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April 2008 rev 1.7 ASM690A/692A ASM802L/802M ASM805L P Power Supply Supervisor With Battery Backup Switch General Description The ASM690A / ASM692A / ASM802L / ASM802M / ASM805L offers complete single chip solutions for power supply monitoring and control battery functions in microprocessor systems. Each device implements four functions: Reset control, watchdog monitoring, batterybackup switching and powerfailure monitoring. In addition to microprocessor reset under power-up and power-down conditions, these devices provide battery-backup switching to maintain control in power loss 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: * 1.6 second watchdog timer to keep microprocessor responsive * 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 * 1.25V threshold detector for power loss or general purpose voltage monitoring These features are pin-compatible with the industry standard power-supply supervisors. Short-circuit and thermal protection have also been added. The ASM690A / ASM802L / ASM805L generate a reset pulse when the supply voltage drops below 4.65V and the ASM692A / ASM802M generate a reset below 4.40V. The ASM802L / ASM802M have power-fail accuracy to 2%. The ASM805L is the same as the ASM690A except that RESET is provided instead of RESET. * Short circuit protection and thermal limiting * Small 8-pin SO and 8-pin PDIP packages * No external components * Specified over full temperature range Applications * Embedded control systems * Portable/Battery operated systems * Intelligent instruments * Wireless instruments * Wireless communication systems * PDAs and hand-held equipments * P / C power supply monitoring * Safety system Typical Operating Circuit Block Diagram Features * Two precision supply-voltage monitor options 4.65V (ASM690A / ASM802L / ASM805L) 4.40V (ASM692A / ASM802M ) * Battery-backup power switch on-chip * Watchdog timer: 1.6 second timeout * Power failure / low battery detection PulseCore Semiconductor Corporation 1715 S. Bascom Ave Suite 200 Campbell, CA 95008 * Tel: 408-879-9077 * Fax: 408-879-9018 www.pulsecoresemi.com Notice: The information in this document is subject to change without notice. April 2008 rev 1.7 Pin Configuration ASM690A/692A ASM802L/802M ASM805L Pin Description Pin Number ASM690A/ ASM692A ASM802L/ ASM802M 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 1 1 VOUT 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. 2 3 2 3 VCC GND +5V power supply input. Ground Power failure monitor input. PFI is connected to the internal power fail 4 4 PFI 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. 5 5 Power-fail output. PFO 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 the WDI is held HIGH 6 6 WDI or LOW for longer than the watchdog timeout period, typically 1.6 seconds, RESET (or RESET) is asserted for the reset pulse width time, tRS, of 140ms, minimum. Active-LOW reset output. When triggered by VCC falling below the reset threshold or by watchdog timer timeout, RESET pulses low for the reset 7 pulse width tRS, typically 200ms. It will remain low if VCC is below the reset RESET threshold (4.65V in ASM690A / ASM802L and 4.4V in the ASM692A / ASM802L) and remains low for 200ms after VCC rises above the reset threshold. 8 7 8 RESET VBATT Active-HIGH reset output. The inverse of RESET. Auxiliary power or backup-battery input. VBATT should be connected to GND if the function is not used. The input has about 40mV of hysteresis to prevent rapid toggling between VCC and VBATT. ASM805L Name Function P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 2 of 15 April 2008 rev 1.7 Detailed Description It is important to initialize a microprocessor to a known state in response to specific events that could create code execution errors and "lock-up". The reset output of these supervisory circuits send a reset pulse to the microprocessor in response to power-up, powerdown/power-loss or a watchdog time-out. RESET/RESET Timing Power-up reset occurs when a rising VCC reaches the reset threshold, VRT, forcing a reset condition in which the reset output is asserted in the appropriate logic state for the duration of tRS. The reset pulse width, tRS, is typically around 200ms and is LOW for the ASM690A, ASM692A, ASM802 and HIGH for the ASM805L. Figure 1 shows the reset pin timing. Power-loss or "brown-out" reset occurs when VCC dips below the reset threshold resulting in a reset assertion for the duration of tRS. The reset signal remains asserted as long as VCC is between VRT and 1.1V, the lowest VCC for which thesedevices can provide a guaranteed logic-low output. To ensure logic inputs connected to the ASM690A / ASM692A/ASM802 RESET pin are in a known state when VCC is under 1.1V, a 100k pull-down resistor at RESET is needed: the logic-high ASM805L will need a pull-up resistor to VCC. Watchdog Timer A Watchdog time-out reset occurs when a logic "1" or logic "0" is continuously applied to the WDI pin for more than 1.6 seconds. After the duration of the reset interval, the watchdog timer starts a new 1.6 second timing interval; the microprocessor must service the watchdog input by changing states or by floating the WDI pin before this interval is finished. If the WDI pin is held either HIGH or LOW, a reset pulse will be triggered every 1.8 seconds (the 1.6 second timing interval plus the reset pulse width tRS). ASM690A/692A ASM802L/802M ASM805L Application Information Microprocessor Interface The ASM690 has logic-LOW RESET output while the ASM805 has an inverted logic-HIGH RESET output. Microprocessors with bidirectional reset pins can pose a problem when the supervisory circuit and the microprocessor output pins attempt to go to opposite logic states. The problem can be resolved by placing a 4.7k resistor between the RESET output and the microprocessor reset pin. This is shown in Figure 2. Since the series resistor limits drive capabilities, the reset signal to other devices should be buffered. P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 3 of 15 April 2008 rev 1.7 Watchdog Input As discussed in the Reset section, the Watchdog input is used to monitor microprocessor activity. It can be used to insure that the microprocessor is in a continually responsive state by requiring that the WDI pin be toggled every second. If the WDI pin is not toggled within the 1.6 second window (minimum tWD + tRS), a reset pulse will be asserted to return the microprocessor to the initial start-up state. Pulses as short as 50ns can be applied to the WDI pin. If this feature is not used, the WDI pin should be open circuited or the logic placed into a highimpedance state to allow the pin to float. Backup-Battery Switchover A power loss can be made less severe if the system RAM contents are preserved. This is achieved in the ASM690/692/ 802/805 by switching from the failed VCC to an alternate power source connected at VBATT when VCC is less than the reset threshold voltage (VCC < VRT), and VCC is less than VBATT. The VOUT pin is normally connected to VCC through a 2 PMOS switch but a brown-out or loss of VCC will cause a switchover to VBATT by means of a 20 PMOS switch. Although both conditions (VCC < VRT and VCC ASM690A/692A ASM802L/802M ASM805L Table 1. Pin Connections in Battery Backup Mode Connection Connected to VBATT through internal PMOS switch Connected to VOUT Disabled Logic-LOW Logic-LOW (except on ASM805 where it is HIGH) Watchdog timer disabled During the backup power mode, the internal circuitry of the supervisory circuit draws power from the battery supply. While VCC is still alive, the comparator circuits remain alive and the current drawn by the device is typically 35A. When VCC drops more than 1.1V below VBATT, the internal switchover comparator, the PFI comparator and WDI comparator will shut off, reducing the quiescent current drawn by the IC to less than 1A. Backup Power Sources - Batteries Battery voltage selection is important to insure that the battery does not discharge through the parasitic device diode D1 (see Figure 3) when VCC is less than VBATT and VCC >VRT. ASM690A/802A/805L Reset Threshold = 4.65V ASM692A /ASM802M Reset Threshold = 4.4V P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 4 of 15 April 2008 rev 1.7 ASM690A/692A ASM802L/802M ASM805L the ASM692A/802M or within 10% of 5V for the Table 2: Maximum Battery Voltages ASM690A/802L/805L to insure that the storage capacitor does not achieve an over voltage state. Note: SuperCapTM is a trademark of Baknor Industries Part Number ASM690A ASM802L ASM805L ASM692A ASM802M MAXIMUM Battery Voltage (V) 4.80 4.80 4.80 4.55 4.55 Although most batteries that meet the requirements of Table2 are acceptable, lithium batteries are very effective backup source due to their high-energy density and very low selfdischarge rates. Battery replacement while Powered Batteries can be replaced even when the device is in a powered state as long as VCC remains above the reset threshold voltage VRT. In the ASM devices, a floating VBATT pin will not cause a powersupply switchover as can occur in some other supervisory circuits. If VBATT is not used, the pin should be grounded. Backup Power Sources - SuperCapTM Capacitor storage, with very high values of capacitance, can be used as a back-up power source instead of batteries. SuperCapTM are capacitors with capacities in the fractional farad range. A 0.1 farad SuperCapTM would provide a useful backup power source. Like the battery supply, it is important that the capacitor voltage remain below the maximum voltages shown in Table 2. Although the circuit of Figure 4 shows the most simple way to connect the SuperCapTM, this circuit cannot insure that an over voltage condition will not occur since the capacitor will ultimately charge up to VCC. To insure that an over voltage condition does not occur, the circuit of Figure 5 is preferred. In this circuit configuration, the diode-resistor pair clamps the capacitor voltage at one diode drop below VCC. VCC itself should be regulated within 5% of 5V for Operation without a Backup Power Source When operating without a back-up power source, the VBATT pin should be connected to GND and VOUT should be connected to VCC, since power source switchover will not occur. Connecting VOUT to VCC eliminates the voltage drop due to the ON-resistance of the PMOS switch. P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 5 of 15 April 2008 rev 1.7 Power-Fail Comparator The Power Fail feature is an independent voltage monitoring function that can be used for any number of monitoring activities. The PFI function can provide an early sensing of power supply failure by sensing the voltage of the unregulated DC ahead of the regulated supply sensing seen by the backup-battery switchover circuitry. The PFI pin is compared to a 1.25V internal reference. If the voltage at the PFI pin is less than this reference voltage, the PFO pin goes low. By sensing the voltage of the raw DC power supply, the microprocessor system can prepare for imminent power-loss, especially if the battery backup supply is not enabled. The input voltage at the PFI pin results from a simple resistor voltage divider as shown in Figure 6. ASM690A/692A ASM802L/802M ASM805L reasonable and should be larger than 10k to avoid excessive loading on the PFO pin. The calculations for the correct values of resistors to set the hysteresis thresholds are given in Figure 7. A capacitor can be added to offer additional noise rejection by low-pass filtering. Power Fail Hysteresis A noise margin can be added to the simple monitoring circuit of Figure 6 by adding positive feedback from the PFO pin. The circuit of Figure 7 adds this positive "latching" effect by means of an additional resistor R3 connected between PFO and PFI which helps in pulling PFI in the direction of PFO and eliminating an indecision at the trip point. Resistor R3 is normally about 10 times higher in resistance than R2 to keep the hysteresis band Monitoring Capabilities Of The Power-fail Input: Although designed for power supply failure monitoring, the PFI pin can be used for monitoring any voltage condition that can be scaled by means of a resistive divider. An example is the negative power supply monitor configured in Figure 8. In this case a good negative supply will hold the PFI pin below 1.25V and the PFO pin P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 6 of 15 April 2008 rev 1.7 will be at logic "0". As the negative voltage declines, the voltage at the PFI pin will rise until it exceeds 1.25V and the PFO pin will go to logic "1". ASM690A/692A ASM802L/802M ASM805L P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 7 of 15 April 2008 rev 1.7 Absolute Maximum Ratings Parameter Pin Terminal Voltage with Respect to Ground VCC VBATT All other inputs1 Input Current at VCC Input Current at VBATT Input Current at GND Output Current VOUT All other inputs Rate of Rise: VBATT and VCC Continuous Power Dissipation Plastic DIP (derate 9mW/C above 70C) SO (derate 5.9mW/C above 70C) Operating Temperature Range (C Devices) Operating Temperature Range (E Devices) Storage Temperature Range Lead Temperature (Soldering, 10 sec) 0 -40 -65 800 500 70 85 160 300 -0.3 -0.3 -0.3 6.0 6.0 ASM690A/692A ASM802L/802M ASM805L Min Max Unit V V V mA mA mA VCC + 0.3 200 50 20 Short circuit protected 20 100 mA V/s mW mW C C C C ESD rating HBM MM 1 100 KV V 1. The input voltage limits on PFI and WDI may be exceeded if the current is limited to less than 10mA Note: These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 8 of 15 April 2008 rev 1.7 Electrical Characteristics ASM690A/692A ASM802L/802M ASM805L Unless other wise noted, VCC = 4.75V to 5.5V for the ASM690A / ASM802L / ASM805L and VCC = 4.5V to 5.5V for the ASM692A / ASM802M;VBATT = 2.8V; and TA = TMIN to TMAX. Parameter VCC, VBATT Voltage Range (Note 1) Supply Current Excluding IOUT ISUPPLY in Battery Backup Mode (Excluding IOUT) VBATT Standby Current (Note 2) VOUT Output VOUT in Battery Backup Mode Battery Switch Threshold, VCC to VBATT Battery Switch over Hysteresis Reset Threshold Reset Threshold Hysteresis Reset Pulse Width SYMBOL Conditions 1.1 Min TYP Max 5.5 Unit V A IS TA = 25C VCC = 0V, VBATT = 2.8V TA =TMIN to TMAX 5.5V>VCC>VBATT + 0.2V IOUT = 5mA IOUT = 50mA IOUT=250A, VCC < VBATT - 0.2V VCC < VRT Power Up Power Down TA = 25C TA =TMIN to TMAX -0.1 -1.0 VCC-0.025 VCC-0.25 VBATT- 0.1 35 1.5 100 A 5.0 0.02 0.02 VCC0.010 VCC0.10 VBATT 0.001 20 -20 40 A V V mV mV 4.75 4.50 4.70 4.45 VRT ASM690A/802L/805L ASM692A, ASM802M ASM802L, TA = 25C, VCC falling ASM802M, TA=25C, VCC falling 4.50 4.25 4.55 4.30 4.65 4.40 V 40 tRS ISOURCE = 800A ISINK = 3.2mA ASM69_AC,ASM802_C,VCC=1.0V,ISINK=50A ASM69_AE,ASM802_E,VCC=1.2V,ISINK=100A ASM805LC, ISOURCE=4A, VCC = 1.1V ASM805LE, ISOURCE=4A, VCC = 1.2V ASM805L, ISOURCE=800A ASM805L, ISINK=3.2mA tWD tWP VIL = 0.4V, VIH = 0.8VCC WDI = VCC WDI = 0V VCC = 5V, Logic LOW VCC = 5V, Logic HIGH 3.5 140 VCC - 1.5 200 280 0.4 0.3 0.3 mV ms Reset Output Voltage 0.8 0.9 VCC - 1.5 0.4 1.00 50 -150 50 -50 150 0.8 1.60 2.25 V Watchdog Timeout WDI Pulse Width WDI Input Current WDI Input Threshold (Note 3) sec ns A A V P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 9 of 15 April 2008 rev 1.7 Parameter PFI Input Threshold PFI Input Current PFO Output Voltage ISOURCE = 800A ISINK = 3.2mA ASM690A/692A ASM802L/802M ASM805L SYMBOL Conditions ASM69_A, ASM805L, VCC = 5V ASM802_C/E, VCC = 5V Min 1.20 1.225 -25 VCC - 1.5 TYP 1.25 1.250 0.01 Max 1.30 1.275 25 0.4 Unit V nA V Notes: 1. If VCC or VBATT is 0V, the other must be greater than 2.0V. 2. Battery charging-current is "-". Battery discharge current is "+". 3. WDI is guaranteed to be in an intermediate level state if WDI is floating and VCC is within the operating voltage range. WDI input impedance is 50 k. WDI is biased to 0.3VCC. P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 10 of 15 April 2008 rev 1.7 Package Dimensions 8-lead PDIP Package ASM690A/692A ASM802L/802M ASM805L P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 11 of 15 April 2008 rev 1.7 8-lead (150-mil) SOIC Package ASM690A/692A ASM802L/802M ASM805L P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 12 of 15 April 2008 rev 1.7 Ordering Information - Tin - Lead Devices Part Number ASM690A ASM690ACPA ASM690ACSA ASM690AEPA ASM690AESA ASM692A ASM692ACPA ASM692ACSA ASM692AEPA ASM692AESA ASM802L ASM802LCPA ASM802LCSA ASM802LEPA ASM802LESA ASM802M ASM802MCPA ASM802MCSA ASM802MEPA ASM802MESA ASM805L ASM805LCPA ASM805LCSA ASM805LEPA ASM805LESA 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 0 to +70 0 to +70 -40 to +85 -40 to +85 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 0 to +70 0 to +70 -40 to +85 -40 to +85 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 0 to +70 0 to +70 -40 to +85 -40 to +85 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 0 to +70 0 to +70 -40 to +85 -40 to +85 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 0 to +70 0 to +70 -40 to +85 -40 to +85 Reset Threshold (V) Temperature (C) ASM690A/692A ASM802L/802M ASM805L Pins-Package 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 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 Package Marking ASM690ACPA ASM690ACSA ASM690AEPA ASM690AESA ASM692ACPA ASM692ACSA ASM692AEPA ASM692AESA ASM802LCPA ASM802LCSA ASM802LEPA ASM802LESA ASM802MCPA ASM802MCSA ASM802MEPA ASM802MESA ASM805LCPA ASM805LCSA ASM805LEPA ASM805LESA P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 13 of 15 April 2008 rev 1.7 Ordering Information - Lead Free Devices Part Number ASM690A ASM690ACPAF ASM690ACSAF ASM690AEPAF ASM690AESAF ASM692A ASM692ACPAF ASM692ACSAF ASM692AEPAF ASM692AESAF ASM802L ASM802LCPAF ASM802LCSAF ASM802LEPAF ASM802LESAF ASM802M ASM802MCPAF ASM802MCSAF ASM802MEPAF ASM802MESAF ASM805L ASM805LCPAF ASM805LCSAF ASM805LEPAF ASM805LESAF 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 0 to +70 0 to +70 -40 to +85 -40 to +85 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 0 to +70 0 to +70 -40 to +85 -40 to +85 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 0 to +70 0 to +70 -40 to +85 -40 to +85 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 4.25 to 4.50 0 to +70 0 to +70 -40 to +85 -40 to +85 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 4.5 to 4.75 0 to +70 0 to +70 -40 to +85 -40 to +85 Reset Threshold(V) Temperature(C) ASM690A/692A ASM802L/802M ASM805L Pins-Package 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 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 Package Marking ASM690ACPAF ASM690ACSAF ASM690AEPAF ASM690AESAF ASM692ACPAF ASM692ACSAF ASM692AEPAF ASM692AESAF ASM802LCPAF ASM802LCSAF ASM802LEPAF ASM802LESAF ASM802MCPAF ASM802MCSAF ASM802MEPAF ASM802MESAF ASM805LCPAF ASM805LCSAF ASM805LEPAF ASM805LESAF Notes: * For parts to be packed in Tape and Reel, add "-T" at the end of the part number. * PulseCore Semiconductor's lead free parts are RoHS compliant. P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 14 of 15 April 2008 rev 1.7 ASM690A/692A ASM802L/802M ASM805L PulseCore Semiconductor Corporation 1715 S. Bascom Ave Suite 200 Campbell, CA 95008 Tel: 408-879-9077 Fax: 408-879-9018 www.pulsecoresemi.com Copyright (c) PulseCore Semiconductor All Rights Reserved Part Number: ASM690A / 692A ASM802L / 802M ASM805L Document Version: 1.7 (c) Copyright 2006 PulseCore Semiconductor Corporation. All rights reserved. Our logo and name are trademarks or registered trademarks of PulseCore Semiconductor. All other brand and product names may be the trademarks of their respective companies. PulseCore reserves the right to make changes to this document and its products at any time without notice. PulseCore assumes no responsibility for any errors that may appear in this document. The data contained herein represents PulseCore's best data and/or estimates at the time of issuance. PulseCore reserves the right to change or correct this data at any time, without notice. If the product described herein is under development, significant changes to these specifications are possible. The information in this product data sheet is intended to be general descriptive information for potential customers and users, and is not intended to operate as, or provide, any guarantee or warrantee to any user or customer. PulseCore does not assume any responsibility or liability arising out of the application or use of any product described herein, and disclaims any express or implied warranties related to the sale and/or use of PulseCore products including liability or warranties related to fitness for a particular purpose, merchantability, or infringement of any intellectual property rights, except as express agreed to in PulseCore's Terms and Conditions of Sale (which are available from PulseCore). All sales of PulseCore products are made exclusively according to PulseCore's Terms and Conditions of Sale. The purchase of products from PulseCore does not convey a license under any patent rights, copyrights; mask works rights, trademarks, or any other intellectual property rights of PulseCore or third parties. PulseCore does not authorize its products for use as critical components in life-supporting systems where a malfunction or failure may reasonably be expected to result in significant injury to the user, and the inclusion of PulseCore products in such life-supporting systems implies that the manufacturer assumes all risk of such use and agrees to indemnify PulseCore against all claims arising from such use. P Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice. 15 of 15 |
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