MAX795RESA Maxim Integrated Products, MAX795RESA Datasheet
MAX795RESA
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... Battery-Powered Computers and Controllers Embedded Controllers Intelligent Controllers Critical µP Power Monitoring Portable Equipment Pin Configurations appear at end of data sheet. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. Supervisory Circuits ____________________________Features MAX793/MAX794/MAX795 ...
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... Adjustable Microprocessor Supervisory Circuits ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) V ......................................................................-0.3V to +6. ...................................................................-0.3V to +6.0V BATT All Other Inputs ..................-0.3V to the higher of V Continuous Input Current V .................................................................................200mA CC V ................................................................................50mA BATT GND ..................................................................................20mA Output Current V ................................................................................200mA OUT All Other Outputs ..............................................................20mA Stresses beyond those listed under “ ...
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... Voltage High RESET Output Leakage I LEAK Current (Note 9) PFO Output Short to GND I SC Current PFO, RESET, RESET, WDO, LOWLINE Output-Voltage V OL Low _______________________________________________________________________________________ Supervisory Circuits = 3.02V to 5.5V for the MAX793S/MAX795S unless otherwise noted. Typical values are MIN MAX CONDITIONS MAX793T/MAX795T V falling MAX793S/MAX795S CC ...
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... Adjustable Microprocessor Supervisory Circuits ELECTRICAL CHARACTERISTICS (continued 3.17V to 5.5V for the MAX793T/MAX795T MAX793R/MAX794/MAX795R 3.6V, T BATT PARAMETER SYMBOL RESET Output-Voltage Low V OL BATT ON Output Voltage Low All Inputs Including PFO V IH (Note 10 MANUAL RESET INPUT MR Pulse Width t MR MR-to-Reset Delay t MD ...
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... TEMPERATURE (°C) MAX793 LOWLINE-TO-RESET THRESHOLD vs. TEMPERATURE 100 V FALLING -40 - 100 TEMPERATURE (°C) _______________________________________________________________________________________ Supervisory Circuits BATT-TO-OUT ON-RESISTANCE vs. TEMPERATURE 160 140 V = 3.0V BATT 120 V = 3.6V BATT 100 250µA OUT BATT CC 40 -40 - 100 TEMPERATURE (°C) RESET TIMEOUT PERIOD vs. TEMPERATURE 250 200 ...
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... Adjustable Microprocessor Supervisory Circuits ____________________________Typical Operating Characteristics (continued +25°C, unless otherwise noted.) A MAX794 RESET IN THRESHOLD AND LOWLINE-TO-RESET IN THRESHOLD vs. TEMPERATURE 1.242 1.241 V RESET IN 1.240 1.239 LOWLINE RST 1.238 1.237 V FALLING CC 1.236 -40 - 100 TEMPERATURE (°C) MAX793/MAX794 WATCHDOG TIMEOUT PERIOD vs. TEMPERATURE 1.70 1.65 1 ...
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... CE OUT — RESET LOWLINE 14 — RESET BATT _______________________________________________________________________________________ Supervisory Circuits FUNCTION Supply Output for CMOS RAM. When OUT is connected to V through an internal p-channel MOSFET switch. When BATT CC V falls below V and V , BATT connects to OUT BATT Main Supply Input Battery Status Output. High in normal operating mode when V wise low ...
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... MR to ground to provide additional noise immunity. A microprocessor’s (µP’s) reset input starts the µ known state. These MAX793/MAX794/MAX795 µP (200ms) supervisory circuits assert a reset to prevent code exe- RP cution errors during power-up, power-down, and V LL ...
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... MAX794 RESET IN CC RST IN RST Figure 2. Timing Diagram, V Falling CC _______________________________________________________________________________________ Supervisory Circuits If a brownout condition occurs (V reset threshold), RESET goes low. Each time RESET is is BATT = asserted, it stays low for the reset timeout period. Any BATT ≥ 1V. time timer restarts. The watchdog output (WDO) can also be used to initi- ate a reset ...
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... Adjustable Microprocessor Supervisory Circuits (OPTIONAL) Si9433DY 3.3V SILICONIX D S 0.1µF PMOS R1 V BATT ON OUT CC RESET IN CE OUT R2 MAX794 ADDRESS CE IN BATT DECODER 0.1µF 3.6V WDI WDO LOWLINE V MR +5V SUPPLY PFO FAILURE +5V RESET PFI GND Figure 3. MAX794 Standard Application Circuit The MAX793T/MAX795T are intended for 3.3V systems with a ± ...
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... WDO returns high. This delay results in a 10µs pulse at WDO, allowing external circuitry to capture a watchdog fault indication. A con- tinuous high or low on WDI causes 200ms reset pulses to be issued every 1.6s. ______________________________________________________________________________________ Supervisory Circuits V CC WDO RESET WDI Figure 6 ...
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... Adjustable Microprocessor Supervisory Circuits MAX793 MAX794 MAX795 CHIP-ENABLE OUTPUT CONTROL RESET P GENERATOR Figure 7. Chip-Enable Transmission Gate The CE transmission gate remains disabled and CE IN remains high impedance (regardless activity) for the first half of the reset timeout period (t time a reset is generated. While disabled high impedance. When the CE transmission gate is enabled, the impedance appears as a 46Ω ...
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... MAX794 PFI PFO R2 GND Figure 10. Using the Power-Fail Comparator to Generate Power-Fail Warning ______________________________________________________________________________________ Supervisory Circuits In most battery-operated portable systems, reserve V CC energy in the battery provides ample time to complete V the shutdown routine once the low-line warning is CC encountered and before reset asserts. If the system ...
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... Adjustable Microprocessor Supervisory Circuits MAX793 PFI MAX794 R2 GND PFO TRIP – TRIP PFT PFH – PFT (a) Figure 12. Using the Power-Fail Comparator to Monitor an Additional Power Supply: (a) V The power-fail comparator turns off and PFO goes low when V falls below V on power-down. During the ...
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... Logic low CE IN High impedance CE OUT Pulled to BATT __________Applications Information These µP supervisory circuits are not short-circuit pro- tected. Shorting V to ground, excluding power-up OUT transients such as charging a decoupling capacitor, destroys the device. Decouple both V pins to ground by placing 0.1µF ceramic capacitors as close to the device as possible ...
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... Adjustable Microprocessor Supervisory Circuits 3.0V OR 3.3V V BATT ON CC MAX793 MAX794 MAX795 GND (a) Figure 14. Driving an External Transistor with BATT ON 3.0V OR 3.3V MAX793 V CC MAX794 1N4148 BATT 0.47F GND (a) Figure 15. Using a Super Cap as a Backup Source Adding Hysteresis to the Power-Fail Comparator (MAX793/MAX794) The power-fail comparator has a typical input hystere- sis of 10mV ...
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... These supervisors are relatively immune to short-dura- tion negative-going V transients (glitches) while issu- CC ing resets to the µP during power-up, power-down, and brownout conditions. Therefore, resetting the µP when V experiences only small glitches is usually not rec- CC ommended. ______________________________________________________________________________________ Supervisory Circuits V CC MAX793 MAX794 GND *OPTIONAL ...
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... Adjustable Microprocessor Supervisory Circuits Figure 18 shows maximum transient duration vs. reset- comparator overdrive, for which reset pulses are not generated. The graph was produced using negative- going V pulses, starting at 3.3V and ending below CC the reset threshold by the magnitude indicated (reset comparator overdrive). The graph shows the maximum ...
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... The MAX794’s reset threshold is adjustable. 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. Chip Information TRANSISTOR COUNT: 1271 ______________________________________________________________________________________ Supervisory Circuits _________________Pin Configurations PIN- PACKAGE TOP VIEW 16 Plastic DIP 16 Narrow SO ...
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... 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. 20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2010 Maxim Integrated Products ...