QuickSaver® Charge Control Nickel-Cadmium Nickel-Metal Hydride Batteri

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QuickSaver® Charge Control Nickel-Cadmium Nickel-Metal Hydride Batteri

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ICS1708
QuickSaver® Charge Control Nickel-Cadmium Nickel-Metal Hydride Batteries
ICS1708 cost CMOS control intelligent charging either nickel-cadmium (NiCd) nickel-metal hydride (NiMH) batteries. ICS1708 uses pulsed-current charging technique together with multiple voltage slope termination methods. ICS1708 employs four stage charge sequence that provides complete recharge without overcharging. controller three user selectable charge rates, user accessible clock, charge status output pins. power-up, ICS1708 monitors presence battery begins charging. ICS1708 applications where battery temperature protection required charge controller.
Applications
Embedded charger stands for: Portable consumer products, Power tools, Audio/video products, Communications products, toys, Wireless products
Features
Charge termination methods include: Voltage slope (+V/dt peak detect), Fast charge time maintenance mode Four stage charge sequence: SoftStart conditioning, Fast charge, Topping charge, Maintenance charge Three user selectable charge rates: minutes (4C), minutes (1C), minutes (C/2.5) Continuous polling mode battery detection Adjustable open circuit battery) voltage reference
Benefits -compared other methods
Peak battery performance extended cycle life Improved battery efficiency reliability Lower internal resistance build-up Lower capacity fade
Block Diagram
OPEN CIRCUIT REFERENCE VOLTAGE 0.5V BATTERY VOLTAGE SENSE
MICROCODE CONTROL FAST CHARGE PROCESSOR OUTPUT CONTROL CHARGE COMPLETE CURRENT SOURCE
(CLOCK)
OSCILLATOR
ICS1708
Configuration
ICS1708 OPREF
8-Pin SOIC
Definitions
Note:
Name OPREF
Type
Definition
Active high (PFET), active (NFET) 25mA max. compatible signal used turn external current source provide pulsed current charge battery. Maintenance mode indicator. NFET drain rated 40mA max. turns external indicator show battery ready topping charge maintenance charge applied. Charge mode indicator. NFET drain rated 40mA max. turns external indicator showing controller applying either SoftStart charge fast charge. Ground. external resistor capacitor sets frequency internal clock. Open circuit battery) voltage reference. pull down external resistor divider from sets voltage reference this used detect presence battery. Battery voltage normalized cell with external resistor divider. Device supply =+5.0 regulated. ICS1708 requires 11mA max. average that includes brief 50mA peak currents. When used, LEDs, pull-up resistors, drivers require additional current from +5VDC supply. electrolytic ceramic capacitor between very close both recommended bypassing.
internal pull-up. Input output pins have internal protection diodes protection method 3015.7.
Controller Operation
Charging Stages
charging sequence consists four stages. application current shown graphically Figure SoftStart stage gradually increases current levels user selected fast charge rate during first minutes. SoftStart stage followed fast charge stage, which continues until termination. After fast charge termination, reduced duty cycle topping charge applied, followed further reduced cycle maintenance charge. After fast charge termination, battery charged ready use.
Fast Charge
Topping Charge
Maintenance Charge
tion
atio
Figure Graphical representation average current levels during four charging stages
ICS1708
SoftStart Conditioning Charge
New, over-discharged, batteries long term storage exhibit initial high impedance conditions response charging, shown Figure Unless dealt with, this high impedance condition cause voltage peak condition beginning charge cycle that appear response already full battery. manage this condition, ICS1708 applies SoftStart conditioning charge.
Figure High impedance voltage spike beginning charge SoftStart charge eases batteries into fast charge stage gradually increasing duty cycle charge. gradual increase alleviates voltage peak condition. duty cycle applied current increased fast charge rate, shown Figure extending current pulse every cycle until pulse about seconds duration. initial current pulse approximately 200ms. indicator continuous active during SoftStart conditioning stage.
Initial Pulse Width
Initial Pulse Width increment time
Initial Pulse Width increment time
cycle time
cycle time
cycle time
Figure Cycle-to-cycle increase SoftStart current pulse widths
ICS1708
Fast Charge
second stage, ICS1708 applies charging current repetitive sequence consisting positive current charging pulses followed rest time voltage acquisition time. cycle, shown with charge, rest, data acquisition periods Figure repeats every seconds until battery fully charged.
rest time fast charge cycle time
voltage isit
Figure Charge cycle showing fast charge current pulses amplitude current pulse determined system parameters such current capability charging system, desired recharge time, battery capacity ability battery accept charge current charging environment. ICS1708 three user-selectable fast charge rates: minutes (4C), minutes (1C), minutes (C/2.5). indicator continuous active during this stage. charge rate determined voltage level indicator when ICS1708 first powered-up. voltage acquisition window immediately follows brief rest time after charge pulse. charge applied during rest time during acquisition window allow battery chemistry settle. Since current flowing, measured cell voltage obscured internal external drops noise. ICS1708 takes samples battery voltage during acquisition window. voltage samples averaged comparisons previous subsequent averages. This method provides most accurate representation true state charge battery.
Topping Charge
third stage topping charge that applies current rate enough prevent cell heating high enough equalize cells multiple cell packs. topping stage required before putting battery into immediate service after fast charge completes. topping charge applied minimum hours. current consists same pulse technique used during fast charge stage; however, delay time extended shown Figure Extending delay time between charge pulses allows same charging current used fast charge stage that changes current source necessary. example, same charge pulse that occurs every second hour) fast charge rate will occur every eleven (11) seconds topping charge rate C/11. indicator continuous active during topping maintenance charge stages.
cycle
cycle
Figure Representative timing diagram topping maintenance charge
Maintenance Charge
maintenance charge intended offset natural self-discharge NiCd NiMH batteries keeping their cells primed peak charge. After topping charge ends, ICS1708 begins this charge stage once again extending delay time between charge pulses. maintenance charge will last long divided down battery voltage greater than 0.5V indicator continuous active during this stage.
ICS1708
Charge Termination Methods
Charge termination methods include voltage slope fast charge time out.
Voltage Slope Termination
most distinctive point voltage curve battery response charging constant amplitude current voltage peak that occurs battery approaches full charge. mathematically calculating first derivative voltage, second curve generated showing change voltage with respect time shown Figure slope will reach maximum just before peak voltage. Using milestone voltage slope data charging progresses, ICS1708 determines when point full charge will occur accurately terminates applied current when battery reaches that point. actual termination point based actual charging characteristics particular battery. Typically, fast charge ends around peak voltage.
Figure Voltage slope curves showing inflection zero slope points New, over-discharged, old, already full batteries often produce voltage profile that varies from that shown Figure ICS1708 fast charge termination these cases based slight decrease voltage. Some batteries need several charge/use cycles before their response fully stabilizes that shown Figure
Charge Timer Termination
controller uses timer limit fast charge duration. These times internally according charge rate selected adjusted slightly changing clock frequency. Fast charge timer termination safety backup feature limit duration fast charge stage. fast charge timer always active cannot disabled. Table Charge Rate List.
ICS1708
Battery Detection
upon initial power-up, voltage less than 0.5V, ICS1708 assumes battery present, polling detect mode initiated. ICS1708 enters polling detect mode using applies 100ms charge pulse. During first pulse, ICS1708 monitors determine voltage above voltage OPREF battery present, voltage will held below voltage OPREF while current pulse applied. battery present, voltage will rise above voltage OPREF voltage exceeds voltage OPREF ICS1708 will wait about one-half second after 100ms charge pulse ends before producing another 100ms charge pulse. process repeats until battery connects. When battery connects, 100ms polling pulse extended another 100ms pulse becomes first SoftStart conditioning pulse 200ms. overdischarged voltage battery does interfere with prompt start SoftStart. ICS1708 will automatically re-enter polling detect mode battery removed.
Battery Removal
During first application charge pulse, voltage compared voltage OPREF voltage greater than voltage OPREF during application current pulse, then battery assumed have been removed ICS1708 enters polling detect mode. voltage held below voltage OPREF charging continues. When topping charge maintenance charge stages, charge pulse occur several seconds longer. during period between charge pulses, voltage compared internal 0.5V reference. voltage less than 0.5V, ICS1708 assumes battery been removed, polling detect mode initiated.
Descriptions
addition regulated supply, ICS1708 requires other external components control clock rate provide indicator display. ICS1708 interfaced turn external current source
Output Logic Signals: pin1
active high/low, compatible output. addition being compatible, CMOS output capable sourcing sinking 25mA which adds flexibility when interfacing other circuitry. logic high indicates that constant current source logic turns constant current source. Normal care must taken control wiring resistance inductance.
Charge Status Indicators:
controller outputs driving external indicators. These pins active low. These indicator outputs open drains when off. They sink 40mA which allows sinking current with external current limiting resistors. These indicator outputs denote charge status: fast charge topping/maintenance charging shown Table Table Indicator Description List
Flash
Description Charge complete (battery ready use) maintenance topping charge applied Fast charge (including SoftStart conditioning) applications information power-up with battery insertion
charge mode (CMN) indicator continuously during SoftStart fast charge stages. When controller enters topping charge stage, output turns indicator turns off. When maintenance mode (MMN) indicator battery ready use, ICS1708 applies topping maintenance charge. ICS1708 does control current flowing into battery other than turning off. required current selected charge rate provided system's input power source. external charging circuitry provides current selected charge rate. example, charge ampere hour battery minutes (1C), amperes required.
ICS1708
Clock Input:
used frequency internal clock. Alternatively, external clock used. Normally external resistor connected between this VDD. external capacitor connected between this ground (VSS). frequency internal clock typically with resistor 100pF capacitor. time durations noted this document based clock. Operating clock lower frequency will proportionally change time durations. Operating clock frequency significantly lower than MHz, without adjusting charge current accordingly, will lessen effectiveness fast charge timer lower accuracy controller. Operating clock frequency greater than will also change time durations and, without adjusting charge current accordingly, cause termination occur fast charge timer expiring rather than battery reaching full charge. clock driven external pulse provided duty cycle between 60%. clock input impedance typically
Voltage Input:
battery voltage normalized external resistor divider network cell. electrochemical potential cell about 1.2V. example, battery consists cells series, voltage should equal total battery voltage divided six. This accomplished with resistors, shown Figure
cells
Figure Resistor divider network determine resistor values, count number cells charged series. Then choose either solve other resistor using: cells
cells value should kept below that 0.047µF capacitor used parallel with more than five time constants occur before data acquisition. Consult factory applications that require higher resistance voltage dividers.
Circuit Voltage Reference: OPREF
OPREF internal pull-up resistor VDD. OPREF requires external pull-down resistor establish open circuit battery) voltage reference. purpose this voltage reference detect removal battery from charging system. voltage this compared voltage first 4mssec after current source turned voltage greater than voltage OPREF, ICS1708 assumes battery been removed ICS1708 enters polling detect mode. proper operation, voltage OPREF below (divided down) battery voltage produced current source (when above maximum normalized voltage with battery present. OPREF voltage must exceed 2.3V will prevent start fast charge. voltage OPREF exceeds controller will shutdown power ICS1708 must removed restored restart ICS1708.
ICS1708
example, suppose that current source open circuit voltage shown Figure
current source battery) (open circuit voltage 12V) 2.21k, OPREF 1.89V 1.3k, cells (9.6 100k 1.60V (battery present) 2.00V battery)
Alternate resistor divider OPREF tight tolerance applications
Resistor divider
Figure Open Circuit Reference Example maximum battery voltage nearly full six-cell pack with current applied determined 9.6V. voltage OPREF should then point between 1.6V (9.6V/6 cells=1.6V) (12V/6=2V). This accomplished with pull-down resistor. Refer OPREF resistor tables Applications Information section. From table, divider resistors 100k From OPREF table, pull-down resistor 47K, voltage OPREF typically 1.78V since internal pull-up OPREF 85k. Figure show alternate approach setting voltage OPREF tight tolerance applications.
Power:
power supply device must connected pin. voltage nominal, series regulated proper noise rejection. 100mA higher current rating supplies controllers maximum 11mA average demand that includes brief 50mA peaks. Peripheral circuits current requirements added these requirements. Descriptions additional information.
Grounding:
This connected directly solid (low impedance) ground that connects close battery minus. section Descriptions Applications Information Board Design Considerations) additional information.
Charge Rate Selection
voltage prior start fast charge sets three fast charge rates shown Table
Table Charge Rate List
Selected Charge Rate
min) min) C/2.5 (150 min)
Topping Charge Pulse Rate
every every every
Maintenance Charge Pulse Rate
every every every
Fast Charge Timer Duration (after powerup battery insertion)
section Controller Operation additional information topping charge maintenance charge. section Charge Termination Methods additional information charge timer.
ICS1708
minute rate) selected using pull-up resistor from (+5V REG.) shown Figure "Charging System Diagram". pull-up resistor required even with current limited pull-up (+5V reg.) used. C/2.5 (150 minute) rate selected using 330/1.3K resistor divider with general purpose shown Figure Based selection, this configuration should provide 2.5V 0.5V prior start fast charge activate C/2.5 (150 minute) rate shown Figure Setting minute) rate involves setting voltage below 0.5V prior start fast charge shown Figure pull-up resistor, pull-down resistor 1N4148 equivalent diode used keep below 0.5V power upon battery removal. When goes ground accord, base 2N3903 equivalent transistor pulled 1N4148 diode allowing indication fast charge.
CONSTANT CURRENT SOURCE INPUT
ON/OFF REG.
4.7uF ICS1708 *10K OPREF SELECTS CHARGE RATE
.047uF
100pF .047uF
FIGURE Charging System Diagram minute) Charge Rate
ICS1708
CONSTANT CURRENT SOURCE INPUT
ON/OFF REG.
4.7uF ICS1708 OPREF
.047uF
GENERAL PURPOSE
OFF=2.5V+/-.5V C/2.5 RATE 1.3K
100pF .047uF
FIGURE Charging ystem Diagram C/2.5 (150 Minute) Charge Rate
CONSTANT CURRENT SOURCE INPUT
ON/OFF REG.
4.7uF ICS1708 OPREF
.047uF
1N4148
100pF .047uF
2N3903
FIGURE Charging ystem Diagram minute) Charge Rate
ICS1708
Data Tables
Table Absolute Maximum Ratings Supply Voltage Input/Output Levels Ambient Operating Temperature Storage Temperature -0.5
Stresses above those listed under Absolute Maximum Ratings cause permanent damage device. This stress rating only. Functional operation device Absolute Maximum Ratings other conditions consistent with characteristics shown this document recommended. Exposure absolute maximum rating conditions extended periods affects product reliability. Table Characteristics Tamb=25°C.
Parameter Supply Voltage Supply Current
Internal pull-up OPREF High Level Source Current Level Sink Current Level Sink Current, indicator CMN,
Symbol
Conditions
UNITS (max) (max) (max)
0.4V V=0.4V V=0.4V
Analog/Digital Converter Range Minimum Battery Threshold
0-2.2
0-2.3
0-2.3
Table Timing Characteristics R15k, C100pF
PARAMETER Clock Frequency Charge Pulse Width Fast Charge Stage Rest Time Data Acquisition Time Cycle Time Polling Detect Pulse Width Polling Detect Pulse Period SoftStart Initial Pulse Width SoftStart Incremental Pulse Width Rate Select Read power-up with battery removed after fast charge starts
SYMBOL
tFCHG tCYCLE
REFERENCE Figure Figure Figure Figure
1048 13.0 16.4 1077 1160
UNITS
ICS1708
Timing Diagram
Figure
FCHG REST DATA ACQUISITION
CYCLE
Applications Information
ensure proper operation ICS1708, external components must properly selected. external current source used must meet several important criteria ensure adequate performance charging system. charging current source amplitude should fairly constant
OPREF Divider Resistors
Figure shows typical application using ICS1708. through must selected properly ensure that battery detection voltage termination methods operate properly. selected scale battery voltage down voltage cell. following table shows some typical values.
Cells 20k* 100k 120k 150k 160k 180k 200k 220k Above R1=R2 cells 5.1V Zener required depending input voltage
current source switch mode type, normal ripple current does effect ICS1708. However, effects line frequency ripple interfere with proper performance. Figure used open circuit battery) reference voltage OPREF pin. function this discussed Open Circuit Reference section. VOPREF
1.68 1.78 1.88 1.99 2.11
Figure alternate resistor divider approach OPREF tight tolerance applications.
ICS1708
With battery removed, current source must capable raising voltage above voltage OPREF ensure proper polling. With batteries installed, current source overshoot characteristics when turned must cause voltage approach voltage OPREF pin. voltage OPREF exceeds voltage when charge pulse applied, polling feature will activated.
Board Design Considerations
very important that care taken minimize noise coupling ground bounce. Careful placement wires connectors helps minimize resistance inductance. When designing printed circuit board, make sure ground power traces wide bypass capacitors used right power ground pins. separate heavy grounds both signal power circuits, connecting their grounds together close where negative lead battery connects. power circuits, keep physical separation between power return (ground) minimum minimize field effects. This precaution most applicable constant current source, particularly switch mode type. Keep ICS1708 constant current source control circuits outside power return loop described above. These precautions will prevent high fields coupled noise from disturbing normal operation. Avoid jumping across power return with signal lines.
Using Voltage Slope Termination Method
general voltage slope termination method works best products where battery fast charged with product off, battery removed from product fast charge charger stand. voltage slope termination method used ICS1708 requires nearly constant amplitude current flow into battery during fast charge. Charging battery products that draw known fairly constant current while battery charging should have this current draw added fast charge current. Using ICS1708 charging batteries products that randomly periodically requires moderate current from battery during fast charge needs evaluation. Products that randomly periodically require high current from battery during fast charge cause voltage inflection that results termination before full charge. voltage inflection occur charge current decreasing fluctuating load changes rather than battery reaching full charge. voltage slope method will terminate charge based voltage inflections that characteristic fully charged battery. ICS1702 ICS1712 charge controllers have temperature termination methods products that randomly periodically draw significant current from battery during fast charge. Charging sources that produce decreasing current fast charge progresses also cause voltage inflection that result termination before full charge. example, charge current supplied through resistor charging source constant current type that insufficient input voltage, current will decrease cause termination before full charge. Other current source abnormalities that cause voltage inflection that characteristic fully charged battery inadequate line frequency ripple attenuation capability charge current decreasing thermal drift thermal limiting. Charging sources that have above characteristics need evaluation access their suitability application voltage slope termination desired. controller SoftStart stage, built-in noise filtering, fast charge timer operate optimally when constant amplitude current source charges battery rate selected. actual charge current significantly less than rate selected, conditioning effect SoftStart stage controller noise immunity lessened. Also, fast charge timer cause termination based time duration rather than battery reaching full charge inadequate charge current.
Charging System Status Indicator
Indicator Description List Table contains some displays that caused charging system abnormalities. When indicator flashes, there voltage present charger terminals with current source with battery connected. Check current source ensure that produces more than 350mV when current source turned with battery connected. divider resistors properly selected, open circuit voltage that should produce less than 350mV with charger battery will divide down open circuit voltage properly produce flash indication. Check divider ensure that properly scales battery voltage cell level flash indication occurs with battery installed, there open connection charger battery. Check wires, connections, battery terminals, battery itself open circuit condition. indicator active initiation fast charge, check external pull-down resistor alternate divider that sets voltage OPREF voltage OPREF greater than 2.3V less than start fast charge will inhibited until voltage OPREF lowered.
ICS1708
Package Information
0.018 0.060
0.016
0.035
QuickSaver
0.250
ICS1708S YRWK
0.155
ICS1708N
0.310 0.375
0.193 0.236
0.250
0.130
0.058
0.130
0.154 0.006 0.008 0.016 0.050 0.025 0.008
0.010 0.015 0.350 0.018 0.100 0.060
package dimensions inches.
8-Pin SOIC Package (150 mil)
package dimensions inches.
8-Pin package (300 mil)
Ordering Information
ICS1708S, ICS1708ST, ICS1708N Example: 1708 Package type: (Plastic) SOIC SOIC Tape Reel
Device type: Prefix:
Consists digits numbers
Intelligent Charging Solution standard device
ICS1708
IMPORTANT NOTICE
Galaxy Power Incorporated makes claim about capability particular battery (NiCd NiMH) accept fast charge. strongly recommends that battery manufacturer consulted before fast charging. shall held harmless misapplication this device such exceeding rated specifications battery manufacturer; charging batteries other than nickel-cadmium nickelmetal hydride type; personal product damage caused charging device, circuit, system itself; unsafe use, application, and/or manufacture charging system using this device. reserves right make changes device data identified this publication without further notice. advises customers obtain latest version device data verify that information being relied upon customer current accurate. does assume liability arising associated with application product integrated circuit component described herein. does convey license under patent rights patent rights others described herein. absence written prior stated agreement contrary, terms conditions stated back order acknowledgment obtain. makes warranty kind with regard this material, including, limited implied warranties merchantability fitness particular purpose. products designed, intended, authorized components systems intended surgical implant into body, other applications intended support sustain life, nuclear facility application, other application which failure product(s) could create situation where personal injury death occur. will knowingly sell products such applications, buyer shall indemnify hold harmless officers, employees, subsidiaries, affiliates, representatives distributors against claims, costs, damages, expenses, tort attorney fees arising directly indirectly, claim personal injury death associated with such unintended unauthorized use, even such claim alleges that negligent regarding design manufacture part. COPYRIGHT 2000 Galaxy Power Incorporated
ICS1708
Galaxy Power, Inc.
2500 Eisenhower Avenue Valley Forge, 19482-0890 Phone: 610-676-0188 FAX: 610-676-0189 WWW: www.galaxypower.com E-mail: halla@galaxypower.com

QuickSaver® Charge Control Nickel-Cadmium Nickel-Metal Hydride Batteri

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