 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| ICL7673 TM Data Sheet April 1999 FN3183.2 Automatic Battery Back-Up Switch The Intersil ICL7673 is a monolithic CMOS battery backup circuit that offers unique performance advantages over conventional means of switching to a backup supply. The ICL7673 is intended as a low-cost solution for the switching of systems between two power supplies; main and battery backup. The main application is keep-alive-battery power switching for use in volatile CMOS RAM memory systems and real time clocks. In many applications this circuit will represent a low insertion voltage loss between the supplies and load. This circuit features low current consumption, wide operating voltage range, and exceptionally low leakage between inputs. Logic outputs are provided that can be used to indicate which supply is connected and can also be used to increase the power switching capability of the circuit by driving external PNP transistors. Features * Automatically Connects Output to the Greater of Either Input Supply Voltage * If Main Power to External Equipment is Lost, Circuit Will Automatically Connect Battery Backup * Reconnects Main Power When Restored * Logic Indicator Signaling Status of Main Power * Low Impedance Connection Switches * Low Internal Power Consumption * Wide Supply Range: . . . . . . . . . . . . . . . . . . . 2.5V to 15V * Low Leakage Between Inputs * External Transistors May Be Added if Very Large Currents Need to Be Switched Ordering Information PART NUMBER ICL7673CPA ICL7673CBA ICL7673ITV TEMP. RANGE (oC) 0 to 70 0 to 70 25 to 85 PACKAGE 8 Ld PDIP8 8 Ld SOIC (N) PKG. NO. E8.3 M8.15 Applications * On Board Battery Backup for Real-Time Clocks, Timers, or Volatile RAMs * Over/Under Voltage Detector * Peak Voltage Detector * Other Uses: - Portable Instruments, Portable Telephones, Line Operated Equipment 8 Ld Metal Can T8.C Pinouts ICL7673 (SOIC, PDIP) TOP VIEW VO VS SBAR GDN 1 2 3 4 8 7 6 5 VP NC PBAR NC Functional Block Diagram VP P1 VO VS P2 SBAR ICL7673 (CAN) TOP VIEW VP 8 VO 1 VS 2 SBAR 3 4 GND 5 7 NC GND 6 PBAR + PBAR VP > VS , P1 SWITCH ON AND PBAR SWITCH ON NC VS > VP, P2 SWITCH ON AND SBAR SWITCH ON 3-81 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a trademark of Intersil Americas Inc. Copyright (c) Intersil Americas Inc. 2002. All Rights Reserved ICL7673 Absolute Maximum Ratings Input Supply (VP or VS) Voltage . . . . . . . . . . . . GND - 0.3V to +18V Output Voltages PBAR and SBAR . . . . . . . . . . . GND - 0.3V to +18V Peak Current Input VP (at VP = 5V) (Note 1) . . . . . . . . . . . . . . . . . . . . . . . 38mA Input VS (at VS = 3V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30mA PBAR or SBAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150mA Thermal Information Thermal Resistance (Typical, Note 2) JA (oC/W) JC (oC/W) PDIP Package . . . . . . . . . . . . . . . . . . . 150 N/A Plastic SOIC Package . . . . . . . . . . . . . 180 N/A Metal Can. . . . . . . . . . . . . . . . . . . . . . . 156 68oC/W Maximum Storage Temperature. . . . . . . . . . . . . . . . -65oC to 150oC Maximum Lead Temperature (Soldering, 10sec). . . . . . . . . . . 300oC (SOIC - Lead Tips Only) Operating Conditions Temperature Range: ICL7673C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0oC to 70oC ICL7673I. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25oC to 85oC CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTES: 1. Derate above 25oC by 0.38mA/oC. 2. JA is measured with the component mounted on an evaluation PC board in free air. Electrical Specifications PARAMETER Input Voltage TA = 25oC Unless Otherwise Specified SYMBOL VP VS TEST CONDITIONS VS = 0V, ILOAD = 0mA VP = 0V, ILOAD = 0mA VP = 0V, VS = 3V, ILOAD = 0mA VP = 5V, VS = 3V, ILOAD = 15mA At TA = +85oC VP = 9V, VS = 3V, ILOAD = 15mA V P = 12V, VS = 3V, ILOAD = 15mA MIN 2.5 2.5 TYP 1.5 8 16 6 5 0.5 40 60 26 16 0.7 0.01 35 0.01 120 85 120 50 40 MAX 15 15 5 15 100 20 50 400 UNITS V V A %/oC %/oC nA nA nA nA mV mV mV mV Quiescent Supply Current Switch Resistance P1 (Note 1) I+ rDS(ON)P1 Temperature Coefficient of Switch Resistance P1 Switch Resistance P2 (Note 1) TC(P1) rDS(ON)P2 VP = 5V, VS = 3v, ILOAD = 15mA VP = 0V, VS = 3V, ILOAD = 1mA At TA = +85oC VP = 0V, VS = 5V, ILOAD = 1mA V P = 0V, VS = 9V, ILOAD = 1mA Temperature Coefficient of Switch Resistance P2 Leakage Current (VP to V S) TC(P2) IL(PS) VP = 0V, VS = 3V, ILOAD = 1mA VP = 5V, VS = 3V, ILOAD = 10mA At TA = +85oC Leakage Current (VP to V S) IL(SP) VP = 0V, VS = 3V, ILOAD = 10mA at TA = + 85oC Open Drain Output Saturation Voltages VOPBAR VP = 5V, VS = 3V, ISINK = 3.2mA, ILOAD = 0mA At TA = 85oC VP = 9V, VS = 3V, ISINK = 3.2mA, ILOAD = 0mA VP = 12V, VS = 3V, ISINK = 3.2mA ILOAD = 0mA 3-82 ICL7673 Electrical Specifications PARAMETER Open Drain Output Saturation Voltages TA = 25oC Unless Otherwise Specified (Continued) SYMBOL VOSBAR TEST CONDITIONS VP = 0V, VS = 3V, ISINK = 3.2mA, ILOAD = 0mA at TA = + 85oC VP = 0V, VS = 5V, ISINK = 3.2mA ILOAD = 0mA VP = 0V, VS = 9V, ISINK = 3.2mA ILOAD = 0mA Output Leakage Currents of PBAR and SBAR ILPBAR VP = 0V, VS = 15V, ILOAD = 0mA at TA = + 85oC ILSBAR VP = 15V, VS = 0V, ILOAD = 0mA at TA = + 85oC Switchover Uncertainty for Complete Switching of Inputs and Open Drain Outputs NOTE: 3. The Minimum input to output voltage can be determined by multiplying the load current by the switch resistance. VP - VS VS = 3V, ISINK = 3.2mA, ILOAD = 15mA MIN TYP 150 210 85 50 50 900 50 900 10 MAX 400 500 500 50 UNITS mV mV mV mV nA nA nA nA mV Typical Performance Curves 100 ILOAD = 15mA ON-RESISTANCE P1 () ON-RESISTANCE P2 () 100 ILOAD = 1mA 10 10 1 0 2 4 6 8 10 12 14 16 INPUT VOLTAGE VP (V) 1 0 2 4 6 INPUT VOLTAGE VS 8 10 FIGURE 1. ON-RESISTANCE SWITCH P1 AS A FUNCTION OF INPUT VOLTAGE V P FIGURE 2. ON-RESISTANCE SWITCH P2 AS A FUNCTION OF INPUT VOLTAGE V S 3-83 ICL7673 Typical Performance Curves 1 OUTPUT SATURATION VOLTAGE (V) (Continued) 5 VO = 5V VO = 3V VO = 9V 0.8 SUPPLY CURRENT (A) 4 VO = 12V 3 0.6 0.4 2 VO = 15V 0.2 -40oC 25 oC 85 oC 0 2 4 6 8 10 12 14 SUPPLY VOLTAGE (V) 16 1 0 40 80 120 OUTPUT CURRENT (mA) 140 180 FIGURE 3. SUPPLY CURRENT AS A FUNCTION OF SUPPLY VOLTAGE FIGURE 4. PBAR OR SBAR SATURATION VOLTAGE AS A FUNCTION OF OUTPUT CURRENT 1mA ILOAD = 10mA VS = 0V 100mA 85 oC 10nA IS LEAKAGE CURRENT inverter drives another large P-Channel switch P2. The ICL7673, connected to a main and a backup power supply, will connect the supply of greater potential to its output. The circuit provides break-before-make switch action as it switches from main to backup power in the event of a main power supply failure. For proper operation, inputs VP and V S must not be allowed to float, and, the difference in the two supplies must be greater than 50mV. The leakage current through the reverse biased parasitic diode of switch P2 is very low. Output Voltage The output operating voltage range is 2.5V to 15V. The insertion loss between either input and the output is a function of load current, input voltage, and temperature. This is due to the P-Channels being operated in their triode region, and, the ON-resistance of the switches is a function of output voltage VO . The ON-resistance of the P-Channels have positive temperature coefficients, and therefore as temperature increases the insertion loss also increases. At low load currents the output voltage is nearly equal to the greater of the two inputs. The maximum voltage drop across switch P1 or P2 is 0.5V, since above this voltage the bodydrain parasitic diode will become forward biased. Complete switching of the inputs and open-drain outputs typically occurs in 50s. 1nA 1000pA 10pA 25 oC 1pA 0 2 4 5 6 INPUT VP (V) 8 10 12 FIGURE 5. IS LEAKAGE CURRENT V P TO VS AS A FUNCTION OF INPUT VOLTAGE Input Voltage The input operating voltage range for VP or V S is 2.5V to 15V. The input supply voltage (VP or VS) slew rate should be limited to 2V per microsecond to avoid potential harm to the circuit. In line-operated systems, the rate-of-rise (or fall) of the supply is a function of power supply design. For battery applications it may be necessary to use a capacitor between the input and ground pins to limit the rate-of-rise of the Detailed Description As shown in the Functional Diagram, the ICL7673 includes a comparator which senses the input voltages VP and VS. The output of the comparator drives the first inverter and the open-drain N-Channel transistor PBAR . The first inverter drives a large P-Channel switch, P1, a second inverter, and another open-drain N-Channel transistor, SBAR . The second 3-84 ICL7673 supply voltage. A low-impedance capacitor such as a 0.047F disc ceramic can be used to reduce the rate-of-rise. +5V PRIMARY SUPPLY 8 VP VO 1 VO +5V OR +3V Status Indicator Outputs The N-Channel open drain output transistors can be used to indicate which supply is connected, or can be used to drive external PNP transistors to increase the power switching capability of the circuit. When using external PNP power transistors, the output current is limited by the beta and thermal characteristics of the power transistors. The application section details the use of external PNP transistors. 2 LITHIUM BATTERY GND + VS Pbar GND 4 6 RI STATUS INDICATOR - FIGURE 7. ICL7673 BATTERY BACKUP CIRCUIT Applications A typical discrete battery backup circuit is illustrated in Figure 6. This approach requires several components, substantial printed circuit board space, and high labor cost. It also consumes a fairly high quiescent current. The ICL7673 battery backup circuit, illustrated in Figure 7, will often replace such discrete designs and offer much better performance, higher reliability, and lower system manufacturing cost. A trickle charge system could be implemented with an additional resistor and diode as shown in Figure 8. A complete low power AC to regulated DC system can be implemented using the ICL7673 and ICL7663S micropower voltage regulator as shown in Figure 9. +5V PRIMARY DC POWER VO +5V OR +3V STATUS INDICATOR +5V PRIMARY SUPPLY RC 8 VP VO 1 VO +5V OR +3V 2 RECHARGEABLE BATTERY GND VS + - GND 4 FIGURE 8. APPLICATION REQUIRING RECHARGEABLE BATTERY BACKUP NiCAD BATTERY STACK A typical application, as illustrated in Figure 12, would be a microprocessor system requiring a 5V supply. In the event of primary supply failure, the system is powered down, and a 3V battery is employed to maintain clock or volatile memory data. The main and backup supplies are connected to VP and VS, with the circuit output VO supplying power to the clock or volatile memory. The ICL7673 will sense the main supply, when energized, to be of greater potential than VS and connect, via its internal MOS switches, V P to output VO. The backup input, VS will be disconnected internally. In the event of main supply failure, the circuit will sense that the backup supply is now the greater potential, disconnect V P from VO , and connect VS. Figure 11 illustrates the use of external PNP power transistors to increase the power switching capability of the circuit. In this application the output current is limited by the beta and thermal characteristics of the power transistors. If hysteresis is desired for a particular low power application, positive feedback can be applied between the input VP and open drain output SBAR through a resistor as illustrated in Figure 12. For high power applications hysteresis can be applied as shown in Figure 13. The ICL7673 can also be used as a clipping circuit as illustrated in Figure 14. With high impedance loads the circuit output will be nearly equal to the greater of the two input signals. GND FIGURE 6. DISCRETE BATTERY BACKUP CIRCUIT Applications for the ICL7673 include volatile semiconductor memory storage systems, real-time clocks, timers, alarm systems, and over/under the voltage detectors. Other systems requiring DC power when the master AC line supply fails can also use the ICL7673. 3-85 ICL7673 VP FUSE BRIDGE RECTIFIER 120/240 VAC STEPDOWN TRANSFORMER C1 8 2 R2 R3 VS D1 + 8 1 VO ICL7663 REGULATOR 4 6 R1 ICL7673 BATTERY BACK-UP 2 BATTERY STACK 4 GND - FIGURE 9. POWER SUPPLY FOR LOW POWER PORTABLE AC TO DC SYSTEMS +5V MAIN POWER POWER FAIL DETECTOR MICROPROCESSOR VP VS VO ICL7673 BACKUP CIRCUIT INTERRUPT SIGNAL + VOLATILE RAM - FIGURE 10. TYPICAL MICROPROCESSOR MEMORY APPLICATION R2 PNP PNP VP 8 ICL7673 2 + 3V BACKUP SUPPLY GND VO P6 S3 VS R1 1 NC R3 (NOTE 4) EXTERNAL EQUIPMENT R4 MAIN SUPPLY NOTE 4. > 1MW FIGURE 11. HIGH CURRENT BATTERY BACKUP SYSTEM RF RS VP 8 ICL7673 VS BATTERY BACKUP GND + 2 3 GND SVO MAIN SUPPLY GND FIGURE 12. LOW CURRENT BATTERY BACKUP SYSTEM WITH HYSTERESIS 3-86 ICL7673 R2 PNP PNP RF R1 +V MAIN SUPPLY RS VP 8 1 PVS 2 + MAIN SUPPLY GND BACKUP SUPPLY ICL7673 6 4 3 SNC R3 EXTERNAL EQUIPMENT R4 - FIGURE 13. HIGH CURRENT BACKUP SYSTEM WITH HYSTERESIS VP VP ICL7673 VS GND VO VS VO FIGURE 14. CLIPPLING CIRCUITS 3-87 |
Price & Availability of ICL7673
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |