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PDF ICL7673 Data sheet ( Hoja de datos )
| Número de pieza | ICL7673 | |
| Descripción | Automatic Battery Back-Up Switch | |
| Fabricantes | Intersil Corporation | |
| Logotipo |  |
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Data Sheet
December 3, 2015
ICL7673
FN3183.5
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.
Ordering Information
PART
NUMBER
TEMP. RANGE
(°C)
PACKAGE
PKG.
DWG. #
ICL7673CPA No
longer available
or supported.
Recommended
Replacement
ICL7673CPAZ
0 to 70
8 Ld PDIP
E8.3
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
8 Ld SOIC (N) M8.15
(Pb-free)
ICL7673CBAZA-T
(See Note)
0 to 70
8 Ld SOIC (N) M8.15
(Pb-free)
*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.
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
• Pb-Free Plus Anneal Available (RoHS Compliant)
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
VO 1
VS 2
SBAR 3
GDN 4
8 VP
7 NC
6 PBAR
5 NC
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.
1 page  
ICL7673
1mA
100mA
10nA
1nA
ILOAD = 10mA
VS = 0V
85°C
1000pA
10pA
25°C
1pA
02
4 56
8 10
INPUT VP (V)
FIGURE 5. IS LEAKAGE CURRENT VP TO VS AS A
FUNCTION OF INPUT VOLTAGE
12
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.
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 body-
drain parasitic diode will become forward biased. Complete
switching of the inputs and open-drain outputs typically
occurs in 50s.
Input Voltage
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
0.047F disc ceramic can be used to reduce the rate-of-rise.
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.
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
NiCAD
BATTERY
STACK
GND
FIGURE 6. DISCRETE BATTERY BACKUP CIRCUIT
5 FN3183.5
December 3, 2015
5 Page | ||
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| PDF Descargar | [ Datasheet ICL7673.PDF ] | |
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