MAX6841EUKD0-T

19-2625; Rev 2; 12/05 Ultra-Low-Voltage µP Reset Circuits and Voltage Detectors The MAX6841–MAX6845 microprocessor (µP) supervisory circuits monitor ultra-low-voltage power supplies in µP and digital systems. They provide excellent circuit reliability at low cost by eliminating external components and adjustments when used with +0.9V to +1.5V systems. Factory-trimmed reset thresholds are available for the MAX6841/MAX6842. The MAX6843/ MAX6844/MAX6845 provide a RESET IN input, allowing the user to externally adjust the reset threshold. The MAX6841–MAX6845 family features a debounced manual reset input (MR). The reset comparator is designed to ignore fast transients on VCC. The MAX6841–MAX6845 assert a reset signal whenever the VCC supply voltage declines below a preset or adjustable threshold or whenever manual reset (MR) is asserted. Reset remains asserted for a fixed timeout delay after VCC has risen above the reset threshold and when manual reset is deasserted. Five timeout periods are available for each part: 150µs (voltage detector version), 1.5ms, 30ms, 210ms, and 1.68s (typ). The MAX6841/MAX6843 have an active-low push-pull reset output. The MAX6841/MAX6842/MAX6844 have an active-high push-pull reset output, and the MAX6842/MAX6845 have an active-low open-drain reset output. The active-low open-drain reset output requires a pullup resistor that can be connected to a voltage from 0 to VCC. The low supply current (5.7µA) and small package (SOT23-5) make the MAX6841–MAX6845 ideal for use in portable equipment. Applications Computers Controllers Intelligent Instruments Critical µP and µC Power Monitoring Portable/Battery-Powered Equipment Features ♦ Factory-Set Reset Threshold Voltages for Monitoring Supplies from 0.9V to 1.5V (MAX6841/MAX6842) ♦ Adjustable Threshold RESET IN (MAX6843/MAX6844/MAX6845) ♦ Low Power Consumption: 5.7µA (typ) ♦ ±2.5% Reset Threshold Accuracy Over Temperature ♦ Five Timeout Periods: 150µs (Voltage Detector Version), 1.5ms, 30ms, 210ms, and 1.68s ♦ Available in Three Output Configurations Push-Pull RESET Push-Pull RESET Open-Drain RESET ♦ Guaranteed Reset Valid to VCC = 0.55V (Active Low) ♦ Manual Reset Input ♦ Immune to Short VCC Transients ♦ Space-Saving 5-Pin SOT23 Package Ordering Information PART TEMP RANGE PIN-PACKAGE MAX6841_UKD_-T -40°C to +85°C 5 SOT23-5 MAX6842_UKD_-T -40°C to +85°C 5 SOT23-5 MAX6843UKD_-T -40°C to +85°C 5 SOT23-5 MAX6844UKD_-T -40°C to +85°C 5 SOT23-5 MAX6845UKD_-T -40°C to +85°C 5 SOT23-5 Note: Insert desired suffix letter (from the Threshold Suffix Guide and the Active Timeout Period tables) into the blanks to complete the part number. For example, the MAX6842GUKD1 has a reset threshold of 1.11V and a typical reset timeout period of 1.5ms. Sample stock is generally available on standard versions only (see the Standard Versions table). Standard versions require a minimum order increment of 2.5k units. Nonstandard versions must be ordered in 10k-unit increments. Contact factory for availability. All parts are offered in tape-and-reel only. Devices are available in both leaded and lead-free packaging. Specify lead-free by replacing “-T” with “+T” when ordering. Pin Configurations Telecom/Networking Equipment Basestations TOP VIEW Servers/Workstations RESET 1 GND 2 Selector Guide and Typical Operating Circuit appear at end of data sheet. 5 VCC MAX6841 MAX6842 GND 2 4 MR RESET 3 SOT23-5 RESET 1 (RESET) 5 VCC MAX6843 MAX6844 MAX6845 4 MR RESET IN 3 SOT23-5 ( ) ARE FOR 6844 ________________________________________________________________ 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 MAX6841–MAX6845 General Description MAX6841–MAX6845 Ultra-Low-Voltage µP Reset Circuits and Voltage Detectors ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) VCC .......................................................................-0.3V to +6V MR, RESET IN, RESET (open-drain).........................-0.3V to +6V Push-Pull RESET and RESET .....................-0.3V to (VCC + 0.3V) Input Current (all pins) ........................................................20mA Output Current (RESET, RESET).........................................20mA Continuous Power Dissipation (TA = +70°C) 5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW 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 = +0.55V to +1.8V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Supply Voltage Range Supply Current Reset Threshold (VCC Falling) SYMBOL VCC ICC VTH RESET IN Threshold VRSTIN RESET IN Leakage Current IRSTIN Reset Threshold Hysteresis VHYS CONDITIONS MIN 0.55 1.80 MAX6841/MAX6842/MAX6844 (Note 2) 0.75 1.80 VCC = 0.9V, no load, reset not asserted 5.7 20 VCC = 1.5V, no load, reset not asserted 7.3 20 VCC = 1.8V, no load, reset not asserted 8.1 20 I 1.350 1.388 1.425 H 1.275 1.313 1.350 G 1.080 1.110 1.140 F 1.020 1.050 1.080 E 0.810 0.833 0.855 D, TA = 0°C to +85°C 0.765 0.788 0.810 MAX6843/MAX6844/MAX6845 (Note 3) 181.2 187.4 191.5 -25 D1 MR Input Voltage (Note 3) tRP +25 0.75 1.5 V mV nA 2 20 30 40 D3 140 210 280 D4 1120 1680 2240 0.3 × VCC VIL 0.7 × VCC MR driven from VCC to 0 (Note 3) MR Glitch Rejection MR driven from VCC to 0 (Note 3) 150 MR to Reset Delay MR driven from VCC to 0 (Note 3) 500 2 µA 0.15 1 MR Minimum Input Pulse Width MR Pullup Resistance to VCC V µs D2 VIH UNITS %VTH 150 D0 (voltage detector) Reset Active Timeout Period MAX MAX6843/MAX6845 VCC falling, step signal from (VTH + 10%) to (VTH - 10%) within 1µs VCC or RESET IN to Reset Delay TYP 1 10 ms V µs 20 _______________________________________________________________________________________ ns ns 26 kΩ Ultra-Low-Voltage µP Reset Circuits and Voltage Detectors (VCC = +0.55V to +1.8V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Open-Drain RESET Output Voltage VOL Open-Drain RESET Output Leakage Current ILKG CONDITIONS MIN TYP MAX VCC ≥ 0.55V, ISINK = 10µA, reset asserted 0.2 × VCC VCC ≥ 0.83V, ISINK = 80µA, reset asserted 0.2 × VCC VCC > VTH, reset not asserted VOL Push-Pull RESET Output Voltage VOH VOH Push-Pull RESET Output Voltage V 1 VCC ≥ 0.55V, ISINK = 10µA, reset asserted 0.2 × VCC VCC ≥ 0.83V, ISINK = 80µA, reset asserted 0.2 × VCC VCC ≥ 0.83V, ISOURCE = 40µA, reset not asserted 0.8 × VCC VCC ≥ 0.75V, ISOURCE = 10µA, reset asserted 0.8 × VCC VCC ≥ 0.83V, ISOURCE = 40µA, reset asserted 0.8 × VCC µA V V VCC ≥ 0.83V, ISINK = 80µA, reset not asserted VOL UNITS 0.2 × VCC Note 1: 100% production tested at +25°C. Overtemperature limits are guaranteed by design. Note 2: The active-low output RESET has VCC(MIN) = 0.55V (MAX6841/MAX6842). Note 3: For VCC > 0.788V, TA = 0°C to +85°C, and for VCC > 0.833V, TA = -40°C to +85°C. Typical Operating Characteristics (VCC = 1.5V, TA = +25°C, unless otherwise noted.) POWER-DOWN RESET DELAY vs. TEMPERATURE 5 VCC = 0.9V 4 3 2 300 VOD = 10mV 250 VOD = 20mV 200 150 100 VOD = 100mV 50 1 1.06 NORMALIZED RESET TIMEOUT PERIOD VCC = 1.5V 6 MAX6841-45 toc02 VCC = 1.8V 7 350 POWER-DOWN RESET DELAY (µs) SUPPLY CURRENT (µA) 8 MAX6841-45 toc01 9 NORMALIZED RESET TIMEOUT PERIOD vs. TEMPERATURE 1.04 MAX6841-45 toc03 SUPPLY CURRENT vs. TEMPERATURE D2 OPTION D3 OPTION 1.02 1.00 D4 OPTION 0.98 0.96 VOD = OVERDRIVE (mV) 0 0 -40 -20 0 20 40 TEMPERATURE (°C) 60 80 0.94 -40 -20 0 20 40 TEMPERATURE (°C) 60 80 -40 -20 0 20 40 60 80 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX6841–MAX6845 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VCC = 1.5V, TA = +25°C, unless otherwise noted.) NORMALIZED VCC RESET THRESHOLD vs. TEMPERATURE NORMALIZED RESET IN THRESHOLD vs. TEMPERATURE 1.010 1.005 1.000 0.995 0.990 MAX6841-45 toc06 1.015 0.985 POWER-UP/POWER-DOWN CHARACTERISTICS (MAX6843AUKD3) MAX6841-45 toc05 VTH = 0.833V NORMALIZED RESET IN THRESHOLD MAX6841-45 toc04 1.015 NORMALIZED VCC RESET THRESHOLD MAX6841–MAX6845 Ultra-Low-Voltage µP Reset Circuits and Voltage Detectors 1.010 VCC 1V/div 1.005 1.000 RESET 1V/div 0.995 0.990 0.985 -40 -20 0 20 40 60 80 -40 -20 TEMPERATURE (°C) 0 20 40 60 80 200ms/div TEMPERATURE (°C) Pin Description PIN MAX6841 MAX6842 1 MAX6843 MAX6845 — MAX6844 NAME Push-Pull (MAX6841) or Open-Drain (MAX6842) Active-Low Reset Output. RESET changes from high to low when VCC drops below the selected reset threshold or MR is pulled low. RESET remains low for the reset timeout period after VCC exceeds the device reset threshold and MR is released high. — RESET — 1 — 2 2 2 3 — GND — RESET — 4 — FUNCTION 1 Push-Pull (MAX6843) or Open-Drain (MAX6845) Active-Low Reset Output. RESET changes from high to low when RESET IN drops below the 187.4mV reset threshold (referenced to VCC) or MR is pulled low. RESET remains low for the reset timeout period after RESET IN exceeds the reset threshold and MR is released high. Ground Push-Pull Active-High Reset Output. RESET changes from low to high when VCC input drops below the selected reset threshold or MR is pulled low. RESET remains high for the reset timeout period after VCC exceeds the device reset threshold and MR is released high. Push-Pull Active-High Reset Output. RESET changes from low to high when the RESET IN input drops below the 187.4mV reset threshold (referenced to VCC). RESET remains high for the reset timeout period after RESET IN exceeds the reset threshold. Adjustable Reset Input. High-impedance input for reset comparator. Connect this pin to an external resistive-divider network to set the reset threshold voltage; the RESET IN typical threshold is 187.4mV (referenced to VCC). The MAX6843/MAX6844/ MAX6845 assert a reset signal when the VCC to RESET IN differential falls below its threshold voltage. — 3 3 4 4 4 MR Active-Low Manual Reset Input. Internal 20kΩ pullup to VCC. Pull low to force a reset. Reset remains active as long as MR is low and for the reset timeout period after MR goes high. Leave unconnected or connect to VCC if unused. 5 5 5 VCC Supply Voltage. Monitored supply for the MAX6841/MAX6842. _______________________________________________________________________________________ Ultra-Low-Voltage µP Reset Circuits and Voltage Detectors MR MR VCC VCC MR PULLUP VREF MANUAL RESET DETECT MAX6841 MAX6842 MR PULLUP MANUAL RESET DETECT VREF = 187.4mV MAX6843 MAX6844 MAX6845 RESET IN RESET TIMEOUT PERIOD RESET OUTPUT RESET TIMEOUT PERIOD RESET RESET RESET OUTPUT RESET RESET GND GND Detailed Description Reset Output A microprocessor’s (µP’s) reset input starts the µP in a known state. The MAX6841–MAX6845 assert a reset during power-up, power-down, and brownout conditions. When the VCC supply voltage falls below a preset threshold (MAX6841/MAX6842) or RESET IN falls below the adjustable threshold (MAX6843/MAX6844/MAX6845), reset asserts and stays asserted for a fixed timeout delay (Table 2) after VCC or RESET IN has risen above the reset threshold. The MAX6841–MAX6845 are available with five typical timeout options for each part: 150µs (voltage detector), 1.5ms, 30ms, 210ms, and 1.68s. The MAX6841/MAX6842 have two reset outputs (RESET and RESET); one is the inverse of the other. The MAX6841 has one active-high push-pull output and one active-low push-pull output. The MAX6842 has one active-high push-pull output and one active-low opendrain output. The MAX6843 features an active-low push-pull output. The MAX6844 features an activehigh push-pull output, and the MAX6845 has an activelow open-drain output stage. Connect a pullup resistor from the open-drain RESET output to any voltage between 0 and 6V. tion, connect a normally open momentary switch from MR to ground; external debounce circuitry is not required. If MR is driven from long cables or the device is used in a noisy environment, connect a 0.1µF capacitor from MR to ground to provide additional noise immunity. RESET IN The MAX6843/MAX6844/MAX6845 feature a RESET IN input, which allows users to adjust the reset threshold voltage. The internal reference voltage is 187.4mV with respect to VCC. An external resistive-divider network can be used to set voltage monitoring thresholds, as shown in Figure 1. The resistive-divider network must be referenced to V CC . As V CC falls, the voltage at VCC R1 VCC RESET IN R2 MAX6843 MAX6844 MAX6845 Manual Reset Input Many µP-based systems require a manual reset capability, allowing the operator, a test technician, or external logic circuitry to initiate a reset. Reset remains asserted while MR is low, and for a fixed timeout delay after MR returns high. This input has an internal 20kΩ pullup resistor, so it can be left open if it is not used. MR can be driven with CMOS logic level or with opendrain/collector outputs. To create a manual reset func- MR R1 = R2 VCC-TH -1 VREF RESET (RESET) GND ( ) ARE FOR MAX6844 WHERE VREF = 187.4mV (WITH RESPECT TO VCC) AND VCC-TH IS THE VCC THRESHOLD. Figure 1. Setting the Adjustable Threshold Externally _______________________________________________________________________________________ 5 MAX6841–MAX6845 Functional Diagrams RESET IN decreases. The MAX6843/MAX6844/ MAX6845 assert a reset when the voltage at RESET IN falls below the RESET IN threshold (VRSTIN). The lowleakage current at RESET IN allows for relatively largevalue resistors to be used, which reduces power consumption. For example, for VCC-TH = 0.9V, if R2 = 100kΩ, then R1 = 26.3kΩ. Applications Information VCC Falling Transients The MAX6841–MAX6845 are relatively immune to shortduration falling V CC transients (glitches). Figure 2 shows typical transient duration vs. reset comparator overdrive, for which the MAX6841–MAX6845 do not generate a reset pulse. The graph was generated using a falling pulse applied to VCC, starting 0.1V above the actual reset threshold and ending below it by the magnitude indicated (reset comparator overdrive). The graph indicates the maximum pulse width that a falling VCC transient can have without causing a reset pulse. As the magnitude of the transient increases (goes further below the reset threshold), the maximum allowable pulse width decreases. A 0.1µF bypass capacitor mounted as close as possible to the VCC pin provides additional transient immunity. Ensuring a Valid Reset Output Down to VCC = 0 When VCC falls below 0.55V, the MAX6841/MAX6843 push-pull RESET output no longer sinks current; it becomes an open circuit. Therefore, high-impedance CMOS-logic inputs connected to RESET can drift to undetermined voltages. This presents no problem in MAXIMUM TRANSIENT DURATION vs. OVERDRIVE most applications, because most µP and other circuitry are inoperative with VCC lower than 0.55V. However, in applications in which RESET must be valid down to 0, adding a pulldown resistor to RESET causes any stray leakage currents to flow to ground, holding RESET low (Figure 3). R3’s value is not critical; 200kΩ is large enough not to load RESET and small enough to pull RESET to ground. VCC MAX6841 MAX6843 RESET GND R3 Figure 3. RESET Valid to VCC = 0 A 200kΩ pullup resistor to VCC is also recommended for the MAX6841/MAX6842/MAX6844 if push-pull RESET is required to remain valid for VCC ≤ 0.75V. Interfacing to µPs with Bidirectional Reset Pins Because the RESET output on the MAX6842/MAX6845 is open drain, these devices interface easily with µPs that have bidirectional reset pins. Connecting the µP supervisor’s RESET output directly to the µP’s RESET pin with a single pullup resistor allows either device to assert reset (Figure 4). 600 MAXIMUM TRANSIENT DURATION (µs) MAX6841–MAX6845 Ultra-Low-Voltage µP Reset Circuits and Voltage Detectors 550 RESET OCCURS ABOVE THIS LINE 500 VCC 450 VCC VCC MAX6842 MAX6845 µP 400 350 300 250 RESET 200 GND 150 RESET INPUT GND 100 1 10 100 OVERDRIVE VTH - VCC (mV) Figure 2. Maximum Transient Duration vs. Overdrive 6 Figure 4. Interfacing to Microprocessors with Bidirectional Reset I/0 _______________________________________________________________________________________ Ultra-Low-Voltage µP Reset Circuits and Voltage Detectors VCC Table 1. Threshold Suffix Guide VCC RPULLUP MAX6842 MAX6845 µP RESET RESET GND MAX6841–MAX6845 +5.0V 0.9V GND SUFFIX RESET THRESHOLD (V) I 1.388 H 1.313 G 1.110 F 1.050 E 0.833 D 0.788 Table 2. Active Timeout Period Guide Figure 5. Using the MAX6842/MAX6845 Open-Drain RESET Output with Multiple Supplies Using the MAX6842/MAX6845 Open-Drain RESET Output with Multiple Supplies Generally, the pullup connected to the MAX6842/ MAX6845 connects to the supply voltage being monitored at the IC’s VCC pin. However, some systems use the open-drain output to level-shift from the monitored supply to reset circuitry powered by some other supply (Figure 5). Note that as the MAX6842/MAX6845’s VCC decreases, so does the IC’s ability to sink current at RESET. Also, with any pullup, 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. Chip Information TRANSISTOR COUNT: 788 PROCESS: BiCMOS SUFFIX RESET ACTIVE TIMEOUT PERIOD (ms) MIN TYP MAX D0 — 0.15 — D1 1 1.5 2 D2 20 30 40 D3 140 210 280 D4 1120 1680 2240 Table 3. Standard Versions DEVICE TOP MARK MAX6841HUKD0 AEDR MAX6841HUKD3 AEDS MAX6841FUKD0 AEDP MAX6841FUKD3 AEDQ MAX6841DUKD0 AEDN MAX6841DUKD3 AEDO MAX6842HUKD0 AEDX MAX6842HUKD3 AEDY MAX6842FUKD0 AEDV MAX6842FUKD3 AEDW MAX6842DUKD0 AEDT MAX6842DUKD3 AEDU MAX6843UKD0 AEDZ MAX6843UKD3 AEAV MAX6844UKD0 AEEB MAX6844UKD3 AEEC MAX6845UKD0 AEAX MAX6845UKD3 AEAY _______________________________________________________________________________________ 7 MAX6841–MAX6845 Ultra-Low-Voltage µP Reset Circuits and Voltage Detectors Selector Guide PART MANUAL RESET ADJUSTABLE RESET INPUT PUSH-PULL RESET PUSH-PULL RESET OPEN-DRAIN RESET MAX6841 ✔ MAX6842 ✔ — ✔ ✔ — — — ✔ ✔ MAX6843 ✔ MAX6844 ✔ ✔ ✔ — — ✔ — ✔ — MAX6845 ✔ ✔ — — ✔ Typical Operating Circuit VIN 3.3V 0.9V DC/DC CONVERTER CORE SUPPLY I/O SUPPLY VCC µP MAX6842D/E RESET PUSHBUTTON SWITCH MR RESET RESET GND GND 8 _______________________________________________________________________________________ Ultra-Low-Voltage µP Reset Circuits and Voltage Detectors SOT-23 5L .EPS PACKAGE OUTLINE, SOT-23, 5L 21-0057 E 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc. MAX6841–MAX6845 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.)