DATASHEET

ICL7673
Data Sheet
December 3, 2015
FN3183.5
Automatic Battery Back-Up Switch
Features
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.
• Automatically Connects Output to the Greater of Either
Input Supply Voltage
Ordering Information
• Pb-Free Plus Anneal Available (RoHS Compliant)
PART
NUMBER
TEMP. RANGE
(°C)
PACKAGE
PKG.
DWG. #
ICL7673CPA No
longer available
or supported.
Recommended
Replacement
ICL7673CPAZ
0 to 70
ICL7673CPAZ
(See Note)
0 to 70
8 Ld PDIP*
(Pb-free)
E8.3
ICL7673CBA No
longer available
or supported.
Recommended
Replacement
ICL7673CBAZA-T
0 to 70
8 Ld SOIC (N)
M8.15
ICL7673CBAZA
(See Note)
0 to 70
ICL7673CBAZA-T
(See Note)
0 to 70
8 Ld PDIP
E8.3
• 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
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
Pinout
ICL7673 (SOIC, PDIP)
TOP VIEW
8 Ld SOIC (N)
(Pb-free)
M8.15
8 Ld SOIC (N)
(Pb-free)
M8.15
VO
1
8
VP
VS
2
7
NC
SBAR
3
6
PBAR
GDN
4
5
NC
*Pb-free PDIPs can be used for through hole wave solder
processing only. They are not intended for use in Reflow solder
processing applications.
NOTE: Intersil Pb-free plus anneal products employ special Pb-free
material sets; molding compounds/die attach materials and 100%
matte tin plate termination finish, which are RoHS compliant and
compatible with both SnPb and Pb-free soldering operations. Intersil
Pb-free products are MSL classified at Pb-free peak reflow
temperatures that meet or exceed the Pb-free requirements of
IPC/JEDEC J STD-020.
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas LLC.
Copyright © Intersil Americas LLC 1999-2005. 2015. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
ICL7673
Functional Block Diagram
VP
VO
P1
VS
P2
SBAR
+
PBAR
GND
VP > VS , P1 SWITCH ON AND PBAR SWITCH ON
VS > VP, P2 SWITCH ON AND SBAR SWITCH ON
2
FN3183.5
December 3, 2015
ICL7673
Absolute Maximum Ratings
Thermal Information
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 Resistance (Typical, Note 2)
JA (°C/W)
JC (°C/W)
PDIP Package* . . . . . . . . . . . . . . . . . .
150
N/A
Plastic SOIC Package . . . . . . . . . . . . .
180
N/A
Maximum Storage Temperature. . . . . . . . . . . . . . . . . -65°C to 150°C
Maximum Lead Temperature (Soldering, 10sec). . . . . . . . . . . 300°C
(SOIC - Lead Tips Only)
Operating Conditions
*Pb-free PDIPs can be used for through hole wave solder processing
only. They are not intended for use in Reflow solder processing
applications.
Temperature Range:
ICL7673C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
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 25°C by 0.38mA/°C.
2. JA is measured with the component mounted on an evaluation PC board in free air.
Electrical Specifications
TA = 25°C Unless Otherwise Specified
PARAMETER
SYMBOL
Input Voltage
Quiescent Supply Current
Switch Resistance P1 (Note 1)
Temperature Coefficient of Switch
Resistance P1
Switch Resistance P2 (Note 1)
TEST CONDITIONS
MIN
TYP
MAX
UNITS
VP
VS = 0V, ILOAD = 0mA
2.5
-
15
V
VS
VP = 0V, ILOAD = 0mA
2.5
-
15
V
I+
VP = 0V, VS = 3V, ILOAD = 0mA
-
1.5
5
A
rDS(ON)P1
VP = 5V, VS = 3V, ILOAD = 15mA
-
8
15

At TA = +85°C
-
16
-

VP = 9V, VS = 3V, ILOAD = 15mA
-
6
-

VP = 12V, VS = 3V, ILOAD = 15mA
-
5
-

TC(P1)
VP = 5V, VS = 3v, ILOAD = 15mA
-
0.5
-
%/°C
rDS(ON)P2
VP = 0V, VS = 3V, ILOAD = 1mA
-
40
100

At TA = +85°C
-
60
-

VP = 0V, VS = 5V, ILOAD = 1mA
-
26
-

VP = 0V, VS = 9V, ILOAD = 1mA
-
16
-

Temperature Coefficient of Switch
Resistance P2
TC(P2)
VP = 0V, VS = 3V, ILOAD = 1mA
-
0.7
-
%/°C
Leakage Current (VP to VS)
IL(PS)
VP = 5V, VS = 3V, ILOAD = 10mA
-
0.01
20
nA
At TA = +85°C
-
35
-
nA
VP = 0V, VS = 3V, ILOAD = 10mA
-
0.01
50
nA
at TA = +85°C
-
120
-
nA
VP = 5V, VS = 3V, ISINK = 3.2mA, ILOAD = 0mA
-
85
400
mV
At TA = 85°C
-
120
-
mV
VP = 9V, VS = 3V, ISINK = 3.2mA, ILOAD = 0mA
-
50
-
mV
VP = 12V, VS = 3V, ISINK = 3.2mA
ILOAD = 0mA
-
40
-
mV
VP = 0V, VS = 3V, ISINK = 3.2mA, ILOAD = 0mA
-
150
400
mV
at TA = +85°C
-
210
-
mV
VP = 0V, VS = 5V, ISINK = 3.2mA ILOAD = 0mA
-
85
-
mV
VP = 0V, VS = 9V, ISINK = 3.2mA ILOAD = 0mA
-
50
-
mV
Leakage Current (VP to VS)
IL(SP)
Open Drain Output Saturation Voltages
Open Drain Output Saturation Voltages
3
VOPBAR
VOSBAR
FN3183.5
December 3, 2015
ICL7673
Electrical Specifications
TA = 25°C Unless Otherwise Specified (Continued)
PARAMETER
SYMBOL
Output Leakage Currents of PBAR and
SBAR
ILPBAR
ILSBAR
Switchover Uncertainty for Complete
Switching of Inputs and Open Drain
Outputs
V P - VS
TEST CONDITIONS
MIN
TYP
MAX
UNITS
VP = 0V, VS = 15V, ILOAD = 0mA
-
50
500
nA
at TA = +85°C
-
900
-
nA
VP = 15V, VS = 0V, ILOAD = 0mA
-
50
500
nA
at TA = +85°C
-
900
-
nA
VS = 3V, ISINK = 3.2mA, ILOAD = 15mA
-
10
50
mV
NOTE:
3. The Minimum input to output voltage can be determined by multiplying the load current by the switch resistance.
Typical Performance Curves
100
100
ILOAD = 1mA
ON-RESISTANCE P2 ()
ON-RESISTANCE P1 ()
ILOAD = 15mA
10
10
1
1
0
2
4
6
8
10
12
14
16
0
2
INPUT VOLTAGE VP (V)
FIGURE 1. ON-RESISTANCE SWITCH P1 AS A FUNCTION OF
INPUT VOLTAGE VP
5
0.4
-40°C
25°C
85°C
0.2
0
2
4
6
8
10
12
14
SUPPLY VOLTAGE (V)
16
FIGURE 3. SUPPLY CURRENT AS A FUNCTION OF SUPPLY
VOLTAGE
4
OUTPUT SATURATION VOLTAGE (V)
SUPPLY CURRENT (A)
0.6
8
10
FIGURE 2. ON-RESISTANCE SWITCH P2 AS A FUNCTION OF
INPUT VOLTAGE VS
1
0.8
4
6
INPUT VOLTAGE VS
VO = 5V
VO = 9V
VO = 3V
4
VO = 12V
3
2
VO = 15V
1
0
40
80
120
OUTPUT CURRENT (mA)
140
180
FIGURE 4. PBAR OR SBAR SATURATION VOLTAGE AS A
FUNCTION OF OUTPUT CURRENT
FN3183.5
December 3, 2015
ICL7673
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 50s.
1mA
ILOAD = 10mA
VS = 0V
Input Voltage
IS LEAKAGE CURRENT
100mA
The input operating voltage range for VP or VS 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
supply voltage. A low-impedance capacitor such as a
0.047F disc ceramic can be used to reduce the rate-of-rise.
85°C
10nA
1nA
1000pA
Status Indicator Outputs
10pA
25°C
1pA
0
2
4
5
6
INPUT VP (V)
8
10
12
FIGURE 5. IS LEAKAGE CURRENT VP TO VS AS A
FUNCTION OF INPUT VOLTAGE
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.
Applications
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
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 VS
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.
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
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
5
NiCAD
BATTERY
STACK
GND
FIGURE 6. DISCRETE BATTERY BACKUP CIRCUIT
FN3183.5
December 3, 2015
ICL7673
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, VP 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 VP
from VO, and connect VS.
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.
8
+5V
PRIMARY
SUPPLY
VP
2
LITHIUM
BATTERY
VO
VS
GND
+
Pbar
1
VO
+5V OR +3V
6
RI
STATUS
INDICATOR
4
-
GND
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.
FIGURE 7. ICL7673 BATTERY BACKUP CIRCUIT
8
+5V
PRIMARY
SUPPLY
VP
1
VO
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.
VO
+5V OR +3V
RC
2
RECHARGEABLE
BATTERY
VS
+
GND
4
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 8. APPLICATION REQUIRING RECHARGEABLE
BATTERY BACKUP
VP
8
FUSE
BRIDGE
RECTIFIER
C1
120/240
VAC
8
2
ICL7663
REGULATOR
4
R2
R3
6
D1
R1
VS
-
STEPDOWN
TRANSFORMER
2
+
VO
1
ICL7673
BATTERY
BACK-UP
4
BATTERY
STACK
GND
FIGURE 9. POWER SUPPLY FOR LOW POWER PORTABLE AC TO DC SYSTEMS
+5V
MAIN
POWER
POWER
FAIL
DETECTOR
MICROPROCESSOR
VP
VS
VO
INTERRUPT SIGNAL
ICL7673
BACKUP CIRCUIT
VOLATILE
RAM
+
-
FIGURE 10. TYPICAL MICROPROCESSOR MEMORY APPLICATION
6
FN3183.5
December 3, 2015
ICL7673
R2
PNP
PNP
VP
MAIN
SUPPLY
1
VO
8
VS
ICL7673
6
2
3
GND
+
R1
R4
NC
P-
EXTERNAL
EQUIPMENT
R3
(NOTE 4)
S-
-
3V
BACKUP
SUPPLY
NOTE 4. > 1MW
FIGURE 11. HIGH CURRENT BATTERY BACKUP SYSTEM
RF
RS
MAIN
SUPPLY
VP
VO
8
ICL7673
VS
BATTERY
BACKUP
S2
+
3
GND
-
GND
GND
FIGURE 12. LOW CURRENT BATTERY BACKUP SYSTEM WITH HYSTERESIS
R2
PNP
PNP
RF
R1
+V
MAIN
SUPPLY
RS
VP
8
VS
+
-
MAIN
SUPPLY
GND
2
NC
1
ICL7673 6
4
R4
P-
R3
S-
EXTERNAL
EQUIPMENT
3
BACKUP
SUPPLY
FIGURE 13. HIGH CURRENT BACKUP SYSTEM WITH HYSTERESIS
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Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
7
FN3183.5
December 3, 2015
ICL7673
VP
VP
VO
ICL7673
VS
VS
GND
VO
FIGURE 14. CLIPPLING CIRCUITS
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to the web to make
sure that you have the latest revision.
DATE
REVISION
December 3, 2015
FN3183.5
CHANGE
Added Revision History beginning with Rev 5.
Added About Intersil Verbiage.
Updated Ordering Information on page 1
About Intersil
Intersil Corporation is a leading provider of innovative power management and precision analog solutions. The company's products
address some of the largest markets within the industrial and infrastructure, mobile computing and high-end consumer markets.
For the most updated datasheet, application notes, related documentation and related parts, please see the respective product
information page found at www.intersil.com.
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Reliability reports are also available from our website at www.intersil.com/support
8
FN3183.5
December 3, 2015
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