19-0411; Rev 3; 3/99 4-Pin µP Voltage Monitors with Manual Reset Input ____________________________Features The MAX811/MAX812 are low-power microprocessor (µP) supervisory circuits used to monitor power supplies in µP and digital systems. They provide excellent circuit reliability and low cost by eliminating external components and adjustments when used with 5Vpowered or 3V-powered circuits. The MAX811/MAX812 also provide a debounced manual reset input. These devices perform a single function: They assert a reset signal whenever the V CC supply voltage falls below a preset threshold, keeping it asserted for at least 140ms after VCC has risen above the reset threshold. The only difference between the two devices is that the MAX811 has an active-low RESET output (which is guaranteed to be in the correct state for VCC down to 1V), while the MAX812 has an active-high RESET output. The reset comparator is designed to ignore fast transients on VCC. Reset thresholds are available for operation with a variety of supply voltages. ♦ Precision Monitoring of 3V, 3.3V, and 5V Power-Supply Voltages Low supply current makes the MAX811/MAX812 ideal for use in portable equipment. The devices come in a 4-pin SOT143 package. ________________________Applications ♦ 6µA Supply Current ♦ 140ms Min Power-On Reset Pulse Width; RESET Output (MAX811), RESET Output (MAX812) ♦ Guaranteed Over Temperature ♦ Guaranteed RESET Valid to VCC = 1V (MAX811) ♦ Power-Supply Transient Immunity ♦ No External Components ♦ 4-Pin SOT143 Package _______________Ordering Information PART* TEMP. RANGE PIN-PACKAGE MAX811_EUS-T -40°C to +85°C 4 SOT143 MAX812_EUS-T -40°C to +85°C 4 SOT143 * 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. Computers RESET THRESHOLD Controllers SUFFIX VOLTAGE (V) Intelligent Instruments L 4.63 Critical µP and µC Power Monitoring M 4.38 Portable/Battery-Powered Equipment T 3.08 S 2.93 R 2.63 ___________Typical Operating Circuit ___________________Pin Configuration TOP VIEW VCC VCC VCC MAX811 MAX812 µP RESET (RESET) MR GND PUSHBUTTON SWITCH 4 VCC 3 MR MAX811 MAX812 RESET INPUT (RESET) RESET GND 1 2 GND SOT143 ( ) ARE FOR MAX812 ( ) ARE FOR MAX812 NOTE: SEE LAST PAGE FOR MARKING INFORMATION. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX811/MAX812 ________________General Description MAX811/MAX812 4-Pin µP Voltage Monitors with Manual Reset Input ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) VCC ......................................................................-0.3V to 6.0V All Other Inputs.......................................-0.3V to (VCC + 0.3V) Input Current, VCC, MR .......................................................20mA Output Current, RESET or RESET .......................................20mA Continuous Power Dissipation (TA = +70°C) SOT143 (derate 4mW/°C above +70°C) 320mW Operating Temperature Range ...........................-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 = 5V for L/M versions, VCC = 3.3V for T/S versions, VCC = 3V for R version, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Operating Voltage Range VCC Supply Current ICC CONDITIONS 1.0 TA = -40°C to +85°C 1.2 MAX81_L/M, VCC = 5.5V, IOUT = 0 MAX81_R/S/T, VCC = 3.6V, IOUT = 0 MAX81_L MAX81_M Reset Threshold VTH MIN TA = 0°C to +70°C MAX81_T MAX81_S MAX81_R TA = +25°C 4.54 TA = -40°C to +85°C 4.50 TA = +25°C 4.30 TA = -40°C to +85°C 4.25 TA = +25°C 3.03 TA = -40°C to +85°C 3.00 TA = +25°C 2.88 TA = -40°C to +85°C 2.85 TA = +25°C 2.58 TA = -40°C to +85°C 2.55 Reset Threshold Tempco Reset Active Timeout Period tRP MR Minimum Pulse Width tMR 15 10 4.63 4.72 4.38 4.46 3.08 3.14 VIL 3.15 2.93 VIH VIL VCC > VTH(MAX), MAX81_R/S/T VOL ISOURCE = 150µA, 1.8V < VCC < VTH(MIN) V 3.00 2.63 2.68 2.70 ppm/°C µs 140 560 ms µs 100 ns 0.5 µs 2.3 0.8 0.7 x VCC V 0.25 x VCC 10 VOH µA 2.98 10 VCC > VTH(MAX), MAX81_L/M V 4.50 20 VCC = VTH(MAX) UNITS 4.75 40 MR Pull-Up Resistance 2 6 2.7 VOD = 125mV, MAX81_R/S/T tMD VIH RESET Output Voltage (MAX812) 5.5 VOD = 125mV, MAX81_L/M MR Glitch Immunity (Note 3) MR Input Threshold MAX 30 VCC to Reset Delay (Note 2) MR to Reset Propagation Delay (Note 2) TYP 20 30 kΩ 0.8VCC MAX812R/S/T only, ISINK = 1.2mA, VCC = VTH(MAX) 0.3 MAX812L/M only, ISINK = 3.2mA, VCC = VTH(MAX) 0.4 _______________________________________________________________________________________ V 4-Pin µP Voltage Monitors with Manual Reset Input (VCC = 5V for L/M versions, VCC = 3.3V for T/S versions, VCC = 3V for R version, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL VOL RESET Output Voltage (MAX811) VOH CONDITIONS MIN TYP MAX MAX811R/S/T only, ISINK = 1.2mA, VCC = VTH(MIN) 0.3 MAX811L/M only, ISINK = 3.2mA, VCC = VTH(MIN) 0.4 ISINK = 50µA, VCC > 1.0V 0.3 MAX811R/S/T only, ISOURCE = 500µA, VCC > VTH(MAX) 0.8VCC MAX811L/M only, ISOURCE = 800µA, VCC > VTH(MAX) VCC - 1.5 UNITS V Note 1: Production testing done at TA = +25°C, over temperature limits guaranteed by design using six sigma design limits. Note 2: RESET output for MAX811, RESET output for MAX812. Note 3: “Glitches” of 100ns or less typically will not generate a reset pulse. _______________________________________________________________________________________ 3 MAX811/MAX812 ELECTRICAL CHARACTERISTICS (continued) __________________________________________Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. TEMPERATURE (MAX81_L/M) VCC = 3.3V 1.5 1.0 0.5 VCC = 3V 2 -40 POWER-DOWN RESET DELAY vs. TEMPERATURE (MAX81_L/M) POWER-UP RESET TIMEOUT vs. TEMPERATURE VOD = 20mV 150 100 50 VOD = 125mV VOD = 200mV 0 -40 -15 10 35 TEMPERATURE (°C) 60 -15 60 85 -40 230 MAX81_R/S/T 210 MAX81_L/M 35 60 85 1.0005 1.0000 0.9995 0.9990 0.9985 0.9980 190 85 10 RESET THRESHOLD DEVIATION vs. TEMPERATURE 220 200 -15 TEMPERATURE (°C) MAX811/12-TOC5 VOD = VTH - VCC 85 MAX811/12-TOC4 60 POWER-UP RESET TIMEOUT (ms) 200 35 VOD = 125mV 20 VOD = 200mV 10 35 TEMPERATURE (°C) 10 40 0 TEMPERATURE (°C) -15 60 VCC = 1V 0 -40 VOD = 20mV 80 MAX811/12-TOC3 MAX811/12-TOC2 4 VCC = 1V 0 4 VCC = 5.5V 6 VOD = VTH - VCC MAX811/12-TOC6 2.0 100 NORMALIZED THRESHOLD (V) SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) VCC = 3.6V 2.5 8 MAX811/12-TOC1 3.0 POWER-DOWN RESET DELAY vs. TEMPERATURE (MAX81_R/S/T) POWER-DOWN RESET DELAY (µs) SUPPLY CURRENT vs. TEMPERATURE (MAX81_R/S/T) POWER-DOWN RESET DELAY (µs) MAX811/MAX812 4-Pin µP Voltage Monitors with Manual Reset Input -40 -15 10 35 TEMPERATURE (°C) 60 85 -40 -15 10 35 TEMPERATURE (°C) _______________________________________________________________________________________ 60 85 4-Pin µP Voltage Monitors with Manual Reset Input PIN NAME FUNCTION MAX811 MAX812 1 1 GND 2 — RESET Active-Low Reset Output. RESET remains low while VCC is below the reset threshold or while MR is held low. RESET remains low for the Reset Active Timeout Period (tRP) after the reset conditions are terminated. — 2 RESET Active-High Reset Output. RESET remains high while VCC is below the reset threshold or while MR is held low. RESET remains high for Reset Active Timeout Period (tRP) after the reset conditions are terminated. Ground 3 3 MR Manual Reset Input. A logic low on MR asserts reset. Reset remains asserted as long as MR is low and for 180ms after MR returns high. This active-low input has an internal 20kΩ pull-up resistor. It can be driven from a TTL or CMOS-logic line, or shorted to ground with a switch. Leave open if unused. 4 4 VCC +5V, +3.3V, or +3V Supply Voltage _______________ Detailed Description Reset Output A microprocessor’s (µP’s) reset input starts the µP in a known state. These µP supervisory circuits assert reset to prevent code execution errors during power-up, power-down, or brownout conditions. RESET is guaranteed to be a logic low for VCC > 1V. Once V CC exceeds the reset threshold, an internal timer keeps RESET low for the reset timeout period; after this interval, RESET goes high. If a brownout condition occurs (VCC dips below the reset threshold), RESET goes low. Any time VCC goes below the reset threshold, the internal timer resets to zero, and RESET goes low. The internal timer starts after VCC returns above the reset threshold, and RESET remains low for the reset timeout period. The manual reset input (MR) can also initiate a reset. See the Manual Reset Input section. The MAX812 has an active-high RESET output that is the inverse of the MAX811’s RESET output. Manual Reset Input Many µP-based products require manual reset capability, allowing the operator, a test technician, or external logic circuitry to initiate a reset. A logic low on MR asserts reset. Reset remains asserted while MR is low, and for the Reset Active Timeout Period (tRP) after MR returns high. This input has an internal 20kΩ pull-up resistor, so it can be left open if it is not used. MR can be driven with TTL or 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 long cables or if the device is used in a noisy environment, connecting a 0.1µF capacitor from MR to ground provides additional noise immunity. Reset Threshold Accuracy The MAX811/MAX812 are ideal for systems using a 5V ±5% or 3V ±5% power supply with ICs specified for 5V ±10% or 3V ±10%, respectively. They are designed to meet worst-case specifications over temperature. The reset is guaranteed to assert after the power supply falls out of regulation, but before power drops below the minimum specified operating voltage range for the system ICs. The thresholds are pre-trimmed and exhibit tight distribution, reducing the range over which an undesirable reset may occur. _______________________________________________________________________________________ 5 MAX811/MAX812 ______________________________________________________________ Pin Description MAX811/MAX812 4-Pin µP Voltage Monitors with Manual Reset Input MAXIMUM TRANSIENT DURATION (ms) 8 TA = +25°C 7 6 VCC MAX81 _L/M 5 4 MAX811 MAX81 _R/S/T 3 RESET 2 R1 1 GND 0 1 10 100 1000 RESET COMPARATOR OVERDRIVE , VTH - VCC (mV) Figure 1. Maximum Transient Duration without Causing a Reset Pulse vs. Comparator Overdrive __________ Applications Information Negative-Going VCC Transients In addition to issuing a reset to the µP during power-up, power-down, and brownout conditions, the MAX811/ MAX812 are relatively immune to short duration negative-going VCC transients (glitches). Figure 1 shows typical transient durations vs. reset comparator overdrive, for which the MAX811/MAX812 do not generate a reset pulse. This graph was generated using a negative-going pulse applied to VCC, starting above the actual reset threshold and ending below it by the magnitude indicated (reset comparator overdrive). The graph indicates the typical maximum 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 125mV below the reset threshold and lasts 40µs or less (MAX81_L/M) or 20µs or less (MAX81_T/S/R) will not cause a reset pulse to be issued. A 0.1µF capacitor mounted as close as possible to VCC provides additional transient immunity. 6 Figure 2. RESET Valid to VCC = Ground Circuit Ensuring a Valid RESET Output Down to VCC = 0V When VCC falls below 1V, the MAX811 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 undetermined 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 (Figure 2). R1’s value is not critical; 100kΩ is large enough not to load RESET and small enough to pull RESET to ground. A 100kΩ pull-up resistor to VCC is also recommended for the MAX812 if RESET is required to remain valid for VCC < 1V. _______________________________________________________________________________________ 4-Pin µP Voltage Monitors with Manual Reset Input µPs with bidirectional reset pins (such as the Motorola 68HC11 series) can contend with the MAX811/MAX812 reset outputs. If, for example, the MAX811 RESET output is asserted high and the µP wants to pull it low, indeterminate logic levels may result. To correct such cases, connect a 4.7kΩ resistor between the MAX811 RESET (or MAX812 RESET) output and the µP reset I/O (Figure 3). Buffer the reset output to other system components. BUFFER BUFFERED RESET TO OTHER SYSTEM COMPONENTS VCC VCC MAX811 RESET µP 4.7k RESET ___________________Chip Information TRANSISTOR COUNT: 341 GND GND Figure 3. Interfacing to µPs with Bidirectional Reset I/O _______________________________________________________________________________________ 7 MAX811/MAX812 Interfacing to µPs with Bidirectional Reset Pins ________________________________________________________Package Information 4.0 ±0.1 ø1.5 ±0.1 2.0 ±0.05 1.75 ±0.1 8.0 ±0.2 3.5 ±0.05 4.0 ±0.1 ø1.1 ±0.1 NOTE: DIMENSIONS ARE IN MM. AND FOLLOW EIA481-1 STANDARD. † ICs MAY ALSO BE MARKED WITH FULL PART NAME: 811L, 811M_… MARKING INFORMATION † LOT SPECIFIC CODE XX XX AMAA or KABB = MAX811L ANAA or KABC = MAX811M APAA or KABD = MAX811T AQAA or KABE = MAX811S ARAA or KABF = MAX811R ASAA or KABG = MAX812L ATAA or KABH = MAX812M AVAA or KABI = MAX812T AWAA or KABJ = MAX812S AXAA or KABK = MAX812R SOT1434.EPS MAX811/MAX812 4-Pin µP Voltage Monitors with Manual Reset Input 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 © 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.