MAX795RESA Maxim Integrated Products, MAX795RESA Datasheet
![no-image](/images/manufacturer_photos/0/4/417/maxim_integrated_products_sml.jpg)
MAX795RESA
Specifications of MAX795RESA
Available stocks
Related parts for MAX795RESA
MAX795RESA Summary of contents
Page 1
... 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 ...
Page 2
... 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 “ ...
Page 3
... 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 ...
Page 4
... 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 ...
Page 5
... 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 ...
Page 6
... 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 ...
Page 7
... 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 ...
Page 8
... 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 ...
Page 9
... 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 ...
Page 10
... 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 ± ...
Page 11
... 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 ...
Page 12
... 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 ...
Page 13
... 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 ...
Page 14
... 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 ...
Page 15
... 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 ...
Page 16
... 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 ...
Page 17
... 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 ...
Page 18
... 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 ...
Page 19
... 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 ...
Page 20
... 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 ...