19-0136; Rev. 2; 12/05 Power-Supply Monitor with Reset The RESET output is guaranteed to be in the correct state with V CC down to 1V. The MAX709 provides excellent circuit reliability and low cost by eliminating external components and adjustments when used with +5V, +3.3V, or +3V powered systems. The MAX709 is available 8-pin DIP, µMAX, and SO packages. ___________________________Features ♦ +5V, +3.3V, and +3V Versions ♦ No External Components ♦ Low Cost ♦ Precise Power-Down Reset Threshold ♦ 140ms Min Power-On Reset Delay ♦ Immune to Short Negative VCC Transients ♦ 8-Pin DIP, µMAX, and SO Packages ♦ Low Supply Current: 35µA - MAX709R/S/T 65µA - MAX709L/M ______________Ordering Information PART TEMP. RANGE MAX709_CPA _______________________Applications Minimum Component Count, Low-Cost Processor Systems PIN-PACKAGE 0°C to +70°C 8 Plastic DIP MAX709_CUA 0°C to +70°C 8 µMAX MAX709_CSA 0°C to +70°C 8 SO MAX709_C/D 0°C to +70°C Dice MAX709_EPA -40°C to +85°C MAX709_EUA -40°C to +85°C 8 Plastic DIP 8 µMAX MAX709_ESA -40°C to +85°C 8 SO Devices 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. *Dice are specified at TA = +25°C, DC parameters only. Note: This part offers a choice of five different reset threshold voltages. Select the letter corresponding to the desired nominal reset threshold voltage, and insert it into the blank to complete the part number. RESET THRESHOLD SUFFIX VOLTAGE (V) L 4.65 M 4.40 T 3.08 S 2.93 R 2.63 __________Typical Operating Circuit VCC VCC µP MAX709 RESET GND RESET __________________Pin Configuration TOP VIEW N.C. 1 8 N.C. VCC 2 7 RESET GND 3 6 N.C. N.C. 4 5 N.C. GND MAX709 DIP/SO/µMAX ________________________________________________________________ Maxim Integrated Products Call toll free 1-800-998-8800 for free samples or literature. 1 MAX709 _______________General Description The MAX709 provides a system reset during power-up, power-down, and brownout conditions. When VCC falls below the reset threshold, RESET goes low and holds the µP in reset for 140ms min after VCC rises above the threshold. MAX709 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/µs Continuous Power Dissipation (TA = +70°C) Plastic DIP (derate 9.09mW/°C above +70°C) . . . . . . . . 727mW µMAX (derate 4.10mW/°C above +70°C) . . . . . . . . . . . . . 330mW SO (derate 5.88mW/°C above +70°C). . . . . . . . . . . . . . . . . 471mW Operating Temperature Ranges MAX709_C___ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C MAX709_E___ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C Storage Temperature Range . . . . . . . . . . . . . . . . . . - 65°C to +160°C Lead Temperature (soldering, 10sec). . . . . . . . . . . . . . . . . . . . +300°C 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 VCC Range CONDITIONS MAX709_E 1.2 5.5 All versions MAX709_C, VCC < 3.6V 35 85 MAX709_E, VCC < 3.6V 35 110 MAX709_C, VCC < 5.5V 65 150 MAX709_E, VCC < 5.5V 65 200 MAX709L 4.50 4.65 4.75 MAX709M 4.25 4.40 4.50 MAX709T 3.00 3.08 3.15 MAX709S 2.85 2.93 3.00 MAX709R 2.55 2.63 2.70 VCC to RESET Delay VCC = reset threshold max to reset threshold min Reset Active Timeout Period VCC = reset threshold max, VCC rising 20 140 280 0.3 ISINK = 3.2mA, VCC = reset threshold min, MAX709L/M only 0.4 ISINK = 50µA, VCC ≥ 1.0V, MAX709_C 0.3 ISINK = 100µA, VCC ≥ 1.2V, MAX709_E 0.4 ISOURCE = 500µA, VCC ≥ reset threshold max, MAX709R/S/T only 0.8 x VCC ISOURCE = 800µA, VCC ≥ reset threshold max, MAX709L/M only VCC - 1.5 _______________________________________________________________________________________ UNITS V µA V µs 560 ISINK = 1.2mA, VCC = reset threshold min, MAX709R/S/T only Note 1: Supply current is measured with VCC = 3.6V for MAX709R/S/T, and VCC = 5.5V for all versions. 2 MAX 5.5 Supply Current (Note 1) RESET Output Voltage TYP 1.0 MAX709R/S/T only RESET Threshold, VTH MIN MAX709_C ms V Power-Supply Monitor with Reset POWER-UP RESET DELAY vs. TEMPERATURE POWER-DOWN RESET DELAY vs. TEMPERATURE 24 VCC = RESET THRESHOLD MAX, VCC RISING 250 POWER-DOWN RESET DELAY (µs) POWER-UP RESET DELAY (ms) 300 200 150 100 50 0 -20 20 60 8 4 VCC STEPPED FROM RESET THRESHOLD MAX TO RESET THRESHOLD MIN 100 -20 20 60 SUPPLY CURRENT vs. TEMPERATURE NORMALIZED RESET THRESHOLD vs. TEMPERATURE 100 1.005 NO LOAD VCC = +5V VCC = +4V 40 VCC = +3V VCC = +2V VCC = +1V -60 -60 TEMPERATURE (°C) NOTE: STEADY-STATE SUPPLY CURRENT IS INDEPENDENT OF RESET OUTPUT STATUS 80 0 12 TEMPERATURE (°C) NORMALIZED RESET THRESHOLD SUPPLY CURRENT (µA) 100 20 16 0 -60 60 20 THE RESET THRESHOLD IS SHOWN NORMALIZED TO 1, REPRESENTING ALL AVAILABLE MAX709 RESET THRESHOLDS 1.003 1.001 0.999 0.997 0.995 -20 20 60 TEMPERATURE (°C) 100 -60 -20 20 60 100 TEMPERATURE (°C) _________________________________________________________________________________________________ 3 MAX709 __________________________________________Typical Operating Characteristics MAX709 ____________________Pin Description PIN NAME 1, 4, 5, 6, 8 N.C. No Connect. There is no internal connection to this pin. 2 VCC +5V, +3.3V, or +3V Supply Voltage 3 GND Ground 7 RESET FUNCTION Reset Output remains low while VCC is below the reset threshold, and for 280ms after VCC rises above the reset threshold. __________Applications Information MAXIMUM TRANSIENT DURATION (µs) Power-Supply Monitor with Reset 150 TA = +25°C 100 MAX709L/M 50 10ns MAX709R/S/T 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 Negative-Going VCC Transients In addition to issuing a reset to the microprocessor (µP) during power-up, power-down, and brownout conditions, the MAX709 is relatively immune to short duration negative-going VCC transients (glitches). Figure 1 shows typical transient duration vs. reset comparator overdrive, for which the MAX709 does not generate a reset pulse. The graph was generated using a negative-going pulse applied to V CC, starting 1.5V above the actual reset threshold and ending below it by the magnitude indicated (reset comparator overdrive). The graph indicates the typical maximum pulse width that 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, for the MAX709L/MAX709M, a VCC transient that goes 100mV below the reset threshold and lasts 40µs or less will not cause a reset pulse to be issued. 4 A 0.1µF 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 MAX709 RESET output no longer sinks current—it becomes an open circuit. Therefore, high-impedance CMOS logic inputs connected to the RESET output can drift to undermined voltages. This presents no problem in most applications, since most µP and other circuitry is inoperative with VCC below 1V. However, in applications where the RESET output must be valid down to 0V, adding a pulldown resistor to the RESET pin will cause any stray leakage currents to flow to ground, holding RESET low (see Figure 2). The resistance value of R1 is not critical. It should be about 100kΩ, which is large enough not to load RESET and small enough to pull RESET to ground. _______________________________________________________________________________________ Power-Supply Monitor with Reset MAX709 BUFFER BUFFERED RESET TO OTHER SYSTEM COMPONENTS VCC VCC VCC MAX709 RESET MAX709 RESET R1 µP 4.7k RESET GND GND Figure 2. RESET Valid to VCC = Ground Circuit GND Figure 3. Interfacing to µPs with Bidirectional Reset I/O Interfacing to µPs with Bidirectional Reset Pins Microprocessors with bidirectional reset pins (such as the Motorola 68HC11 series) can contend with the MAX709 reset output. If, for example the MAX709 RESET output is asserted high and the µP wants to pull it low, indeterminate logic levels may result. To correct this, connect a 4.7kΩ resistor between the MAX709 RESET output and the µP reset I/O (see Figure 3). Buffer the MAX709 RESET output to other system components. _______________________________________________________________________________________ 5 MAX709 Power-Supply Monitor with Reset _____________________________________________________µP 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 - PowerFail Comparator Manual- Watch- LowReset dog Line Input Output Output Active- BatteryHigh On Reset Output ✔ ✔/10ns ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ MAX705/706 4.65/4.40 140 1.6 ✔ ✔ ✔ MAX706P 2.63 140 1.6 ✔ ✔ ✔ MAX706R/S/T 2.63/2.93/ 3.08 140 1.6 ✔ ✔ ✔ MAX707/708 4.65/4.40 140 - ✔ ✔ ✔ MAX708R/S/T 2.63/2.93/ 3.08 140 - ✔ ✔ ✔ MAX709L/M/ R/S/T 4.65/4.40/ 140 2.63/2.93/3.08 - MAX791 4.65 140 1 ✔/10ns ✔ ✔ ✔ ✔ ✔ MAX792L/M/ R/S/T 4.65/4.40/ 140 2.63/2.93/3.08 1 ✔/10ns ✔ ✔ ✔ ✔ ✔ MAX800L/M 4.60/4.40 140 1.6/adj. ✔ ✔/10ns ✔/±2% ✔ ✔ ✔ 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 ✔/10ns 1 MAX1232 4.37/4.62 250 0.15/0.60/1.2 MAX1259 - - - 6 ✔ ✔ ✔ ✔ ✔ ✔ ✔/±2% ✔ ✔ ✔ ✔ ✔ ✔ ✔ _______________________________________________________________________________________ ✔ ✔ ✔ Power-Supply Monitor with Reset MAX709 ___________________Chip Topography V CC RESET 0.045" (1.143mm) GND 0.056" (1.422mm) TRANSISTOR COUNT: 380 SUBSTRATE CONNECTED TO VCC _______________________________________________________________________________________ 7 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) 4X S 8 E Ø0.50±0.1 8 INCHES DIM A A1 A2 b H c D e E H 0.6±0.1 1 L 1 α 0.6±0.1 S BOTTOM VIEW D MIN 0.002 0.030 MAX 0.043 0.006 0.037 0.014 0.010 0.007 0.005 0.120 0.116 0.0256 BSC 0.120 0.116 0.198 0.188 0.026 0.016 6° 0° 0.0207 BSC 8LUMAXD.EPS MAX709 Power-Supply Monitor with Reset MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95 0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0° 6° 0.5250 BSC TOP VIEW A1 A2 e A α c b L SIDE VIEW FRONT VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 8L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0036 REV. J 1 1 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 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.