Document
19-1658; Rev 1; 6/01
SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating
General Description
The MAX6365–MAX6368 supervisory circuits simplify power-supply monitoring, battery-backup control functions, and memory write protection in microprocessor (µP) systems. The circuits significantly improve the size, accuracy, and reliability of modern systems with an ultrasmall integrated solution. These devices perform four basic system functions: 1) Provide a µP reset output during VCC supply powerup, power-down, and brownout conditions. 2) Internally control VCC to backup-battery switching to maintain data or low-power operation for CMOS RAM, CMOS µPs, real-time clocks, and other digital logic when the main supply fails. 3) Provide memory write protection through internal chip-enable gating during supply or processor faults. 4) Include one of the following options: a manual reset input (MAX6365), a watchdog timer function (MAX6366), a battery-on output (MAX6367), or an auxiliary user-adjustable reset input (MAX6368). The MAX6365–MAX6368 operate from VCC supply voltages as low as 1.2V. The factory preset reset threshold voltages range from 2.32V to 4.63V (see Ordering Information). In addition, each part is offered in three reset output versions: push-pull active low, open-drain active low, or open-drain active high (see Selector Guide). The MAX6365–MAX6368 are available in miniature 8-pin SOT23 packages.
Features
o Low +1.2V Operating Supply Voltage (VCC or VBATT) o Precision Monitoring of +5.0V, +3.3V, +3.0V, and +2.5V Power-Supply Voltages o On-Board Gating of Chip-Enable Signals, 1.5ns Propagation Delay o Debounced Manual Reset Input (MAX6365) o Watchdog Timer, 1.6s Timeout (MAX6366) o Battery-On Output Indicator (MAX6367) o Auxiliary User-Adjustable RESET IN (MAX6368) o Low 10µA Quiescent Supply Current o Three Available Output Structures Push-Pull RESET Open-Drain RESET Open-Drain RESET o RESET/RESET Valid Down to 1.2V Guaranteed (VCC or VBATT) o Power-Supply Transient Immunity o 150ms min Reset Timeout Period o Miniature 8-Pin SOT23 Package
MAX6365–MAX6368
Ordering Information
PART* MA X6 36 5LKA_ _-T MAX6365PKA_ _-T MAX6365HKA_ _-T MA X6 36 6LKA_ _-T MAX6366PKA_ _-T MAX6366HKA_ _-T MA X6 36 7LKA_ _-T MAX6367PKA_ _-T MAX6367HKA_ _-T MA X6 36 8LKA_ _-T MAX6368PKA_ _-T MAX6368HKA_ _-T TEMP. RANGE -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C PINPACKAGE 8 SOT23-8 8 SOT23-8 8 SOT23-8 8 SOT23-8 8 SOT23-8 8 SOT23-8 8 SOT23-8 8 SOT23-8 8 SOT23-8 8 SOT23-8 8 SOT23-8 8 SOT23-8
Applications
Critical µP/µC Power Monitoring Fax Machines Industrial Control Computers/Controllers Portable/BatteryPowered Equipment Set-Top Boxes POS Equipment
Pin Configurations
TOP VIEW
RESET, RESET CE IN GND 1 2 8 7 CE OUT BATT OUT VCC
MAX6365
3 6 5 MR 4
*These parts offer a choice of reset threshold voltages. From the Reset Threshold Ranges table, insert the desired threshold voltage code in the blank to complete the part number. SOT parts come in tape-and-reel only and must be ordered in 2500-piece increments. See Device Marking Codes for a complete parts list, including SOT top marks and standard threshold versions. See Selector Guide for a listing of device features.
SOT23 Pin Configurations continued at end of data sheet.
Typical Operating Circuit appears at end of data sheet. 1
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating MAX6365–MAX6368
ABSOLUTE MAXIMUM RATINGS
Terminal Voltages (with respect to GND) VCC, BATT, OUT.......................................................-0.3V to +6V RESET (open drain), RESET (open drain) ................-0.3V to +6V BATT ON, RESET (push-pull), RESET IN, WDI, CE IN, CE OUT ...........................-0.3V to (VOUT + 0.3V) MR ..............................................................-0.3V to (VCC + 0.3V) Input Current VCC Peak ..............................................................................1A VCC Continuous .............................................................250mA BATT Peak .....................................................................250mA BATT Continuous .............................................................40mA GND ...............................................................................75mA Output Current OUT ...............................Short-Circuit Protected for up to 10s RESET, RESET, BATT ON, CE OUT...............................20mA Continuous Power Dissipation (TA = +70°C) 8-Pin SOT23 (derate 8.75mW/°C above +70°C)........700mW Operating Temperature Range ...........................-40°C to +85°C.