MAXIM MAX705 MAX708/MAX813L handbook
Contents
1. 80 66 92 SR908XVIN 80 C E6 CIENT 9c 8 0 0 S lt 0 007 01 OFT JOb S9 L SPVIN IS08XVIN 99 8 0 1 00 LIFA 00 9 80 6 TENT L S A OSXVIN 80 E E6 C C9 C 65 8 soos lt 0 LIA 007 01 2 91 OFT 0 7 09 L SPIIN TCOSXVIN m 8 da da da da 91 STFA Ori 85 7 89 JN N 1108X VIN 88 91 Goos coOoro WTA SULA Sc TI A A pest A OFT 07 7 09 W 1008XVIN m 8 da da dal da 80 t LO C6C EO C L N SRIS6LXVIN 9I da dab 2 2 da 91 OFT pv T6LXVIN m 91 da da 2 da da 2 91 S0 t LOC C6 C CO C L N S MEGLXVIN 80 E E6 T E9 T 9I 4000 A sora OFT 69 L SPVINITCGLXVIN 91 00 9000120 510 Sc TI I 01 597 I6LXVIN 8 0 5 0 OFT 80 6 T 9 7 LSMSOLXVIN 8 0 5 0 OPI 0 9 SOLILOLXVIN 8 0 5 0 91 2 OFT 80 6c 9 c L S I90LX VIN 8 lt 0 lt lt 0 91 59 d90LXVIN 8 0 5 0 2 2 2 91 2 2 0 7 9 90L SOLX VIN 8 OI 0 s 0 007 9 OPI 80 6 c 9 c USRIPOLXVIN 8 0 0 S 0 5 0 2 2 007 01 0 7 9 OL EOLXVIN 8 TOTO 002 11 9 OOLXVIN 91 A pst Pese LOOXVIN 91 A uo AL Pese pv 969XVIN 91 Aroneg umrgir YyWUGTI pue VIGOXVIN qi empour v st 169 LX VIN 9L 1691XVIN 9I 0 00 lt se0 01 0 A sova SZ TI A2. Supply Current MAX705E M MAX706E M MAX813LE M 150 500 UA MAX707C MAX708C 50 350 MAX707E M MAX708E M 50 500 MAX705 MAX707 MAX813L 4 50 4 65 4 75 Basel TIR Do d NOSE VRT MAX706 MAX708 425 440 4580 Reset Threshold Hysteresis Note 2 40 mV Reset Pulse Width Note 2 RS 140 200 280 ms ISOURCE 800A Vcc 1 5 ISINK 2 0 4 RESET Output Voltage MAX70 Voc 1V link SOLA 03 V 70 Voc 1 2V ISINK 100 0 3 707 708 5 800 Voc 1 5 MAX707 708 1 2mA 0 4 MAX813LC Voc 1 1V 0 8 RESET Output Voltage AR SLE Ioue uA Ves 1991 75 MAX813L ISOURCE 800HA Voc 1 5 ISINK 3 2mA 0 4 Watchdog Timeout Period twp MAX705 MAX706 MAX813L 1 00 1 60 2 25 sec WDI Pulse Width twp Vit 0 4V Voc 0 8 50 ns WDI Input Threshold ges 35 V WDI Input Current MAX705 MAX706 MAX813L WDI Vcc 50 150 UA MAX705 706 MAX813L WDI OV 150 50 22 a MAX813L Vcc 1 5 WDO Output Voltage SOURCE 800 V MAX705 MAX706 MAX813L 04 ISINK 1 2mA 2 AVLAZCL VI Low Cost Supervisory Circuits ELECTRICAL CHARACTERISTICS continued Vog 4 75V to 5 5V for MAX705 MAX707 MAX813L Voc 4 5V to 5 5V for 706 708 Ta to Tmax unless otherwise noted PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS MR Pull Up Current MR OV 100 250 60
3. puo A Ipvort Op S9 V 69 V 169XVIN 8 OT 0 5 0 007 9 2 91 80 66 6972 1 5 8069 8 sows z0 se 0 007 01 91 OPI O S9 VZ69 V069XVIN 8 lt 00 20 c V9 sro 052 TETIXVIN 2 g582 3202 98 Ob 92 FA 59297 LP SEE 388 94 SE Eg a S 52 35 Zs 2si zsi 52858 9253 5 2 8 7 28 i s k 2 87 SE 75 9 85 521 5 229 55524592509 79 72 58 53 g 884 9 9 sg sg 8S9 s8 B 8 3 a 8S7 Sg 5 lt lt 5 28 o ag o 5 So a 9 Sg lt co 2 o o syinosig Asosiasadng 11 MAXIM MAX 705 MAX 708 MAX813L Low Cost Supervisory Circuits 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 12 Maxim Integrated Products 120 San Gabriel Drive Sunnyvale CA 94086 408 737 7600 1995 Maxim Integrated Products Printed USA MAXIM is a registered trademark of Maxim Integrated Products
4. 5 RESET Valid to Ground Circuit Figure 6 Monitoring Both 5V and 12V 100k MR MAKIMI MAX70_ VrniP 0v 5 125 1 25 VTRIP R1 R2 lt 0 Figure 7 Monitoring a Negative Voltage BUFFERED RESET TO OTHER SYSTEM COMPONENTS Vcc Vcc MAALM MAX70_ 47k uP RESET RESET GND Figure 8 Interfacing to Ps with Bidirectional Reset I O Interfacing to Ps with Bidirectional Reset Pins uPs with bidirectional reset pins such as the Motorola 68HC11 series can contend with the MAX705 MAX708 RESET output If for example the RESET output is driven high and the uP wants to pull it low indeterminate logic levels may result To correct this connect a 4 7 resistor between the RESET output the uP reset I O as in Figure 8 Buffer the RESET output to other system components AVLAXL VI Low Cost Supervisory Circuits __Ordering Information continued Pin Configuration continued PART TEMP RANGE MAX705EPA 40 C to 85 C 8 Plastic DIP TOP VIEW MAX705ESA 40 C to 85 C 850 RESET RESET MAX705MJA 55 C to 125 C 8 CERDIP WDO MAX706CPA 0 C to 70 G 8 Plastic DIP HIA MAX706CSA 0 C to 70 C 8 SO MAX813L MAX706CUA 0 C to 70 C 8 UMAX MAX706C D 0 C to 70 C Dice MAX706EPA 40 C
5. 6 8 MAX SMALL OUTLINE AVLAXL VI ts sory Circui rvi Low Cost Supe MAX705 MAX 708 MAX813L pue soxe SINP e20 INP are 45 pue Surud 2 0002 1 onn p II soorid peuoreuroyu paou sso un YSNA JOA We pue 8 usisap popraoid sooug panp ooud od 00056 vc 8 000070 ETOSO A 199 Sc CO v LEV 80 6 TIENT 78 E 91 L0 0 S1 0 A SoA OPI 0 59 L SPN 10C8XVIN m 8 dab A OFT op Ver 9I8XVIN m 8 da da A OA 91 Ori COt SCE OL F OS v 518 m 8 da dab 2 CA A I IFIA COE SC OL T OS v L N VMPISXVIN xc 8 0 5 0 WIA 91 Ori Sov IEISXVIN 80 6 TEST H 70 0 90 0 2 2 07 59 L SRVW 1018XVW 80 6 9 72000900 OPI 0 7 9 L S IN 1608XVIN 91 da da dal da WDS TFIA 8 80 JN N 1808X VIN 8 agl da 2 da da 91 A DS Te AS TIFA Ori 8 7 80 JN N 1L08X VIN 06 8 OT 0 5 0 l 007 9 2 2 2 2
6. approximately 10 times the sum of the two resistors in the potential divider net work between PFI and PFO A capacitor between PFI and GND will reduce the power fail circuit s sensitivity to high frequency noise on the line being monitored RESET can be asserted on other voltages in addition to the 5V line Connect PFO to MR to initiate a RESET pulse when PFI drops below 1 25V Figure 6 shows the MAX705 MAX708 configured to assert RESET when the 5V supply falls below the reset threshold or when the 12V supply falls below approximately 11V Monitoring a Negative Voltage The power fail comparator can also monitor a negative supply rail Figure 7 When the negative rail is good a negative voltage of large magnitude PFO is low and when the negative rail is degraded a negative voltage of lesser magnitude PFO is high By adding the resis tors and transistor as shown a high PFO triggers reset As long as PFO remains high the MAX705 MAX708 MAX813L will keep reset asserted RESET low RESET high Note that this circuits accuracy depends on the PFI threshold tolerance the Voc line and the resistors TET8XVIW 80LXVIN SOLXVIN MAX 705 MAX 708 MAX813L Low Cost Supervisory Circuits MAXIM MAX70_ RESET 12V RESET MAXIM MAX70_ TO uP PARAMETER 12V Reset Threshold at 25 C MIN TYP UNIT 10 67 10 87 11 50 V Figure
7. 0 HA MR Pulse Width tMR 150 ns MR input Threshold 29 ue High 2 0 MR to Reset Out Delay Note 2 tMD 250 ns PFI Input Threshold Voc 5V 1 20 1 25 1 30 V PFI Input Current 25 00 0 01 25 00 nA BEA ISOURCE 800A Voc 1 5 PFO Output Voltage len e S2mA 02 V Note 2 Applies to both RESET in the MAX705 MAX708 and RESET in the MAX707 MAX708 MAX813L AVLAXLA TET8XVIW 80LXVIN SOLXVIN MAX 705 MAX 708 MAX813L Low Cost Supervisory Circuits MAX705 MAX707 RESET OUTPUT VOLTAGE vs SUPPLY VOLTAGE 500ms div POWER FAIL COMPARATOR ASSERTION RESPONSE TIME 45V 45V PFO lt 2 lt ov ov 1 30V 9 5 lt 20 0 400ns div MAX707 MAX708 MAX813L RESET OUTPUT VOLTAGE vs SUPPLY VOLTAGE MAX705 MAX707 500ms div POWER FAIL COMPARATOR Typical Operating Characteristics RESET RESPONSE TIME DE ASSERTION RESPONSE TIME Voc 45V TA 425C 44V PFO 94 lt lt Ov 1 30V PA ov 1 20V 400ns div MAX707 MAX707 RESET RESET ASSERTION RESET RESE
8. Continuous Power Dissipation Plastic DIP derate 9 09mW C above 70 C 0 3V to 6 0V 0 3V to 0 3V SO derate 5 88mW C above 70 C derate 4 10mW C above 70 C CERDIP derate 8 00mW C above 70 C Operating Temperature Ranges 20mA MAX70 C MAX813LC 20mA MAX70 E MAX813LE 20mA MAX70 MJA Storage Temperature Range 727mW Lead Temperature soldering 10sec Note 1 The input voltage limits and MR can be exceeded if the input current is less than 10 0 C to 70 C 40 C to 85 C 55 to 125 C 65 C to 160 C 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 Vog 4 75V to 5 5V for MAX705 MAX707 MAX813L Voc 4 5V to 5 5V for MAX706 MAX708 Ta to Tmax unless otherwise noted PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS MAX70_C 1 0 5 5 Operating Voltage Range Voc MAX813LC 1 1 5 5 V 70 MAX813LE M 1 2 5 5 705 706 MAX813LC 150 350
9. EF MAX TOS E 19 4334 Rev 5 9 95 AVLAZX LA Low Cost uP Supervisory Circuits General Description The MAX705 MAX708 MAX813L microprocessor uP supervisory circuits reduce the complexity and number of components required to monitor power supply and battery functions in uP systems These devices signifi cantly improve system reliability and accuracy com pared to separate ICs or discrete components The MAX705 MAX706 MAX813L provide four functions 1 A reset output during power up power down and brownout conditions 2 An independent watchdog output that goes low if the watchdog input has not been toggled within 1 6 seconds 3 A 1 25V threshold detector for power fail warning low battery detection or for monitoring a power sup ply other than 5V 4 An active low manual reset input The MAX707 MAX708 are the same as the MAX705 MAX706 except an active high reset is substituted for the watchdog timer The MAX813L is the same as the 705 except RESET is provided instead of RESET Two supply voltage monitor levels are available The MAX705 MAX707 MAX813L generate a reset pulse when the supply voltage drops below 4 65V while the MAX706 MAX708 generate a reset pulse below 4 40V All four parts are available in 8 pin DIP SO and packages Applications Computers Controllers Intelligent Instruments Automotive Systems Critical uP Power Monitoring Typical Operating Circuit UNREGULATED DC
10. GERED BY MR gy ARE FOR MAX813L ONLY Figure 3 MAX705 MAX706 MAX813L Watchdog Timing ov MR EXTERNALLY DRIVEN LOW Figure 4 MAX705 MAX706 RESET MR and WDO Timing with WDI Three Stated The MAX707 MAX708 MAX813L RESET output is the inverse of RESET shown MAXIM To build an early warning circuit for power failure con nect the PFI pin to a voltage divider see Typical Operating Circuit Choose the voltage divider ratio so that the voltage at PFI falls below 1 25V just before the 5V regulator drops out Use PFO to interrupt the uP so it can prepare for an orderly power down Applications Information Ensuring a Valid RESET Output Down to Vcc When Vcc falls below 1V the MAX705 MAX708 RESET output no longer sinks current it becomes an open cir cuit High impedance CMOS logic inputs can drift to undetermined voltages if left undriven If a pull down resistor is added to the RESET pin as shown in Figure 5 any stray charge or leakage currents will be drained to ground holding RESET low Resistor value R1 is not critical It should be about 100kQ large enough not to load RESET and small enough to pull RESET to ground Monitoring Voltages Other Than the Unregulated DC Input Monitor voltages other than the unregulated DC by connecting a voltage divider to PFI and adjusting the ratio appropriately If required add hysteresis by con necting a resistor with a value
11. MAXIM MAX667 5V DC LINEAR REGULATOR uP Vcc Vcc RESET RESET PF AAAXILAA PFI VO LINE Le mo MR PFO INTERRUPT pusupurton MAxetaL SWITCH qF AVLAXLA Features pu MAX Package Smallest 8 Pin SO Guaranteed RESET Valid at Vog 1V Precision Supply Voltage Monitor 4 65V in MAX705 MAX707 MAX813L 4 40V in MAX706 MAX708 200ms Reset Pulse Width Debounced TTL CMOS Compatible Manual Reset Input Independent Watchdog Timer 1 6sec Timeout MAX705 MAX706 Active High Reset Output MAX707 MAX708 MAX813L Voltage Monitor for Power Fail or Low Battery Warning Ordering Information PART TEMP RANGE PIN PACKAGE MAX705CPA 0 to 70 C 8 Plastic DIP MAX705CSA 0 C to 70 C 8 SO MAX705CUA 0 C to 70 C 8 uMAX MAX705C D 0 C to 70 C Dice Ordering Information continued at end of data sheet Dice are specified at T4 25 C factory for availability and processing to MIL STD 883 Pin Configurations TOP VIEW MAX707 MAX708 DIP SO ARE FOR MAX813L ONLY Pin Configurations continued at end of data sheet Maxim Integrated Products 1 Call toll free 1 800 998 8800 for free samples or literature TET8XVIW 80ZLXVIN SOLXVIN MAX 705 MAX 708 MAX813L Low Cost Supervisory Circuits ABSOLUTE MAXIMUM RATINGS Terminal Voltage with respect to GND Voc All Other Inputs Note 1 Output Current all outputs
12. T DE ASSERTION Voc Var Voc Vat Ta 425 C Ta 25 C 5V RESET Tv b RESET ER ov RESET lt RESET H 10k sz E 330pF ND IT 330pF1 330p OV 400ns div 400ns div MAX813L RESET RESPONSE TIME 2us div MAXIM Low Cost Supervisory Circuits Pin Description PIN MAX705 MAX706 707 708 MAX813L DIP SO MAX DIP SO MAX DIP SO MAX NAME FUNCTION Manual Reset Input triggers a reset pulse when pulled below 0 8V This active low input has an inter nal 250A pull up current It can be driven from a TTL or CMOS logic line as well as shorted to ground with a switch 5V Supply Input GND OV Ground Reference for all signals Power Fail Voltage Monitor Input When PFI is less than 1 25V PFO goes low Connect PFI to GND or Voc when not used Power Fail Output goes low and sinks current when PFI is less than 1 25V otherwise PFO stays high WDI Watchdog Input If WDI remains high or low for 1 6sec the internal watchdog timer runs out and WDO goes low Figure 1 Floating WDI or connect ing WDI to a high impedance three state buffer dis ables the watchdog feature The internal watchdog timer clears whenever reset is asserted WDI is three stated or WDI sees a rising or falling edge N C No Connect Active Low Reset Output pulses low for 200ms when triggered and stays low whenever Vog is below the reset thresh
13. an unknown state it should be held in reset The MAX705 MAX708 MAX813L assert reset during power up and prevent code execu tion errors during power down or brownout conditions On power up once Vog reaches 1V RESET is a guaran teed logic low of 0 4V or less As Voc rises RESET stays low When Vcc rises above the reset threshold an inter nal timer releases RESET after about 200ms RESET puls es low whenever Vog dips below the reset threshold i e brownout condition If brownout occurs in the middle of a previously initiated reset pulse the pulse continues for at least another 140ms On power down once falls below the reset threshold RESET stays low and is guar anteed to be 0 4V or less until Vog drops below 1V The MAX707 MAX708 MAX813L active high RESET output is simply the complement of the RESET output and is guaranteed to be valid with Voc down to 1 1V Some Ps such as Intel s 80C51 require an active high reset pulse Watchdog Timer The MAX705 MAX706 MAX813L watchdog circuit moni tors the uP s activity If the uP does not toggle the watch dog input WDI within 1 6sec and WDI is not three stat ed WDO goes low As long as RESET is asserted or the 6 Figure 2 MAX707 MAX708 Block Diagram WDI input is three stated the watchdog timer will stay cleared and will not count As soon as reset is released and WDI is driven high or low the timer will start counting Pulses as short as 50ns
14. can be detected Typically WDO will be connected to the non maskable interrupt input NMI of a uP When Vcc drops below the reset threshold WDO will go low whether or not the watchdog timer has timed out yet Normally this would trigger an NMI interrupt but RESET goes low simultane ously and thus overrides the NMI interrupt If WDI is left unconnected WDO can be used as a low line output Since floating WDI disables the internal timer WDO goes low only when falls below the reset threshold thus functioning as a low line output The MAX705 MAX706 have a watchdog timer and a RESET output The MAX707 MAX708 have both active high and active low reset outputs The MAX813L has both an active high reset output and a watchdog timer Manual Reset The manual reset input MR allows reset to be trig gered by a pushbutton switch The switch is effectively debounced by the 140ms minimum reset pulse width MR is TTL 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 MAX705 MAX706 MAX813L Simply connect WDO to MR AVLAXL VI Low Cost Supervisory Circuits Power Fail Comparator The power fail comparator can be used for various pur poses because its output and noninverting input are not internally connected The inverting input is internal ly connected to a 1 25V reference RESET EXTERNALLY tpg lt TRIG
15. old 4 65V in the MAX705 and 4 40V in the MAX706 It remains low for 200ms after Vog rises above the reset threshold or MR goes from low to high Figure 3 A watchdog timeout will not trigger RESET unless WDO is connected to MR g Watchdog Output pulls low when the internal watch dog timer finishes its 1 6sec count and does not go high again until the watchdog is cleared WDO also goes low during low line conditions Whenever Voc is below the reset threshold WDO stays low however unlike RESET WDO does not have a minimum pulse width As soon as Vcc rises above the reset thresh old WDO goes high with no delay RESET Active High Reset Output is the inverse of RESET Whenever RESET is high RESET is low and vice versa Figure 2 The MAX813L has a RESET output only MAXIM TET8XVIW 80ZLXVIN SOLXVIN MAX 705 MAX 708 MAX813L Low Cost Supervisory Circuits WATCHDOG WDI TRANSITION DETECTOR WATCHDOG E TIMER WDO TIMEBASE FOR RESET AND WATCHDOG RESET V GENERATOR CC RESET RESET MAKIM MAX705 MAX706 PFI MAX813L PFO 440V FOR MAX706 3 GND ARE FOR MAX813L ONLY MAXIM MAX707 MAX708 4 40V FOR MAX706 Figure 1 MAX705 MAX706 MAX813L Block Diagram Detailed Description Reset Output microprocessor s uP s reset input starts the uP in known state Whenever the uP is in
16. to 85 C 8 Plastic DIP MAX706ESA 40 C to 85 C 8 SO MAX706MJA 55 C to 125 C 8 CERDIP MAX707CPA 0 C to 70 C 8 Plastic DIP MAX707 MAX707CSA 0 C to 70 C 8 SO MAX708 MAX707CUA 0 C to 70 C 8 UMAX MAX707C D 0 C to 70 C Dice SAX MAX707EPA 40 C to 85 C 8 Plastic DIP E AERE MAX707ESA 40 C to 85 C 8 SO MAX707MJA 55 C to 125 C 8 CERDIP MAX708CPA 0 C to 70 C 8 Plastic DIP MAX708CSA 0 C to 70 C 8 SO Chip Topography MAX708CUA 0 C to 70 C 8 UMAX MAX708C D 0 C to 70 C Dice Vec MR WDO RESET MAX708EPA 40 C to 85 C 8 Plastic DIP MAX708ESA 40 C to 85 C 8 SO MAX708MJA 55 C to 125 C 8 CERDIP MAX813LCPA 0 C to 70 C 8 Plastic DIP WDI N C MAX813LCSA 0 C to 70 C 8 SO 0 051 MAX813LCUA O Cto 70 C 8 MAX 1 30mm MAX813LC D 0 C to 70 C Dice GND MAX813LEPA 40 C to 85 C 8 Plastic DIP MAX813LESA 40 C to 85 C 8 SO MAX813LMJA 55 C to 125 C 8 CERDIP Dice are specified at T4 25 C 1 88mm Contact factory for availability and processing to MIL STD 883 ARE FOR MAX813L ONLY TRANSISTOR COUNT 572 SUBSTRATE MUST BE LEFT UNCONNECTED MAXIM 9 TET8XVIW 80LXVIN SOLXVIN MAX 705 MAX 708 MAX813L Low Cost Supervisory Circuits Package Information INCHES MILLIMETERS 0 120 0 120 0 0256 0 188 0 198 0 016 0 026 0
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MAXIM MAX705 MAX708/MAX813L handbook