Power Supply Supervisor With Battery Backup Switch Applications

The Datasheet Archive - 100 Million Datasheets from 7500 Manufacturers.

Power Supply Supervisor With Battery Backup Switch Applications

Datasheet Thumbnail

Top Searches for this datasheet

ASM690A 692A ASM802L 802M ASM805L
Power Supply Supervisor With Battery Backup Switch
Applications
Embedded control systems Portable/Battery operated systems Intelligent instruments Wireless instruments Wireless communication systems PDAs hand-held equipments power supply monitoring Safety system
General Description
AS690A AS692A AS802L AS802M AS805L offers complete single chip solutions power supply monitoring control battery functions microprocessor systems. Each device implements four functions: Reset control, watchdog monitoring, battery-backup switching power-failure monitoring. addition microprocessor reset under power-up power-down conditions, these devices provide batterybackup switching maintain control power loss brownout situations. Additional monitoring capabilities provide early warning unregulated power supply loss before voltage regulator drops out. important features these four functions are:
Typical Operating Circuit
Unregulated Regulated RESET VBATT VOUT RESET
second watchdog timer keep microprocessor responsive 4.40V 4.65V threshold microprocessor reset power-up power-down SPDT (Single-pole, Double-throw) PMOS switch connects backup power fails 1.25V threshold detector power loss general purpose voltage monitoring
LINE
ASM690A
CMOS
These features pin-compatible with industry standard power-supply supervisors. Short-circuit thermal protection have also been added. AS690A AS802L 4.65V AS692A AS802M AS805L generate reset pulse when supply voltage drops below generate reset below
VBATT
Block Diagram
Reset Generator
Battery-Switchover Circuit VOUT RESET (RESET)
4.40V. ASM802L ASM802M have power-fail accuracy ASM805L same ASM690A except that RESET provided instead RESET.
Features
precision supply-voltage monitor options (AS690A AS802L AS805L) (AS692A AS802M Battery-backup power switch on-chip Watchdog timer: second timeout Power failure battery detection Short circuit protection thermal limiting Small 8-pin package external components Specified over full temperature range
1.25V 3.5V
Watchdog Timer
0.8V
1.25V
ASM690A, ASM692A, ASM802L, ASM802M, (ASM805L)
Alliance Semiconductor 2575 Augustine Drive Santa Clara, 95054 Tel: 408.855.4900 Fax: 408.855.4999 www.alsc.com
Notice: information this document subject change without notice
Lithium Battery
ASM690A 692A ASM802L 802M ASM805L
Configuration
Plastic/CerDip/SO
VOUT
ASM690A ASM692A ASM802L ASM802M (ASM805L)
VBATT RESET (RESET)
Description
Number ASM690A ASM692A ASM802L ASM802M Name ASM805L Function
Voltage supply RAM. When above reset threshold, VOUT connects VOUT through P-Channel device. falls below reset threshold, this output will connected backup supply VBATT VCC, whichever higher) through switch provide continuous power CMOS RAM. power supply input. Ground Power failure monitor input. connected internal power fail comparator which referenced 1.25V. power fail output (PFO) active remains HIGH above 1.25V. this feature unused, should connected VOUT. Power-fail output. active whenever less than 1.25V. Watchdog input. input monitors microprocessor activity. internal timer reset with each transition input. held HIGH longer than watchdog timeout period, typically seconds, RESET RESET) asserted reset pulse width time, tRS, 140ms, minimum. Active-LOW reset output. When triggered falling below reset threshold RESET watchdog timer timeout, RESET RESET) pulses reset pulse width tRS, typically 200ms. will remain below reset threshold (4.65V ASM690A ASM802L 4.4V ASM692A ASM802L) remains 200ms after rises above reset threshold. RESET VBATT Active-HIGH reset output. inverse RESET. Auxiliary power backup-battery input. VBATT should connected function used. input about 40mV hysteresis prevent rapid toggling between VBATT.
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
ASM690A 692A ASM802L 802M ASM805L
Application Information
Microprocessor Interface ASM690 logic-LOW RESET output while ASM805 inverted logic-HIGH RESET output. Microprocessors with bidirectional reset pins pose problem when supervisory circuit microprocessor output pins attempt opposite logic states. problem resolved placing 4.7k resistor between RESET output microprocessor reset pin. This shown Figure Since series resistor limits drive capabilities, reset signal other devices should buffered.
Detailed Description
important initialize microprocessor known state response specific events that could create code execution errors "lock-up". reset output these supervisory circuits send reset pulse microprocessor response power-up, power-down/power-loss watchdog time-out. RESET/RESET Timing Power-up reset occurs when rising reaches reset threshold, VRT, forcing reset condition which reset output asserted appropriate logic state duration tRS. reset pulse width, tRS, typically around 200ms ASM690A, ASM692A, ASM802 HIGH ASM805L. Figure shows reset timing. Power-loss "brown-out" reset occurs when dips below reset threshold resulting reset assertion duration tRS. reset signal remains asserted long between 1.1V, lowest which these devices provide guaranteed logic-low output. ensure logic inputs connected ASM690A ASM692A/ASM802 RESET known state when under 1.1V, 100k pull-down resistor RESET needed: logic-high ASM805L will need pull-up resistor VCC. Watchdog Timer Watchdog time-out reset occurs when logic logic continuously applied more than seconds. After duration reset interval, watchdog timer starts second timing interval; microprocessor must service watchdog input changing states floating before this interval finished. held either HIGH LOW, reset pulse will triggered every seconds (the second timing interval plus reset pulse width tRS).
Figure RESET/RESET Timing
Buffered RESET
4.7K Power Supply RESET
RESET
ASM690A
Bi-directional
Figure Interfacing with bi-directional microprocessor reset inputs
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
Watchdog Input discussed Reset section, Watchdog input used monitor microprocessor activity. used insure that microprocessor continually responsive state requiring that toggled every second. toggled within second window (minimum tRS), reset pulse will asserted return microprocessor initial start-up state. Pulses short 50ns applied pin. this feature used, should open circuited logic placed into high-impedance state allow float. Backup-Battery Switchover power loss made less severe system contents preserved. This achieved ASM690/692/ 802/805 switching from failed alternate power source connected VBATT when less than reset threshold voltage (VCC VRT), less than VBATT. VOUT normally connected through PMOS switch brown-out loss will cause switchover VBATT means PMOS switch. Although both conditions (VCC <VBATT) must occur switchover VBATT occur, VOUT will switched back when exceeds irrespective voltage VBATT. should noted that internal device diode Figure will forward biased VBATT exceeds more than diode drop when switched VOUT. Because this recommended that VBATT greater than +0.6V. VBATT
ASM690A 692A ASM802L 802M ASM805L
ASM690A ASM692A ASM802M
ASM805L
ASM802L
VOUT Figure Internal device configuration battery switch-over function
Table Connections Battery Backup Mode VOUT VBATT RESET Connection Connected VBATT through internal PMOS switch Connected VOUT Disabled Logic-LOW Logic-LOW (except ASM805 where HIGH) Watchdog timer disabled
Condition Reset Threshold Reset Threshold VBATT Reset Threshold VBATT
SW1/SW2 open open
SW3/SW4 closed closed During backup power mode, internal circuitry supervisory circuit draws power from battery supply. While still alive, comparator circuits remain alive current drawn device typically 35µA. When drops more than 1.1V below VBATT, internal switchover comparator, comparator comparator will shut off, reducing quiescent current drawn less than 1µA.
closed
open
ASM690A/802A/805L Reset Threshold 4.65V ASM692A /ASM802M Reset Threshold 4.4V
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
Backup Power Sources Batteries Battery voltage selection important insure that battery does discharge through parasitic device diode (see Figure when less than VBATT VRT. Table Maximum Battery Voltages
ASM690A 692A ASM802L 802M ASM805L
diode-resistor pair clamps capacitor voltage diode drop below VCC. itself should regulated within ASM692A/802M within ±10% ASM690A/802L/805L insure that storage capacitor does achieve over voltage state. Note: SuperCapis trademark Baknor Industries
Part Number ASM690A ASM802L ASM805L ASM692A ASM802M
MAXIMUM Battery Voltage 4.80 4.80 4.80 4.55 4.55
VBATT
VOUT
SRAM
RESET (RESET)
0.1F
Although most batteries that meet requirements Table acceptable, lithium batteries very effective backup source their high-energy density very selfdischarge rates. Battery replacement while Powered Batteries replaced even when device powered state long remains above reset threshold voltage VRT. devices, floating VBATT will cause powersupply switchover occur some other supervisory circuits. VBATT used, should grounded. Backup Power Sources SuperCapCapacitor storage, with very high values capacitance, used back-up power source instead batteries. SuperCapare capacitors with capacities fractional farad range. farad SuperCapwould provide useful backup power source. Like battery supply, important that capacitor voltage remain below maximum voltages shown Table Although circuit Figure shows most simple connect SuperCapTM, this circuit cannot insure that over voltage condition will occur since capacitor will ultimately charge VCC. insure that over voltage condition does occur, circuit Figure preferred. this circuit configuration,
ASM692A ASM802M
Figure Capacitor backup power source
VOUT
SRAM
VBATT
100K
RESET (RESET)
0.1F
ASM692A ASM802M
Figure Capacitor backup power source Voltage clamped 0.5V below
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
Operation without Backup Power Source When operating without back-up power source, VBATT should connected VOUT should connected VCC, since power source switchover will occur. Connecting VOUT eliminates voltage drop ON-resistance PMOS switch. Power-Fail Comparator Power Fail feature independent voltage monitoring function that used number monitoring activities. function provide early sensing power supply failure sensing voltage unregulated ahead regulated supply sensing seen backup-battery switchover circuitry. compared 1.25V internal reference. voltage less than this reference voltage, goes low. sensing voltage power supply, microprocessor system prepare imminent power-loss, especially battery backup supply enabled. input voltage results from simple resistor voltage divider shown Figure Power Fail Hysteresis
ASM690A 692A ASM802L 802M ASM805L
noise margin added simple monitoring circuit Figure adding positive feedback from pin. circuit Figure adds this positive "latching" effect means additional resistor connected between which helps pulling direction eliminating indecision trip point. Resistor normally about times higher resistance than keep hysteresis band reasonable should larger than avoid excessive loading pin. calculations correct values resistors hysteresis thresholds given Figure capacitor added offer additional noise rejection low-pass filtering.
ASM690A ASM692A ASM802L ASM802M ASM805L
ASM690A ASM692A ASM802L ASM802M ASM805L
Optional
1.25 TRIP
VTRIP
1.25
1.25V 1.25V
1.25 1.25 1.25
Figure Simple Voltage divider sets trip point Figure Hysterisis Added
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
Monitoring Capabilities Power-fail Input: Although designed power supply failure monitoring, used monitoring voltage condition that scaled means resistive divider. example negative power supply monitor configured Figure this case good negative supply will hold below 1.25V will logic "0". negative voltage declines, voltage will rise until exceeds 1.25V will logic "1".
ASM690A 692A ASM802L 802M ASM805L
ASM692A
ASM802L ASM802M ASM690A
ASM805L
VTRIP
VTRIP
1.25 TRIP 1.25
Figure Using Monitor Negative Supply Voltage
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
ASM690A 692A ASM802L 802M ASM805L
Absolute Maximum Ratings
Parameter Terminal Voltage with Respect Ground VBATT other inputs Input Current Input Current VBATT Input Current Output Current VOUT other inputs Rate Rise: VBATT Continuous Power Dissipation Plastic (derate 9mW/°C above 70°C) (derate 5.9mW/°C above 70°C) CerDIP (derate 8mW/°C above 70°C) Operating Temperature Range Devices) Operating Temperature Range Devices) Storage Temperature Range Lead Temperature Soldering, sec) Short circuit protected V/µs -0.3 -0.3 -0.3 Unit
input voltage limits exceeded current limited less than 10mA Note: These stress ratings only functional operation implied. Exposure absolute maximum ratings prolonged time periods affect device reliability.
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
ASM690A 692A ASM802L 802M ASM805L
Electrical Characteristics:
Unless other wise noted, 4.75V 5.5V ASM690A ASM802L ASM805L 4.5V 5.5V ASM692A ASM802M; VBATT 2.8V; TMIN TMAX.
Parameter
Symbol
Conditions ASM69_AC, ASM802_C
Unit
VCC, VBATT Voltage Range (Note
ASM805LC ASM69_AE, ASM80_E
Supply Current Excluding IOUT ISUPPLY Battery Backup Mode (Excluding IOUT) VBATT Standby Current (Note
ASM69_AC, ASM80_E ASM69_AC, ASM802_C 25°C VBATT=2.8V TMIN TMAX 25°C TMIN TMAX -0.1 -1.0 VCC0.025 VCC-0.25 VBATT-0.1
0.02 0.02
5.5V>VCC>VBATT-0.2V IOUT IOUT 50mA
VOUT Output
VCC-0.010 VCC-0.10 VBATT-0.001
VOUT Battery Backup Mode Battery Switch Threshold, VBATT Battery Switch over Hysteresis
IOUT=250µA, VBATT-0.2V Power Power Down
4.75 4.50 4.70 4.45
ASM690A/802L/805L ASM692A, ASM802M Reset Threshold ASM802L, 25°C, falling ASM802M, TA=25°C, falling Notes: VBATT other must greater than 2.0V.
4.50 4.25 4.55 4.30
4.65 4.40
Battery charging-current "-". Battery discharge current "+". guaranteed intermediate level state floating within operating voltage range. input impedance biased 0.3VCC.
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
Parameter Reset Threshold Hysteresis Reset Pulse Width ISOURCE 800µA ISINK 3.2mA ASM69_AC, ASM802_C, VCC=1.0V, ISINK=50µA Reset Output Voltage ASM69_AE, ASM802_E, VCC=1.2V, ISINK=100µA ASM805LC, ISOURCE=4µA, 1.1V ASM805LE, ISOURCE=4µA, 1.2V ASM805L, ISOURCE=800µA ASM805L, ISINK=3.2mA Watchdog Timeout Pulse Width Input Current Input Threshold (Note Input Threshold Input Current Output Voltage ISOURCE 800µA ISINK 3.2mA 0.4V, 0.8VCC Logic ASM69_A,ASM805L, ASM802_C/E, 1.20 1.225 -150 1.00 Symbol Conditions
ASM690A 692A ASM802L 802M ASM805L
Unit
1.60 2.25 1.25 1.250 0.01 1.30 1.275
Notes: VBATT other must greater than 2.0V. Battery charging-current "-". Battery discharge current "+". guaranteed intermediate level state floating within operating voltage range. input impedance biased 0.3VCC.
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
Plastic (8-Pin)
ASM690A 692A ASM802L 802M ASM805L
Package Information
Inches 0.015 0.115 0.014 0.045 0.030 0.355 0.005 0.300 0.240 0.100 0.300 0.115 0.015 0.014 0.038 0.008 0.005 0.290 0.220 0.100 0.125 0.053 0.004 0.013 0.007 0.050 0.150 0.228 0.016 0.189 0.157 0.244 0.050 0.197 0.200 (8-Pin) 0.069 0.010 0.020 0.010 1.35 0.10 0.33 0.19 1.27 3.80 5.80 0.40 4.80 4.00 6.20 1.27 5.00 1.75 0.25 0.51 0.25 Plastic (8-Pin) 0.210 0.195 0.022 0.070 0.045 0.400 0.325 0.280 0.430 0.060 0.150 CerDIP (8-Pin) 0.200 0.070 0.023 0.065 0.015 0.405 0.320 0.310 0.38 0.36 0.97 0.20 0.13 7.37 5.59 2.54 3.18 5.08 5.08 1.78 0.58 1.65 0.38 10.29 8.13 7.87 2.92 3.81 0.38 2.92 0.36 1.14 0.80 0.80 0.13 7.62 6.10 2.54 7.62 10.92 5.33 4.95 0.56 1.78 1.14 1.14 8.26 7.11 Millimeters
CerDIP (8-Pin)
(8-Pin)
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
ASM690A 692A ASM802L 802M ASM805L
Ordering Information
Part Number ASM690A ASM690ACPA ASM690ACSA ASM690AC/D ASM690AEPA ASM690AESA ASM690AMJA ASM692A ASM692ACPA ASM692ACSA ASM692AC/D ASM692AEPA ASM692AESA ASM692AMJA ASM802L ASM802LCPA ASM802LCSA ASM802LAEPA ASM802LESA ASM802M ASM802MCPA ASM802MCSA ASM802MEPA ASM802MESA ASM805L ASM805LCPA ASM805LCSA ASM805LC/D ASM805LEPA ASM805LESA ASM805LMJA 4.75 4.75 4.75 4.75 4.75 4.75 Contact Factory 8-Plastic 8-SO DICE 8-Plastic 8-SO 8-Cer
Reset Threshold 4.75 4.75 4.75 4.75 4.75 4.25 4.50 4.25 4.50 4.25 4.50 4.25 4.50 4.25 4.50 4.25 4.50 4.75 4.75 4.75 4.75 4.25 4.50 4.25 4.50 4.25 4.50 4.25 4.50
Temperature Range (°C) Contact Factory Contact Factory
Pins-Package 8-Plastic 8-SO DICE 8-Plastic 8-SO 8-Cer 8-Plastic 8-SO DICE 8-Plastic 8-SO 8-Cer 8-Plastic 8-SO 8-Plastic 8-SO 8-Plastic 8-SO 8-Plastic 8-SO
Power Supply Supervisor With Battery Backup Switch
Notice: information this document subject change without notice
ASM690A 692A ASM802L 802M ASM805L
Alliance Semiconductor Corporation 2575, Augustine Drive, Santa Clara, 95054 Tel: 4900 Fax: 4999 www.alsc.com
Copyright Alliance Semiconductor Rights Reserved Part Number: ASM690A 692A ASM802L 802M ASM805L Document Version:
Copyright 2003 Alliance Semiconductor Corporation. rights reserved. three-point logo, name Intelliwatt trademarks registered trademarks Alliance. other brand product names trademarks their respective companies. Alliance reserves right make changes this document products time without notice. Alliance assumes responsibility errors that appear this document. data contained herein represents Alliance's best data and/or estimates time issuance. Alliance reserves right change correct this data time, without notice. product described herein under development, significant changes these specifications possible. information this product data sheet intended general descriptive information potential customers users, intended operate provide, guarantee warrantee user customer. Alliance does assume responsibility liability arising application product described herein, disclaims express implied warranties related sale and/or Alliance products including liability warranties related fitness particular purpose, merchantability, infringement intellectual property rights, except express agreed Alliance's Terms Conditions Sale (which available from Alliance). sales Alliance products made exclusively according Alliance's Terms Conditions Sale. purchase products from Alliance does convey license under patent rights, copyrights; mask works rights, trademarks, other intellectual property rights Alliance third parties. Alliance does authorize products critical components life-supporting systems where malfunction failure reasonably expected result significant injury user, inclusion Alliance products such life-supporting systems implies that manufacturer assumes risk such agrees indemnify Alliance against claims arising from such use.

Power Supply Supervisor With Battery Backup Switch Applications

Top Searches for this datasheet

Other recent searches