19-4638; Rev 2; 11/05 Battery Manager Applications Battery Backup for CMOS RAM Uninterruptible Power Supplies Computers Controllers Automotive Systems Features Switches to Backup Battery if Power Fails Consumes Less than 100nA of Battery Current Power-Fail Output Signals Primary Power-Supply Loss Battery Monitor Indicates Low Battery Battery Can Be Disconnected to Prevent Discharge During Shipping Battery Automatically Reconnected when VCC is Applied Pin-Compatible with the DS1259 Supply Current Three Times Lower than DS1259 Available in Extended-Industrial and Military Temperature Ranges Ordering Information PART MAX1259C/D TEMP RANGE 0C to +70C PIN-PACKAGE Dice* MAX1259CPE 0C to +70C 16 PDIP MAX1259CWE 0C to +70C 16 Wide SO MAX1259EPE -40C to +85C 16 PDIP MAX1259EWE -40C to +85C 16 Wide SO MAX1259MJE -55C to +125C 16 CERDIP *Contact factory for dice specifications. Functional Diagram Devices in PDIP and SO packages are available in both leaded and lead-free packaging. Specify lead free by adding the + symbol at the end of the part number when ordering. Lead free not available for CERDIP package. Pin Configuration VCCO V CCI TOP VIEW N.C. 1 16 V CCI 15 V CCI V BATT V BATT RESET LOGIC 2 MAX1259 RST BF 3 14 N.C. N.C. 4 13 V CCO BAT 5 12 V CCO RST 6 11 PF GND 7 10 N.C. GND 8 9 N.C. PF BF REF MAX1259 BAT GND DIP/SO ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1 MAX1259 General Description The MAX1259 battery manager provides backup-battery switching for CMOS RAM, microprocessors, or other low-power logic ICs. It automatically switches to the backup battery when the primary power supply is interrupted. Low-loss switches guarantee an input-to-output differential of only 200mV while supplying 250mA from the primary power supply or 15mA from the battery. Battery discharge during shipping does not occur in the MAX1259, since the backup battery can be disconnected by strobing the RST input. A battery-fail output signal indicates when the backup battery is below +2V, and a power-fail output signal indicates when the primary power supply is low. The MAX1259 monitors the backup battery, warns of impending power failures, and switches the memory to the battery when failures occur. The MAX1259 is pincompatible with the DS1259, but consumes three times less supply current. Commercial, extended, and military temperature range devices are available. MAX1259 Battery Manager ABSOLUTE MAXIMUM RATINGS Voltage on Any Pin (with respect to GND) ............-0.3V to +7.0V Operating Temperature Range C Suffix................................................................0C to +70C E Suffix .............................................................-40C to +85C M Suffix ..........................................................-55C to +125C Storage Temperature Range .............................-55C to +125C Lead Temperature (soldering, 10s) .................................+300C 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. RECOMMENDED DC OPERATING CONDITIONS (All grades, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER Primary Power Supply Input High Voltage (Note 1) Input Low Voltage SYMBOL VCCI CONDITIONS MIN (Note 1) TYP MAX UNITS 5.0 5.5 V MAX1259C 2.0 VCCI + 0.3 MAX1259E/M 2.4 VCCI + 0.3 VIH VIL V (Note 1) -0.3 Battery Voltage VBATT Pin 2 (Note 2) 2.5 Battery Output BAT Pin 5 (Note 1) VBATT 0.1 3.0 +0.8 V 3.7 V V DC ELECTRICAL CHARACTERISTICS (VCC = +4.5V to +5.5V, all grades, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS Leakage Current ILO Output Current PF, BF IOH VOH = 2.4V (Note 3) IOL VOL = 0.4V Input Supply Current ICCI (Note 4) VCCO Output Current ICCO VCCO = VCCI - 0.2V, pins 12, 13 Power-Fail Trip Point VTP Battery-Fail Trip Point VBATTF MIN TYP -1.0 Pin 11 (Notes 2, 5) MAX UNITS +1.0 A -1.0 4.0 2.00 1.26 x VBATT 250mV Pin 3 (BF detect) (Note 6) 1.26 x VBATT mA 3.33 mA 250 mA 1.26 x VBATT + 250mV V 2.0 V DC ELECTRICAL CHARACTERISTICS (VCCI < VBATT, all grades, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER VCCO Output Current Battery Leakage (Note 8) BAT Output Current 2 SYMBOL ICCO2 IBATT IBATOUT CONDITIONS VCCO = VBATT - 0.2V, pins 12, 13 (Note 7) MIN TYP MAX 15 MAX1259C 100 MAX1259E 150 UNITS mA nA MAX1259M 10 A Pin 5 (Note 9) 100 A _______________________________________________________________________________________ Battery Manager MAX1259 CAPACITANCE (All grades, TA = +25C, unless otherwise noted.) (Note 10) PARAMETER SYMBOL Input Capacitance Output Capacitance CONDITIONS MIN TYP MAX UNITS CIN 5 10 pF COUT 5 10 pF TYP MAX UNITS AC ELECTRICAL CHARACTERISTICS (VCC = 4.0V to 5.5V, all grades, TA = +25C, unless otherwise noted.) PARAMETER SYMBOL VCCI Fall Time CONDITIONS MIN tF 300 s VCCI Rise Time tR 1 s Power-Down to PF Low tPF 0 PF High After Power-Up tREC RST Pulse Width s 100 RSTPW 50 10 s ns Note 1: All voltages referenced to ground. Note 2: Trip-point voltage for power-fail detect: VTP = 1.26 x VBATT. For 5% operation: VBATT = 3.7V max. Note 3: 50pF load capacity. Note 4: Measured with pins 3, 11, 12, 13, and open. Note 5: VTP is the point at which PF is driven low. Note 6: VBATTF is the point at which BF is driven low. Note 7: ICCO2 may be limited by battery capacity. Note 8: Battery leakage is the internal energy consumed by the MAX1259. Note 9: See the Typical Operating Characteristics BAT Switch Drop vs. Battery Voltage graph. Note 10: Guaranteed by design. Not tested. Pin Description PIN NAME FUNCTION 1, 4, 9, 10, 14 N.C. 2 VBATT No Connection. Make no connection to these pins. 3 BF 5 BAT Battery Output. During normal operation, the BAT output supplies up to 1mA of continuous battery current. In shipping mode, the BAT output is high impedance. 6 RST Battery-Disconnect Input. The RST input is used to prevent battery discharge during shipping. Pulsing the RST input disconnects the backup battery from the VCCO and BAT outputs. 7, 8 GND 11 PF Power-Fail Output. PF is high for VCCI greater than 1.26 x VBATT (VTP), indicating a valid VCCI voltage. 12, 13 VCCO CMOS RAM is Powered from VCCO. The battery switchover circuit compares VCCI to the VBATT input, and connects VCCO to whichever is higher. 15, 16 VCCI +5V VCC Input Backup Battery Input Battery-Fail Output. BF is high for VCCI at or above VTP and the backup battery greater than 2V. If the backup battery is below 2V or VCCI falls below VTP, BF will be driven low. Ground _______________________________________________________________________________________ 3 Typical Operating Characteristics (TA = +25C, unless otherwise noted.) VCC MODE TA = +25C VCC MODE TA = +75C BATTERY-BACKUP MODE TA = +25C 150 VCCI = +4.5V 100 50 VBATT - VCCO (mV) 150 VCCI - VCCO (mV) 150 200 MAX1259toc02 200 MAX1259toc01 200 VCCI - VCCO (mV) SWITCH VOLTAGE DROP vs. LOAD CURRENT SWITCH VOLTAGE DROP vs. LOAD CURRENT MAX1259toc03 SWITCH VOLTAGE DROP vs. LOAD CURRENT VCCI = +4.5V 100 VBATT = +2.5V 100 50 50 VCCI = +5.0V VBATT = +3.0V VCCI = +5.0V 0 100 150 200 250 50 100 150 200 0 250 ICCO2 (mA) SWITCH VOLTAGE DROP vs. LOAD CURRENT POWER-FAIL TRIP POINT vs. BATTERY VOLTAGE BATTERY-FAIL TRIP POINT vs. TEMPERATURE 4.8 POWER-FAIL TRIP POINT (V) VBATT = +2.5V 100 50 TA = +25C 4.6 4.4 4.2 VCCI RISING 4.0 3.8 3.6 VCCI FALLING 3.4 VBATT = +3.0V 2.3 VCCI = 5.0V 2.2 BATTERY-FAIL TRIP POINT (V) 5.0 MAX1259toc04 150 0 3.0 5 10 15 VBATT RISING 2.0 1.9 1.8 VBATT FALLING 1.6 2.4 2.6 2.8 3.0 3.2 3.4 3.6 0 3.8 10 20 30 40 50 60 70 80 90 100 ICCO2 (mA) VBATT (V) TEMPERATURE (C) QUIESCENT SUPPLY CURRENT vs. POWER SUPPLY BAT CURRENT vs. BATTERY VOLTAGE BAT SWITCH DROP vs. BATTERY VOLTAGE VBATT - BAT = 100mV 1.8 2.5 IBAT (mA) 1.6 2.0 1.5 100 TA = +25C 1.4 1.2 1.0 IBAT = 1mA 80 VBATT - BAT (mV) VBATT = 3.0V, ICCO = 0mA TA = +25C MAX1259toc08 2.0 MAX1259toc07 3.5 60 40 IBAT = 100A TA = +75C 20 1.0 0.5 0 0.8 0 1 2 3 VCCI (V) 4 2.1 4 5 6 15 1.7 3.2 3.0 10 ICCO (mA) BATTERY-BACKUP MODE TA = +75C 0 5 ICCO (mA) 200 VBATT - VCCO (mV) 0 0 MAX1259toc06 50 MAX1259toc05 0 MAX1259toc09 0 ICCI (mA) MAX1259 Battery Manager 0 2.0 2.5 3.0 VBATT (V) 3.5 4.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 VBATT (V) _______________________________________________________________________________________ Battery Manager MAX1259 VCCI +4.25V +3V tF tR tPF tREC PF BATTERY CURRENT Figure 1. Power-Down/Power-Up Conditions Detailed Description Battery Switchover and VCCO Figure 2 shows a typical application for the MAX1259. CMOS RAM is powered from V CCO . The battery switchover circuit compares VCC to the VBATT input, and connects VCCO to whichever is higher. Switchover occurs when VCC equals VBATT as VCC falls, and when VCC is 60mV greater than VBATT as VCC rises. This hysteresis prevents repeated, rapid switching if V CC falls very slowly or remains nearly equal to the battery voltage. Low-loss switches guarantee an input-to-output differential of only 200mV, while supplying 250mA from the primary power supply or 15mA from the battery. Note: With adequate filtering, the MAX1259 need only supply the average current drawn by the CMOS RAM. Many RAM data sheets specify a 75mA maximum supply current, but this peak current spike lasts only 100ns. If the sum of the peak currents is greater than 250mA, a capacitor placed on the VCCO output can supply the high instantaneous current, while VCCO need only supply the average current, which is much less. The MAX1259 operates with battery voltages from 2.5V to 3.7V. High-value capacitors--either standard electrolytic or farad-sized, double-layer capacitors--can also be used for short-term memory backup (Figure 3). 15, 16 VCC VCCI VCC0 12, 13 TO RAM RAM16 3k RAM2 VCC 15, 16 VCCO VCCI CE1 12, 13 PF NMI GND 7, 8 Figure 2. Typical Application Circuit 2 VBATT 6.2k 11 VBATT 2N3904 CE0 MAX1259 2 MAX1259 CE15 RAM1 ADDRESS DECODE 0.22F MAXCAP GND 7, 8 P NOTE: LARGE VALUE CAPACITORS, SUCH AS A 0.22F MAXCAP, MAY BE USED FOR SHORT-TERM MEMORY BACKUP. Figure 3. Using a MAXCAP as a Backup Battery _______________________________________________________________________________________ 5 MAX1259 Battery Manager +5V VCCI 0V 50ns MIN RST VIH VIL +5V VCCO +3V HIGH IMPEDANCE 0V HIGH IMPEDANCE +3V BAT 0V Figure 4. Reset Timing To achieve rated performance, the VCC input should be connected to both VCCI pins (pins 15 and 16). As well, the switched output should be connected to both VCCO pins (pins 12 and 13). Power Fail The power-fail (PF) output is high for VCCI greater than 1.26 x VBATT (VTP), indicating a valid VCCI voltage. Battery Fail If VCCI is at or above the voltage trip threshold (VTP) and the backup battery is greater than 2V, the batteryfail (BF) output will be held high, indicating a charged battery. If the backup battery drops below 2V or VCCI falls below VTP, BF will be driven low. BAT Output During normal operation, the BAT output stays at the battery voltage, regardless of the VCCI level. This provides 1mA battery current. 6 RESET (Digitally Controlled Battery Disconnect) To prevent battery discharge during shipping, the backup battery can be disconnected from VCCO to BAT. This disconnect feature is activated by pulsing the reset (RST) input high for a minimum of 50ns with VCCI greater than VTP (Figure 4). When primary power is removed, the V CCO and BAT outputs will go high impedance. The next time primary power is applied with VCCI greater than 1.26 x VBATT (VTP), normal operation resumes. Note that when the MAX1259 is first powered up, V CCI must be brought above 1.26 x VBATT. This resets an internal flip-flop, ensuring that the part is in normal VCC mode and not in shipping mode. Applications Information If a protection diode is placed in series with the backup battery, pin 2 must be bypassed with at least a 0.01F capacitor to ground. _______________________________________________________________________________________ Battery Manager Package Information For the latest package outline information, go to www.maxim-ic.com/packages. Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 7 (c) 2005 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX1259 Chip Topography