DS1706LESA+T&R

19-5212; Rev 4/10 DS1705/DS1706 3.3V and 5.0V MicroMonitor www.maxim-ic.com FEATURES           PIN ASSIGNMENT Halts and restarts an out-of-control microprocessor Holds microprocessor in check during power transients Automatically restarts microprocessor after power failure Monitors pushbutton for external override Accurate 5%, 10% or 20% resets for 3.3V systems and 5% or 10% resets for 5.0V systems Eliminates the need for discrete components 3.3V 20% tolerance for use with 3.0V systems Pin-compatible with the MAXIM MAX705/MAX706 in 8-pin DIP, 8-pin SOIC, and -SOP 8-pin DIP, 8-pin SOIC and 8-pin -SOP packages Industrial temperature range -40C to +85C PBRST 1 8 WDS VCC 2 7 RST GND 3 6 ST IN 4 5 NMI 8-Pin DIP (300 -mil) PBRST 1 8 WDS VCC 2 7 RST(*RST) GND 3 6 ST IN 4 5 NMI 8-Pin SOIC (150-mil) RST(*RST) WDS PBRST VCC 1 2 3 4 8 7 6 5 ST NMI IN GND 8-Pin -SOP (118-mil) See Mech. Drawings Section on website DS1705 and DS1706_R/S/T (*DS1706L and DS1706P) PIN DESCRIPTION PBRST VCC GND IN NMI ST RST *RST WDS - Pushbutton Reset Input - Power Supply - Ground - Input - Non-maskable Interrupt - Strobe Input - Active Low Reset Output - Active High Reset Output (DS1706P and DS1706L only) - Watchdog Status Output DESCRIPTION The DS1705/DS1706 3.3- or 5.0-Volt MicroMonitor monitors three vital conditions for a microprocessor: power supply, software execution, and external override. A precision temperature compensated reference and comparator circuit monitor the status of VCC at the device and at an upstream point for maximum protection. When the sense input detects an out-of-tolerance condition, a non-maskable interrupt is generated. As the voltage at the device degrades, an internal power fail signal is generated which forces 1 of 12 DS1705/DS1706 the reset to an active state. When VCC returns to an in-tolerance condition, the reset signal is kept in the active state for a minimum of 130 ms to allow the power supply and processor to stabilize. The second function the DS1705/DS1706 performs is pushbutton reset control. The DS1705/DS1706 debounces the pushbutton input and guarantees an active reset pulse width of 130 ms minimum. The third function is a watchdog timer. The DS1705/DS1706 has an internal timer that forces the WDS output signal to the active state if the strobe input is not driven low prior to time-out. OPERATION Power Monitor The DS1705/DS1706 detects out-of-tolerance power supply conditions and warns a processor-based system of impending power failure. When VCC falls below the minimum VCC tolerance, a comparator outputs the RST (or RST) signal. RST (or RST) is an excellent control signal for a microprocessor, as processing is stopped at the last possible moment of valid VCC. On power-up, RST (or RST) are kept active for a minimum of 130 ms to allow the power supply and processor to stabilize. Pushbutton Reset The DS1705/DS1706 provides an input pin for direct connection to a pushbutton reset (see Figure 2). The pushbutton reset input requires an active low signal. Internally, this input is debounced and timed such that a RST (or RST) signal of at least 130 ms minimum will be generated. The 130 ms delay commences as the pushbutton reset input is released from the low level. The pushbutton can be initiated by connecting the WDS or NMI outputs to the PBRST input as shown in Figure 3. Non-Maskable Interrupt The DS1705/DS1706 generates a non-maskable interrupt ( NMI ) for early warning of a power failure. A precision comparator monitors the voltage level at the IN pin relative to an on-chip reference generated by an internal band gap. The IN pin is a high impedance input allowing for a user-defined sense point. An external resistor voltage divider network (Figure 5) is used to interface with high voltage signals. This sense point may be derived from a regulated supply or from a higher DC voltage level closer to the main system power input. Since the IN trip point VTP is 1.25 volts, the proper values for R1 and R2 can be determined by the equation as shown in Figure 5. Proper operation of the DS1705/DS1706 requires that the voltage at the IN pin be limited to VCC. Therefore, the maximum allowable voltage at the supply being monitored (VMAX) can also be derived as shown in Figure 5. A simple approach to solving the equation is to select a value for R2 high enough to keep power consumption low, and solve for R1. The flexibility of the IN input pin allows for detection of power loss at the earliest point in a power supply system, maximizing the amount of time for system shutdown between NMI and RST (or RST). When the supply being monitored decays to the voltage sense point, the DS1705/DS1706 pulses the NMI output to the active state for a minimum 200 s. The NMI power-fail detection circuitry also has built-in hysteresis of 100 V. The supply must be below the voltage sense point for approximately 5 s before a low NMI will be generated. In this way, power supply noise is removed from the monitoring function, preventing false interrupts. During a power-up, any detected IN pin levels below VTP by the comparator are disabled from generating an interrupt until VCC rises to VCCTP. As a result, any potential NMI pulse will not be initiated until VCC reaches VCCTP. Connecting NMI to PBRST would allow non-maskable interrupt to generate an automatic reset when an out-of-tolerance condition occurred in a monitored supply. An example is shown in Figure 3. 2 of 12 DS1705/DS1706 Watchdog Timer The watchdog timer function forces WDS signals active when the ST input is not clocked within the 1 second time-out period. Time-out of the watchdog starts when RST (or RST) becomes inactive. If a highto-low transition occurs on the ST input pin prior to time-out, the watchdog timer is reset and begins to time out again. If the watchdog timer is allowed to time out, the WDS signal is driven active (low) for a minimum of 130 ms. The ST input can be derived from many microprocessor outputs. The typical signals used are the microprocessors address signals, data signals, or control signals. When the microprocessor functions normally, these signals would, as a matter of routine, cause the watchdog to be reset prior to time-out. To guarantee that the watchdog timer does not time out, a high-to-low transition must occur at or less than the minimum watchdog time-out of 1 second. A typical circuit example is shown in Figure 6. MICROMONITOR BLOCK DIAGRAM Figure 1 40k 180k PUSH-BUTTON RESET Figure 2 3 of 12 DS1705/DS1706 PUSH-BUTTON RESET CONTROLLED BY NMI AND WDS Figure 3 TIMING DIAGRAM: PUSHBUTTON RESET Figure 4 NON-MASKABLE INTERRUPT CIRCUIT EXAMPLE Figure 5 VSENSE = R1 R2 X 1.25 R2 Example: Therefore: VMAX = VSENSE X VCC VTP VSENSE = 4.50V at the trip point VCC = 3.3V 10 kΩ = R2 4.50 X 3.3 = 11.88V maximum 1.25 4.5 = R1  10k X 1.25 10k 4 of 12 R1 = 26 kΩ DS1705/DS1706 WATCHDOG TIMER Figure 6 TIMING DIAGRAM: STROBE INPUT Figure 7 TIMING DIAGRAM: NON-MASKABLE INTERRUPT Figure 8 5 of 12 DS1705/DS1706 TIMING DIAGRAM: POWER-DOWN Figure 9 6 of 12 DS1705/DS1706 TIMING DIAGRAM: POWER-UP Figure 10 7 of 12 DS1705/DS1706 ABSOLUTE MAXIMUM RATINGS Voltage Range on VCC Pin Relative to Ground Voltage Range on I/O Relative to Ground* Operating Temperature Range Storage Temperature Range Lead Temperature (soldering, 10s) Soldering Temperature (reflow) Lead(Pb)-free Containing lead(Pb) -0.5V to +7.0V -0.5V to (VCC + 0.5V) -40C to +85C -55C to +125C +260C +260C +240C This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. *The voltage input on IN, ST, and PBRST can be exceeded if the input current is less than 10 mA. (TA = -40C to +85C) RECOMMENDED DC OPERATING CONDITIONS PARAMETER SYMBOL MIN Supply Voltage VCC TYP MAX UNITS NOTES 1.2 5.5 V 1 ST and PBRST Input High Level VIH 2.0 VCC-0.5 VCC+0.3 V 1, 3 1, 4 ST and PBRST Input Low Level VIL -0.03 +0.5 V 1 DC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL (VCC = 1.2V to 5.5V, TA = -40C to +85C.) MIN TYP MAX UNITS NOTES VCC Trip Point DS1705/DS1706L VCCTP 4.50 4.65 4.75 V 1 VCC Trip Point DS1706 VCCTP 4.25 4.40 4.50 V 1 VCC Trip Point DS1706T VCCTP 3.00 3.08 3.15 V 1 VCC Trip Point DS1706S VCCTP 2.85 2.93 3.00 V 1 VCC Trip Point DS1706P or R VCCTP 2.55 2.63 2.70 V 1 Input Leakage IIL -1.0 +1.0 A 2 Output Current @ 2.4V IOH A 3 Output Current @ 0.4V IOL 10 mA 3 Output Voltage @ -500 A VOH VCC-0.3 V 3 Operating Current @ VCC < 5.5V ICC 60 A 5 Operating Current @ VCC < 3.6V ICC 50 A 5 IN Input Trip Point VTP 1.30 V 1 350 1.20 VCC-0.1 1.25 CAPACITANCE PARAMETER Input Capacitance Output Capacitance SYMBOL MIN TYP MAX (TA = +25C) UNITS NOTES CIN 5 pF COUT 7 pF 8 of 12 DS1705/DS1706 AC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL (VCC = 1.2V to 5.5V, TA = -40C to +85C.) MIN TYP MAX UNITS NOTES tPB 150 Reset Active Time tRST 130 Pulse Width tST 10 PBRST ST = VIL VCC Detect to RST and RST VCC Slew Rate VCC Detect to RST and RST VCC Slew Rate PBRST Stable Low to RST and RST tRPD ns 205 5 tF 20 tRPU 130 tR 0 tTD VIN Detect to NMI tIPD 1.0 8 ms ns 6 s 9 s 205 285 ms 7 ns tPDLY Watchdog Timeout 285 250 ns 1.6 2.2 s 8 5 8 s 9 NOTES: 1. All voltages are referenced to ground. 2. PBRST is internally pulled up to VCC with an internal impedance of 40 ktypical and the ST input is internally pulled up to VCC with an internal impedance of 180 ktypical. 3. VCC ≥ 2.4V. 4. VCC < 2.4V. 5. Measured with outputs open and all inputs at VCC or ground. 6. Must not exceed tTD minimum. 7. tR = 5 s. 8. Minimum watchdog time-out tested at 2.7V for the 3.3V devices and 4.5V for the 5.0V devices. 9. Noise immunity  pulses < 2 s will not cause a reset. 9 of 12 DS1705/DS1706 PART MARKING CODES DS170AB yywwrv 8-pin DIP (300 MIL) 8-pin SOIC (150 MIL) 8-pin µSOP (118 MIL) CODE AB yww or yyww rv ###xx cccccc cccccc ###xx DS170AB yywwrv ###xx cccccc 170AB ywwrv ###xx BRAND CODES DESCRIPTION VALUES Device type and tolerance 5_, 6_, 6L, 6P, 6R, 6S, 6T (where’_’ is a blank) Date Code. Identifies the year and work y, the last digit of the year. week the device was assembled. yy, the last two digits of the year. ww, the work week (values 01 through 52). Die Revision A letter followed by a number (eg. B1) Lot Code Three numbers followed by 2 letters Country of Assembly Abbreviation of country name. 10 of 12 DS1705/DS1706 ORDERING INFORMATION PART DS1705EPA DS1705ESA DS1705EUA DS1706EPA DS1706ESA DS1706EUA DS1706LEPA DS1706LESA DS1706LEUA DS1706PEPA DS1706PESA DS1706PEUA DS1706REPA DS1706RESA DS1706REUA DS1706SEPA DS1706SESA DS1706SEUA DS1706TEPA DS1706TESA DS1706TEUA TEMP RANGE -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C PIN-PACKAGE 8-pin PDIP (300 mils) 8-pin SO (150 mils) 8-pin µSOP (118 mils) 8-pin PDIP (300 mils) 8-pin SO (150 mils) 8-pin µSOP (118 mils) 8-pin PDIP (300 mils) 8-pin SO (150 mils) 8-pin µSOP (118 mils) 8-pin PDIP (300 mils) 8-pin SO (150 mils) 8-pin µSOP (118 mils) 8-pin PDIP (300 mils) 8-pin SO (150 mils) 8-pin µSOP (118 mils) 8-pin PDIP (300 mils) 8-pin SO (150 mils) 8-pin µSOP (118 mils) 8-pin PDIP (300 mils) 8-pin SO (150 mils) 8-pin µSOP (118 mils) VERSION 5V-5% MONITOR, /RST, /WDS 5V-5% MONITOR, /RST, /WDS 5V-5% MONITOR, /RST, /WDS 5V-10% MONITOR, /RST, /WDS 5V-10% MONITOR, /RST, /WDS 5V-10% MONITOR, /RST, /WDS 5V-5% MONITOR, RST, /WDS 5V-5% MONITOR, RST, /WDS 5V-5% MONITOR, RST, /WDS 3.3V-20% MONITOR, RST, /WDS 3.3V-20% MONITOR, RST, /WDS 3.3V-20% MONITOR, RST, /WDS 3.3V-20% MONITOR, /RST, /WDS 3.3V-20% MONITOR, /RST, /WDS 3.3V-20% MONITOR, /RST, /WDS 3.3V-10% MONITOR, /RST, /WDS 3.3V-10% MONITOR, /RST, /WDS 3.3V-10% MONITOR, /RST, /WDS 3.3V-5% MONITOR, /RST, /WDS 3.3V-5% MONITOR, /RST, /WDS 3.3V-5% MONITOR, /RST, /WDS Note: Devices are also available in a lead(Pb)-free/RoHS-compliant package. Specify lead-free by adding a plus (+) to the part number when ordering. E = -40°C to +85°C temperature range A = 8-lead device P = Plastic DIP (300 mils) S = SO (150 mils) U = µSOP (118 mils) PACKAGE INFORMATION For the latest package outline information and land patterns, go to www.maxim-ic.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 DOCUMENT NO. 8 PDIP 8 SO P8-2 S8-2 U8-1 21-0043 21-0041 21-0036 8 SOP 11 of 12 DS1705/DS1706 REVISION HISTORY REVISION DATE DESCRIPTION PAGES CHANGED 4/10 Added the lead temperature and updated the soldering temperature in the Absolute Maximum Ratings; corrected Note 9. 8, 9 12 of 12 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 © 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. The Dallas logo is a registered trademark of Maxim Integrated Products, Inc.