MAX1538 19-3169 Rev 0 1/04 Power-Source Selector for Dual-Battery Systems General Description Features The MAX1538 selector provides power-source control Automatically Detects and Responds to for dual-battery systems. The device selects between Low-Battery Voltage Condition an AC adapter and dual batteries based on the pres- Battery Insertion and Removal ence of the three power sources and the state of AC-Adapter Presence charge of each battery. The MAX1538 includes analog Airline-Adapter Presence comparators to detect AC/airline-adapter presence and Step-Down and Step-Up Charger Compatibility determine battery undervoltage. Fast analog circuitry Fast Break-Before-Make Selection allows the device to switch between power sources to Allows Hot Swapping of Power Sources implement a break-before-make time, which allows hot No External Schottky Diodes Needed swapping of battery packs. The MAX1538 indepen- dently performs power-source monitoring and selec- 50A Maximum Battery Quiescent Current tion, freeing the system power-management P for Implements Battery Capacity Relearning other tasks. This simplifies the development of P Allows Usage of Aircraft Supply power-management firmware and allows the P to enter standby, reducing system power consumption. Direct Drive of P-Channel MOSFETs The MAX1538 supports relearn mode, which allows Simplifies Power-Management P Firmware the system to measure and fully utilize battery capacity. 4.75V to 28V AC-Adapter Input Voltage Range In this state, the part allows the selected battery to be Small 28-Pin Thin QFN Package (5mm x 5mm) discharged even when an AC adapter is present. The MAX1538 can also be used to power the system in an Ordering Information aircraft. On detecting an airline adapter, the MAX1538 automatically disables charging or discharging of bat- PART TEMP RANGE PIN-PACKAGE tery packs and only allows the system to be powered MAX1538ETI -40C to +85C 28 Thin QFN from the adapter. The MAX1538 is available in a space-saving 28-pin thin Typical Operating Circuit QFN package with a maximum footprint of 5mm x 5mm. Applications ACDET Notebook and Subnotebook Computers CHRG AIRDET BATSEL Internet Tablets RELRN ADPIN Dual-Battery Portable Equipment OUT2 OUT1 REVBLK OUT0 EXTLD BATTERY CHARGER MAX1538 V DD ADPBLK CHG OUT CHGIN MINVA Pin Configuration appears at end of data sheet. CHGA MINVB CHGB DISB GND DISA BATB BATA BATSUP Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. SYSTEM LOAD BATTERY B ADAPTER BATTERY APower-Source Selector for Dual-Battery Systems ABSOLUTE MAXIMUM RATINGS V , V , V , V , V , Continuous Power Dissipation (T = +70C) EXTLD BATSUP ADPIN BATA BATB A V to GND .................................................-0.3V to +30V 28-Pin Thin QFN 5mm x 5mm CHGIN V to GND...................................-0.3V to (V + 0.3V) (derate 20.8mW/C above +70C)..........................1666.7mW ADPPWR ADPIN V , V to GND ...................-0.3V to (V + 0.3V) Operating Temperature Range REVBLK ADPBLK EXTLD V , V V to GND ..........-0.3V to (V + 0.3V) MAX1538ETI ....................................................-40C to +85C CHGA CHGB, DISBAT CHGIN V to GND..........................................-0.3V to (V + 0.3V) Junction Temperature......................................................+150C DISA BATA V to GND..........................................-0.3V to (V + 0.3V) Storage Temperature Range .............................-65C to +150C DISB BATB V , V , V , V , V , V , V , Lead Temperature (soldering, 10s) .................................+300C DD CHRG BATSEL RELRN OUT0 OUT1 OUT2 V , V , V , V to GND..........-0.3V to +6V MINVA MINVB AIRDET ACDET Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (V = V = V = 16.8V, C = 1F, V = V = 0.93V, V = V = 28V, V = V = V = 0, BATA BATB CHGIN VDD MINVA MINVB EXTLD ADPIN CHRG BATSEL RELRN C = C = C = C = C = C = C = C = 4.7nF, T = 0C to +85C, unless otherwise noted. ADPPWR REVBLK ADPBLK DISBAT DISA DISB CHGA CHGB A Typical values are at T = +25C.) A PARAMETER CONDITIONS MIN TYP MAX UNITS ADPIN, EXTLD Supply Voltage 4.75 28.00 V Range CHGIN, BATA, BATB and 4.75 19.00 V BATSUP Supply Voltage Range V = highest, ADPIN 21 50 V = high ADPPWR V = highest, ADPIN 23 54 V = low ADPPWR V = 4.75V to 19V, BATA V = highest, ADPIN, BATA, BATB, BATSUP V = 4.75V to 19V, BATA BATB 21 42 V = high Quiescent Current (Current from V = 4.75V to 19V, DISA A BATSUP V = 4.75V to 28V, the Highest Voltage Supply) ADPIN V = highest, V = low 24 50 BATA DISA no external load at V DD V = highest, BATB 21 42 V = high DISB V = highest, V = low 24 50 BATB DISB V = highest 18 40 BATSUP ADPIN Quiescent Current (ADPIN V = high 0.01 0.5 ADPPWR V = 4.75V to 18V, ADPIN Current When Not the Highest A no external load at V DD V = low 2.6 6 Voltage) ADPPWR BATA Quiescent Current (BATA V = high 3.9 6.0 DISA V = 4.75V to 19V, BATA Current When Not the Highest A no external load at V DD V = low 7.0 12 Voltage) DISA BATB Quiescent Current (BATB V = high 3.9 6.0 DISB V = 4.75V to 19V, BATB Current When Not the Highest A no external load at V DD V = low 7.0 12 DISB Voltage) Adapter selected (REVBLK or ADPBLK pins low) 3.0 6.1 EXTLD Quiescent Current A Adapter not selected (REVBLK and ADPBLK pins high) 0.02 1.0 AC or ai r l i ne state (C H G A, CH GB, and D ISBA T pi ns hi g h) 0.03 1.5 Charge state (CHGA or CHGB pin low, DISBAT pin high) 3.1 6.2 CHGIN Quiescent Current A Discharge or relearn state (CHGA or CHGB pin low, 6.1 12.1 DISBAT pin low) 2 MAX1538