IMP705/6/7/8, 813L8. atchdog timer Brownout detection. ection supply y monitor POWER MANAGEMENT. Key Features. Applications.

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1 POWER MANAGEMENT Low-P -Power µp P Supervisor Circuits WatcW atchdog timer Brownout detection ection Power P supply y monitor or The IMP0/0/0/0 and IMPL CMOS supervisor circuits monitor power-supply and battery voltage level, and µp/µc operation. Compared to pin-compatible devices offered by Maxim Integrated Products, IMP devices feature 0 percent lower maximum supply current. The family offers several functional options. Each device generates a reset signal during power-up, power-down and during brownout conditions. A reset is generated when the supply drops below. (IMP0/0/L) or. (IMP0/0). For power supply applications, refer to the IMP0P/R/S/T data sheet. In addition, the IMP0/0/L feature a. second watchdog timer. The IMP0/0 have both active-high and active-low reset outputs but no watchdog function. The IMPL has the same pin-out and functions as the IMP0 but has an active-high reset output. A versatile power-fail circuit has a. threshold, useful in checking battery levels and non- supplies. All devices have a manual reset () input. The watchdog timer output will trigger a reset if connected to. All devices are available in -pin DIP, SO and MicroSO packages. Block Diagrams Key Features Improved replacements for the Maxim MAX0///, MAXL 0µA maximum supply current 0% improvement Precision power supply monitor. threshold (IMP0/0/L). threshold (IMP0/) Debounced manual reset input oltage monitor. threshold Battery monitor/auxiliary supply monitor Watchdog timer (IMP0/0/L) 00ms reset pulse width Active HIGH reset output (IMP0/0/L) MicroSO package Applications Computers and embedded controllers Battery-operated systems Intelligent instruments Wireless communication systems PDAs and handheld equipment WDI Transition Detector 0.mA Watchdog Timer Timebase 0.mA Generator () (IMPL) Generator. (IMP0/L). (IMP0). (IMP0). (IMP0) IMP0 IMP0 IMPL. IMP0 IMP0. 0_0.eps 0_0.eps

2 Pin Configuration DIP/SO MicroSO IMP0 IMP0 NC IMP0 IMP0 (IMPL) () WDI IMP0 IMP0 NC () IMP0 IMP0 (IMPL) WDI 0_0.eps Ordering Information Part Number Reset Threshold () Temperature Range Pins-Package IMP0 Active LOW Reset, Watchdog Output and Manual IMP0CPA. 0 C to 0 C -Plastic DIP IMP0CSA. 0 C to 0 C -SO IMP0CUA. 0 C to 0 C -MicroSO IMP0C/D. C Dice IMP0EPA. 0 C to C -Plastic DIP IMP0ESA. 0 C to C -SO IMP0ESA.0 0 C to C -SO IMP0 Active LOW Reset, Watchdog Output and Manual IMP0CPA.0 0 C to 0 C -Plastic DIP IMP0CSA.0 0 C to 0 C -SO IMP0CUA.0 0 C to 0 C -MicroSO IMP0C/D.0 C Dice IMP0EPA.0 0 C to C -Plastic DIP IMP0ESA.0 0 C to C -SO IMP0 Active LOW & HIGH Reset with Manual IMP0CPA. 0 C to 0 C -Plastic DIP IMP0CSA. 0 C to 0 C -SO IMP0CUA. 0 C to 0 C -MicroSO IMP0C/D. C Dice IMP0EPA. 0 C to C -Plastic DIP IMP0ESA. 0 C to C -SO IMP0 Active LOW & HIGH Reset with Manual IMP0CPA.0 0 C to 0 C -Plastic DIP IMP0CSA.0 0 C to 0 C -SO IMP0CUA.0 0 C to 0 C -MicroSO IMP0C/D.0 C Dice IMP0EPA.0 0 C to C -Plastic DIP IMP0ESA.0 0 C to C -SO IMPL Active HIGH Reset, Watchdog Output and Manual IMPLCPA. 0 C to 0 C -Plastic DIP IMPLCSA. 0 C to 0 C -SO IMPLCUA. 0 C to 0 C -MicroSO IMPLC/D. C Dice IMPLEPA. 0 C to C -Plastic DIP IMPLESA. 0 C to C -SO

3 IMP0///, L Absolute Maximum Ratings Pin Terminal oltage with Respect to Ground Operating Temperature Range CC to. IMP0E/0E/0E/0E/LE C to C All other inputs to (CC0.) IMP0C/0C/0C/LC C to 0 C Input Current at CC and mA Storage Temperature Range C to 0 C Output Current: All outputs mA Lead Temperature Soldering(0 sec) C Rate of Rise at CC /µs Plastic DIP Power Dissipation mw Note:. The input voltage limits on and can be exceeded if (Derate 9 mw/ C above 0 C) the input current is less than 0mA. SO Power Dissipation mw (Derate.9 mw/ C above 0 C) These are stress ratings only and functional operation is not implied. MicroSO Power Dissipation mW (Derate. mw/ C above 0 C) Typical values at Ta= C, CC = to. for the IMP0C/E,0C/E,L. CC= to. for the IMP0C/E,0C/E. Parameter Operating oltage Range Symbol CC Conditions IMP0///C IMPL Min. Electrical Characteristics Typ Max... IMP0///E, IMPlE.. Supply Current Threshold Threshold Hysteresis ICC RT IMP0C/0C/LC IMP0E, IMP0E, IMPLE IMP0C, IMP0C IMP0E, IMP0E IMP0, IMP0, IMPL, Note IMP0, IMP0, Note Note Pulse Width trs Note Pulse Width t 0. to Out Delay Input Threshold tmd IH IL Note Pull-up Current = µa Output oltage ISOURCE = 00µA CC-. ISINK=.mA 0. Output oltage IMP0///, CC =., ISINK = 00µA IMP0/0/L, ISOURCE = 00µA CC-. 0. IMP0/0, ISINK =.ma 0. IMPL, ISINK=.mA 0. Watchdog Timeout Period WDI Pulse Width twd twp IMPL, CC =., ISOURCE = µa IMP0/0/L IL = 0., IH = 0.CC IMP0/0/L, CC WDI Input Threshold IH = Units µa m ms µs µs.0. s ns IL 0. WDI Input Current IMP0/0/L, WDI = CC 0 0 µa IMP0/0/L, WDI = 0 0 Output oltage IMP0/0/L, ISOURCE = 00µA CC-. IMP0/0/L, ISINK =.ma 0. Input Threshold CC =... Input Current 0.0 na Output oltage ISOURCE = 00µA CC -. ISINK =.ma 0. Notes:. (IMP0///), (IMP0/, IMPL)

4 Pin Descriptions Pin Number IMP0/0 IMP0/0 IMPL DIP/SO MicroSO DIP/SO MicroSO DIP/SO MicroSO Name Function Manual input. The active LOW input triggers a reset pulse. A 0µA pull-up current allows the pin to be driven by TTL / CMOS logic or shorted to ground with a switch. power supply input. Ground reference for all signals. Power-fail voltage monitor input. With less than., goes low. Connect to ground or when not used. Power-fail output. The output is active LOW and sinks current when is less than.. Watchdog input. WDI controls the internal watchdog timer. A HIGH or LOW signal for.sec at WDI allows the internal timer to run-out, setting LOW. WDI The watchdog function is disabled by floating WDI or by connecting WDI to a high-impedance three-state buffer. The internal watchdog timer clears when: is asserted; WDI is three-stated; or WDI sees a rising or falling edge. NC Not connected. Active-LOW reset output. Pulses LOW for 00ms when triggered, and stays low whenever is below the reset threshold (IMP0:., IMP0J:.0, IMP0:.). remains LOW for 00ms after rises above the threshold or goes from LOW to HIGH. A watchdog timeout will not trigger unless is connected to. Watchdog output. pulls LOW when the. sec internal watchdog timer times-out and does not go HIGH until the watchdog is cleared. In addition, when is below the reset threshold, remains low. Unlike, does not have a minimum pulse width and as soon as exceeds the reset threshold, goes HIGH with no delay. Active-HIGH reset output. is the inverse of. The IMPL has only a output. Feature Summary IMP0 IMP0 IMP0 IMP0 IMPL Power-fail detector Brownout detection Manual input Power-up/down Watchdog timer Active-HIGH output Active-LOW output threshold./.0....

5 L Detail Descriptions / Operation The / signals are designed to start a µp/µc in a known state or return the system to a known state. The IMP0/0 have two outputs, one active-high and one active-low output. The IMPL has only an active-high output. is simply the complement of. is guaranteed to be LOW with above.. During a power-up sequence, remains low until the supply rises above the threshold level, either.,. or.0. goes high approximately 00ms after crossing the threshold. During power-down, goes LOW as falls below the threshold level and is guaranteed to be under 0. with above.. In a brownout situation where falls below the threshold level, pulses low. If a brownout occurs during an alreadyinitiated reset, the pulse will continue for a minimum of 0ms. Auxiliary Comparator All devices have an auxiliary comparator with. trip point and uncommitted output () and noninverting input (). This comparator can be used as a supply voltage monitor with an external resistor voltage divider. The attenuated voltage at should be set just below the. threshold. As the supply level falls, is reduced causing the output to transit LOW. Normally interrupts the processor so the system can be shut down in a controlled manner. Manual Reset () The active-low manual reset input is pulled high by a 0µA pull-up current and can be driven low by CMOS/TTL logic or a mechanical switch to ground. An external debounce circuit is unnecessary since the 0ms minimum reset time will debounce mechanical pushbutton switches. By connecting the watchdog output () and, a watchdog timeout forces to be generated. The IMPL should be used when an active-high is required. Watchdog Timer The watchdog timer available on the IMP0/0/L monitors µp/µc activity. If activity is not detected within. seconds, the internal timer puts the watchdog output,, into a LOW state. will remain LOW until activity is detected at WDI. The watchdog function is disabled, meaning it is cleared and not counting, if WDI is floated or connected to a three-stated circuit. The watchdog timer is also disabled if is asserted. When becomes inactive and the WDI input sees a high or low transition as short as 0ns, the watchdog timer will begin a. second countdown. Additional transitions at WDI will reset the watchdog timer and initiate a new countdown sequence. will also become LOW and remain so, whenever the supply voltage,, falls below the device threshold level. goes HIGH as soon as transitions above the threshold. There is no minimum pulse width for as there is for the outputs. If WDI is floated, essentially acts as a low-power output indicator. v RT t RS t RS WDI t WP t WD t WD t WD extermally set low triggered by t MD t t RS () IMPL 0_0.eps Figure. WDI Three-state operation 0_0.eps Figure. Watchdog Timing

6 Application Information Ensuring That is alid Down to = When falls below., the IMP0-0 output no longer pulls down; it becomes indeterminate. To avoid the possibility that stray charges build up and force to the wrong state, a pull-down resistor should be connected to the pin, thus draining such charges to ground and holding low. The resistor value is not critical. A 00kΩ resistor will pull to ground without loading it. Bi-directional Reset Pin Interfacing The IMP0/// can interface with µp/µc bi-directional reset pins by connecting a.kω resistor in series with the output and the µp/µc bi-directional pin. BUF Buffered <. IMP0x 00kW Power Supply IMP0x.kΩ Input µc or µp Bi-directional I/O Pin (Example: HC) 0_0.eps 0_0.eps Figure. Ensuring That is alid Down to = Figure. Bi-directional Reset Pin Interfacing

7 L Application Information Monitoring oltages Other Than The IMP0-0 can monitor voltages other than using the Power Fail circuitry. If a resistive divider is connected from the voltage to be monitored to the Power Fail input,, the (output) will go LOW if the divider voltage goes below its. reference. Should hysteresis be desired, connect a resistor (equal to approximately 0 times the sum of the two resistors in the divider) between the and pins. A capacitor between and will reduce circuit sensitivity to input high-frequency noise. If it is desired to assert a in addition to the flag, this may be achieved by connecting the output to. Monitoring a Negative oltage The Power-Fail circuitry can also monitor a negative supply rail. When the negative rail is OK, will be LOW, and when the negative rail is failing (not negative enough), goes HIGH (the opposite of when positive voltages are monitored). To trigger a reset, these outputs need to be inverted: adding the resistors and transistor as shown achieves this. The output will then have the same sense as for positive voltages: good = HIGH, bad = LOW. It should be noted that this circuit s accuracy depends on the line, the threshold tolerance, and the resistors. = IN = MW IMP0x RP IMP0x To Processor 0kW Threshold ~0. 0_0.eps RN Negative Input oltage.. TRIP = RP RN 0_09.eps Figure. Monitoring oltages Other Than Figure. Monitoring a Negative oltage

8 Package Dimensions A L A A e e D D Plastic DIP (-Pin)* b D b b E H E E 0 C ea eb MicroSO (-Pin)** A A E E A D 0.0mm 0.00in SO (-Pin)*** Plastic DIP (-Pin)a.eps a C MicroSO (-Pin).eps 0 L L Inches Millimeters Min Max Min Max Plastic DIP (-Pin) A 0.0. A A b b b D D E E e ea eb ec 0.00 L MicroSO (-Pin) A A A b C D e 0.0 BSC 0. BSC E 0.9 BSC.90 BSC E L a 0 0 SO (-Pin) A A B C e E H L D D A C * JEDEC Drawing MS-00BA ** JEDEC Drawing MO-AA *** JEDEC Drawing MS-0AA e B A SO (-Pin).eps

9 IMP0///, L Microelectronics Co.,Ltd keda Road, Hi-Tech Park, NingBo,Zhejiang, P.R.C. Post Code : 00 Tel:(0)--90 Fax:(0)--90 sales@ds-imp.com.cn Website: The IMP logo is a registered trademark of. All other company and product names are trademarks of their respective owners. 0 Revision : B Issue Date: 0/0/ Type: Product