19-4249; Rev 0; 8/08 Battery-Backup Circuits with Regulated Output Voltage The MAX16023/MAX16024 low-power battery-backup circuits with a regulated output are capable of delivering up to 100mA output current. The MAX16023/MAX16024 include a low-dropout regulator, a microprocessor (P) reset circuit, and a battery switchover circuit. Additional available features include a manual reset, a power-fail comparator, and a battery-on indicator. These devices reduce the number of external components to minimize board space and improve reliability. The MAX16023/MAX16024 are ideally suited for providing power for backing up critical memory such as static random-access memory (SRAM) or real-time clocks (RTCs). The regulated output is powered by VCC when it is present and switches over to the backup power during brownout. The MAX16023/MAX16024 accept an input voltage from 1.53V to 5.5V and provide fixed standard output voltages of 1.2V, 1.8V, 2.5V, 3.0V, and 3.3V. The MAX16024 offers the ability to externally set the output voltage using a resistive divider. All outputs are available with push-pull or open-drain configurations. The MAX16023 offers a power-fail comparator for monitoring an additional voltage or for providing an early powerfail warning. Another feature includes a manual-reset input (MAX16023/MAX16024). The MAX16024 also features a battery-on indicator and chip-enable gating function. The MAX16023/MAX16024 are offered in 8- and 10-pin TDFN packages and are fully specified from -40C to +85C temperature range. Applications Main/Backup Power for RTCs/SRAM Industrial Controls GPS Systems Set-Top Boxes Point-of-Sale Equipment Portable/Battery Equipment Features System Monitoring for 5V, 3.3V, 3V, 2.5V, or 1.8V Power-Supply Voltages 100mA Low-Dropout Regulator Factory-Trimmed and Adjustable Output Voltages 1.53V to 5.5V Operating Voltage Range Low-Power Consumption: 4A (typ) Power-Fail Comparators for Monitoring Voltages Down to 0.6V Battery-On Indicator Battery Freshness Seal On-Board Gating of CE Signals, 1.5ns Propagation Delay (MAX16024) Debounced Manual-Reset Input 145ms (min) Reset Timeout Period Tiny 8-Pin and 10-Pin TDFN Packages UL(R) Certified to Conform to IEC 60950-1 Ordering Information PART TEMP RANGE PIN-PACKAGE MAX16023_TA_ _ _+T -40C to +85C 8 TDFN-EP* MAX16024_TB_ _ _+T -40C to +85C 10 TDFN-EP* The first placeholder "_" designates reset output options. A letter "L" in this placeholder indicates a push-pull output and letter "P" indicates an open-drain output. The next placeholder "_" designates the reset threshold (Table 1). The last two placeholders "_ _" designate output voltage (Table 2). For the MAX16024 with adjustable output voltage version, there are no last two placeholders. +Denotes a lead-free/RoHS-compliant package. T = Tape and reel. *EP = Exposed pad. UL is a registered trademark of Underwriters Laboratories, Inc. OUT RESET GND PFO CEOUT OUT RESET GND BATT ON Pin Configurations 8 7 6 5 10 9 8 7 6 MAX16023 MAX16024 *EP *EP = EXPOSED PAD MR PFI 2 3 4 5 SET BATT TDFN 1 MR 4 BATT 3 VCC 2 *EP + CEIN 1 VCC + TDFN ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1 MAX16023/MAX16024 General Description MAX16023/MAX16024 Battery-Backup Circuits with Regulated Output Voltage ABSOLUTE MAXIMUM RATINGS VCC, BATT, OUT to GND..........................................-0.3V to +6V RESET, PFO, BATT ON (all open drain) to GND..................................................................-0.3V to +6V RESET, PFO, BATT ON (all push-pull) to GND .................................................-0.3V to (VOUT + 0.3V) PFI, CEIN, CEOUT to GND.......................-0.3V to (VOUT + 0.3V) MR to GND .................................................-0.3V to (VCC + 0.3V) Input Current VCC Peak Current.....................................................................1A VCC Continuous Current ...............................................250mA BATT Peak Current .......................................................500mA BATT Continuous Current ...............................................70mA Output Current OUT Short Circuit to GND Duration ....................................10s RESET, BATT ON, CEOUT..............................................20mA Continuous Power Dissipation (TA = +70C) 8-Pin TDFN (derate 24.4mW/C above +70C) .........1951mW 10-Pin TDFN (derate 24.4mW/C above +70C) .......1951mW Thermal Resistance (Note 1) JA (8-Pin and 10-Pin TDFN)........................................41C/W Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. 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 (VCC = 1.53V to 5.5V, VBATT = 3V, reset not asserted, TA = TJ = -40C to +85C, COUT = 10F, unless otherwise noted. Typical values are at TA = TJ = +25C.) (Note 2) PARAMETER Operating Voltage Range SYMBOL VCC, VBATT CONDITIONS (Note 3) VCC = LDO + 0.5V, no load Supply Current ICC VCC = LDO + 0.5V, IOUT = 20mA Supply Current in Battery-Backup Mode IBATT BATT Standby Current SET Reference Voltage VSET SET Input Leakage Current Output Voltage Range Output Voltage Accuracy 2 VOUT MIN MAX UNITS 5.5 V LDO = 1.2V 4.3 LDO = 1.8V 4.7 7 LDO = 2.5V 5.2 7.5 LDO = 3V 5.5 8 6 LDO = 3.3V 5.7 8 LDO = 1.2V 16 20 LDO = 1.8V 16 21 LDO = 2.5V 16 18.1 LDO = 3V 17 18.6 LDO = 3.3V 17 19 3.5 5.26 A +0.01 A VCC = 0, VBATT = 3V, no dropout, no load VCC > VBATT + 0.2V -0.01 MAX16024_TB_, VCC = 2.2V 1.144 MAX16024_TB_, SET = 1.2V -20 MAX16024_TB_, VCC > VOUT IOUT = 1mA TYP 1.53 1.2 1.8 1.272 V +20 nA 5.25 V LDO = 1.2V 1.145 1.2 1.270 LDO = 1.8V 1.704 1.8 1.900 LDO = 2.5V 2.368 2.5 2.634 LDO = 3V 2.837 3 3.165 LDO = 3.3V 3.114 3.3 3.482 _______________________________________________________________________________________ A V Battery-Backup Circuits with Regulated Output Voltage (VCC = 1.53V to 5.5V, VBATT = 3V, reset not asserted, TA = TJ = -40C to +85C, COUT = 10F, unless otherwise noted. Typical values are at TA = TJ = +25C.) (Note 2) PARAMETER SYMBOL TYP MAX UNITS Line Regulation VCC = (VOUT + 1V) to (VOUT + 2V), IOUT = 1mA CONDITIONS 0.2 1.0 %/V Load Regulation VCC = VOUT + 1V, IOUT = 1mA to 2mA 0.15 1.0 % IOUT = 50mA (Note 4) Dropout Voltage Output Current Limit Battery Freshness Leakage Current MIN LDO = 1.2V 500 LDO = 1.8V 200 LDO = 2.5V 180 LDO = 3V 150 LDO = 3.3V 150 VCC = 1.6V 75 VCC 2V 150 mV mA VBATT = 5.5V 10 nA RESET OUTPUT (RESET) Reset Threshold VTH VCC Falling to Reset Delay tRD VCC falling at 10V/ms Reset Timeout Period tRP VCC rising RESET Output Low Voltage VOL RESET Output High Voltage (Push-Pull Output) VOH RESET Output Leakage Current (Open-Drain Output) (See Table 1) V 20 s 145 215 285 VOUT = 3.3V, ISINK = 3.2mA, RESET asserted 0.3 VOUT = 1.8V, ISINK = 1mA, RESET asserted 0.3 VOUT = 1.2V, ISINK = 100A, RESET asserted 0.3 VCC 1.1 x VTH, ISOURCE = 100A, RESET deasserted VOUT - 0.3V ms V V V RESET = 5.5V, reset deasserted 1 A POWER-FAIL COMPARATOR (PFI, PFO) PFI Input Threshold VPFT PFI Input Hysteresis VPFI-HYS PFI Input Current VPFI falling, 1.6V VCC 5.5V 0.590 0.611 30 IPFI PFO Output Low Voltage 0.570 -1 +1 VOUT = 1.8V, ISINK = 1mA, PFO asserted 0.3 VOUT =1.2V, ISINK = 100A, PFO asserted 0.3 PFO Output High Voltage (Push-Pull Output) ISOURCE = 100A, PFO deasserted PFO Leakage Current (Open-Drain Output) V PFO = 5.5V, PFO deasserted PFO Delay Time (VPFI + 100mV) to (VPFI - 100mV) V mV VOUT - 0.3V A V V 1 20 A s MANUAL RESET (MR) Input Low Voltage VIL Input High Voltage VIH Pullup Resistance 0.3 x VCC 0.7 x VCC Pullup resistance to VCC 20 V 30 k Glitch Immunity 100 ns MR to Reset Delay 120 ns _______________________________________________________________________________________ 3 MAX16023/MAX16024 ELECTRICAL CHARACTERISTICS (continued) MAX16023/MAX16024 Battery-Backup Circuits with Regulated Output Voltage ELECTRICAL CHARACTERISTICS (continued) (VCC = 1.53V to 5.5V, VBATT = 3V, reset not asserted, TA = TJ = -40C to +85C, COUT = 10F, unless otherwise noted. Typical values are at TA = TJ = +25C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS BATTERY-ON INDICATOR (BATT ON) Output Low Voltage Output High Voltage (Push-Pull Output) VOL VOH VOUT = 1.2V, ISINK = 100A, BATT ON deasserted 0.3 VOUT = 1.8V, ISINK = 1mA, BATT ON deasserted 0.3 VOUT = 3.3V, ISINK = 3.2mA, BATT ON deasserted 0.3 ISOURCE = 100A, BATT ON asserted Output Leakage Current (Open-Drain Output) VCC = 5.5V Output Short-Circuit Current Sink current, VCC = 5V (Note 6) VOUT - 0.3V V V 1 60 A mA CE GATING (CEIN, CEOUT) CEIN Leakage Current Reset asserted, VCC = 0.9 x VTH or 0 +1 A CEIN to CEOUT Resistance VCC = 5V, reset deasserted 8 50 CEOUT Short-Circuit Current Reset asserted, CEOUT = 0 0.75 2 mA CEIN to CEOUT Propagation Delay 50 source, CLOAD = 50pF, VCC = 4.75V 1.5 7 ns Output High Voltage Reset to CEOUT Delay Note 2: Note 3: Note 4: Note 5: Note 6: 4 VOH ISOURCE = 100A, reset asserted -1 VOUT - 0.3V V 12 s All devices are 100% production tested at TA = +25C and TA = +85C. Limits over temperature are guaranteed by design. VBATT can be 0 anytime or VCC can go down to 0 if VBATT is active (except at startup). Dropout voltage is defined as (VIN - VOUT) when VOUT is 2% below the value of VOUT when VIN = VOUT + 1V. CEIN to CEOUT resistance is tested with VCC = 5V and V CEIN = 0 or 5V. Use external current-limiting resistor to limit current to 20mA (max). _______________________________________________________________________________________ Battery-Backup Circuits with Regulated Output Voltage Table 2. Fixed Output Voltage RESET THRESHOLD RANGES (V) SUFFIX MIN TYP MAX SUFFIX NOMINAL OUTPUT VOLTAGE (V) L 4.508 4.63 4.906 33 3.3 M 4.264 4.38 4.635 30 3.0 T 2.991 3.08 3.239 25 2.5 S 2.845 2.93 3.080 18 1.8 R 2.549 2.63 2.755 12 1.2 Z 2.243 2.32 2.425 Y 2.117 2.19 2.288 W 1.603 1.67 1.733 V 1.514 1.575 1.639 Typical Operating Characteristics (VCC = 5V, VBATT = 0, IOUT = 0, TA = +25C, unless otherwise noted.) VCC SUPPLY CURRENT vs. TEMPERATURE 15 10 8 7 6 5 4 3 2 5 6 MAX16024PTBS25+ VOUT = 2.5V VTH = 2.93V 5 MAX16023 toc03 MAX16024PTBS25+ VOUT = 2.5V VTH = 2.93V 9 BATT SUPPLY CURRENT (A) 20 10 BATT SUPPLY CURRENT vs. VCC SUPPLY VOLTAGE MAX16023 toc02 MAX16024PTBS25+ VOUT = 2.5V VTH = 2.93V VCC SUPPLY CURRENT (A) VCC SUPPLY CURRENT (A) 25 MAX16023 toc01 VCC SUPPLY CURRENT vs. VCC SUPPLY VOLTAGE 4 3 VBATT = 3.0V 2 VBATT = 2.8V 1 1 0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 -15 10 35 60 85 0 0.5 1.0 1.5 2.0 2.5 3.0 TEMPERATURE (C) VCC SUPPLY VOLTAGE (V) BATTERY SUPPLY CURRENT vs. TEMPERATURE BATT STANDBY CURRENT vs. TEMPERATURE RESET OUTPUT VOLTAGE LOW vs. SINK CURRENT 3 2 1 VCC = 3.3V VBATT = 3.0V 8 6 4 2 0 -2 -4 -6 1.0 MAX16024PTBS25+ OUTPUT VOLTAGE LOW (V) 4 10 BATT STANDBY CURRENT (nA) MAX16024PTBS25+ VBATT = +3.0V VCC = 0 MAX16023 toc05 VCC SUPPLY VOLTAGE (V) 5 BATTERY SUPPLY CURRENT (A) 0 -40 5.5 MAX16023 toc04 1.5 0.8 3.5 MAX16023 toc06 0 0.6 0.4 0.2 -8 -10 0 -40 -15 10 35 TEMPERATURE (C) 60 85 0 -40 -15 10 35 TEMPERATURE (C) 60 85 0 2 4 6 8 10 12 14 16 18 20 SINK CURRENT (mA) _______________________________________________________________________________________ 5 MAX16023/MAX16024 Table 1. Reset Threshold Ranges Typical Operating Characteristics (continued) (VCC = 5V, VBATT = 0, IOUT = 0, TA = +25C, unless otherwise noted.) RESET TIMEOUT PERIOD vs. TEMPERATURE 60 50 40 30 210 205 200 195 190 20 185 10 -15 10 35 60 0.990 -15 10 35 60 85 -40 10 35 60 MAXIMUM TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE DROPOUT VOLTAGE vs. LOAD CURRENT OUTPUT VOLTAGE vs. LOAD CURRENT MAX16023 toc10 500 RESET OCCURS ABOVE THE CURVE 50 400 2.70 350 300 250 200 150 2.62 2.50 2.42 2.38 2.34 0 0 2.30 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) TA = +25C 2.46 50 0 TA = -40C 2.54 25 1000 85 2.58 100 200 400 600 800 RESET THRESHOLD OVERDRIVE (mV) MAX16024PTBS25+ VOUT = 2.5V 2.66 OUTPUT VOLTAGE (V) 100 MAX16024PTBS25+ 450 DROPOUT VOLTAGE (mV) 125 0 -15 TEMPERATURE (C) 150 MAX16023 toc09 0.995 TEMPERATURE (C) 175 6 1.000 TEMPERATURE (C) 200 75 1.005 0.980 -40 85 MAX16023 toc11 -40 1.010 0.985 180 0 MAX16024PTBS25+ VOUT = 2.5V 1.015 MAX16023 toc12 DELAY (s) 70 215 1.020 NORMALIZED RESET THRESHOLD 80 220 NORMALIZED RESET THRESHOLD vs. TEMPERATURE MAX16023 toc08 VCC FALLING 10V/ms 90 RESET TIMEOUT PERIOD (ms) 100 MAX16023 toc07 VCC FALLING TO RESET DELAY vs. TEMPERATURE TRANSIENT DURATION (ms) MAX16023/MAX16024 Battery-Backup Circuits with Regulated Output Voltage TA = +85C 0 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) _______________________________________________________________________________________ Battery-Backup Circuits with Regulated Output Voltage OUTPUT VOLTAGE (V) OUTPUT VOLTAGE vs. VCC VOLTAGE STARTUP RESPONSE LOAD-TRANSIENT RESPONSE MAX16023 toc15 MAX16023 toc14 MAX16023 toc13 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 MAX16024PTBS25+ IOUT = 0 COUT = 10F OUT AC-COUPLED 100mV/div VCC 2V/div 50mA IOUT 20mA/div 10mA OUT 1V/div MAX16024PTBS25+ IOUT = 0 MAX16024PTBS25+ 0 1 2 3 4 5 6 2ms/div 1ms/div VCC VOLTAGE (V) CHIP-ENABLE LOCKING OUT SIGNAL DURING RESET MR FALLING TO RESET DELAY MAX16023 toc16 MAX16023 toc17 RESET 5V/div MR 5V/div CEIN 2V/div RESET 5V/div 200ns/div CEOUT 2V/div 40s/div _______________________________________________________________________________________ 7 MAX16023/MAX16024 Typical Operating Characteristics (continued) (VCC = 5V, VBATT = 0, IOUT = 0, TA = +25C, unless otherwise noted.) Battery-Backup Circuits with Regulated Output Voltage MAX16023/MAX16024 Pin Description PIN FUNCTION MAX16024 1 2 VCC Supply Voltage Input. Bypass VCC to GND with a 0.1F capacitor. 2 3 BATT Backup Battery Input. If VCC falls below its reset threshold (VTH), VBATT VCC, and if the regulator enters dropout, the regulator is powered from BATT. If VBATT < VCC, the regulator is powered from VCC. Bypass BATT to GND with a 0.1F capacitor. 3 4 MR Active-Low, Manual-Reset Input. RESET asserts when MR is pulled low. RESET remains low for the duration of reset timeout period after MR transitions from low to high. Connect MR to OUT or leave unconnected if not used. MR is internally connected to VCC through a 30k pullup resistor. 4 -- PFI Power-Fail Comparator Input. Connect PFI to a resistive divider to set the desired PFI threshold. The PFI input is referenced to an internal VPFT threshold. A VPFI-HYS internal hysteresis provides noise immunity. The power-fail comparator is powered from OUT. 5 -- PFO Active-Low, Power-Fail Comparator Output. PFO goes low when VPFI falls below the internal VPFT threshold and goes high when VPFI rises above VPFT + VPFI-HYS hysteresis. 6 7 GND 7 8 NAME MAX16023 8 RESET Ground Active-Low Reset Output. RESET asserts when VCC falls below the reset threshold or MR is pulled low. RESET remains low for the duration of the reset timeout period after VCC rises above the reset threshold and MR goes high. RESET is available in pushpull and open-drain options. 8 9 OUT Linear Regulator Output Voltage. Available in the following factory-fixed voltages of 1.2V, 1.8V, 2.5V, 3.0V, or 3.3V for all devices. The MAX16024 is also available with an adjustable output voltage (1.8V to 5.25V). Bypass OUT to GND with a 10F capacitor. -- 1 CEIN Chip-Enable Input. The input to CE gating circuitry. Connect to GND or OUT if not used. -- 5 SET -- 6 BATT ON -- 10 CEOUT -- -- EP Set Output Voltage Input. For the fixed output voltage versions (MAX16024_TB_ _ _), SET is not used. Connect SET to GND. For MAX16024_TB_, connect SET to an external resistive divider to set the desired output voltage between 1.8V and 5.25V. Active-High, Battery-On Output. BATT ON goes high when in the battery backup mode. Active-Low, Chip-Enable Output. CEOUT goes low only when CEIN is low and reset is not asserted. If CEIN is low when reset is asserted, CEOUT stays low for 12s (typ) or until CEIN goes high, whichever occurs first. Exposed Pad. Internally connected to GND. Connect EP to a large ground plane to aid heat dissipation. Do not use EP as the only ground connection for the device. _______________________________________________________________________________________ Battery-Backup Circuits with Regulated Output Voltage BATT LDO OUT VCC LOGIC DROPOUT MR RESET DELAY RESET OUT REF OUT PFO PFI MAX16023 GND _______________________________________________________________________________________ 9 MAX16023/MAX16024 Functional Diagrams Battery-Backup Circuits with Regulated Output Voltage MAX16023/MAX16024 Functional Diagrams (continued) BATT OUT LDO VCC SET LOGIC BATT ON DROPOUT MR RESET DELAY RESET VCC REF CE OUTPUT CONTROL CEIN CEOUT MAX16024 GND 10 ______________________________________________________________________________________ Battery-Backup Circuits with Regulated Output Voltage The Typical Applications Circuit shows a typical connection using the MAX16024. OUT powers the SRAM. If VCC is higher than the reset threshold (VTH), or if VCC is lower than VTH but higher than VBATT, the regulator is powered from VCC. If VCC < VTH, VCC < VBATT, and the regulator is in dropout, the regulator is powered from BATT (see the Functional Diagrams). OUT supplies up to 100mA from VCC. Backup-Battery Switchover In a brownout or power failure, it may be necessary to preserve the contents of the RAM. With a backup-battery installed at BATT, the MAX16023/MAX16024 automatically switch the RAM to backup power when VCC falls. The MAX16024 has a BATT ON output that goes high when in battery-backup mode. Three conditions must be met for these devices to switch to battery backup mode: 1) VCC is lower than the reset threshold. 2) VCC is lower than VBATT. 3) The regulator is in dropout (except for the 1.2V output version). Chip-Enable Signal Gating (MAX16024) The MAX16024 provides internal gating of CE signals to prevent erroneous data from being written to CMOS RAM in the event of a power failure or brownout. During normal operation, the CE gate enables and passes all CE transitions. When the reset output asserts, this path becomes disabled, preventing erroneous data from corrupting the CMOS RAM and CEOUT is pulled up to OUT through an internal current source. The 1.5ns propagation delay from CEIN to CEOUT allows the devices to be used with most Ps and high-speed DSPs. During normal operation (reset not asserted), CEIN is connected to CEOUT through a low on-resistance transmission gate. If CEIN is high when a reset asserts, CEOUT remains high regardless of any subsequent transition on CEIN during the reset event. If CEIN is low when reset asserts, CEOUT is held low for 12s to allow completion of the read/write operation. After the 12s delay expires, CEOUT goes high and stays high regardless of any subsequent transitions on CEIN during the reset event. When CEOUT is disconnected from CEIN, CEOUT is actively pulled up to OUT. The propagation delay through the chip-enable circuitry depends on both the source impedance of the drive to CEIN and the capacitive loading at CEOUT. Minimize the capacitive load at CEOUT to minimize propagation delay, and use a low-output-impedance driver. VCC RESET THRESHOLD VTH CEIN CEOUT * RESET-TO-CEOUT DELAY (12s) tRD RESET tRD tRP tRP * IF CEIN GOES HIGH BEFORE RESET ASSERTS, CEOUT GOES HIGH WITHOUT DELAY AS CEIN GOES HIGH. Figure 1. Reset and Chip-Enable Timing ______________________________________________________________________________________ 11 MAX16023/MAX16024 Detailed Description MAX16023/MAX16024 Battery-Backup Circuits with Regulated Output Voltage Manual-Reset Input (MAX16023/MAX16024) Many P-based products require manual-reset capability, allowing the operator, a test technician, or external logic circuitry to initiate a reset. For the MAX16023/ MAX16024, a logic-low on MR asserts RESET. RESET remains asserted while MR is low. When MR goes high, RESET deasserts after a minimum of 145ms (tRP). MR has an internal 30k pullup resistor to VCC. MR can be driven with TTL/CMOS logic levels or with opendrain/collector outputs. Connect a normally open momentary switch from MR to GND to create a manualreset function; external debounce circuitry is not required. If MR is driven from a long cable or the device is used in a noisy environment, connect a 0.1F capacitor from MR to GND to provide additional noise immunity. Battery-On Indicator (MAX16024) The MAX16024's BATT ON output goes high when in battery-backup mode. Use BATT ON to indicate battery-switchover status. Battery Freshness Seal The MAX16023/MAX16024 battery freshness seal disconnects the backup battery from internal circuitry and OUT until VCC is applied. This ensures the backup battery connected to BATT is fresh when the final product is used for the first time. The internal freshness seal latch prevents BATT from powering OUT until VCC has come up for the first time, setting the latch. When VCC subsequently turns off, BATT begins to power OUT. To reenable the freshness seal (MAX16023/ MAX16024): 1) Connect a battery to BATT. 2) Bring VCC to 0. 3) Drive MR higher than VBATT + 1.2V for at least 3s. 4) Pull OUT to 0. above the reset threshold. RESET also asserts when MR is low. RESET is available in both push-pull and open-drain configurations. Power-Fail Comparator (MAX16023) The MAX16023 offers an additional undervoltage comparator. The output PFO goes low when the voltage at PFI falls below its VPFT threshold. Common uses for the power-fail comparator include monitoring the input of the power supply (such as a battery) before any voltage regulation to provide an early power-fail warning, so software can conduct an orderly system shutdown. The power-fail comparator has a typical input hysteresis of VPFI-HYS and is powered from OUT, making it independent of the reset circuit. Connect PFI to GND, if not used. Regulator Output Fixed output voltages of 1.2V, 1.8V, 2.5V, 3.0V, and 3.3V are available for all devices. The regulator output delivers up to 100mA of load current. The MAX16024 is available with both fixed and adjustable output-voltage options. Use an external resistive divider network connected between OUT, SET, and GND (Figure 2) to set the adjustable output voltage from 1.8V to 5.25V. Connect SET to GND for parts with fixed output voltage option. 1.53 TO 5.5V VCC 1.8V TO 5.25V OUT 0.1F 10F MAX16024 R1 TO P RESET SET R2 GND Reset Output (MAX16023/MAX16024) A P's reset input starts the P in a known state. The MAX16023/MAX16024 P supervisory circuits assert a reset to prevent code-execution errors during powerup, power-down, and brownout conditions. RESET asserts when V CC is below the reset threshold and remains low for at least 145ms (tRP) after VCC rises 12 VOUT = VSET (1 + R1/R2) VSET = 1.2V Figure 2. Setting the Adjustable Output Voltage (MAX16024 Only) ______________________________________________________________________________________ Battery-Backup Circuits with Regulated Output Voltage The MAX16023/MAX16024 are protected for typical short-circuit conditions of 10s or less. Shorting OUT to ground for longer than 10s might damage the device. Bypass VCC and BATT to GND with a 0.1F capacitor each. Connect a 10F low-ESR capacitor from OUT to GND. All capacitors should be mounted as close as possible to the device. Monitoring an Additional Supply The MAX16023 power-fail comparator can monitor either positive or negative supplies using a resistive divider to PFI (Figures 3 and 4). PFO can be used to generate an interrupt to the P or to trigger a reset. To monitor a negative supply, connect the top of the resistive divider to VCC. Connect the bottom of the resistive divider to the negative voltage to be monitored. V1 Adding Hysteresis to PFI The power-fail comparators have a typical input hysteresis of VPFI-HYS. This is sufficient for most applications where a power-supply line is being monitored through an external voltage-divider (see the Monitoring an Additional Supply section). Figure 5 shows how to add hysteresis to the power-fail comparator. Select the ratio of R1 and R2 such that PFI sees VPFT when VIN falls to the desired trip point (VTRIP). Resistor R3 adds hysteresis. R3 is typically an order of magnitude greater than R1 or R2. The current through R1 and R2 should be at least 100A to ensure that the 1A (max) PFI input current does not shift the trip point. R3 should be larger than 50k to prevent it from loading down PFO. Capacitor C1 adds additional noise rejection. 5V 0.1F 0.1F R1 V2 VCC VCC RESET R1 RESET PFI PFO P PFI R2 MAX16023 MAX16023L PFO R2 MR V- ( VTRIP = VPFT - R2 5 - VPFT R1 GND GND ) VTRIP IS NEGATIVE ADDITIONAL SUPPLY RESET VOLTAGE ( V2(RESET) = VPFT x R1 + R2 R2 ) Figure 3. Monitoring an Additional Supply by Connecting PFO to MR PFO +5V 0 VTRIP 0 V- Figure 4. Monitoring a Negative Supply ______________________________________________________________________________________ 13 MAX16023/MAX16024 Applications Information MAX16023/MAX16024 Battery-Backup Circuits with Regulated Output Voltage +5V Replacing the Backup Battery VCC When VCC is above VTH, the backup power source can be removed without danger of triggering a reset pulse. The device does not enter battery-backup mode when VCC stays above the reset threshold voltage. VIN 0.1F R1 PFI R2 ( ) ) x ( R1R2 + -V )+V R3 VTRIP = VPFT x R1 + R2 R2 C1* ( VH = VPFT + VPFI - HYS R3 MAX16023 ( VL = R1 x VPFT - VCC R2 PFT ) R1 + 1 R3 PFT WHERE VPFT IS THE POWER-FAIL THRESHOLD VOLTAGE. PFO GND TO P Negative-Going VCC Transients The MAX16023/MAX16024 are relatively immune to short duration, negative-going V CC transients. Resetting the P when V CC experiences only small glitches is usually not desirable. A 0.1F bypass capacitor mounted close to the VCC pin provides additional transient immunity. Capacitor Selection and Regulator Stability +5V PFO For stable operation, connect a low-ESR 10F (min) output capacitor from OUT to GND. To reduce noise and improve load-transient response and power-supply rejection, use larger output capacitor values. 0 VL VTRIP VH VIN *OPTIONAL Figure 5. Adding Hysteresis to the Power-Fail Comparator Operation Without a Backup Power Source The MAX16023/MAX16024 provide battery-backup functions. If a backup power source is not used, connect BATT to GND. Part Number Table PART OUTPUT TYPE RESET REGULATED THRESHOLD OUTPUT VOLTAGE VOLTAGE (V) (V) PART OUTPUT TYPE RESET REGULATED THRESHOLD OUTPUT VOLTAGE VOLTAGE (V) (V) MAX16023LTAL12+T Push-Pull 4.63 1.2 MAX16024LTBL12+T Push-Pull 4.63 1.2 MAX16023LTAL18+T Push-Pull 4.63 1.8 MAX16024LTBL18+T Push-Pull 4.63 1.8 MAX16023LTAL25+T Push-Pull 4.63 2.5 MAX16024LTBL25+T Push-Pull 4.63 2.5 MAX16023LTAL33+T Push-Pull 4.63 3.3 MAX16024LTBL33+T Push-Pull 4.63 3.3 MAX16023LTAM12+T Push-Pull 4.38 1.2 MAX16024LTBM12+T Push-Pull 4.38 1.2 MAX16023LTAM18+T Push-Pull 4.38 1.8 MAX16024LTBM18+T Push-Pull 4.38 1.8 MAX16023LTAM25+T Push-Pull 4.38 2.5 MAX16024LTBM25+T Push-Pull 4.38 2.5 MAX16023LTAM33+T Push-Pull 4.38 3.3 MAX16024LTBM33+T Push-Pull 4.38 3.3 MAX16023LTAT12+T Push-Pull 3.08 1.2 MAX16024LTBT12+T Push-Pull 3.08 1.2 MAX16023LTAT18+T Push-Pull 3.08 1.8 MAX16024LTBT18+T Push-Pull 3.08 1.8 MAX16023LTAT25+T Push-Pull 3.08 2.5 MAX16024LTBT25+T Push-Pull 3.08 2.5 MAX16023LTAS12+T Push-Pull 2.93 1.2 MAX16024LTBS12+T Push-Pull 2.93 1.2 MAX16023LTAS18+T Push-Pull 2.93 1.8 MAX16024LTBS18+T Push-Pull 2.93 1.8 MAX16023LTAS25+T Push-Pull 2.93 2.5 MAX16024LTBS25+T Push-Pull 2.93 2.5 MAX16023LTAR12+T Push-Pull 2.63 1.2 MAX16024LTBR12+T Push-Pull 2.63 1.2 MAX16023LTAR18+T Push-Pull 2.63 1.8 MAX16024LTBR18+T Push-Pull 2.63 1.8 MAX16023LTAR25+T Push-Pull 2.63 2.5 MAX16024LTBR25+T Push-Pull 2.63 2.5 MAX16023LTAZ12+T Push-Pull 2.32 1.2 MAX16024LTBZ12+T Push-Pull 2.32 1.2 14 ______________________________________________________________________________________ Battery-Backup Circuits with Regulated Output Voltage RESET REGULATED THRESHOLD OUTPUT VOLTAGE VOLTAGE (V) (V) RESET REGULATED THRESHOLD OUTPUT VOLTAGE VOLTAGE (V) (V) PART OUTPUT TYPE 1.8 MAX16024LTBZ18+T Push-Pull 2.32 1.8 1.2 MAX16024LTBY12+T Push-Pull 2.19 1.2 2.19 1.8 MAX16024LTBY18+T Push-Pull 2.19 1.8 1.67 1.2 MAX16024LTBW12+T Push-Pull 1.67 1.2 Push-Pull 1.575 1.2 MAX16024LTBV12+T Push-Pull 1.575 1.2 MAX16023PTAL12+T Open-Drain 4.63 1.2 MAX16024PTBL12+T Open-Drain 4.63 1.2 MAX16023PTAL18+T Open-Drain 4.63 1.8 MAX16024PTBL18+T Open-Drain 4.63 1.8 MAX16023PTAL25+T Open-Drain 4.63 2.5 MAX16024PTBL25+T Open-Drain 4.63 2.5 MAX16023PTAL33+T Open-Drain 4.63 3.3 MAX16024PTBL33+T Open-Drain 4.63 3.3 MAX16023PTAM12+T Open-Drain 4.38 1.2 MAX16024PTBM12+T Open-Drain 4.38 1.2 MAX16023PTAM18+T Open-Drain 4.38 1.8 MAX16024PTBM18+T Open-Drain 4.38 1.8 MAX16023PTAM25+T Open-Drain 4.38 2.5 MAX16024PTBM25+T Open-Drain 4.38 2.5 MAX16023PTAM33+T Open-Drain 4.38 3.3 MAX16024PTBM33+T Open-Drain 4.38 3.3 MAX16023PTAT12+T Open-Drain 3.08 1.2 MAX16024PTBS12+T Open-Drain 3.08 1.2 MAX16023PTAT18+T Open-Drain 3.08 1.8 MAX16024PTBS18+T Open-Drain 3.08 1.8 MAX16023PTAT25+T Open-Drain 3.08 2.5 MAX16024PTBS25+T Open-Drain 3.08 2.5 MAX16023PTAS12+T Open-Drain 2.93 1.2 MAX16024PTBT12+T Open-Drain 2.93 1.2 MAX16023PTAS18+T Open-Drain 2.93 1.8 MAX16024PTBT18+T Open-Drain 2.93 1.8 MAX16023PTAS25+T Open-Drain 2.93 2.5 MAX16024PTBT25+T Open-Drain 2.93 2.5 MAX16023PTAR12+T Open-Drain 2.63 1.2 MAX16024PTBR12+T Open-Drain 2.63 1.2 MAX16023PTAR18+T Open-Drain 2.63 1.8 MAX16024PTBR18+T Open-Drain 2.63 1.8 MAX16023PTAR25+T Open-Drain 2.63 2.5 MAX16024PTBR25+T Open-Drain 2.63 2.5 MAX16023PTAZ12+T Open-Drain 2.32 1.2 MAX16024PTBZ12+T Open-Drain 2.32 1.2 MAX16023PTAZ18+T Open-Drain 2.32 1.8 MAX16024PTBZ18+T Open-Drain 2.32 1.8 MAX16023PTAY12+T Open-Drain 2.19 1.2 MAX16024PTBY12+T Open-Drain 2.19 1.2 MAX16023PTAY18+T Open-Drain 2.19 1.8 MAX16024PTBY18+T Open-Drain 2.19 1.8 MAX16023PTAW12+T Open-Drain 1.67 1.2 MAX16024PTBW12+T Open-Drain 1.67 1.2 MAX16023PTAV12+T Open-Drain 1.575 1.2 MAX16024PTBV12+T Open-Drain 1.575 1.2 MAX16024PTBL+T Open-Drain 4.63 Adjustable MAX16024LTBL+T Push-Pull 4.63 Adjustable MAX16024PTBM+T Open-Drain 4.38 Adjustable MAX16024LTBM+T Push-Pull 4.38 Adjustable MAX16024PTBT+T Open-Drain 3.08 Adjustable MAX16024LTBT+T Push-Pull 3.08 Adjustable MAX16024PTBS+T Open-Drain 2.93 Adjustable MAX16024LTBS+T Push-Pull 2.93 Adjustable MAX16024PTBR+T Open-Drain 2.63 Adjustable MAX16024LTBR+T Push-Pull 2.63 Adjustable MAX16024PTBZ+T Open-Drain 2.32 Adjustable MAX16024LTBZ+T Push-Pull 2.32 Adjustable MAX16024PTBY+T Open-Drain 2.19 Adjustable MAX16024LTBY+T Push-Pull 2.19 Adjustable PART OUTPUT TYPE MAX16023LTAZ18+T Push-Pull 2.32 MAX16023LTAY12+T Push-Pull 2.19 MAX16023LTAY18+T Push-Pull MAX16023LTAW12+T Push-Pull MAX16023LTAV12+T MAX16024PTBW+T Open-Drain 1.67 Adjustable MAX16024LTBW+T Push-Pull 1.67 Adjustable MAX16024PTBV+T Open-Drain 1.575 Adjustable MAX16024LTBV+T Push-Pull 1.575 Adjustable Bold parts denote standard versions. Samples are generally available on standard versions. Contact factory for availability of nonstandard versions. ______________________________________________________________________________________ 15 MAX16023/MAX16024 Part Number Table (continued) MAX16023/MAX16024 Battery-Backup Circuits with Regulated Output Voltage Selector Guide OUTPUTS (RESET, PFO, BATT ON ) RESET MR POWER-FAIL COMPARATOR CE GATE BATT ON REGULATOR OUTPUT VOLTAGE MAX16023L Push-Pull -- -- Fixed MAX16023P Open Drain -- -- Fixed MAX16024L Push-Pull -- Fixed/adjustable MAX16024P Open Drain -- Fixed/adjustable PART Typical Applications Circuit 3.3V 0.1F 0.1F VCC VCC RST RESET P BATT 3V 0.1F BATT ON A0-A15 MAX16024L OUT 10F MR RAM PUSHBUTTON RTC CEOUT CE SET CEIN GND 16 ADDRESS DECODE ______________________________________________________________________________________ Battery-Backup Circuits with Regulated Output Voltage PROCESS: BiCMOS For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 8 TDFN T833-2 21-0137 10 TDFN T1033-1 21-0137 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 ____________________ 17 (c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX16023/MAX16024 Package Information Chip Information