19-2637; Rev 1; 4/03 µP Supervisors with Separate VCC Reset and Manual Reset Outputs The MAX6453/MAX6455 have active-low push-pull reset and manual reset outputs, and the MAX6454/ MAX6456 have active-low open-drain reset and manual reset outputs. All devices are available in small SOT236 packages and are fully specified over the extended temperature range (-40°C to +85°C). Features ♦ Precision Factory-Set Reset Thresholds From 1.6V to 4.6V ♦ Adjustable Threshold to Monitor Voltages Down to 0.63V ♦ Manual Reset Input with Extended 3.36s Setup Period ♦ Immune to Short Voltage Transients ♦ Low 6µA Supply Current ♦ Guaranteed Valid Reset Down to VCC = 1.0V ♦ Active-Low RESET (Push-Pull or Open-Drain) Outputs ♦ 140ms (min) Reset Timeout Period ♦ Small SOT Package Ordering Information TEMP RANGE PIN-PACKAGE MAX6453UT_ _S-T PART -40°C to +85°C 6 SOT23-6 MAX6454UT_ _S-T -40°C to +85°C 6 SOT23-6 MAX6455UT_ _S-T -40°C to +85°C 6 SOT23-6 MAX6456UT_ _S-T -40°C to +85°C 6 SOT23-6 Note: The “_” is a placeholder for the threshold voltage level of the devices. A desired threshold level is set by the part number suffix found in Table 1. All devices are available in tapeand-reel only. There is a 2500-piece minimum order increment for standard versions (Table 2). Sample stock is typically held on standard versions only. Nonstandard versions require a minimum order increment of 10,000 pieces. Contact factory for availability. Selector Guide appears at end of data sheet. Pin Configurations Applications Set-Top Boxes TOP VIEW Consumer Electronics DVD Players RESET 1 Modems MP3 Players GND 2 MAX6453 MAX6454 6 MR 5 RSTIN 4 VCC RESET 1 GND 2 MAX6455 MAX6456 6 MR 5 RSTIN 4 VCC Industrial Equipment MROUT 3 Automotive Medical Devices SOT23-6 MROUT 3 SOT23-6 ________________________________________________________________ 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 MAX6453–MAX6456 General Description The MAX6453–MAX6456 are low-power, dual-voltage µP supervisors featuring separate VCC reset and manual reset outputs. The dual outputs support both softsystem reset (interrupt) and hard-system reset (reboot) functions. The reset output asserts when any of the monitored voltages falls below its specified threshold and remains asserted for the reset timeout (140ms min) after all voltages exceed their respective reset thresholds. All devices are offered with nine factory-fixed reset thresholds for monitoring primary system voltages (VCC) from 1.8V to 5V and an adjustable reset input for monitoring a secondary system voltage down to 0.63V. Each device has a manual reset input, a VCC reset output, and a manual reset output. The MAX6453/ MAX6454 manual reset output asserts when the manual reset input is low. It remains asserted for the manual reset timeout period (140ms min) after the manual reset input transitions high. The MAX6453/MAX6354 manual reset input controls only the manual reset output and does not affect the VCC reset output. The manual reset input of the MAX6455/MAX6456 controls both the manual reset and VCC reset outputs. When the manual reset input is low for less than 3.3s (typ), only the manual reset output asserts and remains asserted for the manual reset timeout period (140ms min) after the manual reset input transitions high. If the manual reset input is low for at least 3.3s (typ), the reset output also asserts and remains asserted for the reset timeout period (140ms min) after the manual reset input transitions high. This enhanced feature allows the implementation of a soft/hard-system reset combination. MAX6453–MAX6456 µP Supervisors with Separate VCC Reset and Manual Reset Outputs ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND) VCC ..........................................................................-0.3V to +6V Open-Drain RESET, MROUT ....................................-0.3V to +6V Push-Pull RESET, MROUT..........................-0.3V to (VCC + 0.3V) MR, RSTIN ...............................................................-0.3V to +6V Input Current, All Pins.......................................................±20mA Continuous Power Dissipation (TA = +70°C) 6-Pin SOT23 (derate 8.7mW/°C above +70°C).............696mW Operating Temperature Range .......................... -40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+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 = 1.0V to 5.5V, TA = -40°C to +85°C, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Operating Voltage Range VCC VCC Supply Current ICC VCC Reset Threshold VTH CONDITIONS MIN RSTIN Threshold Hysteresis VHYST RSTIN Input Current IRSTIN RSTIN to Reset Output Delay 20 6 16 46 4.50 4.63 4.75 44 4.25 4.38 4.50 31 3.00 3.08 3.15 29 2.85 2.93 3.00 26 2.55 2.63 2.70 23 2.25 2.32 2.38 22 2.12 2.19 2.25 17 1.62 1.67 1.71 16 1.52 1.58 1.62 TA = 0°C to +85°C 0.615 TA = -40°C to +85°C 0.610 VCC to RESET Output Delay tRD VCC falling at 1mV/µs MR Minimum Setup Period (Pulse Width) tMR MR to MROUT mV 0.630 0.645 0.650 RESET asserted, MAX6455/MAX6456 210 +25 nA 280 ms µs µs 1 2.24 µs 3.36 4.48 100 MR to MROUT Delay 140 210 _______________________________________________________________________________________ s ns 200 tMRP V mV 20 MR Glitch Rejection 2 ppm/°C 15 140 V 2 × VTH -25 tRP µA 60 2.5 Reset Timeout Period Manual Reset Timeout Period V 7 VRSTIN falling at 1mV/µs MR Minimum Input Pulse UNITS 5.5 VCC = 3.6V, no load Reset Threshold Hysteresis VTH-RSTIN MAX VCC = 5.5V, no load Reset Threshold Tempco RSTIN Threshold TYP 1.0 ns 280 ms µP Supervisors with Separate VCC Reset and Manual Reset Outputs (VCC = 1.0V to 5.5V, TA = -40°C to +85°C, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MR to VCC Pullup Impedance RESET, MROUT Output Low (Open Drain or Push-Pull) RESET, MROUT Output High (Push-Pull) RESET, MROUT Output Open-Drain Leakage Current VOL VOH ILKG MR Input Low Voltage VIL MR Input High Voltage VIH MIN TYP MAX UNITS 25 50 75 kΩ VCC ≥ 1.00V, ISINK = 50µA, outputs asserted 0.3 VCC ≥ 1.20V, ISINK = 100µA, outputs asserted 0.3 VCC ≥ 2.55V, ISINK = 1.2mA, outputs asserted 0.3 VCC ≥ 4.25V, ISINK = 3.2mA, outputs asserted 0.4 V VCC ≥ 1.80V, ISOURCE = 200µA, outputs deasserted 0.8 × VCC VCC ≥ 3.15V, ISOURCE = 500µA, outputs deasserted 0.8 × VCC VCC ≥ 4.75V, ISOURCE = 800µA, outputs deasserted 0.8 × VCC Outputs deasserted V 1 0.3 × VCC 0.7 × VCC µA V V Note 1: Devices production tested at 25°C. Overtemperature limits are guaranteed by design. _______________________________________________________________________________________ 3 MAX6453–MAX6456 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = 3.3V, TA = +25°C, unless otherwise noted.) 5 TA = -40°C 4 3 2 1 1.03 1.02 1.01 1.00 0.99 0.98 MAX6453 toc03 1.04 TRANSIENT DURATION (µs) 6 250 MAX6453 toc02 TA = +25°C 7 1.05 NORMALIZED TIMEOUT PERIOD TA = +85°C 8 200 150 RESET OCCURS ABOVE THE CURVE 100 50 0.97 VTH = 4.4V 0.96 0 0 0.95 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 -40 -15 10 35 60 0 85 200 400 600 800 TEMPERATURE (°C) RESET THRESHOLD OVERDRIVE (mV) NORMALIZED VCC RESET THRESHOLD vs. TEMPERATURE VCC TO RESET DELAY vs. TEMPERATURE RSTIN TO RESET DELAY vs. TEMPERATURE (RSTIN FALLING) 1.01 1.00 0.99 0.98 0.97 24.0 23.2 22.8 22.4 22.0 21.6 21.2 -15 10 35 60 85 23.2 22.8 22.4 22.0 21.6 21.2 20.8 20.8 20.4 20.4 20.0 -40 RSTIN FALLING AT 1mV/µs 23.6 RSTIN TO RESET DELAY (µs) VCC TO RESET DELAY (µs) 1.02 VCC FALLING AT 1mV/µs 23.6 MAX6453 toc06 24.0 MAX6453 toc04 1.03 20.0 -40 TEMPERATURE (°C) -15 10 35 60 85 -40 -15 10 TEMPERATURE (°C) MANUAL RESET TO MROUT AND RESET DELAY (MAX6455/MAX6456) 35 60 TEMPERATURE (°C) VCC TO RESET DELAY MAX6453 toc07 MAX6453 toc08 VCC = 5V MR (5V/div) VCC = 4.5V VTH = 4.392V VCC = 4.3V MROUT (5V/div) VCC (100mV/div) RESET (5V/div) RESET (2V/div) TIME (1s/div) 4 1000 SUPPLY VOLTAGE (V) MAX6453 toc05 SUPPLY CURRENT (µA) MAX6453 toc01 9 MAXIMUM TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE NORMALIZED RESET TIMEOUT PERIOD vs. TEMPERATURE SUPPLY CURRENT vs. SUPPLY VOLTAGE NORMALIZED VCC RESET THRESHOLD MAX6453–MAX6456 µP Supervisors with Separate VCC Reset and Manual Reset Outputs TIME (100µs/div) _______________________________________________________________________________________ 85 µP Supervisors with Separate VCC Reset and Manual Reset Outputs PIN MAX6453 MAX6454 1 MAX6455 MAX6456 NAME Active-Low Push-Pull or Open-Drain Output. RESET changes from high to low when VCC or RSTIN drops below its selected reset threshold. RESET remains low for the 140ms (min) reset timeout period after all monitored power-supply inputs exceed their selected reset thresholds. MR does not affect RESET output. For open-drain outputs, connect to an external pullup resistor. — RESET — 1 2 2 GND 3 3 MROUT 4 4 VCC 5 5 RSTIN 6 — 6 Active-Low Push-Pull or Open-Drain Output. RESET changes from high to low when VCC or RSTIN drops below its selected reset threshold. RESET remains low for the 140ms (min) reset timeout period after all monitored power-supply inputs exceed their selected reset thresholds. RESET changes from high to low after MR input is held low for the 3.36s (typ) setup period and deasserts 140ms (min) after MR deasserts. For open-drain outputs, connect to an external pullup resistor. Ground Manual Reset Push-Pull or Open-Drain Output. MROUT asserts immediately after MR is pulled low. MROUT remains low for 140ms (min) after MR is deasserted. For opendrain outputs, connect to an external pullup resistor. VCC Voltage Input. Power supply and input for the primary microprocessor voltage reset monitor. Reset Input. High-impedance input to the adjustable reset comparator. Connect RSTIN to the center point of an external resistor divider to set the threshold of the externally monitored voltage. Manual Reset Input. Internal 50kΩ pullup to VCC. Pull MR low to immediately assert MROUT. MR does not affect RESET output. MR — FUNCTION Manual Reset Input. Internal 50kΩ pullup to VCC. Pull MR low to immediately assert MROUT. RESET changes from high to low after MR input is held low for the 3.36s (typ) setup period. _______________________________________________________________________________________ 5 MAX6453–MAX6456 Pin Description MAX6453–MAX6456 µP Supervisors with Separate VCC Reset and Manual Reset Outputs MR 210ms MROUT Figure 1. MAX6453/MAX6454 Timing Diagram Detailed Description Reset Output The reset output is typically connected to the reset input of a microprocessor (µP). A µP’s reset input starts or restarts the µP in a known state. The MAX6453– MAX6456 µP supervisory circuits provide the reset logic to prevent code-execution errors during powerup, power-down and brownout conditions (see the Typical Operating Circuit). RESET changes from high to low whenever the monitored voltage (RSTIN or VCC) drops below the reset threshold voltages. When VRSTIN and VCC exceed their respective reset threshold voltages, RESET remains low for the reset timeout period, and then goes high. RESET changes from high to low after MR input is held low for the 3.36s (typ) setup period and deasserts 140ms (min) after MR deasserts. RESET is guaranteed to be in the proper output logic state for VCC inputs ≥ 1V. For applications requiring valid reset logic when VCC is less than 1V, see the Ensuring a Valid RESET Output Down to VCC = 0V section. Manual Reset The MAX6453/MAX6454 contain a manual reset output (MROUT) that asserts low immediately after driving MR low and remains low for the reset timeout period after MR goes high (Figure 1). The pushbutton manual reset has no effect on the RESET output. MROUT output can be used to drive an NMI (nonmaskable interrupt) on the processor to save valuable data. The MAX6455/MAX6456’s MROUT is asserted immediately upon driving MR low. Driving MR low for longer than the 3.36s (typ) setup period asserts RESET. When MR is deasserted, MROUT and RESET remain asserted low for the reset timeout period after MR goes high (Figure 2). Adjustable Input Voltage (RSTIN) The MAX6453–MAX6456 monitor the voltage on RSTIN using an adjustable reset threshold set with an external resistor voltage divider (Figure 3). Use the following formula to calculate the externally monitored voltage (VMON-TH): VMON-TH = VTH-RSTIN ✕ (R1 +R2) / R2 where VMON_TH is the desired reset threshold voltage and V TH-RSTIN is the reset input threshold (0.63V). Resistors R1 and R2 can have very high values to minimize current consumption due to low leakage currents. Set R2 to some conveniently high value (250kΩ, for example) and calculate R1 based on the desired reset threshold voltage, using the following formula: R1 = R2 ✕ (VMON_TH / VTH - 1)Ω LONG SETUP PERIOD, 3.36s MR 210ms MROUT RESET Figure 2. MAX6455/MAX6456 Timing Diagram 6 _______________________________________________________________________________________ µP Supervisors with Separate VCC Reset and Manual Reset Outputs R1 MAX6453 MAX6455 RSTIN VCC R2 GND RESET VMON_TH = 0.63 x (R1 + R2) / R2 Figure 3. Calculating The Monitored Threshold Voltages Applications Information Interrupt Before Reset To minimize data loss and speed system recovery/test, many applications interrupt the processor or reset only portions of the system before a processor hard reset is asserted. The extended setup time of the MAX6455/ MAX6456 MR input allows the same pushbutton (Figure 4) to control both the interrupt and hard reset functions. If the pushbutton is closed for less than 3.36s (typ), the processor is only interrupted (MROUT). If the system still does not respond properly, the pushbutton can be closed for the full extended setup period (3.36s typ) to hard reset the processor (RESET). If desired, connect a LED to the RESET output to turn off (or on) to signify when the pushbutton is closed long enough for a hard reset (the same LED can be used as the front panel power-on display). Interfacing to Other Voltages for Logic Compatibility The open-drain RESET output can be used to interface to a µP with other logic levels. As shown in Figure 5, the open-drain output can be connected to voltages from 0 to 6V. Ensuring a Valid RESET Down to VCC = 0V (Push-Pull RESET) When VCC falls below 1V, RESET current-sinking capabilities decline drastically. The high-impedance CMOSlogic inputs connected to RESET can drift to undetermined voltages. This presents no problem in most applications, because most µPs and other circuitry do not operate with VCC below 1V. In applications where RESET must be valid down to 0V, add a pulldown resistor between RESET and GND for the push/pull outputs. The resistor sinks any stray leakage currents, holding RESET low (Figure 6). The value of the pulldown resistor is not critical; 100kΩ is large enough not to load RESET and small enough to pull RESET to ground. The external pulldown cannot be used with the open-drain reset outputs. Transient Immunity In addition to issuing a reset to the µP during power-up, power-down and brownout conditions, these supervisors are relatively immune to short duration falling transients (glitches). The graph Maximum Transient Duration vs. Reset Threshold Overdrive in the Typical Operating Characteristics section shows this relationship. The area below the curves of the graph is the region in which these devices typically do not generate a reset pulse. This graph was generated using a negative going pulse applied to VCC, starting above the actual reset threshold (VTH) and ending below it by the magnitude indicated (reset-threshold overdrive). As the magnitude of the transient increases (V CC goes further below the reset threshold), the maximum allowable pulse width decreases. Typically, a VCC transient that goes 100mV below the reset threshold and lasts 20µs or less does not cause a reset pulse to be issued. _______________________________________________________________________________________ 7 MAX6453–MAX6456 VCC VMON_TH Generally, the pullup resistor connected to the RESET connects to the supply voltage being monitored at the IC’s VCC pin. However, some systems might use the open-drain output to level-shift from the monitored supply to reset circuitry powered by some other supply (Figure 5). Keep in mind that as the supervisor’s VCC decreases toward 1V, so does the IC’s ability to sink current at RESET (RESET is pulled high as VCC decays toward 0). The voltage where this occurs depends on the pullup resistor value and the voltage to which it is connected. MAX6453–MAX6456 µP Supervisors with Separate VCC Reset and Manual Reset Outputs +3.3V +1.5V CORE SUPPLY VCC RESET RESET 5V 3.3V VCC VCC I/O SUPPLY MAX6455 µP RSTIN LED GND 100kΩ MAX6454 MAX6456 µP NMI MROUT MR RESET RESET GND GND PUSHBUTTON SWITCH CLOSE FOR IMMEDIATE SYSTEM INTERRUPT CLOSE FOR >3.36s FOR SYSTEM RESET Figure 4. Interrupt Before Reset Application Circuit Figure 5. Interfacing to Other Voltage Levels Functional Diagram VCC MAX6453– MAX6456 VCC VCC MAX6453 MAX6455 RESET TIMOUT PERIOD (210ms typ) RSTIN RESET 100kΩ MR-TO-RESET SETUP PERIOD (3.36s typ) MAX6455/MAX6456 VCC GND RESET 0.63V 1.23V MROUT TIMOUT PERIOD (210ms typ) VCC GND MR Figure 6. Ensuring RESET Valid to VCC = 0 8 _______________________________________________________________________________________ MROUT µP Supervisors with Separate VCC Reset and Manual Reset Outputs Table 2. Standard Versions Table PART NO. SUFFIX (__) VCC NOMINAL VOLTAGE THRESHOLD (V) MAX6453UT16S ABOG MAX6455UT16S ABOL 46 4.625 MAX6453UT23S ABOH MAX6455UT23S ABOM 44 4.375 MAX6453UT26S ABOI MAX6455UT26S ABON 31 3.075 MAX6453UT29S ABOJ MAX6455UT29S ABOO 29 2.925 MAX6453UT46S ABOK MAX6455UT46S ABER 26 2.625 MAX6454UT16S ABOP MAX6456UT16S ABES 23 2.313 MAX6454UT23S ABEQ MAX6456UT23S ABOT 22 2.188 MAX6454UT26S ABOQ MAX6456UT26S ABOU 17 1.665 MAX6454UT29S ABOR MAX6456UT29S ABOV 16 1.575 MAX6454UT46S ABOS MAX6456UT46S ABOW TOP MARK PART TOP MARK PART Selector Guide PART MR TO RESET DELAY MR ASSERTION MROUT AND RESET PUSH-PULL OUTPUT MROUT AND RESET OPEN-DRAIN OUTPUT MAX6453 — MROUT ✓ — MAX6454 — MROUT — ✓ MAX6455 3.36s MROUT and RESET ✓ — MAX6456 3.36s MROUT and RESET — ✓ *Other timing options may be available. Contact factory for availability. Typical Operating Circuit Chip Information TRANSISTOR COUNT: 1384 PROCESS: BiCMOS +3.3V +1.5V CORE SUPPLY VCC RESET RESET I/O SUPPLY MAX6453 µP RSTIN MROUT MR GND NMI GND _______________________________________________________________________________________ 9 MAX6453–MAX6456 Table 1. Reset Voltage Threshold 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.) 6LSOT.EPS MAX6453–MAX6456 µP Supervisors with Separate VCC Reset and Manual Reset Outputs PACKAGE OUTLINE, SOT-23, 6L 21-0058 F 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. 10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.