MAX6706LKA-T

MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer General Description The MAX6701–MAX6708 microprocessor (µP) supervisory circuits reduce the complexity and components required to monitor power-supply functions in µP systems. These devices significantly improve system reliability and accuracy compared to separate ICs or discrete components. The MAX6701−MAX6708 family provides four functions: a reset output during power-up, power-down, and brownout conditions; an independent watchdog output that goes low if the watchdog input has not been toggled within 1.6s; a 0.62V threshold detector for power-fail warning; and an active-low manual reset input. The MAX6701–MAX6708 family offers several pinout options to accommodate a variety of multivoltage microprocessor supervision applications. The MAX6701(A)/MAX6702(A)/MAX6703(A) monitor three supply voltages (one fixed threshold and two adjustable) to drive a single reset output and include a manual reset input and a watchdog timer with an independent output. The MAX6704 monitors a single-supply voltage to drive complementary reset outputs and includes an independent adjustable power-fail-in/powerfail-out comparator, a manual reset input, and a resetbased watchdog timer. The MAX6705(A)/MAX6706(A)/ MAX6707(A) monitor a single-supply voltage to drive a single reset output and include an independent adjustable power-fail-in/power-fail-out comparator, a manual reset input, and a watchdog timer with an independent output. The MAX6708 is the same as the MAX6704 but without the watchdog timer function. See the Detailed Description for differences between non-A and A versions. Applications ●● Computers ●● Controllers ●● Intelligent Instruments ●● Critical µP Power Monitoring ●● White Goods ●● Networking ●● Telecommunications Typical Operating Circuit and Selector Guide appear at end of data sheet. Features ●● Small 8-Pin SOT23 Package ●● Precision Monitoring of +5.0V, +3.3V, +3.0V, +2.5V Supply Voltages ●● 140ms Reset Timeout Delay ●● Power-Fail Input with Independent Output; Monitor Inputs Down to 0.62V (MAX6704−MAX6708) ●● Dual Adjustable Reset Input for Triple-Voltage Monitoring (MAX6701(A)/MAX6702(A)/MAX6703(A)) ●● 1.6s Watchdog Timeout Period (MAX6701(A)−MAX6707(A)) ●● Independent Watchdog Output (MAX6701(A)/MAX6702(A)/MAX6703(A)/ MAX6705(A)/MAX6706(A)/MAX6707(A)) ●● Manual Reset Input ●● Four Reset Output Stage Options Active Low Push-Pull (MAX6701(A), MAX6705(A)) Active Low Open Drain (MAX6703(A), MAX6707(A)) Active High Push-Pull (MAX6702(A), MAX6706(A)) Dual Active Low/High Push-Pull (MAX6704, MAX6708) ●● Guaranteed Reset Valid to VCC = 1V ●● Immune to Short Falling VCC Transients ●● Low Cost, Few External Components Ordering Information PART TEMP RANGE PIN-PACKAGE MAX6701_KA-T -40°C to +125°C 8 SOT23 MAX6701A_KA-T -40°C to +125°C 8 SOT23 Insert the desired suffix letter (from the Threshold Suffix Guide table) into the blank to complete the part number. All devices must be ordered in increments of 2500 pieces. Sample stock is typically held on standard versions only. Contact factory for availability. Devices are available in both leaded and lead-free packaging. Specify lead-free by replacing “-T” with “+T” when ordering. Ordering Information continued at end of data sheet. Pin Configurations TOP VIEW 1 8 VCC 2 7 RESET (RESET) 6 WDI 5 RST_IN2 MR GND 3 MAX6701(A) MAX6702(A) MAX6703(A) RST_IN1 4 ( ) ARE FOR MAX6702(A) ONLY. WDO SOT23 Pin Configurations continued at end of data sheet. 19-1952; Rev 4; 5/14 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer Absolute Maximum Ratings VCC........................................................................-0.3V to +6.0V Open-Drain RESET, WDO, PFO .........................-0.3V to +6.0V Push-Pull RESET, RESET, WDO, PFO.... -0.3V to (VCC + 0.3V) MR, WDI, PFI, RST_IN1, RST_IN2.......... -0.3V to (VCC + 0.3V) Input Current (VCC).............................................................20mA Output Current (O, WDO)...................................................20mA Continuous Power Dissipation (TA = +70°C) 8-Pin SOT23 (derate 8.9mW/°C above +70°C)...........714mW Operating Temperature Range.......................... -40°C to +125°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 = +4.25V to +5.5V for L/M versions, VCC = +2.55V to +3.6V for the T/S/R versions, VCC = +2.1V to +2.75V for the Z/Y versions. TA = -40°C to +125°C, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Operating Voltage Range VCC Supply Current MR Unconnected ICC CONDITIONS 1.0 5.5 1.2 5.5 VCC < 5.5V, no load 12 25 VCC < 3.6V, no load 9 20 VCC < 3.6V, no load (MAX6708 only) 6 20 4.63 4.75 MAX670_T/MAX670_AT MAX670_S/MAX670_AS MAX670_R/MAX670_AR MAX670_Z/MAX670_AZ MAX670_Y/MAX670_AY Reset Threshold Temperature Coefficient Reset Timeout Period TA = -40°C to +85°C 4.50 TA = -40°C to +125°C 4.47 TA = -40°C to +85°C 4.25 TA = -40°C to +125°C 4.22 TA = -40°C to +85°C 3.00 TA = -40°C to +125°C 2.97 TA = -40°C to +85°C 2.85 TA = -40°C to +125°C 2.83 TA = -40°C to +85°C 2.55 TA = -40°C to +125°C 2.53 TA = -40°C to +85°C 2.25 TA = -40°C to +125°C 2.24 TA = -40°C to +85°C 2.12 TA = -40°C to +125°C 2.11 ∆VTH VCC to Reset Output Delay VCC falling at 10mV/µs tRP TA = -40°C to +85°C 140 TA = -40°C to +125°C 120 VCC Falling to WDO Delay MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/ MAX6706(A)/MAX6707(A) PFI, RST_IN1, RST_IN2 Threshold VCC = 1.8V to 5.5V PFI Hysteresis www.maximintegrated.com MAX TA = -40°C to +125°C MAX670_M/MAX670_AM VTH TYP TA = 0°C to +125°C MAX670_L/MAX670_AL VCC Reset Threshold (VCC falling) MIN 602 TA = -40°C to +125°C 593 V µA 4.78 4.38 4.50 4.53 3.08 3.15 3.17 2.93 3.00 3.02 2.63 V 2.70 2.72 2.32 2.38 2.40 2.19 2.25 2.27 60 ppm/°C 12 µs 200 280 300 5 TA = -40°C to +85°C UNITS 618 µs 634 642 6 ms mV mV Maxim Integrated │  2 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer Electrical Characteristics (continued) (VCC = +4.25V to +5.5V for L/M versions, VCC = +2.55V to +3.6V for the T/S/R versions, VCC = +2.1V to +2.75V for the Z/Y versions. TA = -40°C to +125°C, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL PFI, RST_IN1, RST_IN2 Leakage Current PFI to PFO Delay MR Input Voltage CONDITIONS (Note 2) MIN TYP TA = -40°C to +85°C -50 +50 TA = -40°C to +125°C -200 +200 tPF 1 VIL VIH 0.7 x VCC 1 MR Glitch Rejection tMD MAX6701(A)/MAX6702(A)/MAX6703(A)/ MAX6705(A)/MAX6706(A)/MAX6707(A) VCC Rising to WDO Delay MR Pullup Resistance Watchdog Timeout Period tWD WDI Pulse Width tWDI WDI Input Voltage WDI Input Current RESET, WDO Output Low (Push-Pull or Open Drain) PFO Output Low (Push-Pull or Open Drain) IWDI VOL VOL RESET, WDO, PFO Output High (Push-Pull Only) VOH RESET, WDO, PFO Output Open-Drain Leakage Current ILKG RESET Output High (Push-Pull Only) RESET Output Low (Push-Pull Only) VOH VOL ns 200 ns 100 ns TA = -40°C to +85°C 1.12 1.6 TA = -40°C to +125°C 0.96 75 2.4 2.52 50 0.7 x VCC VWDI = 0V or VCC -1 +1 VCC ≥ 1.0V, ISINK = 50µA, output asserted (TA = 0°C to +125°C) 0.3 VCC ≥ 1.2V, ISINK = 100µA, output asserted 0.3 VCC ≥ 4.25V, ISINK = 3.2mA, output asserted 0.4 VCC ≥ 2.55V, ISINK = 1.2mA, output asserted 0.3 VCC ≥ 2.55V, ISINK = 1.2mA, output asserted 0.3 VCC ≥ 1.80V, ISINK = 200µA, output asserted 0.3 VCC ≥ 4.25V, ISINK = 3.2mA, output asserted VCC ≥ 2.7V, ISOURCE = 500µA, output not asserted VCC ≥ 4.75V, ISOURCE = 800µA, output not asserted 1.0 0.8 x VCC VCC ≥ 1.2V, ISOURCE = 50µA, reset asserted 0.8 x VCC VCC ≥ 4.25V, ISOURCE = 800µA, reset asserted 0.8 x VCC VCC ≥ 4.75V, ISINK = 3.2mA, reset not asserted V µA V V V 0.8 x VCC VCC ≥ 1.0V, ISOURCE = 1µA, reset asserted (TA = 0°C to +125°C) VCC ≥ 2.7V, ISINK = 1.2mA, reset not asserted s 0.4 0.8 x VCC VCC > VTH, output not asserted VCC ≥ 2.55V, ISOURCE = 500µA, reset asserted kΩ ns 0.3 x VCC VIH V µs 50 (Note 2) nA 100 25 VIL UNITS µs 0.3 x VCC MR Minimum Input Pulse MR to Reset Delay MAX µA V 0.8 x VCC 0.3 0.4 V Note 1: Over-temperature limits are guaranteed by design and not production tested. Devices are tested at TA = +25°C. Note 2: Guaranteed by design. Not production tested. www.maximintegrated.com Maxim Integrated │  3 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) RESET TIMEOUT PERIOD vs. TEMPERATURE MAX6705(A) VCC = 5V 8 -15 10 35 60 190 85 -15 10 35 60 -15 10 35 60 85 WATCHDOG TIMEOUT PERIOD vs. TEMPERATURE NORMALIZED RESET THRESHOLD vs. TEMPERATURE MAXIMUM VCC TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE MAX6701 toc04 1.55 1.05 1.04 1.03 1.02 1.01 1.00 0.99 0.98 0.97 0.96 -15 10 35 60 85 0.95 -40 -15 10 35 OUTPUT-VOLTAGE LOW vs. SINK CURRENT 40 RESET OCCURS ABOVE LINE 30 20 10 0 0 VCC 4.25V 300 VCC - VOH (mV) 50 40 80 120 160 RESET THRESHOLD OVERDRIVE (mV) VCC - VOH vs. SOURCE CURRENT 350 MAX6701 toc07 VCC 4.25V 75 VOL (mV) 85 MAX670_Y 50 TEMPERATURE (°C) TEMPERATURE (°C) 100 60 60 MAX6701 toc06 TEMPERATURE (°C) 1.60 -40 -40 TEMPERATURE (°C) 1.65 1.50 5 0 85 MAX6701 toc03 MAX6701 toc02 -40 10 TEMPERATURE (°C) 1.70 WATCHDOG TIMEOUT PERIOD (s) 195 15 MAX6701 toc08 -40 200 20 MAXIMUM TRANSIENT DURATION (µs) 0 MAX6708 VCC = 3.3V 4 205 MAX6701 toc05 12 RESET TIMEOUT PERIOD (ms) MAX6701 toc01 16 210 NORMALIZED RESET THRESOLD SUPPLY CURRENT (µA) 20 VCC TO RESET OUTPUT DELAY vs. TEMPERATURE VCC TO RESET OUTPUT DELAY (s) SUPPLY CURRENT vs. TEMPERATURE 250 200 150 100 25 50 0 0 400 800 1200 1600 2000 2400 2800 3200 SINK CURRENT (µA) www.maximintegrated.com 0 0 400 800 1200 1600 2000 2400 2800 3200 SOURCE CURRENT (µA) Maxim Integrated │  4 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer Pin Description PIN MAX6701(A) MAX6702(A) MAX6703(A) MAX6704 MAX6705(A) MAX6706(A) MAX6707(A) MAX6708 NAME FUNCTION 1 1 1 1 MR Active-Low, Manual Reset Input, Internal 50kΩ Pullup to VCC. Pull low to force a reset. Reset remains active as long as MR is low and the reset timeout period after MR goes high. Leave unconnected or connect to VCC if unused. WDO deasserts when MR is low (MAX6701(A)/ MAX6702(A)/MAX6703(A)/ MAX6705(A)/ MAX6706(A)/ MAX6707(A) only) 2 2 2 2 VCC Supply Voltage for MAX6701–MAX6708 and Input for Primary Reset Threshold Monitor. Push-pull outputs are powered by VCC. 3 3 3 3 GND Ground — 4 4 4 PFI Power-Fail Voltage Monitor Input. High-impedance input for internal power-fail comparator. Connect this pin to an external resistive-divider network to set the reset threshold voltage; 0.62V (typ) threshold. Connect to GND or VCC when not used. — 5 5 5 PFO Power-Fail Monitor Output. Open drain or push-pull active low. PFO goes low when PFI is less than 0.62V. 6 6 6 — WDI Watchdog Input. If WDI remains high or low for longer than the watchdog timeout period, the internal watchdog timer runs out and WDO is asserted. WDO is asserted low after each watchdog overflow and remains low until the watchdog timer is cleared (the reset output is not affected). The internal watchdog timer clears whenever a VCC/RST_IN1/RST_IN2 reset is asserted, the manual reset is asserted, or WDI sees a rising or falling edge. The watchdog timer remains cleared until the reset output is deasserted. On the MAX6704, RESET pulse asserts for the reset timeout period after each watchdog timeout overflow. The watchdog timer cannot be disabled. — — — 6 N.C. No Connection. Not internally connected. 7 7 www.maximintegrated.com 7 7 RESET Active-Low Reset Output (Open Drain or Push-Pull). RESET changes from high to low when the VCC input drops below the selected reset threshold (or RST_IN1/ RST_IN2 for the MAX6701(A)/MAX6702(A)/MAX6703(A), MR is pulled low, or the watchdog triggers a reset (MAX6704 only). RESET remains low for the reset timeout period after the reset conditions are terminated. Maxim Integrated │  5 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer Pin Description (continued) PIN MAX6701(A) MAX6702(A) MAX6703(A) 8 7* 4 5 MAX6704 — 8 — — MAX6705(A) MAX6706(A) MAX6707(A) 8 7* — — MAX6708 — 8 — — NAME FUNCTION WDO Active-Low Watchdog Output (Open Drain or PushPull). WDO is asserted whenever the watchdog times out and VCC or the reset inputs are below their respective thresholds. WDO deasserts after a valid WDI transition without a reset timeout period. In the A versions, WDO deasserts without a timeout delay when VCC, RST_IN1, and RST_IN2 rises above its threshold. Pull MR low to assert WDO (MAX6701/MAX6702/ MAX6703/MAX6705/MAX6706/MAX6707 only). Pull MR low to deassert WDO (MAX6701(A)/MAX6702(A) / MAX6703(A)/ MAX6705(A)/MAX6706(A)MAX6707(A) only) RESET Active-High Reset Output (Push-Pull). RESET changes from low to high when the VCC input drops below the selected reset threshold (or RST_IN1/RST_IN2 for MAX6701(A)/MAX6702(A)/ MAX6703(A), MR is pulled low, or the watchdog triggers a reset (MAX6704 only). RESET remains high for the reset timeout period after the reset conditions are terminated. RST_IN1 Input for User-Adjustable V CC2 Monitor. Highimpedance input for second internal reset comparator. Connect this pin to an external resistive-divider network to set the reset threshold voltage; 0.62V (typ) threshold. Connect to V CC when not used. Reset is asserted when either V CC, RST_IN1, or RST_IN2 are below threshold. RST_IN2 Input for User-Adjustable V CC3 Monitor. Highimpedance input for third internal reset comparator. Connect this pin to an external resistive-divider network to set the reset threshold voltage; 0.62V (typ) threshold. Connect to V CC when not used. Reset is asserted when either V CC, RST_IN1, or RST_IN2 are below threshold. *RESET active-high for the MAX6702(A)/MAX6706(A). Detailed Description Figures 1, 2, and 3 are functional diagrams for the MAX6705(A)/MAX6706(A)/MAX6707(A), MAX6704/ MAX6708, and MAX6701(A)/MAX6702(A)/MAX6703(A), respectively. Reset Output A microprocessor’s (µP’s) reset input starts the µP in a known state. The MAX6701–MAX6708 assert reset during power-up and prevent code execution errors during power-down or brownout conditions. On power-up, once VCC reaches 1V, RESET is a guaranteed logic-low of 0.4V or less. As VCC rises, www.maximintegrated.com RESET stays low. After VCC, RST_IN1, or RST_IN2 rise above the reset threshold, an internal timer holds RESET low for about 200ms. RESET pulses low whenever VCC dips below the reset threshold, including brownout conditions. If a brownout occurs in the middle of a previously initiated reset pulse, the pulse continues for at least another 140ms. On power-down, once VCC falls below the reset threshold, RESET stays low and is guaranteed to be 0.4V or less, until VCC drops below 1V. The MAX6702(A)/MAX6704/MAX6706(A)/MAX6708 active-high RESET output is the complement of the RESET output, and is guaranteed to be valid with VCC down to 1V. Maxim Integrated │  6 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer VCC 6 WDI 8 WATCHDOG TIMER VCC WDO MR 50kΩ VCC MR 1 VCC 2 7 RESET GENERATOR 4 RESET GENERATOR RESET (RESET) 5 WDO RST_IN1 RST_IN2 50kΩ MR VCC GND MAX6704 MAX6708 1 2 ( ) ARE FOR MAX6702(A) ONLY. Figure 3. MAX6701(A)/MAX6702(A)/MAX6703(A) Functional Diagram VCC VTH VTH tRP 8 RESET GENERATOR 7 WATCHDOG TIMER 6 RESET RESET WDI (MAX6704 ONLY) tRP VCC RESET 0V MR VCC 0V VREF PFI 0.62V 0.62V Figure 1. MAX6705(A)/MAX6706(A)/MAX6707(A) Functional Diagram VCC WDI PFO 0.62V ( ) ARE FOR MAX6706(A) ONLY. 3 RESET (RESET) WATCHDOG TIMER VREF MAX6705(A) MAX6706(A) MAX6707(A) VREF PFI MAX6701(A) MAX6702(A) MAX6703(A) 50kΩ tMD VCC WDO 4 5 0V PFO VCC 0.62V MR EXTERNALLY DRIVEN LOW WDI 0V 3 GND Figure 2. MAX6704/MAX6708 Functional Diagram www.maximintegrated.com NOTE: THE MAX6706 RESET OUTPUT IS THE INVERSE OF THE RESET SHOWN. Figure 4. MAX6705/MAX6706/MAX6707 RESET, MR, WDO, and WDI Timing Maxim Integrated │  7 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer Standard- vs. A-Version Comparison threshold, WDO goes low whether or not the watchdog timer has timed out. Normally this would trigger an NMI, but RESET goes low simultaneously, and thus overrides the NMI. ●● The watchdog timer times out (1.6s, typ). The MAX6704 watchdog circuit does not have an independent watchdog output (WDO). If the µP does not toggle the watchdog input within 1.6s, the MAX6704 asserts a reset output pulse for the reset timeout period. The MAX6701/MAX6702/MAX6703/MAX6705/MAX6706/ MAX6707s’ WDO latches low when one of the following events occurs: ●● VCC, RST_IN1, or RST_IN2 is below its reset threshold. ●● MR is pulled low. ●● WDO only deasserts with a valid WDI transition. The MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/ MAX6706(A)/ MAX6707(A)s’ WDO asserts when either VCC, RST_IN1, or RST_IN2 is below its reset threshold. WDO deasserts without a timeout delay when the undervoltage situation has expired. WDO is latched low when the watchdog timer elapses without seeing a WDI transition. WDO deasserts with a valid WDI transition OR by pulling MR low. See Figures 4 and 5 for standard-version timing. See Figures 6 and 7 for A-version timing. Watchdog Timer The MAX6701–MAX6707 watchdog circuit monitors the µP’s activity. If the µP does not toggle the WDI within 1.6s, WDO goes low. When RESET is asserted, the watchdog timer stays cleared and does not count. As soon as reset is released, the timer starts counting. WDO deasserts after a valid transition is detected at WDI. Pulses as short as 50ns can be detected. Typically, WDO is connected to the NMI input of a µP. When VCC, RST_IN1, or RST_IN2 drop below the reset tWDI WDI WDO tWD Manual Reset The manual reset input (MR) allows reset to be triggered by a pushbutton switch. The switch is effectively debounced by the reset pulse width. MR is CMOS logic compatible, so it can be driven by an external logic line. MR can be used to force a watchdog timeout to generate a reset pulse in the MAX6701(A)/MAX6702(A)/ MAX6703(A)/MAX6705(A)/MAX6706(A)/MAX6707(A) by connecting WDO to MR. Power-Fail Comparator The uncommitted power-fail comparator can be used for various purposes because its noninverting input and output are externally available. The inverting input is internally connected to a 0.62V reference. To build an early warning circuit for power failure, connect the PFI pin to a voltage-divider (see the Typical Operating Circuit). Choose the voltage-divider ratio so that the voltage at PFI falls below 0.62V just before the regulator drops out. Use PFO to interrupt the µP so it can prepare for an orderly power-down. The low-input current at this pin allows for large resistor values in the divider. tWD VCC +5V VTH VTH tRP 0V tRP +5V +5V RESET 0V 0V +5V RESET 0V +5V (RESET) 0V MR RESET EXTERNALLY TRIGGERED BY MR t RP MR 0V +5V +5V 0V ( ) ARE FOR MAX6702/MAX6706 ONLY. Figure 5. MAX6701/MAX6702/MAX6703/MAX6705/MAX6706/ MAX6707 Watchdog www.maximintegrated.com +5V tMD tMR WDO 0V Figure 6. MAX6701(A)/MAX6702(A)/MAX6703(A)/ MAX6705(A)/ MAX6706(A)/MAX6707(A) RESET, MR, and WDO Timing with WDI Three-Stated Maxim Integrated │  8 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A tWDI WDI WDO tWD Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer tWD +5V tWD 0V MAX6701(A)– MAX6708 VEXTERNAL +5V R1 0V +5V RESET 0V PFI, RST_IN1, OR RST_IN2 R2 0.62V t RP +5V (RESET) 0V MR +5V 0V ( ) VEXT-TH = 1 + R1 x 0.62V R2 R1 = R2 x - 1) (VEXT-TH 0.62 WHERE VEXT-TH IS THE EXTERNAL VOLTAGE TRIP LEVEL. ( ) ARE FOR MAX6702(A)/MAX6706(A) ONLY. Figure 7. MAX6701(A)/MAX6702(A)/MAX6703(A)/ MAX6705(A)/ MAX6706(A)/MAX6707(A) Watchdog Timing Figure 8. Calculating Adjustable Voltage Thresholds Reset Input Monitoring Other System Voltages The MAX6701(A)/MAX6702(A)/MAX6703(A) include two adjustable reset inputs for monitoring up to a total of three system voltages (including VCC). The thresholds for the monitored RST_IN supplies are externally set with resistor-divider networks (Figure 8). The reset output is asserted if any of the monitored supplies (VCC, RST_IN1, or RST_IN2) go below its specified threshold and remains asserted for the reset timeout period after all supplies are above their thresholds. Applications Information Ensuring a Valid RESET Output Down to VCC = 0 When VCC falls below 1V, the MAX6701–MAX6708 RESET output no longer sinks current; it becomes an open circuit. High-impedance CMOS logic inputs can drift to undetermined voltages if left undriven. If a pulldown resistor is added to the RESET pin, as shown in Figure 9, any stray charge or leakage currents are drained to ground, holding RESET low. A resistor value (R1) is not critical; 100kΩ is large enough not to load RESET and small enough to pull RESET to ground. This application works for push-pull output only (not for open-drain resets). www.maximintegrated.com Other systems can be monitored by connecting a voltage-divider to PFI and adjusting the ratio appropriately. In noisy systems, a capacitor between PFI and GND reduces the power-fail circuit’s sensitivity to highfrequency noise on the line being monitored. Reset can be asserted on other voltages in addition to the VCC supply line. Connect PFO to MR to initiate a reset output pulse when PFI drops below 0.62V. Figure 10 shows the MAX6704–MAX6708 configured to assert a reset output when the secondary supply falls below the reset threshold. Generating a Reset from Watchdog Overflow Connect WDO to MR to force a watchdog timeout to generate a reset pulse for only the reset timeout period on the MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/ MAX6706(A)/MAX6707(A). When the MAX6704 watchdog times out, reset outputs are automatically asserted (no external connections required). For the MAX6701/ MAX6702/MAX6703/MAX6705/MAX6706/MAX6707 non-A versions, do not connect WDO to MR; this creates a locked condition. Maxim Integrated │  9 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer 0.9V 3.3V MAX6701(A) MAX6704 MAX6705(A) MAX6708 VCC RESET I/O SUPPLY RESET (RESET) PFI RESET µP MAX6704– MR MAX6708 PFO R1 (100kΩ) CORE SUPPLY () ARE FOR MAX6704/MAX6706(A)/MAX6708 ONLY. Figure 9. RESET Valid to Ground Circuit Figure 10. Monitoring Other System Voltages Selector Guide RESET PP LOW RESET PP HIGH RESET OD-LOW WDI WDO PFI, PFO RST_IN1, RST_IN2 MAX6701 ✔ — — ✔ ✔ PP — ✔ MAX6701A* ✔ — — ✔ ✔ PP — ✔ MAX6702 — ✔ — ✔ ✔ PP — ✔ MAX6702A* — ✔ — ✔ ✔ PP — ✔ MAX6703 — — ✔ ✔ ✔ OD — ✔ MAX6703A* — — ✔ ✔ ✔ OD — ✔ MAX6704 ✔ ✔ — ✔ — ✔ PP — MAX6705 ✔ — — ✔ ✔ PP ✔ PP — MAX6705A* ✔ — — ✔ ✔ PP ✔ PP — MAX6706 — ✔ — ✔ ✔ PP ✔ PP — MAX6706A* — ✔ — ✔ ✔ PP ✔ PP — MAX6707 — — ✔ ✔ ✔ OD ✔ OD — MAX6707A* — — ✔ ✔ ✔ OD ✔ OD — ✔ — — — ✔ PP — PART MAX6708 ✔ PP = push-pull, OD = open drain. *WDO deasserts when MR is pulled low. See the Standard- vs. A-Version Comparison section for the differences on WDO. Threshold Suffix Guide SUFFIX RESET THRESHOLD (V) L 4.63 M 4.38 T 3.08 S 2.93 R 2.63 Z 2.32 Y 2.19 Bold indicates standard version. www.maximintegrated.com Maxim Integrated │  10 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer Pin Configurations (continued) TOP VIEW 1 8 RESET MR 7 RESET VCC 2 3 6 WDI GND PFI 4 5 PFO MR VCC 2 GND MAX6704 1 3 MAX6705(A) MAX6706(A) MAX6707(A) PFI 4 SOT23 8 WDO 8 RESET 7 RESET (RESET) VCC 2 7 RESET 6 WDI 3 6 N.C. 5 PFO PFI 4 5 PFO MR GND 1 MAX6708 SOT23 SOT23 ( ) ARE FOR MAX6706(A) ONLY. Typical Operating Circuit UNREGULATED DC Ordering Information (continued) PART TEMP RANGE PIN-PACKAGE DC-DC MAX6702_ KA-T -40°C to +125°C 8 SOT23 REGULATOR MAX6702A_ KA-T -40°C to +125°C 8 SOT23 MAX6703_ KA-T -40°C to +125°C 8 SOT23 MAX6703A_ KA-T -40°C to +125°C 8 SOT23 MAX6704_KA-T -40°C to +125°C 8 SOT23 MAX6705_KA-T -40°C to +125°C 8 SOT23 MAX6705A_KA-T -40°C to +125°C 8 SOT23 MAX6706_KA-T -40°C to +125°C 8 SOT23 MAX6706A_KA-T -40°C to +125°C 8 SOT23 MAX6707_KA-T -40°C to +125°C 8 SOT23 MAX6707A_KA-T -40°C to +125°C 8 SOT23 MAX6708_KA-T -40°C to +125°C 8 SOT23 µP VCC PUSHBUTTON SWITCH RESET PFI MAX6705(A) WDI MAX6706(A) WDO MR MAX6707(A) PFO VCC RESET I/O NMI INTERRUPT Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 8 SOT23 K8+2 21-0078 90-0176 Insert the desired suffix letter (from the Threshold Suffix Guide table) into the blank to complete the part number. All devices must be ordered in increments of 2500 pieces. Sample stock is typically held on standard versions only. Contact factory for availability. Devices are available in both leaded and lead(Pb)-free packaging. Specify lead-free by replacing “-T” with “+T” when ordering. T = Tape and reel. Chip Information TRANSISTOR COUNT: 716 PROCESS: BiCMOS www.maximintegrated.com Maxim Integrated │  11 MAX6701-08/ MAX6701A-03A/ MAX6705A-07A Low-Voltage, SOT23 µP Supervisors with Power-Fail In/Out, Manual Reset, and Watchdog Timer Revision History REVISION NUMBER REVISION DATE 4 5/14 PAGES CHANGED DESCRIPTION No /V OPNs; removed Automotive reference from Applications section 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2014 Maxim Integrated Products, Inc. │  12