Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - battery management Dual battery system controller VRLA, Li-Ion, NiCd, NiMH SSOP 3

LTC1479

PowerPath Controller

for Dual Battery Systems

FEATURES

DESCRIPTION

■

Complete Power Path Management for Two

Batteries, DC Power Source, Charger and Backup

■

Compatible with Li-Ion, NiCd, NiMH and Lead-Acid

Battery Chemistries

■

“3-Diode” Mode Ensures Powers is Available

under “Cold Start” Conditions

■

All N-Channel Switching Reduces Power Losses

■

Capacitor and Battery Inrush Current Limited

■

“Seamless” Switching Between Power Sources

■

Independent Charging and Monitoring of Two

Battery Packs

■

New, Small Footprint, 36-Lead SSOP Package

The LTC

1479 is the “heart” of a total power management

solution for single and dual battery notebook computers

and other portable equipment. The LTC1479 directs power

from up to two battery packs and a DC power source to the

input of the main system switching regulator. It works in

concert with related LTC power management products

(e.g. LTC1435, LT

1511, etc.) to create a total system

solution; starting from the batteries and the DC power

source, and ending at the input of each of the computer’s

complex loads. A system-provided power management

µP monitors and actively directs the LTC1479.

The LTC1479 uses low loss N-channel MOSFET switches

to direct power from three main sources. An adaptive

current limiting scheme reduces capacitor and battery

inrush current by controlling the gates of the MOSFET

switches during transitions. The LTC1479 interfaces di-

rectly to the LT1510, LT1511 and LT1620/LTC1435 bat-

tery charging circuits.

TYPICAL APPLICATION

Dual Battery PowerPath

Controller System Block Diagram

PowerPath is a trademark of Linear Technology Corporation.

, LTC and LT are registered trademarks of Linear Technology Corporation.

■

Notebook Computer Power Management

■

Portable Instruments

■

Handheld Terminals

■

Portable Medical Equipment

■

Portable Industrial Control Equipment

APPLICATIONS

BAT1

BAT2

BATTERY CHARGER

(LT1510/LT1511/

LT1620/LTC1435)

SW A/B

SENSE

SW C/D

SW E/F

SW G

SW H

DCIN

1479 TA01

AC

ADAPTER

POWER

MANAGEMENT

µP

BACKUP

REGULATOR

(LT1304)

HIGH EFFICIENCY 

DC/DC SWITCHING 

REGULATOR

(LTC1435/LTC1438

ETC.)

LTC1479

PowerPath CONTROLLER

STATUS &

CONTROL

Summary of content (24 pages)

PAGE 1
LTC1479 PowerPath Controller for Dual Battery Systems U DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ The LTC ®1479 is the “heart” of a total power management solution for single and dual battery notebook computers and other portable equipment. The LTC1479 directs power from up to two battery packs and a DC power source to the input of the main system switching regulator. It works in concert with related LTC power management products (e.g. LTC1435, LT ®1511, etc.
PAGE 2
LTC1479 U W U U W W W ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION DCIN, BAT1, BAT2 Supply Voltages .......... – 0.3V to 32V SENSE +, SENSE –, VBAT, V + ..................... – 0.3V to 32V GA, GB, GC, GD, GE, GF, GG, GH .............. – 0.3V to 42V SAB, SCD, SEF, SG, SH ............................ – 0.3V to 32V SW, VGG ................................................... – 0.3V to 42V DCDIV, BDIV ............................................ – 0.3V to 5.5V All Logic Inputs (Note 1)............
PAGE 3
LTC1479 DC ELECTRICAL CHARACTERISTICS VDCIN = 25V, VBAT1 = 16V, VBAT2 = 12V, TA = 25°C unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS MIN TYP MAX 1.190 1.215 1.240 10 35 50 UNITS DCIN Good Monitor VTHDCDIV DCDIV Threshold Voltage (Mode 1) VDCDIV Rising from 1V to 1.5V VHYSDCDIV DCDIV Hysteresis Voltage (Mode 1) VDCDIV Falling from 1.5V to 1V IBIASDCDIV DCDIV Input Bias Current (Mode 1) VDCDIV = 1.
PAGE 4
LTC1479 AC ELECTRICAL CHARACTERISTICS VDCIN = 25V, VBAT1 = 16V, VBAT2 = 12V, TA = 25°C unless otherwise noted.
PAGE 5
LTC1479 U W TYPICAL PERFORMANCE CHARACTERISTICS MODE 1, DCDIV = 1.
PAGE 6
LTC1479 U U U PIN FUNCTIONS External Power Supply Pins DCIN (Pin 1): Supply Input. A 330Ω resistor should be put in series with this pin and the external DC power source. A 0.1µF bypass capacitor should be connected to this pin as close as possible. DCDIV (Pin 2): Supply Divider Input. This is a high impedance comparator input with a 1.215V threshold (rising edge) and approximately – 35mV hysteresis. BAT1, BAT2 (Pins 35, 34): Supply Input. These two pins are the inputs from the two batteries.
PAGE 7
LTC1479 U U U PIN FUNCTIONS SENSE – (Pin 14): Inrush Current Input. This pin should be connected directly to the “bottom” (output side) of the low valued resistor in series with the three input power selector switch pairs, SW A/B, SW C/D and SW E/F, for detecting and controlling the inrush current into and out of the power supply sources and the output capacitor. Battery Charging Switches GG, GH (Pins 29, 27): Charger Switch Gate Drive.
PAGE 8
LTC1479 W BLOCK DIAGRAM DCIN GA SAB GB GC SCD GD GE SEF GF VSENSE + DCIN MONITOR DCDIV SW A/B GATE DRIVERS BAT1 BAT2 SW C/D GATE DRIVERS BAT2 INRUSH SENSE SW E/F GATE DRIVERS BAT1 INRUSH SENSE DCIN DCIN INRUSH SENSE V+ VCC VSENSE – VCC REGULATOR & BIAS GENERATOR VCCP VCCP VCCP 2µA 2µA 2µA VCCP VGG SWITCH CONTROL LOGIC SW 3DM BATDIS DCIN/BAT DCINGOOD VGG SWITCHING REGULATOR BAT1 BAT2 DCIN VCCP VBKUP 2µA LOBAT BATTERY MONITOR VCCP BAT2 SW G GATE DRIVER GND SW H GATE
PAGE 9
LTC1479 WU W TI I G DIAGRA S DC and Battery Operation Timing MODE 1 DC OPERATION BAT1 DISCONNECTED MODE 2 DC OPERATION BAT1 CHARGING MODE 3 DC OPERATION BAT2 DISCONNECTED MODE 4 DC OPERATION BAT2 CHARGING MODE 5 BAT1 OPERATION MODE 6 BAT2 OPERATION 25V DCIN 0V 25V (16V) OUTPUT (12V) 0V DCINGOOD DCIN/BAT BATDIS BATSEL CHGSEL 1479 TD01 NOTE: FOR MODES 1 TO 6, 3DM = H, BAT1 = 16V, BAT2 = 12V Backup and DC Restoration Timing MODE 7 BAT1 LOW & DISCONNECTED MODE 8 BACKUP OPERATION MODE 9 NO POWER
PAGE 10
LTC1479 U OPERATION The LTC1479 is responsible for low-loss switching at the “front end” of the power management system, where up to two battery packs and a DC power source can be indiscriminately connected and disconnected. Smooth switching between input power sources is accomplished with the help of low-loss N-channel switches driven by special gate drive circuitry which limits the inrush current in and out of the battery packs and the system power supply capacitors.
PAGE 11
LTC1479 U OPERATION This scheme allows capacitors and MOSFET switches of differing sizes and current ratings to be used in the same system without circuit modifications. After the transition period has passed, the VGS of both MOSFETs in the selected switch pair rises to approximately 6V. The gate drive is set at 6V to provide ample overdrive for logic level MOSFET switches without exceeding their maximum VGS rating.
PAGE 12
LTC1479 U U W U APPLICATIONS INFORMATION POWER PATH SWITCHING CONCEPTS Power Source Selection The LTC1479 drives low-loss switches to direct power in the main power path of a dual rechargeable battery system — the type found in most notebook computers and other portable equipment. Figure 3 is a conceptual block diagram which illustrates the main features of an LTC1479 dual battery power management system, starting with the three main power sources and ending at the system DC/DC regulator.
PAGE 13
LTC1479 U U W U APPLICATIONS INFORMATION In the “3-diode” mode, only the first half of each power path switch pair, i.e., SW A, SW C and SW E, is turned on; and the second half, i.e., SW B, SW D and SW F, is turned off. These three switch pairs now act simply as three diodes connected to the three main input power sources as illustrated in Figure 4.
PAGE 14
LTC1479 U W U U APPLICATIONS INFORMATION be high enough to withstand the maximum battery or charger output voltage. In most cases, this will allow the use of 20V MOSFET switches in the charger path, while 30V switches are used in the main power path. DC SUPPLY TO SW A/B LTC1479 DCIN DCINGOOD + 1.
PAGE 15
LTC1479 U U W U APPLICATIONS INFORMATION ) ) The VCC supply is approximately 3.60V and provides power for the VGG switching regulator control circuitry and the gate drivers. Bypass this output with a 2.2µF tantalum capacitor. This capacitor is required for stability of the VCC regulator output. V RB2 = 121k LOBAT – 1 1.
PAGE 16
LTC1479 U U W U APPLICATIONS INFORMATION SW A DCIN RSENSE 0.033Ω SW B 12V AUX SW C LTC1538-AUX TRIPLE, HIGH EFFICIENCY, SWITCHING REGULATOR SW D SW E RDC2 3.3V SW F 0.1µF 330Ω Li-ION BATTERY PACK #1 5V BACKUP NiCD GA SAB GB DCIN GE SEF GF SENSE + SENSE – GC SCD GD DCDIV BACKUP REGULATOR VBKUP RDC1 BAT1 BAT2 Li-ION BATTERY PACK #2 LTC1479 2 VBAT RB2 BDIV 5 POWER MANAGEMENT µP RB1 CHGMON VCC 2.2µF 16V V+ VCCP + SW VGG GG SG GH SH DCIN 1mH* + 0.
PAGE 17
LTC1479 U U W U APPLICATIONS INFORMATION LT1511 Battery Charger Interface the charging battery through one of the N-channel switch pairs, SW G or SW H. The charging battery voltage is simultaneously connected through the CHGMON switch in the LTC1479 to the top of the charger voltage resistor divider, R4 and R5, for constant voltage charging. (See the LT1510 data sheet for further detail.
PAGE 18
LTC1479 U W U U APPLICATIONS INFORMATION The LT1511 has a third control loop that regulates the current drawn from the AC adapter. Therefore, the DC input to the LTC1479 and the input to the host system through SW A/B, is obtained from the “output” of the LT1511 adapter sense resistor, RS4, and not directly from the DC input connector as with the LT1510. This allows simultaneous operation of the host system while charging a battery without overloading the AC adapter.
PAGE 19
LTC1479 U U W U APPLICATIONS INFORMATION CHGMON POWER MANAGEMENT µP LTC1479 DC INPUT (FROM AC ADAPTER) 330Ω BAT2 GG SG GH SH DCIN BAT1 0.1µF TO SW C/D TO SW E/F TO W A/B + + BAT1 4 Li-ION BATTERY PACK SW G Si9926DY – R2 76.8k 0.1% + BAT2 4 Li-ION BATTERY PACK + CBAT2 10µF SW H Si9926DY – + C11 56pF SHDN R5 1.5M C3 0.1µF C2 100pF 1 COSC TG 2 RUN/SS BOOST 3 SW ITH LTC1435 4 VIN SFB 5 INTV SGND CC 6 VOSENSE BG C9, 100pF 7 SENSE – PGND C10 8 VCC SENSE + 100pF C4 0.
PAGE 20
LTC1479 U W U U APPLICATIONS INFORMATION Interfacing to the Battery Pack The LTC1479 is designed to work with virtually any battery pack chemistry or cell count, as long as the battery pack operating voltage range is somewhere between 6V and 28V. This permits great flexibility in system design. The low-battery threshold is adjustable and can be set anywhere between 6V and 28V.
PAGE 21
LTC1479 U TYPICAL APPLICATIONS N Dual NiMH Battery Power Management System (Using an LT1510, 1A Charger) RSENSE 0.033Ω Si4936DY SW A SW B Si4936DY SW C SW D 330Ω RDC2 205k 1% GA SAB GB DCIN GC SCD GD GE SEF GF SENSE + D1 L2** 10µH MBR0530 R8 10k NiCD CELL + VBKUP R2 390k 1% Q2 2N7002 LTC1479 R7 470k BDIV RB1 121k 1% VCC GND V + SW C1 0.
PAGE 22
LTC1479 U TYPICAL APPLICATIONS N Dual Li-Ion Battery Power Management System RSENSE 0.033Ω Si4936DY SW A SW B Si4936DY SW C SW D 330Ω RDC2 205k 1% GA SAB GB DCIN GC SCD GD GE SEF GF SENSE + R2 390k 1% Q2 2N7002 LTC1479 RB1 121k 1% R7 470k VCC GND V + SW C1 0.1µF + C10 0.1µF BATSEL CHGSEL DCINGOOD 3DM VCCP VGG GG SG GH SH BATDIS DCIN/BAT CHGMON LOBAT + C3 1µF 50V + 6 R1 22k 5VCC FROM DC/DC 5 C11 0.1µF (BACKUP) VCC 100k L1* 1mH C2 2.
PAGE 23
LTC1479 U TYPICAL APPLICATIONS N Dual Li-Ion Battery Power Management System (Using an LT1511, 3A Charger) RSENSE 0.033Ω Si4936DY SW A SW B Si4936DY SW C SW D 330Ω RDC2 205k 1% RDC1 12.1k 1% GA SAB GB DCIN GC SCD GD GE SEF GF ROHM DTA144E 5VCC FROM DC/DC Si4936DY SW E SW F 0.1µF (BOLD LINES INDICATE HIGH CURRENT PATHS) SENSE + + R2 390k 1% Q2 2N7002 BAT1 LTC1479 R11 470k BDIV RB1 121k 1% VCC GND V + SW C1 0.1µF + C14 0.
PAGE 24
LTC1479 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. G Package 36-Lead Plastic SSOP (0.209) (LTC DWG # 05-08-1640) 0.499 – 0.509* (12.67 – 12.93) 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 0.301 – 0.311 (7.65 – 7.90) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 0.205 – 0.212** (5.20 – 5.38) 0.068 – 0.078 (1.73 – 1.99) 0° – 8° 0.005 – 0.009 (0.13 – 0.22) 0.022 – 0.037 (0.55 – 0.95) 0.0256 (0.65) BSC *DIMENSIONS DO NOT INCLUDE MOLD FLASH.