Power-Supply Monitor with Reset

Transcription

1 9-036; Rev. 2; 2/05 Power-Supply Monitor with Reset General Description The provides a system reset during power-up, power-down, and brownout conditions. When falls below the reset threshold, goes low and holds the µp in reset for 40ms min after rises above the threshold. The output is guaranteed to be in the correct state with down to V. The provides excellent circuit reliability and low cost by eliminating external components and adjustments when used with +5V, +3.3V, or +3V powered systems. The is available 8-pin DIP, µmax, and SO packages. Applications Minimum Component Count, Low-Cost Processor Systems Typical Operating Circuit Features +5V, +3.3V, and +3V Versions No External Components Low Cost Precise Power-Down Reset Threshold 40ms Min Power-On Reset Delay Immune to Short Negative Transients 8-Pin DIP, µmax, and SO Packages Low Supply Current: 35µA - R/S/T 65µA - L/M Ordering Information PART TEMP. RANGE PIN-PACKAGE _CPA 0 C to +70 C 8 Plastic DIP _CUA 0 C to +70 C 8 µmax _CSA 0 C to +70 C 8 SO _C/D 0 C to +70 C Dice _EPA -40 C to +85 C 8 Plastic DIP _EUA -40 C to +85 C 8 µmax _ESA -40 C to +85 C 8 SO Devices are available in both leaded and lead-free packaging. Specify lead free by adding the + symbol at the end of the part number when ordering. *Dice are specified at T A = +25 C, DCparameters only. Note: This part offers a choice of five different reset threshold voltages. Select the letter corresponding to the desired nominal reset threshold voltage, and insert it into the blank to complete the part number. THRESHOLD SUFFIX VOLTAGE (V) L 4.65 M 4.40 T 3.08 S 2.93 R 2.63 Pin Configuration µp TOP VIEW DIP/SO/µMAX Maxim Integrated Products Call toll free for free samples or literature.

2 ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to ) V to 6.0V V to ( + 0.3V) Input Current,...20mA Output Current,... 20mA Rate-of-Rise,...00V/µs Continuous Power Dissipation (T A = +70 C) Plastic DIP (derate 9.09mW/ C above +70 C)...727mW µmax (derate 4.0mW/ C above +70 C)...330mW SO (derate 5.88mW/ C above +70 C)...47mW Operating Temperature Ranges _C...0 C to +70 C _E C to +85 C Storage Temperature Range C to +60 C Lead Temperature (soldering, 0sec) 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 ( = full range, T A = T MIN to T MAX, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS Range _C _E V Supply Current (Note ) R/S/T only All versions _C, < 3.6V _E, < 3.6V _C, < 5.5V _E, < 5.5V µa Threshold, V TH L M T S R V to Delay = reset threshold max to reset threshold min 20 µs Reset Active Timeout Period = reset threshold max, rising ms I SINK =.2mA, = reset threshold min, R/S/T only I SINK = 3.2mA, = reset threshold min, L/M only Output Voltage I SINK = 50µA,.0V, _C 0.3 I SINK = 00µA,.2V, _E 0.4 V I SOURCE = 500µA, reset threshold max, R/S/T only I SOURCE = 800µA, reset threshold max, L/M only 0.8 x -.5 Note : Supply current is measured with = 3.6V for R/S/T, and = 5.5V for all versions. 2

3 Typical Operating Characteristics POWER-UP DELAY (ms) POWER-UP DELAY vs. TEMPERATURE = THRESHOLD MAX, RISING TEMPERATURE ( C) POWER-DOWN DELAY (µs) POWER-DOWN DELAY vs. TEMPERATURE 4 STEPPED FROM THRESHOLD MAX TO THRESHOLD MIN TEMPERATURE ( C) SUPPLY CURRENT (µa) SUPPLY CURRENT vs. TEMPERATURE NOTE: STEADY-STATE SUPPLY CURRENT IS INDEPENDENT OF OUTPUT STATUS NO LOAD = +5V = +4V = +3V = +2V NORMALIZED THRESHOLD NORMALIZED THRESHOLD vs. TEMPERATURE THE THRESHOLD IS SHOWN NORMALIZED TO, REPRESENTING ALL AVAILABLE THRESHOLDS 0 = +V TEMPERATURE ( C) TEMPERATURE ( C) 3

4 Pin Description PIN NAME FUNCTION, 4, 5, 6, 8 No Connect. There is no internal connection to this pin. 2 +5V, +3.3V, or +3V Supply Voltage 3 Ground 7 Reset Output remains low while is below the reset threshold, and for 280ms after rises above the reset threshold. MAXIMUM TRANSIENT DURATION (µs) 50 T A = +25 C 00 L/M 50 0ns R/S/T k 0k COMPARATOR OVERDRIVE, V TH - (mv) Applications Information Negative-Going Transients In addition to issuing a reset to the microprocessor (µp) during power-up, power-down, and brownout conditions, the is relatively immune to short duration negative-going transients (glitches). Figure shows typical transient duration vs. reset comparator overdrive, for which the does not generate a reset pulse. The graph was generated using a negative-going pulse applied to, starting.5v above the actual reset threshold and ending below it by the magnitude indicated (reset comparator overdrive). The graph indicates the typical maximum pulse width that a negative-going transient may have without causing a reset pulse to be issued. As the magnitude of the transient increases (goes farther below the reset threshold), the maximum allowable pulse width decreases. Typically, for the L/M, a transient that goes 00mV below the reset threshold and lasts 40µs or less will not cause a reset pulse to be issued. Figure. Maximum Transient Duration without Causing a Reset Pulse vs. Reset Comparator Overdrive A 0.µF bypass capacitor mounted as close as possible to pin 2 ( ) provides additional transient immunity. Ensuring a Valid Output Down to = 0V When falls below V, the output no longer sinks current it becomes an open circuit. Therefore, high-impedance CMOS logic inputs connected to the output can drift to undermined voltages. This presents no problem in most applications, since most µp and other circuitry is inoperative with below V. However, in applications where the output must be valid down to 0V, adding a pulldown resistor to the pin will cause any stray leakage currents to flow to ground, holding low (see Figure 2). The resistance value of R is not critical. It should be about 00kΩ, which is large enough not to load and small enough to pull to ground. 4

5 R 4.7k BUFFER µp BUFFERED TO OTHER SYSTEM COMPONENTS Figure 2. Valid to = Ground Circuit Figure 3. Interfacing to µps with Bidirectional Reset I/O Interfacing to µps with Bidirectional Reset Pins Microprocessors with bidirectional reset pins (such as the Motorola 68HC series) can contend with the reset output. If, for example the output is asserted high and the µp wants to pull it low, indeterminate logic levels may result. To correct this, connect a 4.7kΩ resistor between the output and the µp reset I/O (see Figure 3). Buffer the output to other system components. 5

6 µp Supervisory Circuits Minimum Nominal Nominal Reset Watchdog Power- Reset Pulse Timeout Backup- CE - Fail Manual- Watch- Low- Active- Battery- Part Threshold Width Period Battery Write Com- Reset dog Line High On Number (V) (ms) (sec) Switch Protect parator Input Output Output Reset Output MAX690A/692A 4.65/ MAX69A/693A 4.65/ /adj..6/adj. /0ns MAX696 Adj. 35/adj..6/adj. MAX697 Adj. 35/adj..6/adj. MAX /adj MAX703/ / MAX705/ / MAX706P MAX706R/S/T 2.63/2.93/ MAX707/ / MAX708R/S/T 2.63/2.93/ L/M/ 4.65/4.40/ 40 - R/S/T 2.63/2.93/3.08 MAX /0ns MAX792L/M/ 4.65/4.40/ 40 /0ns R/S/T 2.63/2.93/3.08 MAX800L/M 4.60/ /adj. /0ns /±2% MAX802L/M 4.60/ /±2% MAX805L MAX83L MAX820L/M/ 4.65/4.40/ 40 /0ns /±2% R/S/T 2.63/2.93/3.08 MAX / /0.60/.2 MAX

7 Chip Topography 0.045" (.43mm) 0.056" (.422mm) TRANSISTOR COUNT: 380 SUBSTRATE CONNECTED TO 7

8 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 0.6±0. 0.6±0. 8 Ø0.50±0. D TOP VIEW E H 4X S BOTTOM VIEW 8 DIM A A INCHES MIN MAX BSC A b c D e E 0.6 H 0.88 L 0.06 α 0 S BSC MILLIMETERS MIN MAX BSC BSC 8LUMAXD.EPS A2 A A e b c L α FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 8L umax/usop APPROVAL DOCUMENT CONTROL NO. REV J 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. 8 Maxim Integrated Products, 20 San Gabriel Drive, Sunnyvale, CA (408) Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.