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Part: IMP690A
Category:
Analog & Mixed-Signal Processing
-> Power
Description: Power Supply Supervisor With Battery Backup Switch
Company: IMP, Inc.
Datasheet: Download IMP690A datasheet File size : 29 kB
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Datasheet text preview:
IMP690A , 692A , 802L/M, 805L
POWER MANAGEMENT
µP Power Supply Supervisor with Battery Backup Switch
The IMP690A/IMP692A/IMP802L/IMP802M/IMP805L simplify power supply monitoring and control in microprocessor systems. Each circuit implements four functions: Reset control, watchdog monitoring, batterybackup switching and power-failure monitoring. In addition to microprocessor reset under powerup and power-down conditions, these devices provide battery-backup switching to maintain control in powerloss and brown-out situations. Additional monitoring capabilities can provide an early warning of unregulated power-supply loss before the voltage regulator drops out. The important features of these four functions are: a) 1.6 second watchdog timer to keep microprocessor responsive b) c) 4.40V or 4.65V VCC threshold for microprocessor reset at power-up and power-down SPDT (single-pole, double-throw) PMOS switch connects backup power to RAM if VCC fails
Key Features
x Design improvement over Maxim MAX690A/692A/802L/802M/805L -- 70% lower current than Maxim: 100µA maximum -- RESET Operation to 1.1V x Two precision supply-voltage monitor options -- 4.65V (IMP690A/802L/805L) -- 4.40V (IMP692A/802M) x Batter y-backup power switch on-chip x Watchdog timer: 1.6 second timeout x Power failure/low battery detection x Shor t-circuit protection and thermal limiting x Small 8-pin SO package x No external components x Specified over full temperature range
d) 1.25V threshold detector for power loss or general purpose voltage monitoring While these features are pincompatible with the industry standard powersupply supervisors offered by Maxim, the IMP devices are superior replacements and can reduce power requirements by 70 percent when compared to Maxim MAX690/MAX692A/MAX802L/MAX802M/ MAX805L devices. Short-circuit and thermal protection have also been added. The IMP690A/IMP802L/IMP805L generate a reset pulse when the supply voltage drops below 4.65V, and the IMP692A/IMP802M generate a reset below 4.40V. The IMP802L/IMP802M have powerfail accuracy to ±2%. The IMP805L is the same as the IMP690A except that RESET is provided instead ofET. RES
Applications
x Embedded control systems x Batter yoperated systems x Intelligent instruments x Wireless communication systems x PDAs and handheld equipment x µP/µC power supply monitoring
Block Diagrams
VBATT VCC
+
Typical Application
1 7 VOUT RESET (RESET) Unregulated DC 0.1µF PFI R2 Regulated +5V VCC RESET PFO WDI VOUT NMI I/O LINE GND BUS CMOS VCC RAM GND
690A_01.eps
8 2
Battery-Switchover Circuit Reset Generator
+
VCC RESET
R1
1.25V 3.5V 6 WDI
+ + + +
Watchdog Timer
+
3.6V Lithium Battery
VBATT GND
0.8V 4 PFI
1.25V
+ +
IMP690A
5 PFO
IMP690A, IMP692A, IMP802L, IMP802M, IMP805L ( ) IMP805L 3 GND
690A_03.eps
IMP, Inc.
San Jose, CA
408-432-9100/www.impweb.com
I M P 6 9 0 A , 692A , 802L, 802M, 805L
Pin Configuration
Plastic/CerDip/SO
VOUT VCC GND PFI 1 2 3 4 IMP690A IMP692A IMP802L IMP802M IMP805L 8 7 6 5 VBATT RESET (RESET) WDI PFO
( ) IMP805L
690A_02.eps
Ordering Information
Part Number IMP690A
IMP690ACPA IMP690ACSA IMP690AC/D IMP690AEPA IMP690AESA IMP690AMJA 4.5 to 4.75 4.5 to 4.75 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75
Reset Threshold (V)
4.5 to 4.75 4.5 to 4.75 4.5 to 4.75
Temperature Range
0°C to +70°C 0°C to +70°C 25°C 40°C to +85°C 40°C to +85°C Contact Factory 0°C to +70°C 0°C to +70°C 25°C 40°C to +85°C 40°C to +85°C Contact Factory 0°C to +70°C 0°C to +70°C 40°C to +85°C 40°C to +85°C 0°C to +70°C 0°C to +70°C 40°C to +85°C 40°C to +85°C 0°C to +70°C 0°C to +70°C 25°C 40°C to +85°C 40°C to +85°C Contact Factory
Pins-Package
8-Plastic DIP 8-SO DICE 8-Plastic DIP 8-SO 8-CerDIP 8-Plastic DIP 8-SO DICE 8-Plastic DIP 8-SO 8-CerDIP 8-Plastic DIP 8-SO 8-Plastic DIP 8-SO 8-Plastic DIP 8-SO 8-Plastic DIP 8-SO 8-Plastic DIP 8-SO DICE 8-Plastic DIP 8-SO 8-CerDIP
IMP692A
IMP692ACPA IMP692ACSA IMP692AC/D IMP692AEPA IMP692AESA IMP692AMJA
IMP802L
IMP802LCPA IMP802LCSA IMP802LEPA IMP802LESA
IMP802M
IMP802MCPA IMP802MCSA IMP802MEPA IMP802MESA
IMP805L
IMP805LCPA IMP805LCSA IMP805LC/D IMP805LEPA IMP805LESA IMP805LMJA
2
I M P 6 9 0 A , 692A , 802L, 802M, 805L IMP690A
Pin Description
Pin Number IMP690A/IMP692A IMP802L/IMP802M
1
IMP805L
1
Name
VOUT
Function
Voltage supply for RAM. When VCC is above the reset threshold, VOUT connects to VCC through a P-channel MOS device. If VCC falls below the reset threshold, this output will be connected to the backup supply at VBATT (or VCC, whichever is higher) through the MOS switch to provide continuous power to the CMOS RAM. +5V power supply input Ground Power failure monitor input. PFI is connected to the internal power fail comparator which is referenced to 1.25V. The power fail output (PFO) is active LOW but remains HIGH if PFI is above 1.25V. If this feature is unused, the PFI pin should be connected to GND or VOUT. Power-fail output. is active LOW whenever the PFI pin is less than PFO 1.25V. Watchdog input. The WDI input monitors microprocessor activity. An internal timer is reset with each transition of the WDI input. If WDI is held HIGH or LOW for longer than the watchdog timeout period, typically 1.6 seconds, RESET (orRS T) is asserted for the reset pulse width time, E E tRS, of 140ms, minimum. Active-LOW reset output. When triggered by VCC falling below the reset threshold or by watchdog timer timeout, RESET (orRS T) pulses low E E for the reset pulse width, t RS, typically 200ms. It will remain low if VCC is below the reset threshold (4.65V in the IMP690A/IMP802L and 4.4V in the IMP692A/IMP802L) and remains low for 200ms after VCC rise above the reset threshold. Active-HIGH reset output. The inverse of T. RESE Auxiliary power or backup-battery input. VBATT should be connected to GND if the function is not used. This input has about 40mV of hysteresis to prevent rapid toggling between VCC and VBATT.
2 3 4
2 3 4
VCC GND PFI
5 6
5 6
PFO WDI
7
RET ES
8
7 8
RESET VBATT
Absolute Maximum Ratings
Pin Terminal Voltage with Respect to Ground VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3V to 6.0V VBATT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3V to 6.0V All Other Inputs* . . . . . . . . . . . . . . . . . . . 0.3V to (VCC + 0.3V) Input Current at VCC . . . . . . . . . . . . . . . . . . 200mA Input Current at VBATT . . . . . . . . . . . . . . . . . 50mA Input Current at GND . . . . . . . . . . . . . . . . . 20mA Output Current: VOUT . . . . . . . . . . . . . . . Short circuit protected All Other Inputs . . . . . . . . . . . . . . . . . . . 20mA Rate of Rise: VBATT and VCC . . . . . . . . . . 100V/µs Continuous Power Dissipation Plastic DIP (derate 9mW/°C above 70°C) . . . 800mW SO (derate 5.9mW/°C above 70°C) . . . . . . . . 500mW CerDIP (derate 8mW/°C above 70°C) . . . . . . 650mW Operating Temperature Range (C Devices) . . . . 0°C to 70°C Operating Temperature Range (E Devices) . . . . 40°C to 85°C Storage Temperature Range . . . . . . . . . . . . . . . . . 65°C to 160°C Lead Temperature Soldering, (10 sec) . . . . . . . . 300°C * The input voltage limits on PFI and WDI may be exceeded if the current is limited to less than 10mA These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability.
3
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