engineers. Sometimes, although it may not be shown in the catalog, the appropriate battery has become available through recent development or improvement. As a rule, the required specifications are finalized at this stage. ● Requests for developing or improving batteries If the battery that meets the essential and specific requirements cannot be found through the selection process described above, a request for battery development or improvement should be made to our technical Department. A request like this should be coordinated as early as possible to allow for a sufficient study period. While this period depends on the nature of the request and the difficulties involved, a lead time of at least 6 to 12 months is usually required. ■ Technical conditions for selecting batteries Electrical characteristics Temperature and humidity conditions Size, weight and terminal type Voltage range _____Vmax. _____Vmin. Temperature and humidity during use _____˚Cmax._____˚Cmin. _____%max. _____%min. Diameter (mm)_______max. Load pattern Continuous load ___________mA(max.) ___________mA(av.) ___________mA(min.) Temperature and humidity during storage _____˚Cmax._____˚Cmin. _____%max. _____%min. Operating life Length (mm)_______max. Width (mm)_______max. ● Charge voltage Mass (g)__________av. ● Charge time Terminal type ___________ Intermittent time conditions Operating time ___________ Non-operating time ___________ Others Atmospheric pressure Mechanical conditions Safety ___________mA(min.) Storage period ● Cycle charge (mm)_______max. Battery life Intermittent load/ pulse load ___________mA(max.) ___________mA(av.) Charge conditions* Height Chapter 1 Model Number ● Trickle float charge ● Charge temperature and atmosphere ❋ Only for rechargeable batteries Interchangeability Marketability Price Selection of the battery Chapter 1 3-7 2006 Chapter 1 Battery Selector Chart Coin Type Primary Lithium Batteries (Example) Temp : 20˚C Cut off voltage : 2.0V Discharge life as a function of operating current Overview 10 9 8 7 6 5 247 7(1 Ah ) ) ) Ah Ah 60m 00m 0m 4(5 2(5 ,00 235 303 ) Duration (years) CR BR CR ) Ah 55m 0(2 233 BR ) Ah 90m ) h 2(1 203 65mA BR 5(1 232 BR ) Ah Ah 5m 8m 0(3 5(4 122 122 BR BR 4 3 2.5 2 1.5 1 0.6 0.7 0.8 0.9 1.0 1.5 2 2.5 3 4 5 6 7 8 9 10 15 20 Current drain(µA) General formula (rough value with 20˚C, standard load) Calculation Duration (years) = Chapter 1 3-8 2006 Nominal capacity(mAh) Current drain (mA) ✕ 24(hours)✕ 365(days) The data in this document are for descriptive purposes only and are not intended to make or imply any guarantee or warranty. 25 30 40 Chapter 1 Cylindrical Type Primary Lithium Batteries (Example) Discharge life as a function of operating current Cut off voltage : 2.0V Duration (years) 10 7 6 5 4 BR -A /3 A 3 BR BR -2 5 10 20 30 50 ) ) ) 3 Ah Ah Ah 2 m m m 2 00 00 00 (5 ,0 ,8 (1 ,2 1 1 -C (1 100 200 300 500 1,000 Current drain(µA) General formula (rough value with 20˚C, standard load) Calculation Duration (years) = Nominal capacity(mAh) Current drain (mA) ✕ 24(hours)✕ 365(days) The data in this document are for descriptive purposes only and are not intended to make or imply any guarantee or warranty. Chapter 1 3-9 2006 Overview Temp : 20˚C Chapter 1 Coin Type Rechargeable Lithium Batteries (Example) Discharge life as a function of operating current Overview Temp : 20˚C Cut off voltage : 2.5V 500 400 300 VL 200 VL 23 30 30 (5 Duration (days) 100 VL 50 23 VL 40 32 (1 0m 20 20 (3 20 Ah (2 20 VL 62 1( 10 5 1 3 1. 5m Ah 20 (7 m Ah Ah ) Ah 0m ) Ah ) ) ) 7 5 12 m ) 0m 30 VL 00 10 30 50 100 300 500 700 1,000 Current drain(µA) Temp : 20˚C Cut off voltage : 1.0V 500 300 200 50 M 20 T9 30 (5 .0 m ) 21 20 Ah T6 M Duration (days) 100 (2 .5 m Ah ) M T6 16 M T5 10 16 (1 .1 5m (1 Ah .5 m Ah ) ) 5 3 2 1 3 5 7 10 30 50 100 Current drain(µA) Chapter 1 3 - 10 2006 The data in this document are for descriptive purposes only and are not intended to make or imply any guarantee or warranty. 300 500 700 1,000 Applicable Both Primary and Rechargeable Batteries Item Voltage measurement Batteries Internal resistance measurement Battery compartments in equipment To measure the battery voltage, use an instrument with an input resistance of 10MΩ or higher. To measure the internal resistance, use a 1000Hz AC instrument. Electrical characteristics check Even minimal shorting causes the battery voltage to drop, requiring a period of time for the voltage to recover. Checking the voltage characteristics before the voltage has sufficiently recovered in such a situation may result in a misjudgment of battery voltage. Cleaning Prior to installation in the equipment, wipe the batteries and equipment terminals clean using a dry cloth, etc. Washing and drying - Washing: Use of a conductive detergent causes batteries to discharge, the battery voltage to drop and the battery performance to deteriorate in other ways. Be sure to use a non-conductive detergent. - Drying: The heat produced when the temperature of the battery units rises above 85˚C deforms the gaskets and causes electrolyte leakage and a deterioration in performance. Be sure to dry batteries only for short periods of time at temperatures below 85˚C. Mounting U Contacts and connection terminals Precaution L - Ensure that dust and other foreign substance will not cause shorting between the poles. - When handling batteries, wear finger covers or gloves made of rubber, cotton, etc. to protect the batteries from dirt. Strictly comply with the conditions outlined on the next page. Use of multiple batteries Give sufficient consideration to safety in design when a multiple number of batteries are to be used. Consult with Panasonic concerning packs of multiple batteries. Simultaneous use of other types of batteries When other types of batteries are also to be used in the some equipment, design the circuitry in such a way that the current (leakage current) from the other batteries will not flow to the lithium batteries. (This applies to primary batteries.) Use of batteries in series or in parallel This requires special circuitry:Please consult with Panasonic. Do not use lithium batteries together with different types of batteries in series or in parallel. Battery life Take precautions in design since the internal resistance increases when batteries approach the end of their service life. Design - Ensure that the batteries can be replaced easily and that they will not fall out of position. - Give consideration to the battery dimensions, tolerances, etc. - Give consideration to the shape of + and - electrodes of the batteries and their tolerances to prevent installation in reverse. - Clearly indicate on the battery compartment the type of batteries to be used and their correct installation direction (polarities). - Limit the electrical circuits inside the battery compartment only to the circuits relating to the battery contacts. - With the exception of the terminal areas, insulate the battery compartment from the electrical circuits. - Take steps to minimize any damage to the equipment resulting from electrolyte leakage from the battery compartment. - Batteries should be free from leakage of liquids, which can damage equipment and spoil the contact at terminals, making the operation of equipment unstable. Battery layout and construction and materials of compartment Contact point materials Contact pressure of contacts Shape of terminals Connection terminals - Take steps to ensure the batteries are not located heat generating component in the equipment. Installing batteries near a heat source will heat up the batteries, causing thermal deformation of the gasket and resulting in electrolyte leakage and a deterioration in characteristics. - Adopt a construction which allows the gases to be vented. - Give consideration to the impact and the effect on the environment in selecting the materials to be used. Use nickel-plated iron or nickel-plated stainless steel for the contact points. In order to ensure stable contact, use the following levels of contact as a general guideline: 5N to 15N for cylindrical types 2N to 10N for coin types. Use of Y-shaped terminals (2-point contact) for both the + and - electrodes yield stable contact. If lead wires and connection terminals such as tab terminals are required for the batteries, consult with Panasonic since we offer a range of external terminals (connectors, etc.). Chapter 1 3 - 11 2006 Overview Classification Chapter 1 General Safety Precautions for Using, Handling and Designing Chapter 1 Item Overview Notes Precaution (1)Shorting causes the battery voltage to drop to about 0V before slowly recovering from the open state. It takes BR-2/3A voltage recovery after short-circuited (example) time for the initial voltage to be restored. Notice that 3.5 Temp : 20˚C measuring the open-circuit voltage immediately after shorting may lead to a misjudgment that the battery is 3.0 Shorting time abnormal. The figure on the right illustrates how voltage 3-5 sec. 10 sec. 20 sec. recovers after shorting. 2.5 (2)Reverse current preventing diodes.Since lithium primary (V) 3.0 batteries are not rechargeable, use of a reverse current 2.0 2.5 preventing diode and a protective resistor in series is 2.0 required where there is the possibility of charging in the 1.5 1.5 equipment circuit. Use a silicon diode or Schottky diode ~ 0 30 60 90 120 with a low reverse current as the reverse current Recovery time(sec) 1.0 preventing diode. To maintain the characteristics of a ~~ coin-type lithium battery, the total charging amount of 0 the battery during its total usage period must be kept 0 1 2 3 4 5 Recovery time(hour) within 3% of the nominal capacity of the battery. Voltage(V) Classification IC （1）2-cell 6V usage Chapter 1 3 - 12 2006 IC （2）Parallel usage IC （3）UL conditions Since lithium primary batteries are not rechargeable, use a reverse current blocking diode and a protective resistor in series where there is the possibility of charging in the equipment circuit. ■ Reverse current blocking diode ■ Use of protective resistor in series: Selection and installation (UL Standard) A resistor must be installed in series with the battery to limit the charge current which will flow to the battery in case of destruction in continuity of the reverse current preventing diode. The maximum allowable current is specified for each battery size in the table at the right, and the resistance value of the protective resistor is determined as: R>V ÷ I (where "I" is the maximum allowable charge current specified by UL). * This circuit is also recommended for products which are not UL-approved. The batteries below were approved by UL, File No. MH12210 Shape Cylindrical type BR series Cylindrical type CR series Coin type BR series Coin type CR series Conditions for UL Standard (Contact Panasonic for further details.) 1. Use of protective resistor in series [Selection] Select the protective resistor in such a way that the charge current which will flow to the battery when the diode is destroyed is less than the value given in the table on the right. [Installation] To protect the battery from being charged in the event of the destruction of the diode, install a protective resistor in series with the battery. 2. Battery replacement [Replacement by qualified engineer]These batteries are intended for use as a part of an electrical circuit in equipment and any battery with an asterisk " * " in the table on the right should only be replaced by a qualified engineer. [Replacement by user]Those lithium batteries which are not accompanied by an asterisk " * " in the table on the right and which include the use of up to four of them in series or in parallel may be replaced by users provided that the conditions specified by the UL Standard are met. [Use in series or in parallel]In replacing up to four batteries, the batteries must all be replaced with new ones at the same time. Set the maximum allowable charge current to within the current permitted by the number of batteries in series or in parallel. Pin type BR series Coin type VL series (Rechargeable ) battery Coin type ML series (Rechargeable ) battery Model number *BR-C *BR-A BR-1/2AA BR-2/3A BR-2/3AH BR-2/3AG *BR-AG *BR-AH BR-1/2A BR-2/3AA CR2 CR123A 2CR5 CR-P2 *CR-AG CR-2/3AG CR-V3 CR-V6 CR-2/3A CR-2/3AF3 CR-2/3AL3 CR-2/3AT3 CR-2/3AF4 CR-2/3AL4 CR-2/3AG4 CR-2/3AH4 2CR5M CR14505 BR3032 *BR2330 BR2325 BR2320 *BR2032 BR2020 BR2016 BR1632 BR1616 BR1225 BR1220 BR1216 *BR2777A *BR2477A *BR2450A *BR2330A BR1632A BR1225A CR3032 CR2477 CR2450 CR2430 CR2412 CR2354 CR2330 *CR2320 CR2032 CR2025 CR2016 CR2012 CR1632 CR1620 CR1616 CR1612 CR1220 CR1216 CR1212 CR1025 CR2450A BR435 BR425 *VL621 VL1216 VL1220 VL1220/S55 VL2020 VL2320 VL2330 VL2330/SGA VL3032 ML414 ML414R ML421 ML612 ML614 ML616 ML621 ML920 ML1220 *ML2020 ML2430 ML2430/SGA ML2430/SGB UL approval As of Oct.,2002 Maximum abnormal charging current (mA) 20 15 5 10 10 10 15 15 5 5 20 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 5 5 5 5 5 5 4 4 4 3 3 3 5 5 5 5 4 3 10 10 30 30 10 10 10 5 10 10 10 10 4 4 4 3 3 3 2 2 30 0.2 0.1 300 300 300 300 300 300 300 300 300 300 300 300 300 300 300 300 300 300 300 300 1000 1000 *Please read "Conditions for compliance with UL Standard" carefully Rechargeable Batteries · Use of multiple batteries: Consult with Panasonic if two or more Vanadium rechargeable lithium batteries (VL series) or Manganese rechargeable lithium batteries (ML series) are to be used in series or in parallel. · Charging: Details on the charge voltage, charge current and charge circuit are given for each type of battery. · Conditions of UL approval: The maximum charge current must be restricted to 300mA when protective components have been subjected to short- or open-circuiting. Chapter 1 3 - 13 2006 Overview · Diode used: Use a low leak current diode (this current varies with temperature). · Selection standard : The total allowable charging amount of a battery during its total usage period must be no greater than 3% of the nominal capacity of the battery for a coin type battery or 1% for A cylindrical battery. [Example]: When a CR2477 (1000mAh) coin-type battery is to be used for 5 years, a reverse current preventing diode with a reverse current of 0.7µ A or less is required. <Calculation method> 1000mAh (CR2477) x <= 3% (coin type battery) = <= 30mAh 30mAh ÷ usage period (5 years x 365 days x 24 hours) = 0.7µA ■ UL approval and maximum allowable charge current Chapter 1 Primary Batteries Chapter 1 Design for Memory Back-up Use ■ Selecting batteries When selecting batteries, give consideration to such factors as the current consumption of the equipment in which the batteries are to be used, the expected life of the batteries, and temperature in the operating environment. At low Overview operating environment temperatures, the consumption current of the ICs drops but the discharge voltage of the batteries will also decrease. Also it is important to note that the capacity deterioration of batteries in long-term use becomes significant at high operating environment temperatures. ■ Memory backup circuit and holding voltage IR IF VF The circuit typically used for memory backup is shown in the figure on the right. The memory holding voltage is expressed as: VB - VF - IF x R >memory holding voltage of IC. IC R VB B ■ Reverse current blocking diode Since lithium primary batteries are not rechargeable, use of a reverse current blocking diode and a protective resistor in series is required where there is the possibility of charging in the equipment circuit. Use a diode with a low leak current as the reverse current blocking diode. To maintain the characteristics of a coin type lithium battery, the total charging amount of the battery during its total usage period must be kept within 3% of the nominal capacity of the battery. For example, assuming that a CR2477 (1000mAh) will be used in a memory backup power supply for 5 years, charging by the leak current of the reverse current blocking diode should be no greater than 30mAh (=3% of 1000mAh), thus: 30mAh ÷ usage period (5 years x 365 days x 24 hours) = 0.7µA. In other words, a leak current blocking diode whose reverse current is not greater than 0.7µA must be selected. Allowable total charging amount : Within 3% for coin type batteries Within 1% for cylindrical type batteries Note that the leak current of reverse current blocking diodes varies with temperature. A B IC IC 2-cell 6V usage C D IC UL conditions (When a protective resistor has been inserted ) Chapter 1 3 - 14 2006 Parallel usage IC UL conditions (Protective Diode) BR-2/3A (cylindrical type) charge test 5.0 BR-2/3A(cylindrical type) discharge test after charging 4.0 4.0 3.0 Charge to 1% of capacity Charge to 3% of capacity 3.5 Voltage(V) Voltage(V) 4.5 Temp : 20°C Load resistance : 1k 1% charge before charge 2.0 3% charge 1.0 3.0 0 100 200 300 400 0 100 Charge time(h) The data in this document are for descriptive purposes only and are not intended to make or imply any guarantee or warranty. 200 300 400 500 Duration(h) Chapter 1 3 - 15 2006 Overview Temp : 20°C Charge current : 100µA Chapter 1 ■ Charge test results assuming diode leakage current