LM2601 Adapter Interface Circuit General Description The Adapter Interface Circuit (AIC) is used to sense the presence of an external power source for a portable computer. It notifies the computer if a source is present and indicates if the source is appropriate for charging battery packs inside the computer. The AIC also senses an adapter current and its direction. AIC isolates the adapter and signals the computer when peak current threshold is exceeded. LM2601 drives P-channel FETs. No high current rated Schottky diode is required to implement an adapter switchover circuit. This significantly decreases additional heat dissipation during simultaneous fast battery charging while running a computer, particularly in Maximum Performance mode of operation Features n Detects an AC-DC adapter suitable for battery charging or an airplane or car power line adapter that should not be used for battery charging n Allows the implementation of intelligent switchover circuits for portable systems n LM2601 shuts down automatically when adapter is removed n Low leakage current from battery when not powered n Drives P-channel FETs, no Schottky diodes are required n No reverse inrush current from battery into the adapter output capacitance n Allows for battery capacity gas-gauge calibration under system software/firmware control n Adapter over current threshold programmable with external resistors n Wide input range: 5V - 24V n Available in TSSOP-14 package Applications n Portable Computers n Portable IAs (Internet Appliances, Information Appliances) n Other Battery Powered Devices Block Diagram 10130901 © 2001 National Semiconductor Corporation DS101309 www.national.com LM2601 Adapter Interface Circuit April 2001 LM2601 Pin Configuration TSSOP-14 10130902 Ordering Information Order Number Supplied As* Package Number Package Type LM2601MTC MTC14 TSSOP-14 Rail (94 Units/Rail) LM2601MTCX MTC14 TSSOP-14 Tape and Reel (2500 Units/Reel) * Partial Rails are available, there is no minimum order quantity. Tape and Reel is supplied as full reels only. Pin Description Pin No. Name Function 1 MPS DELAY A capacitor between this pin and ground sets the delay of the MPS risetime. See MPS DELAY description in Typical Application section. 2 MASTER POWER SOURCE Bi-directional logic pin. If driven high by an external source, indicates that a battery is powering the power bus. If driven high by the AIC, indicates the adapter is powering the bus. AIC cannot drive MPS low. If there is no valid adapter voltage present, the pin is not an output but a high impedance logic input. The input is pulled-down via an internal 40k resistor. 3 ADAPTER ENABLE Logic input pin. Active high. Grants permission to the adapter to drive both the power bus and the MPS signal. 4 ADAPTER PRESENT Logic output pin. High when 12 volts < VADAPTER < 17 volts. The output typically has 40k pull-down resistor. The source current is not internally limited and the part can be damaged if the output is shorted to ground when driven HIGH. 5 CHARGER PRESENT Logic output pin. High when VADAPTER > 17 volts. The output typically has 40k pull-down resistor. The source current is not internally limited and the part can be damaged if the output is shorted to ground when driven HIGH. 9 GND IC ground pin. 10 DISCONNECT Drives the gate of the disconnect P-ch FET. 11 BACKFEED Drives the gate of the backfeed P-ch FET. 12 DIRECTION SENSE Connection for current sense resistor to control BACKFEED. 13 PEAK SENSE Connection for current sense resistor to control DISCONNECT. 14 VADAPTER Power input pin. Output of AC adapter, auto adapter or airline adapter. www.national.com 2 (Note 1) Storage Temperature ESD Ratings Human Body Model (Note 2) Machine Model (Note 3) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VADAPTER −40˚C to 125˚C 2kV 200V −0.3V to 28V VPEAK SENSE, VDIRECTION SENSE, VBACKFEED, VDISCONNECT Operating Ratings (Note 1) −0.3V to VADAPTER VADAPTER ENABLE, VMASTER POWER SOURCE Supply Voltage (VADAPTER) −0.3V to 5.5V VMPS DELAY −0.3V to 2V 5V to 24V Ambient Temp. Range −20˚C to 70˚C Junction Temp. Range −20˚C to 85˚C Electrical Characteristics Limits with standard typeface apply for TJ = 25˚C, and limits in boldface type apply over the full temperature range (Note 4) Symbol VAE VAP, CP VMPSI VMPSO VADAPTER VCHARGER ∆VBACKFEED Parameter Conditions High Low 2.0 Logic Output Voltage Adapter present, Charger present High Low, ISINK = 5µA 2.9 Master Power Source 5V-CMOS Logic Input High Low 4.0 Logic Output Voltage Master Power Source VADAPTER > 5.8V High Low IQ Max Units V 3.1 0.25 V 0.6 V 0.8 4.5 4.75 0.05 0.5 V Adapter Voltage for VAP Low-to-High Transition 11.7 12.0 12.3 Hysteresis 1.8 2.0 2.2 Adapter Voltage for VCP Low-to-High Transition 16.5 17.0 17.4 Hysteresis 0.08 0.10 0.12 4 3 9 17 18 mV 127 125 135 143 145 mV Current Sense Differential Voltage Threshold for Driving Backfeed FET FET Control Voltage VDISCONNECT tDRIVE Typ 0.8 V V Vadapter − Direction sense, VADAPTER = 5V ∆VDISCONNECT Current Sense Differential Voltage Vadapter − Peak sense, Threshold for Driving Disconnect FET VADAPTER = 24V VBACKFEED, Min Adapter Enable 3V- or 5V-CMOS or TTL Logic Input Rise/Fall Time of FET Drive (Note 5) VADAPTER > 11V High VADAPTER 0.5V VADAPTER > 11V Low VADAPTER 10V or GND+0.5V, whichever is greater VADAPTER = 10V CLoad = 3000pF 3 6 µS V Quiescent Current VADAPTER = 24V 2 10 mA IL,B, IL,D Leakage Current into Backfeed or Disconnect VADAPTER = 0V VBACKFEED, VDISCONNECT = 18V 1 15 µA IL,AE Input Current into Adapter Enable Input VAE = 3.3V, Backfeed/Disconnect = 18V 50 µA Input Current into MPS Input VMPS = 5.5V 175 µA 4000 ppm/˚C IL, MPS TCDELAY Delay Time Temperature Coefficient Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. Note 2: The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. Note 3: The machine model is a 200pF capacitor discharged directly into each pin. All pins are rated for 200V except pins 4 and 5 which are rated for 100V. Note 4: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. 3 www.national.com LM2601 Absolute Maximum Ratings LM2601 Electrical Characteristics (Continued) Note 5: Adapter Enable input is used to change the state of Disconnect, Direction Sense input is used to change the state of Backfeed. a. Fall time is measured as the time it takes Backfeed or Disconnect voltage to go from a high level (approx. VADAPTER − 0.5V) to (VADAPTER − 4V) after the signal is initiated at Adapter Enable or Direction Sense. b. Rise time is measured as the time it takes Backfeed or Disconnect voltage to go from a low level (approx. 0.5V) to (VADAPTER − 2V) after the signal is initiated at Adapter Enable or Direction Sense. Typical Application 10130903 Notes 1. RSENSE value should be selected to guarantee that a programmed over current will cause a voltage drop across RSENSE of approx. 135mV. If a higher value of RSENSE has to be selected then R1/R3 resistor divider should be used to scale the voltage drop down. CDELAY value can be calculated from the following formula: CDELAY(nF) = TDELAY(µs)/90 at 25˚C 6. TDELAY temperature coefficient equals 4000ppm/˚C. See also the Typical Delay Time vs. Temperature graph. 7. Pin Master Power Source (MPS) should be connected to System Management Controller’s (SMC) and battery packs’ GPIOs. When SMC detects a powered AC adapter via active signals at Charger Present or Adapter Present outputs, it asserts Adapter Enable signal and isolates the battery pack(s). Adapter Enable signal turns the Disconnect FET on. When the AC adapter is unplugged or powered off, SMC enables one of the system battery packs. The battery packs’ embedded controller starts driving the logic MPS signal high that turns the Disconnect FET off. 5. 2. Internal and external circuits associated with Direction Sense and Backfeed FET pins allow to emulate a Schottky diode functionality with much lower forward voltage drop and, therefore, with much lower power dissipation. R2/R4 resistor divider programs the backfeed current protection threshold. The backfeed FET Q1 turns off when the backfeed current pulse level causes more than 9 mV (typical value) voltage drop between Vadapter pin and Direction Sense pin. 3. Voltage difference (VDIRECTION SENSE - VADAPTER) must be higher than 20mV to reliably isolate the adapter in case of leakage. 4. R5 and R6 prevent the FETs from turning on unless driven by LM2601. www.national.com 4 LM2601 Typical Delay Time vs. Temperature 10130905 necessary sometimes to have a computer fully discharging the battery and then fully recharging it (for battery gas gauge calibration purposes) while being powered by an AC adapter. AIC will also allow a computer to prevent backfeeding current into an adapter if the adapter is not powered while being plugged into the computer (some of existing adapters can draw current from the computer under this conditions for charging the AC adapter output bulk capacitance from the computer battery). While the lowest usable adapter voltage is about 9.5V, that is VADAPTER = 11.7V minus 2.2V hysteresis, AIC is operational down to VADAPTER = 5V. This means that AIC will not generate false readings down to VADAPTER = 5V. Such false readings would be MPS = HIGH, ADAPTER PRESENT = HIGH, CHARGER PRESENT = HIGH. AIC determines usable voltage ranges by comparing VADAPTER with an internal 2.5V voltage reference (see also Electrical Characteristics). AIC detects operating current limit and leakage current limit into the adapter jack by differential sensing across current sense resistor RSENSE either directly or scaled down by resistor dividers R1/R3 and R2/R4. When designing the LM2601 into a system it may be necessary to consider ESD protection requirements for the adapter jack according to your system design spec. Application Information The adapter interface circuit (AIC) IC provides the control functions necessary for use in mating a constant voltage output AC-DC adapter or airline adapter to a notebook computer system or a portable device. It allows optimal battery charging during computer operation, and allows battery discharge for battery gas gauge calibration. It receives control signals from the notebook computer, monitors input current from the adapter, provides adapter voltage status to the notebook system management microcontroller (or ″embedded controller″), and appropriately drives MOSFET switches to electrically connect the adapter to the computer. AIC will allow a system designer to solve various power management tasks typical for an adapter powered systems containing a rechargeable battery. When a notebook computer is being powered from a battery and the adapter is plugged in, the computer should start drawing power from the adapter, not from the battery. The most time efficient charging scenario is when a computer draws the full rated current from a constant voltage adapter. The computer uses what it needs to run, and passes all remaining power on to the battery for charging. The computer should be able to automatically refuse to charge a battery when powered from an airplane power line. It may be 5 www.national.com LM2601 Adapter Interface Circuit Physical Dimensions inches (millimeters) unless otherwise noted TSSOP-14 Package 14-Lead Thin Shrink Small-Outline Package For Ordering, Refer to Ordering Information Table NS Package Number MTC14 LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 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