MAX792_05 Datasheet, PDF (1/16 Pages) Maxim Integrated Products – Microprocessor and Nonvolatile Memory Supervisory Circuits

19-0147; Rev. 4; 11/05
Microprocessor and Nonvolatile
Memory Supervisory Circuits
General Description
The MAX792/MAX820 microprocessor (µP) supervisory
circuits provide the most functions for power-supply
and watchdog monitoring in systems without battery
backup. Built-in features include the following:
• µP reset: Assertion of RESET and RESET outputs during
power-up, power-down, and brownout conditions.
RESET is guaranteed valid for V_CC down to 1V.
• Manual-reset input.
• Two-stage power-fail warning: A separate low-line
comparator compares V_CC to a preset threshold
120mV above the reset threshold; the low-line and
reset thresholds can be programmed externally.
• Watchdog fault output: Assertion of WDO if the watchdog
input is not toggled within a preset timeout
period.
• Pulsed watchdog output: Advance warning of
impending WDO assertion from watchdog timeout that
causes hardware shutdown.
• Write protection of CMOS RAM, EEPROM, or other
memory devices.
The MAX792 and MAX820 are identical, except the
MAX820 guarantees higher low-line and reset threshold
accuracy (±2%).
Applications
Computers
Controllers
Intelligent Instruments
Critical µP Power Monitoring
Features
♦ Manual-Reset Input
♦ 200ms Power-OK / Reset Time Delay
♦ Independent Watchdog Timer—Preset or Adjustable
♦ On-Board Gating of Chip-Enable Signals
♦ Memory Write-Cycle Completion
♦ 10ns (max) Chip-Enable Gate Propagation Delay
♦ Voltage Monitor for Overvoltage Warning
♦ ±2% Reset and Low-Line Threshold Accuracy
(MAX820, external programming mode)
Ordering Information
PART**
TEMP. RANGE
PIN-PACKAGE
MAX792_CPE
0°C to +70°C
16 Plastic DIP
MAX792_CSE
0°C to +70°C
16 Narrow SO
MAX792_C/D
0°C to +70°C
Dice*
Ordering Information continued at end of data sheet.
* Dice are tested at T_A = +25°C, DC parameters only.
**These parts offer 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.
Devices in PDIP, SO and µMAX packages are available in both lead-
ed and lead-free packaging. Specify lead free by adding the + sym-
bol at the end of the part number when ordering. Lead free not avail-
able for CERDIP package.
SUFFIX
RESET THRESHOLD (V)
L
4.62
M
4.37
T
3.06
S
2.91
R
2.61
Typical Operating Circuit
V_CC
3
0.1µF
V_CC
V_CC
4
CE OUT
RESET IN/INT
13
MAX792
5 _LLIN/
14
CE IN
REFOUT
OVO ⁶
ADDRESS
DECODER
µP
RAM
A0-A15
7 _OVI
8 _SWT
LOW LINE ¹⁰
RESET ¹
MR ⁹
GND
12
NMI
RESET
GND
________________________________________________________________ Maxim Integrated Products 1
For free samples and the latest literature, visit www.maxim-ic.com or phone [phone].
For small orders, phone [phone].