19-0151; Rev 0; 6/93 P Power-Supply Monitor with Reset FEATURE No External Components Low Cost Precise Reset Threshold 280ms Power-On Reset Delay 8-Pin DIP and SO Packages ______________Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX7705 TL7705 MAX7705CPA 0C to +70C 8 Plastic DIP 0 3 MAX7705CSA 0C to +70C 8 SO MAX7705C/D 0C to +70C MAX7705EPA -40C to +85C 8 Plastic DIP MAX7705ESA -40C to +85C 8 SO No. of External Components Required Operating Supply Current ____________________________Features +5V 65A 1.8mA +3V 35A 1.8mA Power-Supply Glitch Immunity Yes No Guaranteed Minimum Reset Delay Yes No Dice* * Contact factory for dice specifications. ________________________Applications Minimum Component Count, Low-Cost Processor Systems __________Typical Operating Circuit __________________Pin Configuration VCC MAX7705 TOP VIEW * N.C. 1 8 VCC N.C. 2 7 N.C. 6 N.C. 5 RESET N.C. 3 MAX7705 GND 4 DIP/SO * 1 N.C. VCC 8 2 N.C. N.C. 7 3 N.C. N.C. 6 4 GND RESET 5 P * RESET GND * THE MAX7705 ELIMINATES THREE EXTERNAL COMPONENTS REQUIRED BY THE TL7705. ________________________________________________________________ Maxim Integrated Products Call toll free 1-800-998-8800 for free samples or literature. 1 MAX7705 _______________General Description In applications with microprocessors (Ps) that have a RESET input, the MAX7705 is functionally and socket compatible with the TL7705, but requires no external components. It provides power-supply glitch immunity and a guaranteed power-up reset delay, while typically consuming 1/27th the power from a +5V supply. The MAX7705 monitors the power supply in P and digital systems. The RESET output is valid for VCC down to 1V. The device offers excellent circuit reliability and low cost by eliminating external components and adjustments. A system reset is provided during power-up, powerdown, and brownout conditions. When VCC is below the reset threshold, RESET is low and holds the P in reset. RESET will go high 280ms after VCC rises above the reset threshold. The MAX7705 is available in 8-pin DIP and SO packages. MAX7705 P Power-Supply Monitor with Reset ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) VCC ......................................................................-0.3V to 6.0V RESET....................................................-0.3V to (VCC + 0.3V) Input Current, VCC ..............................................................20mA Output Current, RESET ......................................................20mA Rate-of-Rise, VCC ............................................................100V/s Continuous Power Disipation (TA = +70C) Plastic DIP (derate 9.09mW/C above +70C) ............727mW SO (derate 5.88mW/C above +70C) .........................471mW Operating Temperature Ranges: MAX7705C_ _ .....................................................0C to +70C MAX7705E_ _ ..................................................-40C to +85C Storage Temperature Range .............................-65C to +160C Lead Temperature (soldering, 10sec) .............................+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. ELECTRICAL CHARACTERISTICS (VCC = full range, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX MAX7705C 1.0 5.5 MAX7705E 1.2 5.5 VCC Range V MAX7705C, VCC < 5.5V 65 150 MAX7705E, VCC < 5.5V 65 200 4.65 4.75 Supply Current A RESET Threshold 4.50 VCC to RESET Delay VCC = reset threshold max to reset threshold min Reset Active Timeout Period VCC = reset threshold max, VCC rising RESET Output Voltage 20 140 280 V s 560 ISINK = 3.2mA, VCC = reset threshold min 0.4 ISINK = 50A, VCC 1.0V, MAX7705C 0.3 ISINK = 100A, VCC 1.2V, MAX7705E 0.4 ISOURCE = 800A, VCC reset threshold max 2 UNITS ms V VCC - 1.5 _______________________________________________________________________________________ P Power-Supply Monitor with Reset POWER-UP RESET DELAY vs. TEMPERATURE SUPPLY CURRENT vs. TEMPERATURE 100 250 200 150 100 80 60 -60 -20 20 60 VCC = +5V VCC = +4V 40 VCC = +3V 0 0 4.660 NO LOAD 20 50 4.665 NOTE: STEADY-STATE SUPPLY CURRENT IS INDEPENDENT OF RESET OUTPUT STATUS 100 VCC = +2V 4.650 4.645 4.640 4.630 -20 20 60 100 TEMPERATURE (C) TEMPERATURE (C) 4.655 4.635 VCC = +1V -60 RESET THRESHOLD (V) VCC = RESET THRESHOLD MAX VCC RISING SUPPLY CURRENT (A) POWER-UP RESET DELAY (ms) 300 RESET THRESHOLD vs. TEMPERATURE -60 -20 20 60 100 TEMPERATURE (C) POWER-DOWN RESET DELAY vs. TEMPERATURE POWER-DOWN RESET DELAY (s) 24 20 16 12 8 4 VCC STEPPED FROM RESET THRESHOLD MAX TO RESET THRESHOLD MIN 0 -60 -20 20 60 100 TEMPERATURE (C) ______________________________________________________________Pin Description PIN NAME FUNCTION 1,2,3,6,7 N.C. No Connection. There is no internal connection to these pins. 4 GND Ground 5 RESET 8 VCC Reset Output remains low while VCC is below the reset threshold, and for 280ms after VCC rises above the reset threshold. +5V Supply Voltage _______________________________________________________________________________________ 3 MAX7705 __________________________________________Typical Operating Characteristics (TA = +25C, unless otherwise noted.) MAXIMUM TRANSIENT DURATION (s) MAX7705 P Power-Supply Monitor with Reset 150 TA = +25C 100 50 10ns 0 10 100 1k 10k RESET COMPARATOR OVERDRIVE, VTH - VCC (mV) Figure 1. Maximum Transient Duration without Causing a Reset Pulse vs. Reset Comparator Overdrive __________Applications Information Replacing the TL7705 with a MAX7705 in an Existing Design The MAX7705 has only three active pins: VCC, GND, and RESET. When using a TL7705 with a P that has a RESET input, simply plug the MAX7705 into the same socket and omit the RESET pull-up resistor, reset timing capacitor, and reference bypass capacitor (see the Typical Operating Circuit). The MAX7705 monitors the VCC voltage and asserts reset whenever VCC falls below the reset threshold. The reset power-up delay is created by an internal fixed oscillator. This delay is 100% tested and guaranteed over the full temperature range. The RESET output both sources and sinks current (see RESET Output Voltage in the Electrical Characteristics). Negative-Going VCC Transients The MAX7705 asserts RESET during power-up, power-down, and brownout conditions. However, it is relatively immune to short-duration negative-going VCC transients (glitches). Figure 1 shows typical transient duration vs. reset comparator overdrive for which the MAX7705 does not generate a reset pulse. The graph was generated using a fast-edge, negative-going pulse applied to VCC, starting 1.5V above the actual reset threshold and ending below the reset threshold by the magnitude indicated (reset comparator overdrive). It indicates the typical maxi- 4 mum pulse width a negative-going VCC transient may have without causing a reset pulse to be issued. As the magnitude of the transient increases (goes farther below the reset threshold), the maximum allowable pulse width decreases. Typically, a VCC transient that goes 100mV below the reset threshold and lasts 40s or less will not cause a reset pulse to be issued. A 0.1F bypass capacitor mounted as close as possible to pin 2 (VCC) provides additional transient immunity. Ensuring a Valid RESET Output Down to VCC = 0V When VCC falls below 1V, the MAX7705 RESET output no longer sinks current; it becomes high impedance. Therefore, high-impedance CMOS logic inputs connected to the RESET output can drift to indeterminate voltages. In most applications this presents no problem, as P and other circuitry is generally inoperative with VCC below 1V. In applications where the RESET output must be valid down to 0V, adding a pull-down resistor to the RESET pin (as shown in Figure 2) will cause any stray leakage currents to flow to ground, holding RESET low. The resistance value of R1 is not critical. It should be about 100k, which is large enough not to load RESET and small enough to pull RESET to ground. VCC MAX7705 RESET R1 GND Figure 2. RESET Valid to VCC = Ground Circuit _______________________________________________________________________________________ P Power-Supply Monitor with Reset Ps with bidirectional reset pins, such as Motorola's 68HC11 series, can contend with the MAX7705 reset output. If, for example, the MAX7705 RESET output is asserted high and the P wants to pull it low, an indeterminate logic level may result. To correct this, connect a 4.7k resistor between the MAX7705 RESET output and the P reset I/O, as in Figure 3. Buffer the RESET signal to other system components. BUFFER BUFFERED RESET TO OTHER SYSTEM COMPONENTS VCC VCC MAX7705 RESET GND ___________________Chip Topography V CC RESET 0.045" (1.143mm) GND 0.056" (1.422mm) P 4.7k RESET TRANSISTOR COUNT = 380; SUBSTRATE CONNECTED TO VCC. GND Figure 3. Interfacing to Ps with Bidirectional Reset I/O _______________________________________________________________________________________ 5 MAX7705 Interfacing to Ps with Bidirectional Reset Inputs MAX7705 P Power-Supply Monitor with Reset _______________________________________________________Package Information DIM D1 A A1 A2 A3 B B1 C D D1 E E1 e eA eB L E E1 D A3 A A2 L A1 MILLIMETERS MIN MAX - 5.08 0.38 - 3.18 4.45 1.40 2.03 0.41 0.56 1.27 1.65 0.20 0.30 8.84 9.91 0.13 0.89 7.62 8.26 6.10 7.11 2.54 BSC 7.62 BSC - 10.16 2.92 3.81 0 15 21-324A C e B1 B 6 INCHES MAX MIN 0.200 - - 0.015 0.175 0.125 0.080 0.055 0.022 0.016 0.065 0.050 0.012 0.008 0.390 0.348 0.035 0.005 0.325 0.300 0.280 0.240 0.100 BSC 0.300 BSC 0.400 - 0.150 0.115 15 0 eA 8-PIN PLASTIC DUAL-IN-LINE PACKAGE eB _______________________________________________________________________________________ P Power-Supply Monitor with Reset DIM E A A1 B C D E e H h L H INCHES MAX MIN 0.069 0.053 0.010 0.004 0.019 0.014 0.010 0.007 0.197 0.189 0.157 0.150 0.050 BSC 0.244 0.228 0.020 0.010 0.050 0.016 8 0 MILLIMETERS MIN MAX 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 4.80 5.00 3.80 4.00 1.27 BSC 5.80 6.20 0.25 0.50 0.40 1.27 0 8 21-325A h x 45 D A 0.127mm 0.004in. e A1 C L 8-PIN PLASTIC SMALL-OUTLINE PACKAGE B _______________________________________________________________________________________ 7 MAX7705 __________________________________________ Package Information (continued) MAX7705 P Power-Supply Monitor with Reset P Supervisory Circuits Part Number Minimum Nominal Reset Reset Pulse Threshold Width (V) (ms) Nominal Watchdog Timeout Backup- CE Period Battery Write (sec) Switch Protect MAX690A/692A 4.65/4.40 140 1.6 MAX691A/693A 4.65/4.40 140/adj. 1.6/adj. MAX696 Adj. 35/adj. 1.6/adj. MAX697 Adj. 35/adj. 1.6/adj. MAX700 4.65/adj. 200 - MAX703/704 4.65/4.40 140 - MAX705/706 4.65/4.40 140 MAX706P 2.63 140 MAX706R/S/T 2.63/2.93/ 3.08 MAX707/708 MAX708R/S/T MAX709L/M/ R/S/T PowerFail Comparator Manual- Watch- LowReset dog Line Input Output Output Active- BatteryHigh On Reset Output /10ns 1.6 1.6 140 1.6 4.65/4.40 140 - 2.63/2.93/ 3.08 140 - 4.65/4.40/ 140 2.63/2.93/3.08 /10ns /10ns /10ns /2% MAX791 4.65 140 1 MAX792L/M/ R/S/T 4.65/4.40/ 140 2.63/2.93/3.08 1 MAX800L/M 4.60/4.40 140 1.6/adj. MAX802L/M 4.60/4.40 140 1.6 /2% MAX805L 4.65 140 1.6 MAX813L 4.65 140 1.6 MAX820L/M/ R/S/T 4.65/4.40/ 140 2.63/2.93/3.08 1 MAX1232 4.37/4.62 250 0.15/0.60/1.2 MAX1259 - - - /10ns /2% 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. 8 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1993 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.