®1479 "heart" total power management solution single dual battery note

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®1479 "heart" total power management solution single dual battery note

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LTC1479 PowerPath Controller Dual Battery Systems
®1479 "heart" total power management solution single dual battery notebook computers other portable equipment. LTC1479 directs power from battery packs power source input main system switching regulator. works concert with related power management products (e.g. LTC1435, ®1511, etc.) create total system solution; starting from batteries power source, ending input each computer's complex loads. system-provided power management monitors actively directs LTC1479. LTC1479 uses loss N-channel MOSFET switches direct power from three main sources. adaptive current limiting scheme reduces capacitor battery inrush current controlling gates MOSFET switches during transitions. LTC1479 interfaces directly LT1510, LT1511 LT1620/LTC1435 battery charging circuits.
registered trademarks Linear Technology Corporation.
PowerPath trademark Linear Technology Corporation.
Complete Power Path Management Batteries, Power Source, Charger Backup Compatible with Li-Ion, NiCd, NiMH Lead-Acid Battery Chemistries "3-Diode" Mode Ensures Powers Available under "Cold Start" Conditions N-Channel Switching Reduces Power Losses Capacitor Battery Inrush Current Limited "Seamless" Switching Between Power Sources Independent Charging Monitoring Battery Packs New, Small Footprint, 36-Lead SSOP Package
APPLICATIONS
Notebook Computer Power Management Portable Instruments Handheld Terminals Portable Medical Equipment Portable Industrial Control Equipment
TYPICAL APPLICATION
Dual Battery PowerPathController System Block Diagram
DCIN BAT2 BATTERY CHARGER (LT1510/LT1511/ LT1620/LTC1435) BACKUP REGULATOR (LT1304) POWER MANAGEMENT HIGH EFFICIENCY DC/DC SWITCHING REGULATOR (LTC1435/LTC1438 ETC.)
ADAPTER
RSENSE
BAT1
LTC1479 PowerPath CONTROLLER
STATUS CONTROL
1479 TA01
LTC1479
ABSOLUTE MAXIMUM RATINGS
DCIN, BAT1, BAT2 Supply Voltages 0.3V SENSE SENSE VBAT, 0.3V 0.3V SAB, SCD, SEF, 0.3V 0.3V DCDIV, BDIV 0.3V 5.5V Logic Inputs (Note 0.3V 7.5V Logic Outputs (Note 0.3V 7.5V Regulator Output Current VCCP Regulator Output Current Output Current Regulator Output Current 100µA Operating Temperature LTC1479CG 70°C LTC1479IG 40°C 85°C Junction Temperature. 125°C Storage Temperature Range 65°C 150°C Lead Temperature (Soldering, sec). 300°C
PACKAGE/ORDER INFORMATION
VIEW DCIN DCDIV LOBAT VBKUP BAT1 BAT2 BDIV VBAT CHGMON BATSEL DCINGOOD DCIN/BAT BATDIS CHGSEL VCCP
ORDER PART NUMBER LTC1479CG LTC1479IG
SENSE SENSE
PACKAGE (209 mils) 36-LEAD PLASTIC SSOP
TJMAX 100°C, 95°C/
Consult factory Military grade parts.
ELECTRICAL CHARACTERISTICS
VDCIN 25V, VBAT1 16V, VBAT2 12V, 25°C unless otherwise noted. (Note
SYMBOL VDCIN VBAT1 VBAT2 VBKUP IDCIN IVBAT1 IVBAT2 IVBKUP VCCP VUVLO VUVLOHYS PARAMETER DCIN Operating Range Battery Operating Range Battery Operating Range Backup Operating Range DCIN Operating Current Battery Operating Current Battery Operating Current Backup Operating Current VCCP Regulator Output Voltage Regulator Output Voltage Gate Supply Voltage Lockout Threshold Lockout Hysteresis CONDITIONS (Mode DCIN Selected (Mode Battery Selected (Mode Battery Selected (Mode Backup Operation (Mode DCIN Selected (Mode Battery Selected (Mode Battery Selected (Mode Backup Operation (VBKUP (Modes DCIN, Battery Battery Selected (Modes DCIN, Battery Battery Selected (Modes DCIN, Battery Battery Selected (Mode Power, VBATX Falling from (Mode Power, VBATX Rising from
UNITS
Power Supplies
34.0 36.3
40.0
LTC1479
ELECTRICAL CHARACTERISTICS
VDCIN 25V, VBAT1 16V, VBAT2 12V, 25°C unless otherwise noted. (Note
SYMBOL VTHDCDIV PARAMETER DCDIV Threshold Voltage CONDITIONS (Mode VDCDIV Rising from 1.5V (Mode VDCDIV Falling from 1.5V (Mode VDCDIV 1.5V (Mode VDCDIV IDCINGOOD 100µA (Mode VDCDIV 1.5V, VDCINGOOD (Mode VDCDIV 1.5V, VDCINGOOD (Modes VBDIV Falling from 1.5V (Modes VBDIV Rising from 1.5V (Modes VBDIV 1.5V (Modes VBDIV ILOBAT 100µA (Modes VBDIV 1.5V, VLOBAT (Modes Each Switch Tested Independently (Modes Each Switch Tested Independently
1.190
1.215
1.240
UNITS
DCIN Good Monitor VHYSDCDIV DCDIV Hysteresis Voltage IBIASDCDIV DCDIV Input Bias Current VLODCGD IPUDCGD ILKGDCGD VTHLOBAT IBIASBDIV VLOLOBAT ILKGLOBAT DCINGOOD Output Voltage DCINGOOD Pull-Up Current DCINGOOD Leakage Current Low-Battery Threshold Voltage BDIV Input Bias Current LOBAT Output Voltage LOBAT Output Leakage Current
Battery Monitor 1.190 1.215 0.20
1.240
VHYSLOBAT Low-Battery Hysteresis Voltage
RONBATSW Battery Switch Resistance ILKGBATSW Battery Switch Leakage Gate Drivers VGS(ON) VGS(OFF) IBSENSE+ IBSENSE- VSENSE IPDSAB IPDSCD IPDSEF IPDSG IPDSH RONCMON ILKGCMON VHIDIGIN VLODIGIN IHIDIGIN ILODIGIN IPUDIGIN
Gate-to-Source Voltage (Modes -1µA Gate-to-Source Voltage (GG, (Modes -1µA Gate-to-Source Voltage SENSE Input Bias Current SENSE Input Bias Current Inrush Current Limit Sense Voltage Pull-Down Current Pull-Down Current Pull-Down Current Pull-Down Current Pull-Down Current CHGMON Switch Resistance CHGMON Switch Leakage Input High Voltage Input Voltage Input Leakage Current Input Leakage Current Input Pull-Up Current (Modes 100µA (Modes (Modes (Modes (Modes VSAB (Mode VSCD (Mode VSEF (Mode (Mode (Modes Each Switch Tested Independently (Modes Each Switch Tested Independently (Mode Digital Inputs (Mode Digital Inputs (Mode Digital Inputs, VDIGINX (Mode VDIGINX (Note (Mode VDIGINX (Note
0.25
0.15
Charge Monitor
Digital Inputs
LTC1479
ELECTRICAL CHARACTERISTICS
VDCIN 25V, VBAT1 16V, VBAT2 12V, 25°C unless otherwise noted. (Note
SYMBOL tONGA/GB tONGC/GD tONGE/GF tOFFGA/GB tOFFGC/GD tOFFGE/GF tONGG/GH tOFFGG/GH fOVGG tdLOBAT tdDCINGOOD PARAMETER Gate Turn-On Time Gate Turn-On Time Gate Turn-On Time Gate Turn-Off Time Gate Turn-Off Time Gate Turn-Off Time Gate Turn-On Time Gate Turn-Off Time Operating Frequency LOBAT Delay Times DCINGOOD Delay Times CONDITIONS (Note (Note (Note (Note (Note (Note (Note (Note VBDIV ±100mV, RPULLUP VDCDIV ±100mV, RPULLUP UNITS
denotes specifications which apply over full operating temperature range. Note logic inputs high impedance CMOS gates with protection diodes ground therefore should forced below ground. These inputs however driven above VCCP supply rails there clamping diodes connected between input pins supply rails. This facilitates operation mixed 5V/3V systems. Note Selected Operating Mode Truth Table, which defines operating conditions logical states associated with each "normal" operating mode, should used conjunction with Electrical
Characteristics table establish test conditions. Actual production test conditions more stringent. Note following inputs high impedance CMOS inputs: DCIN/BAT have internal pull-up current. Note following inputs have built-in pull-up current sources (passed through series diodes): BATSEL, BATDIS CHGSEL. Note Gate turn-on turn-off times measured with inrush current limiting, VSENSE using Si4936DY MOSFETs typical application circuit.
TRUTH TABLE
SELECTED MODES
(Selected Operating Modes)
LOGIC INPUTS SWITCH STATUS OUTPUTS CHGMON Hi-Z BAT1 Hi-Z BAT2 Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z VBAT LOBAT BAT1 BAT1 BAT2 BAT2 BAT1 BAT2 BAT1 BAT1 BAT2 BAT1 BAT1 DCINGOOD
MODE DCIN/BAT BATSEL BATDIS CHGSEL Operation Operation BAT1 Charging Operation BAT2 Disconnected Operation BAT2 Charging BAT1 Operation BAT2 Operation BAT1 Disconnected Backup Operation Power Backup) Reconnected 3DM* 3DM* Connected Reset Three Diode Mode. When this mode invoked, only first MOSFET switch each back-to-back switch pair, turned Current still pass through inherent body diode idled switches, i.e., help restart
3DM*
system after abnormal operating conditions have been encountered. Timing Diagram Applications Information sections further details.
LTC1479 TYPICAL PERFORMANCE CHARACTERISTICS
DCIN Supply Current
DCIN SUPPLY CURRENT (µA)
BAT1 SUPPLY CURRENT (µA)
DCIN SUPPLY VOLTAGE
BAT1 SUPPLY VOLTAGE
BAT2 SUPPLY CURRENT (µA)
MODE DCDIV 1.5V OTHER POWER 25°C
VBKUP Supply Current
VBKUP SUPPLY VOLTAGE MODE OTHER POWER 25°C
VBKUP SUPPLY CURRENT (µA)
SUPPLY VOLTAGE
Supply Voltage
SUPPLY VOLTAGE
MODE VDCIN
JUNCTION TEMPERATURE (°C)
VCCP SUPPLY VOLTAGE
1479
BAT1 Supply Current
MODE OTHER POWER 25°C
BAT2 Supply Current
MODE OTHER POWER 25°C
BAT2 SUPPLY VOLTAGE
1479
1479
Supply Voltage
JUNCTION TEMPERATURE (°C) MODE VDCIN
1479
1479
VCCP Supply Voltage
JUNCTION TEMPERATURE (°C) MODE VDCIN
1479
1479
LTC1479
FUNCTIONS
External Power Supply Pins DCIN (Pin Supply Input. resistor should series with this external power source. 0.1µF bypass capacitor should connected this close possible. DCDIV (Pin Supply Divider Input. This high impedance comparator input with 1.215V threshold (rising edge) approximately 35mV hysteresis. BAT1, BAT2 (Pins 34): Supply Input. These pins inputs from batteries. bypass capacitor should connected each close possible there larger battery supply capacitor within VBAT (Pin 32): Battery Voltage Sense. This connects battery resistor ladder either BAT1 BAT2. BDIV (Pin 33): Battery Divider Input. high impedance comparator input with 1.215V threshold (falling edge) approximately 35mV hysteresis. VBKUP (Pin 36): Supply Input. This input supplies power LTC1479 when backup mode operation. bypass capacitor should connected VBKUP close possible there larger backup supply capacitor within Internal Power Supply Pins VCCP (Pin 20): Power Supply Output. Bypass this output with least 0.1µF capacitor. VCCP power supply used primarily power internal logic circuitry. (Pin 15): Power Supply Output. This nominal 3.60V output. Bypass this regulator output with 2.2µF tantalum capacitor. This capacitor required stability. (Pin 17): Supply. connected three internal diodes DCIN, BAT1 BAT2 pins powers switching regulator inductor. Bypass this with 1µF/35V capacitor. (Pin 16): Gate Supply. This high voltage (36.5V) switching regulator intended only driving internal micropower gate drive circuitry. load this with external circuitry. Bypass this with 1µF/50V capacitor. (Pin 18): Output. This drives "bottom" switching regulator inductor which connected between this pin. (Pin 19): Ground. bypass capacitors should returned this ground which connected directly source N-channel switch regulator. Input Power Switches (Pins DCIN Switch Gate Drive. These pins drive gates back-to-back N-channel switches series with DCIN input. (Pin Source Return. connected sources small pull-down current source returns this node when switches turned off. (Pins BAT1 Switch Gate Drive. These pins drive gates back-to-back N-channel switches series with BAT1 input. (Pin Source Return. connected sources small pull-down current source returns this node when switches turned off. (Pins 12): BAT2 Switch Gate Drive. These pins drive gates back-to-back N-channel switches series with BAT2 input. (Pin 11): Source Return. connected sources small pull-down current source returns this node potential when switches turned off. SENSE (Pin 13): Inrush Current Input. This should connected directly "top" (switch side) valued resistor series with three input power selector switch pairs, A/B, E/F, detecting controlling inrush current into power supply sources output capacitor.
LTC1479
FUNCTIONS
SENSE (Pin 14): Inrush Current Input. This should connected directly "bottom" (output side) valued resistor series with three input power selector switch pairs, A/B, E/F, detecting controlling inrush current into power supply sources output capacitor. Battery Charging Switches (Pins 27): Charger Switch Gate Drive. These pins drive gates back-to-back N-channel switch pairs, between charger output batteries. (Pin 26): Source Returns. These pins connected sources respectively. small pull-down current source returns these nodes when switches turned off. CHGMON (Pin 31): Battery Selector Output. This output internal switch which connected BAT1 BAT2 connects positive terminal selected battery voltage feedback resistors charger circuit. Microprocessor Interface DCINGOOD (Pin 25): Comparator Output. This open-drain output internal pull-up current source connected through diode VCCP power supply. external pull-up resistor added more pull-up current required. This output active high when supply rises above programmed voltage. LOBAT (Pin Comparator Output. This open-drain output does have internal pull-up current source active when selected battery voltage drops below programmed voltage. DCIN/BAT (Pin 24): Selector Input. This high impedance logic input allows make ultimate decision connection power source, based upon DCINGOOD information. some minimized systems, DCIN/BAT connected directly DCINGOOD pin. BATDIS (Pin 23): Battery Disconnect Input. This highimpedance logic input built-in pull-up current source allows disconnect battery from system. (Pin 22): Three Diode Mode Input. This high impedance logic input built-in pull-up current source. Connect 100k resistor from this ground ensure three diode mode operation from "cold start." CHGSEL (Pin 21): Battery Charger Selector Input. This high impedance logic input built-in pull-up current source allows determine which battery being charged connecting selected battery charger output switch pairs, (The charger voltage feedback ladder simultaneously switched selected battery.) BATSEL (Pin 30): Battery Selector Input. This high impedance logic input built-in pull-up current source allows select which battery connected system battery monitor comparator input. Battery selected with logic high this input battery selected with logic low.
LTC1479
BLOCK DIAGRAM
DCIN
DCDIV
DCIN MONITOR GATE DRIVERS BAT1 BAT2 DCIN GATE DRIVERS GATE DRIVERS
REGULATOR BIAS GENERATOR VCCP SWITCH CONTROL LOGIC SWITCHING REGULATOR
VCCP
VCCP BAT2
BAT1
BATSEL
VBAT
VSENSE VSENSE BAT2 INRUSH SENSE BAT1 INRUSH SENSE DCIN INRUSH SENSE VCCP VCCP VCCP BATDIS DCIN/BAT DCINGOOD BAT1 BAT2 DCIN VBKUP LOBAT BATTERY MONITOR GATE DRIVER GATE DRIVER CHGSEL CHGMON BDIV
1479
LTC1479
DIAGRA
Battery Operation Timing
MODE OPERATION BAT1 DISCONNECTED DCIN OUTPUT DCINGOOD DCIN/BAT BATDIS BATSEL CHGSEL (16V) (12V) MODE OPERATION BAT1 CHARGING MODE OPERATION BAT2 DISCONNECTED MODE OPERATION BAT2 CHARGING
NOTE: MODES BAT1 16V, BAT2
MODE BAT1 DISCONNECTED DCIN
OUTPUT LOBAT BATDIS DCIN/BAT
BAT1 DISCHARGING (VBKUP (0V)
NOTE: MODES BATSEL BAT1 DISCHARGING, BAT2
MODE BAT1 OPERATION
MODE BAT2 OPERATION
1479 TD01
Backup Restoration Timing
MODE BACKUP OPERATION
MODE POWER BACKUP)
MODE RESTORED (THREE DIODE MODE)
MODE RECONNECTED
MODE THREE DIODE MODE
(25V) (24.3V) (24.3V)
1479 TD02
LTC1479
OPERATION
LTC1479 responsible low-loss switching "front end" power management system, where battery packs power source indiscriminately connected disconnected. Smooth switching between input power sources accomplished with help low-loss N-channel switches driven special gate drive circuitry which limits inrush current battery packs system power supply capacitors. N-Channel Switching LTC1479 drives external back-to-back N-channel MOSFET switches direct power from three main power sources: external power source, primary battery secondary battery connected main supply pins-DCIN, BAT1 BAT2 respectively. (N-channel MOSFET switches more cost effective provide lower voltage drops than their P-channel counterparts.) Gate Drive (VGG) Power Supply gate drive low-loss N-channel switches supplied micropower boost regulator which regulated approximately 36.5V. supply provides sufficient headroom above maximum operating voltage three main power sources ensure that MOSFET switches fully enhanced. power this inductor based regulator taken from three internal diodes shown Figure three
DCIN BAT1 BAT2 LTC1479 LTC1479 DCIN
GATE DRIVERS
SWITCHING REGULATOR
Figure Switching Regulator
diodes connected each three main power sources, DCIN, BAT1 BAT2. highest voltage potential directed boost regulator inductor maximize regulator efficiency. provides filtering switched inductor, which housed small surface mount package. fourth internal diode directs current from inductor output capacitor, further reducing external parts count. fact, demonstrated Figure only three external components required regulator, Inrush Current Limiting LTC1479 uses adaptive inrush current limiting scheme reduce current flowing three main power sources DC/DC converter input capacitor during switch-over transitions. voltage across single small-valued resistor, RSENSE, measured ascertain instantaneous current flowing through three main switch pairs, A/B, C/D, during transitions. Figure block diagram showing only DCIN switch pair, A/B. (The gate drive circuits switch pairs identical). bidirectional current sensing limiting circuit determines when voltage drop across RSENSE reaches plus minus 200mV. gate-to-source voltage, VGS, appropriate switch limited during transition period until inrush current subsides, generally within milliseconds, depending upon value DC/DC converter input capacitor.
RSENSE OUTPUT DC/DC CONVERTER COUT
±200mV THRESHOLD VSENSE VSENSE
(36.5V)
GATE DRIVERS
1479
BIDIRECTIONAL INRUSH CURRENT SENSING LIMITING
1479
Figure Inrush Current Limiting
LTC1479
OPERATION
This scheme allows capacitors MOSFET switches differing sizes current ratings used same system without circuit modifications. After transition period passed, both MOSFETs selected switch pair rises approximately gate drive provide ample overdrive logic level MOSFET switches without exceeding their maximum rating. Internal Power Supplies internal supplies provide power control logic power source monitoring functions. VCCP logic supply approximately provides power majority internal logic circuitry. supply approximately 3.60V provides power switching regulator control circuitry gate drivers. supply undervoltage lockout circuit which minimizes power consumption event total loss system power; i.e., when available power sources fall below approximately 4.5V. DCIN Voltage Monitoring DCIN input continuously monitored resistor ladder connected between DCIN DCDIV input. input threshold 1.215V (rising edge) with approximately 35mV hysteresis. definitive voltage threshold ensures that supply only connected "healthy" before being attached DC/DC converter input. Battery Voltage Monitoring LTC1479 ability independently monitor both battery packs. (Because this, battery pack discharged other being charged.) low-battery detector signals when selected battery pack dropped level where shutdown sequence should initiated other battery pack engaged. Battery Charging Management Functions LTC1479 directly interfaces with LT1510/LT1511 battery charger circuits. gate drive circuits control back-to-back N-channel switch pairs, under logic (CHGSEL) control connect output charger selected battery pack. Breakbefore-make action ensures that current does pass from battery pack other during switch-over charger output. CHGSEL input also simultaneously switches positive terminal selected battery pack voltage feedback resistor ladder charger system through CHGMON pin. Backup Supply Interface Power LTC1479 obtained from backup supply when power unavailable from three main sources power. Interface Companion Microprocessor companion must used conjunction with LTC1479 provide overall control power management system. LTC1479 communicates with means five logic inputs logic outputs described Table
Table LTC1479 Interface Inputs Outputs
INPUT DCIN/BAT BATDIS BATSEL CHGSEL OUTPUT DCINGOOD LOBAT ACTION Logic High Required Connect Good Supply Logic Disconnects Battery from System Selects Which Battery Connected System (Logic High Selects BAT1; Logic Selects BAT2) Selects Which Battery Charged Monitored (Logic High Selects BAT1; Logic Selects BAT2) Forces Main Three Power Path Switches Into "3-Diode Mode." Applications Information Section ACTION Logic High When Good Supply Present Logic When Selected Battery Voltage
LTC1479
APPLICATIONS INFORMATION
POWER PATH SWITCHING CONCEPTS Power Source Selection LTC1479 drives low-loss switches direct power main power path dual rechargeable battery system type found most notebook computers other portable equipment. Figure conceptual block diagram which illustrates main features LTC1479 dual battery power management system, starting with three main power sources ending system DC/DC regulator. Switches A/B, direct power from either adapter (DCIN) battery packs (BAT1 BAT2) input DC/DC switching regulator. Switches connect desired battery pack battery charger. Each five switches intelligently controlled LTC1479 which interfaces directly with power management system Using Tantalum Capacitors inrush "outrush" current system DC/DC regulator input capacitor limited LTC1479. i.e., current flowing both capacitor during transitions from input power source another limited. many applications, this inrush current limiting makes feasible lower cost/size tantalum surface mount capacitors place more expensive/larger aluminum electrolytics input DC/DC converter.
DCIN BAT1 BAT2 BATTERY CHARGER LTC1479 PowerPath CONTROLLER POWER MANAGEMENT RSENSE
Figure LTC1479 PowerPath Conceptual Diagram
Note: capacitor manufacturer should consulted specific inrush current specifications limitations some experimentation required ensure compliance with these limitations under possible operating conditions.
Back-to-Back Switch Topology simple SPST switches shown Figure actually consist back-to-back N-channel switches. These low-loss, N-channel switch pairs housed 8-pin SSOP packaging available from number manufacturers. back-to-back topology eliminates problems associated with inherent body diodes power MOSFET switches allows each switch pair block current flow either direction when switches turned off. back-to-back topology also allows independent control each half switch pair which facilitates bidirectional inrush current limiting called "3diode" mode described following section. "3-Diode" Mode Under normal operating conditions, both halves each switch pair turned simultaneously. example, when input power source switched from good input adapter) good battery pack, BAT1, both gates switch pair turned both gates switch pair turned back-toback body diodes switch pair, A/B, block current flow input connector.
HIGH EFFICIENCY DC/DC SWITCHING REGULATOR
3.3V
1479
LTC1479
APPLICATIONS INFORMATION
"3-diode" mode, only first half each power path switch pair, i.e., turned second half, i.e., turned off. These three switch pairs simply three diodes connected three main input power sources illustrated Figure power `diode' with highest input voltage passes current through input DC/DC converter ensure that power management powered start-up under abnormal operating conditions. undervoltage lockout circuit defeats this mode when drops below approximately 4.5V). "Cold Start" Initial Condition LTC1479 designed start diode" mode when five logic inputs low- when power available (including backup system). 100k resistor from input ground ensures that this input during "cold start." This will cause main PowerPath switches pass highest voltage available input DC/DC converter. Normal operation will then resume after good power source identified. Recovery from Uncertain Power Conditions "3-diode" mode also asserted applying active input) when abnormal conditions exist system, i.e., when power sources deemed "good" depleted, management system being reset functioning properly. (See
DCIN BAT1 BAT2 RSENSE
LTC1479 PowerPath CONTROLLER
Figure LTC1479 PowerPath Switches "3-Diode" Mode
Power Management Interface section additional information when invoke "3-diode" mode.) COMPONENT SELECTION N-Channel Switches LTC1479 adaptive inrush limiting circuitry permits wide range logic-level N-channel MOSFET switches. number dual RDS(ON) N-channel switches 8-lead surface mount packages available that well suited LTC1479 applications. maximum allowable drain source voltage, VDS(MAX), three main switch pairs, A/B, E/F, must high enough withstand maximum supply voltage. supply range, MOSFET switches. supply range, well regulated, then MOSFET switches. general rule, select switch with lowest RDS(ON) maximum allowable VDS. This will minimize heat dissipated switches while increasing overall system efficiency. Higher switch resistances tolerated some systems with lower current requirements, care should taken ensure that power dissipated switches never allowed rise above manufacturer's recommended levels. maximum allowable drain-source voltage, VDS(MAX), charger switch pairs, need only
HIGH EFFICIENCY DC/DC SWITCHING REGULATOR
3.3V
POWER MANAGEMENT
1479
LTC1479
APPLICATIONS INFORMATION
high enough withstand maximum battery charger output voltage. most cases, this will allow MOSFET switches charger path, while switches used main power path. Inrush Current Sense Resistor, RSENSE small valued sense resistor (current shunt) used three main switch pair drivers measure limit inrush current flowing through conducting switch pair.
SUPPLY LTC1479 DCIN RDC2 DCDIV RDC1 12.1k 1.215V DCINGOOD
should noted that inrush limiting circuit intended provide short-circuit protection rather, designed limit large peak currents which flow into large power supply capacitors battery packs during power supply switch-over transitions. inrush current limit should approximately maximum required DC/DC input current.
example, maximum current required DC/DC converter inrush current limit selecting 0.033 sense resistor, RSENSE, using following formula: RSENSE (200mV)/IINRUSH Note that voltage drop across resistor this example only 66mV under normal operating conditions. Therefore, power dissipated resistor extremely small (132mW), small 1/4W surface mount resistor used this application. number small valued, surface mount resistors available that have been specifically designed high efficiency current sensing applications. Input Monitor Resistor Divider DCDIV input continuously monitors power supply voltage resistor divider network, RDC1 RDC2, shown Figure threshold voltage good comparator 1.215V when power supply input voltage rising. Approximately 35mV hysteresis provided ensure clean switching comparator when supply voltage falling. minimize errors input bias current good comparator, RDC1 12.1k that approximately 100µA flows through resistor divider when desired
1479
Figure Monitor Resistor Divider
BATSEL BAT1 BAT2 VBAT LOBAT SWITCH CONTROL LOGIC
BDIV 121k
1.215V
LTC1479
1479
Figure Battery Monitor Resistor Divider
threshold reached. RDC2 then selected according following formula: RDC2 12.1k
VGOOD 1.215V
Battery Monitor Resistor Divider switch controlled BATSEL input connects batteries VBAT therefore battery resistor divider shown Figure threshold voltage low-battery comparator 1.215V when battery voltage falling. Approximately +35mV hysteresis provided ensure clean switching comparator when battery voltage rises again. minimize errors input bias current battery comparator, assume 121k that approximately 10µA flows through resistor divider when threshold reached. selected according following formula:
LTC1479
APPLICATIONS INFORMATION
121k LOBAT 1.215V
Regulator Inductor Capacitors regulator provides power supply voltage significantly higher than three main power source voltages allow control N-channel MOSFET switches. This 36.5V micropower, step-up voltage regulator powered highest potential available from three main power sources maximum regulator efficiency. Because three input supply diodes regulator output diode built into LTC1479, only three external components required regulator: shown Figure small, current surface mount inductor. provides filtering switched inductor should filter switching transients. output capacitor, provides storage filtering output should rated operation. either tantalum ceramic capacitors. VCCP Regulator Capacitors VCCP logic supply approximately provides power majority internal logic circuitry. Bypass this output with 0.1µF capacitor.
DCIN BAT1 BAT2 LTC1479
GATE DRIVERS
(36.5V)
SWITCHING REGULATOR
1479
*COILCRAFT 1812LS-105 XKBC (708) 639-6400 EQUIVALENT
Figure Step-Up Switch Regulator
supply approximately 3.60V provides power switching regulator control circuitry gate drivers. Bypass this output with 2.2µF tantalum capacitor. This capacitor required stability regulator output. SYSTEM LEVEL CONSIDERATIONS Complete Power Management System LTC1479 "heart" complete power management system responsible main power path charger switching. companion power management provides overall control power management system concert with LTC1479 auxiliary power management systems. typical dual Li-Ion battery power management system illustrated Figure "good" power available DCIN input (from adapter), switch pair turned on-providing low-loss path current flow input LTC1538-AUX DC/DC converter. Switch pairs, turned block current from flowing back into battery packs from input. this case, LT1510 (CC/CV) battery charger circuit used alternately charge Li-Ion battery packs. "decides" which battery need recharging either querying "smart" battery directly more indirect means. After determination made, either switch pair, turned pass charger output current batteries. Simultaneously, selected battery voltage returned voltage feedback input LT1510 CV/CC battery charger CHGMON output LTC1479. After first battery been charged, disconnected from charger circuit second battery connected through other switch pair second battery charged. Backup power provided LT1304 circuit which ensures that DC/DC input voltage does drop below Backup System Interface LTC1479 designed work concert with related power management products including LT1304
LTC1479
APPLICATIONS INFORMATION
DCIN RDC2 Li-ION BATTERY PACK 0.1µF BACKUP NiCD SENSE SENSE BACKUP REGULATOR RSENSE 0.033 LTC1538-AUX TRIPLE, HIGH EFFICIENCY, SWITCHING REGULATOR 3.3V
DCIN DCDIV
RDC1
BAT1 BAT2 Li-ION BATTERY PACK VBAT BDIV CHGMON 2.2µF VCCP
1mH*
0.1µF
*COILCRAFT 1812LS-105 XKBC (708) 639-1469
Figure Simplified Dual Li-Ion Battery Power Management System
FROM PowerPath CONTROLLER 5VCC FROM DC/DC
(BOLD LINES INDICATE HIGH CURRENT PATHS) ROHM DTA144E NiCD CELL 10µH MBR0530
0.1µF 390k 100k
BACKUP 2N7002 BAS16LT1
LT1304 ILIM
SHDN
470k
5VCC FROM DC/DC 0.1µF
1479
0.1µF
Figure LT1304 Micropower Backup Converter Circuit
VBKUP
LTC1479
POWER MANAGEMENT
DCIN
1479
LT1510 Li-ION BATTERY CHARGER
INPUT DC/DC CONVERTER
cropower DC/DC converter. shown Figure LT1304 monitors input supply voltage activates when drops below Power DCIN battery monitors logic supply LTC1479 then obtained from output LT1304 step-up regulator. Charger System Interface LTC1479 designed work directly with constantvoltage (CV), constant-current (CC) battery chargers such LT1510 LT1511. LT1510 Battery Charger Interface illustrated Figure LT1510 CV/CC battery charger, takes power from adapter input through Schottky diode output charger directed
LTC1479
APPLICATIONS INFORMATION
charging battery through N-channel switch pairs, charging battery voltage simultaneously connected through CHGMON switch LTC1479 charger voltage resistor divider, constant voltage charging. (See LT1510 data sheet further detail.)
POWER MANAGEMENT CHGMON LTC1479 BAT1 BAT2 DCIN 0.1µF 10µF CERAMIC MBRS140T PROG BOOST 0.1µF LT1510 SENSE 115k 0.25% 0.22µF 1N4148 33µH 649k 0.25% INPUT (FROM ADAPTOR) MBRS140T
BAT1 Li-ION BATTERY PACK
BAT1
47µF
Si9926DY
BAT2 Li-ION BATTERY PACK
CBAT2
47µF Si9926DY
*COILTRONICS CTX33-2
CURRENT CONTROL FROM POWER MANAGEMENT
Figure Interfacing LT1510 Battery Charger
POWER MANAGEMENT
CHGMON LTC1479 BAT1 BAT2 DCIN
BAT1 Li-ION BATTERY PACK
CBAT1 47µF
Si9926DY
BAT2 Li-ION BATTERY PACK
CBAT2 47µF
Si9926DY
CURRENT CONTROL FROM POWER MANAGEMENT
Figure Interfacing LT1511 Battery Charger with Input Current Limiting
LT1511 Battery Charger Interface LT1511, CC/CV battery charger with input current limiting, connected slightly different manner than LT1510 illustrated Figure
RPROG 2N7002
100k
(CHARGER OUTPUT)
CCHG 22µF TANT
1479
10µF CERAMIC
0.05
MBRS340T 6.8k
0.1µF
10µF
INPUT (FROM ADAPTOR)
PROG 0.33µF COMP1 BOOST 200pF LT1511 SPIN SENSE
MBRS340T 0.47µF 20µH MBR0540T
RPROG 4.93k
649k 0.25% 115k 0.25%
1479
2N7002 (CHARGER OUTPUT)
50pF
0.033 CCHG 22µF TANT
LTC1479
APPLICATIONS INFORMATION
LT1511 third control loop that regulates current drawn from adapter. Therefore, input LTC1479 input host system through A/B, obtained from "output" LT1511 adapter sense resistor, RS4, directly from input connector with LT1510. This allows simultaneous operation host system while charging battery without overloading adapter. Charging current reduced keep adapter current within specified levels. However, with LT1510 output LT1511 directed charging battery through either charging battery voltage connected voltage resistor divider, constant voltage charging. (See LT1511 data sheet further detail battery charging techniques applications hints.) LT1620/LTC1435 Battery Charger Interface LTC1479 also interfaces with LT1620/LTC1435 synchronous high efficiency dropout battery charger. circuit shown Figure constant-current/ constant-voltage battery charger specifically designed lithium-ion applications having thermal, output current, input voltage headroom constraints which preclude other high performance chargers such LT1510 LT1511. This circuit charge batteries precision current sensing LT1620 combined with high efficiency dropout characteristics LTC1435 provide battery charger with over efficiency requiring only 0.5V input-to-output differential charging current. Charge current programming achieved applying 100µA current from LT1620 PROG ground, which derived from resistor output controlled power management (See LT1620 data sheet further details this circuit.) Capacitive Loading CHGMON Output most applications, there virtually capacitive loading CHGMON output-just simple resistor divider. Care should taken restrict amount capacitance ground CHGMON output less than 100pF. more capacitance required, become necessary "mask" LOBAT output when charge monitor switched between batteries. (Internal resistance between BAT1 BAT2 inputs charge monitor switch create transient voltage drop VBAT output during transitions which could falsely interpreted battery condition.) POWER MANAGEMENT MICROPROCESSOR Interfacing LTC1479 LTC1479 thought "real world" interface power management takes logic level commands directly from makes changes high current high voltage levels power path. Further, provides information directly status adapter, batteries charging system. LTC1479 logic inputs level compatible therefore interface directly with standard power management µPs. Further, because direct interface five logic inputs logic outputs, there virtually latency (i.e. time delay) between LTC1479. this way, time critical decisions made without inherent delays associated with protocols, etc. These delays acceptable certain portions power management system, vital that power path switching control made through direct connection power management remainder power management system easily interfaced through serial interface. Selecting Power Management Microprocessor power management provides intelligence entire power system, programmed accommodate custom requirements each individual system allow performance updates without resorting costly hardware changes. power management must meet requirements total power management system, including LTC1479 controller, batteries (and interface), backup system, charging system host processor. number inexpensive processors available which easily fulfill these requirements.
LTC1479
APPLICATIONS INFORMATION
POWER MANAGEMENT CHGMON LTC1479 BAT1 BAT2 DCIN 0.1µF INPUT (FROM ADAPTER)
BAT1 Li-ION BATTERY PACK
CBAT1 10µF
Si9926DY
BAT2 Li-ION BATTERY PACK
CBAT2 10µF
Si9926DY
SHDN
0.1µF 0.033µF
1.5M COSC RUN/SS BOOST LTC1435 INTVCC SGND VOSENSE 100pF SENSE PGND SENSE 100pF 0.1µF 0.33µF 0.1µF CMDSH-3 0.33µF
100pF
SENSE IOUT
PROG LT1620
IPROG
0.01µF
*CENTRAL SEMICONDUCTOR (516) 435-1110
Figure Interfacing LT1620/LTC1435 High Efficiency Battery Charger
100pF 76.8k 0.1%
0.1%
56pF 0.1µF
Si4412DY 27µH CMDSH-3 Si4412DY
22µF
0.025
22µF
4.7µF
1479
LTC1479
APPLICATIONS INFORMATION
Interfacing Battery Pack LTC1479 designed work with virtually battery pack chemistry cell count, long battery pack operating voltage range somewhere between 28V. This permits great flexibility system design. low-battery threshold adjustable anywhere between 28V. Conventional Battery Packs Conventional battery packs include "smart" battery interface between battery pack host system. Thus, these battery packs generally have only three terminals connect battery temperature sensor (thermistor) host system. thermistor typically nominal resistance room temperature used monitor battery pack temperature. LOBAT DCINGOOD Blanking/Filtering good practice include some delay accepting battery DCIN good information during transitional periods, e.g., when switching charger from battery another when switching from batteries power. This technique will eliminate false triggering associated I/O. (Remember that "3-diode" mode used during periods uncertainty eliminate need "instantaneous" DCIN battery status information.) Smart Battery Packs Smart battery packs, compliant with Smart Battery System specification, have five-terminal connector. terminals minus plus connections battery. third terminal connected thermistor NiCd NiMH battery packs resistor Li-Ion battery packs. fourth fifth terminal connected Smart Management (SMBus) SMBDATA SMBCLK lines from integrated circuit inside battery pack. Applications Assistance Linear Technology applications engineers have developed smart battery charger around LT1511 charger Contact factory applications assistance developing complete smart battery system with intelligent PowerPath control using LTC1479.
LTC1479
TYPICAL APPLICATIONS
Dual NiMH Battery Power Management System (Using LT1510, Charger)
Si4936DY Si4936DY Si4936DY RSENSE 0.033
0.1µF
RDC2 205k RDC1 12.1k
DCIN DCDIV
BAT1 BAT2 VBAT LTC1479 BDIV
909k 121k
VCCP 0.1µF 2.2µF
BAT1 12-CELL NiMH BATTERY PACK
RTH1
CBAT1 10µF Si9926DY RPROG 2N7002
BAT2 12-CELL NiMH BATTERY PACK
RTH1
CBAT2 10µF
Si9926DY (CHARGER OUTPUT)
(BOLD LINES INDICATE HIGH CURRENT PATHS) ROHM DTA144E NiCD CELL L2** 10µH MBR0530
INPUT DC/DC CONVERTER
5VCC FROM DC/DC
0.1µF 390k
SENSE
SENSE VBKUP 2N7002 BAS16LT1 LT1304 SHDN ILIM 0.1µF
100k
5VCC FROM DC/DC
470k
0.1µF
BATSEL CHGSEL DCINGOOD BATDIS DCIN/BAT CHGMON LOBAT RCM2 909k 100k
(BACKUP)
POWER MANAGEMENT
RCM1 100k
SMBUS RTH1 RTH2 INPUT (FROM ADAPTOR)
MBRS140T 10µF CERAMIC PROG BOOST 0.1µF LT1510
CDCIN 10µF ALUM MBRS140T
0.22µF
100k
1N4148
L3*** 33µH
SENSE
*1812LS-105 XKBC, COILCRAFT **CD43, SUMIDA ***CTX33-2, COILTRONICS
CCHG 22µF TANT
1479 TA02
LTC1479
TYPICAL APPLICATIONS
Dual Li-Ion Battery Power Management System
Si4936DY Si4936DY Si4936DY RSENSE 0.033
0.1µF
RDC2 205k RDC1 12.1k
DCIN DCDIV
BAT1 BAT2 VBAT LTC1479 BDIV
909k 121k
VCCP 0.1µF 2.2µF
BAT1 Li-ION SMART BATTERY PACK
RBAT1
CBAT1 10µF Si9926DY RPROG 3.83k 2N7002
BAT2 Li-ION SMART BATTERY PACK
RBAT2
CBAT2 10µF
Si9926DY (CHARGER OUTPUT)
(BOLD LINES INDICATE HIGH CURRENT PATHS) ROHM DTA144E NiCD CELL L2** 10µH MBR0530 0.1µF
INPUT DC/DC CONVERTER
5VCC FROM DC/DC
SENSE
SENSE VBKUP 2N7002 BAS16LT1 LT1304 SHDN ILIM 0.1µF
390k 100k
5VCC FROM DC/DC
470k
0.1µF
BATSEL CHGSEL DCINGOOD BATDIS DCIN/BAT CHGMON LOBAT 100k
(BACKUP)
RBAT1 RBAT2
POWER MANAGEMENT
SMBUS
MBRS140T 10µF CERAMIC PROG BOOST 0.1µF 7-10, LT1510 SENSE
CDCIN 10µF ALUM
INPUT (FROM ADAPTOR) MBRS140T
0.22µF 1N4148 L3*** 33µH 649k 0.25% 115k 0.25%
CCHG 22µF TANT
*1812LS-105 XKBC, COILCRAFT **DT1608-223, COILCRAFT ***CTX33-2, COILTRONICS
1479 TA03
LTC1479
TYPICAL APPLICATIONS
Dual Li-Ion Battery Power Management System (Using LT1511, Charger)
Si4936DY Si4936DY Si4936DY RSENSE 0.033 (BOLD LINES INDICATE HIGH CURRENT PATHS) ROHM DTA144E NiCD CELL L2** 10µH MBR0530 INPUT DC/DC CONVERTER
0.1µF
RDC2 205k RDC1 12.1k
DCIN DCDIV
BAT1 BAT2 VBAT LTC1479 BDIV
1.05M 121k
VCCP 0.1µF 2.2µF
BAT1 Li-ION SMART BATTERY PACK
RBAT1
CBAT1 10µF Si9926DY RPROG 4.93k
BAT2 Li-ION SMART BATTERY PACK
RBAT2
CBAT2 10µF
Si9926DY
Information furnished Linear Technology Corporation believed accurate reliable. However, responsibility assumed use. Linear Technology Corporation makes representation that interconnection circuits described herein will infringe existing patent rights.
5VCC FROM DC/DC
0.1µF 390k
SENSE
SENSE VBKUP 2N7002 BAS16LT1 LT1304 SHDN ILIM 0.1µF
100k
5VCC FROM DC/DC
470k
0.1µF
BATSEL CHGSEL DCINGOOD BATDIS DCIN/BAT CHGMON LOBAT 100k
(BACKUP)
RBAT1 RBAT2
POWER MANAGEMENT
SMBUS
0.05 10µF CERAMIC
MBRS340T 6.8k
10µF
CDCIN 10µF ALUM
INPUT (FROM ADAPTOR)
PROG COMP1 BOOST 200pF LT1511 SPIN 0.33µF SENSE (CHARGER OUTPUT) 0.033 CCHG 22µF TANT
MBRS340T 0.47µF MBR0540T L3*** 20µH 649k 0.25% 115k 0.25%
2N7002
50pF
*1812LS-105 XKBC, COILCRAFT **DT1608-223, COILCRAFT ***CTX20-4, COILTRONICS
1479 TA04
LTC1479
PACKAGE
0.205 0.212** (5.20 5.38)
0.005 0.009 (0.13 0.22)
0.022 0.037 (0.55 0.95)
*DIMENSIONS INCLUDE MOLD FLASH. MOLD FLASH SHALL EXCEED 0.006" (0.152mm) SIDE **DIMENSIONS INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL EXCEED 0.010" (0.254mm) SIDE
RELATED PARTS
PART NUMBER
LT1304 LTC1435 LTC1438 LTC1473 LT1510 LT1511 LTC1538-AUX LT1620 LT1621
Micropower DC/DC Step-Up Converter High Efficiency Synchronous Step-Down Converter Dual High Efficiency Synchronous Step-Down Converter Dual PowerPath Switch Driver Battery Charger Battery Charger Dual, Synchronous Controller with Regulator Battery Charger Current Controller Dual Battery Charger Current Controller
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, 95035-7417 (408) 432-1900 FAX: (408) 434-0507q TELEX: 499-3977 www.linear-tech.com
Dimensions inches (millimeters) unless otherwise noted. Package 36-Lead Plastic SSOP (0.209)
(LTC 05-08-1640)
0.499 0.509* (12.67 12.93)
0.301 0.311 (7.65 7.90)
0.068 0.078 (1.73 1.99)
0.0256 (0.65)
0.010 0.015 (0.25 0.38)
0.002 0.008 (0.05 0.21)
SSOP 1196
COMMENTS
200mA from Cells, 10µA Shutdown Fixed Frequency, Ultrahigh Efficiency Fixed Frequency, Lockable, Ultrahigh Efficiency Protected Power Management Building Block 1.5A Internal Switch, Precision 0.5% Reference Adapter Current Limit Loop Standby Shutdown Efficiency When Used with LTC1435 Dual Loop Applications
1479f LT/TP 0697 PRINTED
LINEAR TECHNOLOGY CORPORATION 1996

®1479 "heart" total power management solution single dual battery note

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