MAX791C/D MAXIM [Maxim Integrated Products], MAX791C/D Datasheet

no-image

MAX791C/D

Manufacturer Part Number
MAX791C/D
Description
Microprocessor Supervisory Circuit
Manufacturer
MAXIM [Maxim Integrated Products]
Datasheet
1.MAX791CD.pdf (20 pages)
The MAX791 microprocessor (µP) supervisory circuit
reduces the complexity and number of components need-
ed to monitor power-supply and battery-control functions
in µP systems. The 50µA supply current makes the
MAX791 ideal for use in portable equipment, while the 6ns
chip-enable propagation delay and 250mA output capa-
bility (25mA in battery-backup mode) make it suitable for
larger, higher-performance equipment.
The MAX791 comes in 16-pin DIP and narrow SO pack-
ages and provides the following functions:
6) Software monitoring of backup-battery voltage.
1) µP reset—
2) Manual-reset input.
3) A 1.25V threshold detector provides for power-fail
4) Two-stage power-fail warning—a separate low-line
5) Backup-battery switchover for CMOS RAM, real-time
7) A watchdog-fault output is asserted if the watchdog
8) Write protection of CMOS RAM or EEPROM.
9) Pulsed watchdog output, to give advance warning of
________________________Applications
19-0075; Rev. 5; 7/95
_____________________
Call toll free 1-800-998-8800 for free samples or literature.
__________________Pin Configuration
Computers
Controllers
Portable/Battery-Powered Equipment
MaxCap is a registered trademark of The Carborundum Corp.
power-down, and brownout conditions, and is guaran-
teed to be in the correct state for V
even with no battery in the circuit.
warning and low-battery detection, or monitors a
power supply other than +5V.
comparator compares V
above the reset threshold.
clocks, µPs, or other low-power logic.
input has not been toggled within either a preset or
an adjustable timeout period.
impending
TOP VIEW
BATT ON
–
R
—
–
W
—
VBATT
E
—
V
D
GND
SWT
PFO
S
—
V
OUT
—
PFI
CC
O
E
—
–
________________________________________________________________ Maxim Integrated Products
–
T
assertion caused by watchdog timeout.
1
2
3
4
5
6
7
8
output is asserted during power-up,
General Description
MAX791
DIP/SO
Critical µP Power Monitoring
Intelligent Instruments
CC
Microprocessor Supervisory Circuit
to a threshold 150mV
16
15
14
13
12
11
10
9
WDPO
RESET
WDO
WDI
LOWLINE
MR
CE IN
CE OUT
CC
down to 1V,
SuperCap is a registered trademark of Baknor Industries.
____________________________Features
* Dice are specified at T
__________Typical Operating Circuit
RESET SOURCES
OTHER SYSTEM
______________Ordering Information
MAX791CPE
MAX791CSE
MAX791C/D
MAX791EPE
MAX791ESE
MAX791EJE
MAX791MJE
Precision 4.65V Voltage Monitoring
200ms Power-OK / Reset Time Delay
Independent Watchdog Timer—Preset or Adjustable
1µA Standby Current
Power Switching
On-Board Gating of Chip-Enable Signals
MaxCap
Voltage Monitor for Power-Fail or Low-Battery Warning
Backup-Battery Monitor
Guaranteed
* MaxCap
+5V
0.1 F
PART
250mA Output in V
25mA Output in Battery-Backup Mode
Memory Write-Cycle Completion
6ns CE Gate Propagation Delay
0.47F*
+12V
+12V SUPPLY
‰
FAILURE
or SuperCap
–
R
—
E
—
S
—
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
E
V
VBATT
MR
PFI
PFO
—
TEMP. RANGE
GND
CC
0°C to +70°C
0°C to +70°C
0°C to +70°C
T
–
A
MAX791
= +25°C.
Valid to V
BATT
ON
CC
‰
LOWLINE
CE OUT
Compatible
RESET
Mode
CE IN
WDO
V
SWT
WDI
OUT
CC
ADDRESS
DECODE
= 1V
0.1 F
16 Plastic DIP
16 Narrow SO
Dice*
16 Plastic DIP
16 Narrow SO
16 CERDIP
16 CERDIP
PIN-PACKAGE
I/O
NMI
RESET
INT
A0–A15
P
CMOS
RAM
1

Related parts for MAX791C/D

Image
Part Number
Description
Manufacturer
Datasheet
Request R
5962-89877012C
Part Number:
5962-89877012C
Description:
LCC/M°/CIRCUITI INTEGRATI MAXIM
Manufacturer:
Maxim Integrated Products
Datasheet:
5962-89877012C.pdf (36 pages)
MAXPMBAE1#
Part Number:
MAXPMBAE1#
Description:
KIT/E/MAXIM ANALOG ESSENTIALS # COLLECTION OF PLUG-IN EVALUATION MODULES
Manufacturer:
Maxim Integrated Products
MAX3261CCJ
Part Number:
MAX3261CCJ
Description:
Single +5V, fully integrated, 1.25Gbps laser diode driver.
Manufacturer:
Maxim Integrated Products
Datasheet:
MAX3261CCJ.pdf (12 pages)
MAX3263CAG
Part Number:
MAX3263CAG
Description:
Single +5V, fully integrated, 155Mbps laser diode driver.
Manufacturer:
Maxim Integrated Products
Datasheet:
MAX3263CAG.pdf (12 pages)
MAX8809AETL+
Part Number:
MAX8809AETL+
Description:
VRD11/VRD10, K8 Rev F 2/3/4-Phase PWM Controllers with Integrated Dual MOSFET Drivers
Manufacturer:
Maxim Integrated Products
Datasheet:
MAX8809AETL.pdf (50 pages)
MAX1535CETJ+T
Part Number:
MAX1535CETJ+T
Description:
Highly Integrated Level 2 SMBus Battery Chargers
Manufacturer:
Maxim Integrated Products
Datasheet:
MAX1535CETJT.pdf (39 pages)
DS2741N+
Part Number:
DS2741N+
Description:
Current Monitor and Accumulator with Integrated Sense Resistor; ; Temperature Range: -40°C to +85°C
Manufacturer:
Maxim Integrated Products
MAX13450EAUD+T
Part Number:
MAX13450EAUD+T
Description:
TSSOP 14/A°/RS-485 Transceivers with Integrated 100O/120O Termination Resis
Manufacturer:
Maxim Integrated Products
MAX13451EAUD+T
Part Number:
MAX13451EAUD+T
Description:
TSSOP 14/A°/RS-485 Transceivers with Integrated 100O/120O Termination Resis
Manufacturer:
Maxim Integrated Products
MAX17497BATE+
Part Number:
MAX17497BATE+
Description:
QFN 16/A°/AC-DC and DC-DC Peak-Current-Mode Converters with Integrated Step
Manufacturer:
Maxim Integrated Products
MAX17502FATB+T
Part Number:
MAX17502FATB+T
Description:
TDFN/A/65V, 1A, 600KHZ, SYNCHRONOUS STEP-DOWN REGULATOR WITH INTEGRATED SWI
Manufacturer:
Maxim Integrated Products
MAX1978EVKIT
Part Number:
MAX1978EVKIT
Description:
Integrated Temperature Controller f
Manufacturer:
Maxim Integrated Products
MAX2606EUT+
Part Number:
MAX2606EUT+
Description:
SOT23-6/I°/45MHz to 650MHz, Integrated IF VCOs with Differential Output
Manufacturer:
Maxim Integrated Products
MAX2608EUT+
Part Number:
MAX2608EUT+
Description:
SOT23-6/I°/45MHz to 650MHz, Integrated IF VCOs with Differential Output
Manufacturer:
Maxim Integrated Products
MAX2831EVKIT+
Part Number:
MAX2831EVKIT+
Description:
EVALUATION KIT/2.4GHZ TO 2.5GHZ 802.11G/B RF TRANSCEIVER WITH INTEGRATED PA
Manufacturer:
Maxim Integrated Products

MAX791C/D Summary of contents

Page 1

... MaxCap or SuperCap CC Voltage Monitor for Power-Fail or Low-Battery Warning Backup-Battery Monitor – Guaranteed R ______________Ordering Information PART MAX791CPE MAX791CSE MAX791C/D MAX791EPE MAX791ESE MAX791EJE MAX791MJE * Dice are specified at T __________Typical Operating Circuit +5V 0.1 F 0.47F* OTHER SYSTEM RESET SOURCES WDPO RESET +12V ...

Page 2

Microprocessor Supervisory Circuit ABSOLUTE MAXIMUM RATINGS Input Voltage (with respect to GND) V .......................................................................-0.3V to +6V CC VBATT..................................................................-0. All Other Inputs.....................................-0. Input Current V Peak ..........................................................................1. Continuous ............................................................250mA CC VBATT Peak ..................................................................250mA VBATT ...

Page 3

Microprocessor Supervisory Circuit ELECTRICAL CHARACTERISTICS (continued 4.75V to 5.5V, VBATT = 2.8V PARAMETER I BATT ON Output SINK Low Voltage I SINK Sink current BATT ON Output Short-Circuit Current Source current RESET, LOW-LINE ...

Page 4

Microprocessor Supervisory Circuit ELECTRICAL CHARACTERISTICS (continued 4.75V to 5.5V, VBATT = 2.8V PARAMETER V WDI Threshold Voltage IH (Note WDI = 0V WDI Input Current WDI = V POWER-FAIL COMPARATOR ...

Page 5

Microprocessor Supervisory Circuit __________________________________________Typical Operating Characteristics (T = +25°C, unless otherwise noted SUPPLY CURRENT vs. TEMPERATURE CC (NORMAL OPERATING MODE +5V CC VBATT = 2.8V 54 PFI ...

Page 6

Microprocessor Supervisory Circuit ____________________________Typical Operating Characteristics (continued +25°C, unless otherwise noted.) A BATTERY CURRENT vs. INPUT SUPPLY VOLTAGE 20 VBATT = 2.8V OUT ...

Page 7

Microprocessor Supervisory Circuit ______________________________________________________________Pin Description PIN NAME 1 VBATT Backup-Battery Input. Connect to external battery or capacitor and charging circuit. Output Supply Voltage threshold. When V falls below VBATT and V OUT CC Connect a 0.1µF capacitor ...

Page 8

Microprocessor Supervisory Circuit 150mV 4.65V VBATT CHIP-ENABLE OUTPUT CONTROL OUT 9 RESET MR GENERATION TIMEBASE FOR 8 RESET AND SWT WATCHDOG WATCHDOG 11 WATCHDOG TRANSITION WDI DETECTOR 7 PFI 1.25V MAX791 4 ...

Page 9

Microprocessor Supervisory Circuit 15 RESET 10k MAX791 Figure 4. Adding an external pull-down resistor ensures – — — — — – valid with V down to GND. CC RESET Output The MAX791’s RESET output ...

Page 10

Microprocessor Supervisory Circuit +5V 3. +5V REACTIVATE *SETS Q HIGH ON POWER-UP Figure 6. Two consecutive watchdog faults latch the system in reset. dog-timeout period, WDO goes low 70ns after the falling edge of WDPO and remains low ...

Page 11

Microprocessor Supervisory Circuit V CC RESET THRESHOLD OUT 15 s 100 s RESET RESET Figure 7. Reset and Chip-Enable Timing Chip-Enable Signal Gating The MAX791 provides internal gating of chip-enable (CE) signals, to prevent erroneous data from ...

Page 12

Microprocessor Supervisory Circuit FROM REGULATED 3 2 SUPPLY OUT 0.1 F 0.1 F MAX791 1 VBATT 3.0V 15 RESET 10 LOWLINE 11 WDI GND OUT 0.1 0 VOLTAGE ...

Page 13

Microprocessor Supervisory Circuit 1 VBATT MAX791 Figure 10. V and VBATT-to-V Switch CC OUT Battery-Backup Mode The MAX791 requires two conditions to switch to bat- tery-backup mode must be below the reset CC threshold; ...

Page 14

Microprocessor Supervisory Circuit + 1N4148 1 VBATT V OUT 0.47F MAX791 GND 4 Figure 12. SuperCap or MaxCap on VBATT Low-Battery Monitor The MAX791 low-battery voltage function monitors VBATT. Low-battery detection of 2.0V ±0.15V is moni- tored ...

Page 15

Microprocessor Supervisory Circuit PFI C1* R3 MAX791 R2 PFO GND TO P +5V PFO TRIP 1.25 TRIP ...

Page 16

Microprocessor Supervisory Circuit + PFI MAX791 R2 GND V- +5V PFO 0V V TRIP 1.25 1. TRIP = R1 R2 NOTE NEGATIVE TRIP Figure 15. Monitoring a Negative Voltage Monitoring ...

Page 17

Microprocessor Supervisory Circuit START SET WDI LOW SUBROUTINE OR PROGRAM LOOP, SET WDI HIGH RETURN END Figure 17. Watchdog Flow Diagram ______________________________________________________________________________________ Watchdog Software Considerations A way to help the watchdog timer keep a closer watch on software execution involves ...

Page 18

Microprocessor Supervisory Circuit __________________Chip Topography V VBATT WDPO OUT V CC GND BATT ON PFO PFI SWT MR LOWLINE 0.07" (1.778mm) SUBSTRATE CONNECTED TO V OUT TRANSISTOR COUNT: 729 18 ______________________________________________________________________________________ RESET WDO CE IN 0.11" CE OUT (2.794mm) WDI ...

Page 19

Microprocessor Supervisory Circuit ________________________________________________________Package Information ______________________________________________________________________________________ 0° - 15° Plastic DIP PLASTIC DUAL-IN-LINE PACKAGE (0.300 in.) 0°-8° 0.101mm ...

Page 20

Microprocessor Supervisory Circuits ___________________________________________Package Information (continued 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 ...

Related keywords