LINER LTC1998IS6-TRPBF 2.5î¼a, 1% accurate sot-23 comparator and voltage reference for battery monitoring Datasheet

LTC1998
2.5µA, 1% Accurate
SOT-23 Comparator and Voltage
Reference for Battery Monitoring
DESCRIPTION
FEATURES
n
n
n
n
n
n
n
High Accuracy Trip Voltage: 1% Max Error Using
External 1% Resistors
Adjustable Threshold Voltage and Hysteresis
Quiescent Current: 2.5μA Typ
Output Swings Rail-to-Rail
Thresholds Programmable from 2.5V to 3.25V
Output State Guaranteed for VBATT ≥1.5V
Low Profile (1mm) ThinSOT™ Package
The LTC®1998 is a micropower comparator and a precision
adjustable reference in a 6-pin SOT-23 package that is
optimized for lithium-ion low battery detection circuits.
The LTC1998 features a voltage detection circuit with an
adjustable threshold voltage and hysteresis. The threshold
voltage can be programmed from 2.5V to 3.25V with two
external resistors. A 10mV to 750mV hysteresis can be
added with a third external resistor.
A proprietary internal architecture maintains 1% threshold voltage accuracy over temperature with low cost 1%
external resistors.
APPLICATIONS
n
Lithium-Ion Battery-Powered Equipment
PDAs
Cell Phones
Handheld Instruments
Battery Packs
Pagers
Palm Top Computers
POS Terminals
A separate power supply pin, VLOGIC, allows the battery-low
logic output to operate below the battery voltage, allowing
compatibility with low voltage microprocessors without a
pull-up resistor. Power supply glitches are eliminated by
preventing the cross-conducting current which occurs
when the output changes state.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. ThinSOT is
a trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
The LTC1998 operates with battery or supply voltages
up to 5.5V and its battery-low output is valid for battery
voltages above 1.5V.
BLOCK DIAGRAM
Threshold Voltage Error vs Temperature
1.0
BATT
0.9
VLOGIC
0.7
THRESHOLD
ADJUST
BATTLO
R
VTH.A
% ERROR
1.1R
VHYST.A
VTH.A SET BY 1%
EXTERNAL R,
THRESHOLD = 3V
0.8
0.6
0.5
0.4
VTH.A = 1V
THRESHOLD = 3V
0.3
1.2V
0.2
VTH.A SHORTED
TO GROUND,
THRESHOLD = 2.5V
0.1
1998 BD
0
–45 –25
35
15
55
–5
TEMPERATURE (°C)
75
95
1998 TA02
1998fa
1
LTC1998
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
TOP VIEW
Total Supply Voltage (BATT or VLOGIC to GND)............6V
Voltage
VTH.A, VH.A ....................... BATT + 0.3V to GND – 0.3V
BATTLO ..........................VLOGIC + 0.3V to GND – 0.3V
Operating Temperature Range (Note 3).... –40°C to 85°C
Specified Temperature Range (Note 4)
LTC1998C ............................................ –40°C to 85°C
LTC1998I.............................................. –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
BATT 1
6 BATTLO
GND 2
5 VLOGIC
VTH.A 3
4 VH.A
S6 PACKAGE
6-LEAD PLASTIC SOT-23
TJMAX = 150°C, θJA = 250°C/W
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC1998CS6#PBF
LTC1998CS6#TRPBF
LTTY
6-Lead Plastic SOT-23
–40°C to 85°C
LTC1998IS6#PBF
LTC1998IS6#TRPBF
LTTY
6-Lead Plastic SOT-23
–40°C to 85°C
LEAD BASED FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC1998CS6
LTC1998CS6#TR
LTTY
6-Lead Plastic SOT-23
–40°C to 85°C
LTC1998IS6
LTC1998IS6#TR
LTTY
6-Lead Plastic SOT-23
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
1998fa
2
LTC1998
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VGND = 0V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Power Supply
Supply Voltage Range-BATT
l
1.5
Supply Voltage Range-VLOGIC
l
1
5.5
V
VBATT
V
2.5
3.5
4.2
4.5
μA
μA
μA
3
4.3
5.2
5.5
μA
μA
μA
l
0.6
0.8
0.85
1
%
%
VBATT.Th = 3V, Pin 3 Driven by Precision Voltage Source to 1V
LTC1998C
LTC1998I
l
l
0.5
0.6
0.61
0.71
%
%
VBATT.Th = 3V, VTH.A = 1V (Note 5)
Programmed with 1% Max External Resistors
LTC1998C
LTC1998I
l
l
0.8
0.9
1
1.1
%
%
VBATT.Th = 3.25V, Pin 3 Driven by Precision Voltage Source to 1.5V
LTC1998C
LTC1998I
l
l
0.6
0.7
0.65
0.85
%
%
VBATT.Th = 3.25V, VTH.A = 1.5V (Note 5)
Programmed with 1% Max External Resistors
LTC1998C
LTC1998I
l
l
0.9
1
1.1
1.3
%
%
VHYST ≤ 250mV
250mV ≤ VHYST ≤ 750mV
l
l
–5
5
mV
mV
l
10
750
mV
Supply Current, VBATT = 3V,
VTH.A = 1.5V
TA = 25°C
LTC1998CS6
LTC1998IS6
l
l
Supply Current, VBATT = 5.5V,
VTH.A = 1.5V
TA = 25°C
LTC1998CS6
LTC1998IS6
l
l
Monitor
Threshold Accuracy
Hysteresis Accuracy
VBATT.Th = 2.5V, Pin 3 Shorted to Ground
Allowable Hysteresis Range (Note 2)
Propagation Delay
±5
COUT = 100pF
Overdrive = 10mV
Overdrive = 100mV
350
150
μs
μs
VTH.A ≤ 1.5V
l
0.01
1
nA
VH.A ≤ 1.5V
l
0.01
1
nA
BATTLO High Voltage
IOUT = –1mA, VLOGIC ≥ 1.5V
l
BATTLO Low Voltage
IOUT = 1mA, VBATT ≥ 2V
l
0.2
V
BATTLO Low Voltage
IOUT = 0.25mA, VBATT = 1V
l
Threshold Adjust Pin Leakage, ITH.A
Hysteresis Adjust Pin Leakage, IH.A
Output
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: Maximum allowable hysteresis depends on desired trip voltages.
See application notes for details.
Note 3: LTC1998C and LTC1998I are guaranteed functional over the
operating temperature range of –40°C to 85°C.
VLOGIC – 0.3
V
0.3
V
Note 4: The LTC1998C is guaranteed to meet specified performance from
0°C to 70°C. The LTC1998C is designed, characterized and expected to
meet specified performance from –40°C to 85°C but is not tested or QA
sampled at these temperatures. The LTC1998I is guaranteed to meet
specified performance from –40°C to 85°C.
Note 5: This parameter is not 100% tested.
1998fa
3
LTC1998
TYPICAL PERFORMANCE CHARACTERISTICS
Quiescent Supply Current vs
Supply Voltage
3.0
3.5
TA = 25°C
VLOGIC = VBATT
SUPPLY CURRENT (μA)
SUPPLY CURRENT (μA)
3.5
VBATT = VLOGIC = 3V
3.0
VTH.A = 1.5V
2.5
Threshold Voltage vs Threshold
Adjust Voltage
VTH.A = 0V
2.0
1.5
1.0
THRESHOLD VOLTAGE (V)
3.5
Quiescent Supply Current vs
Temperature
2.5
VTH.A = 1.5V
2.0
1.5
1.0
3.0
0.5
0.5
0
–50
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
–30
–10
10
30
50
TEMPERATURE (°C)
70
2.5
90
0
1998 G02
1998 G01
Available Hysteresis vs
Threshold Voltage
1998 G03
Threshold Voltage Error vs
Temperature
750
Input Current vs Temperature
1.0
10000
0.7
250
0.6
0.5
0.4
VTH.A = 1V
THRESHOLD = 3V
0.3
0.2
VTH.A SHORTED
TO GROUND,
THRESHOLD = 2.5V
INPUT CURRENT VTH.A, VH.A (pA)
VTH.A SET BY 1%
EXTERNAL R,
THRESHOLD = 3V
0.8
% ERROR
AVAILABLE HYSTERESIS (mV)
0.9
500
1.5
0.5
1.0
THRESHOLD ADJUST VOLTAGE (V)
VIN = 1.5V
1000
VIN = 1V
100
VIN = 0.5V
10
1
0.1
0
2.5
3.25
2.75
3.0
LOW BATTERY THRESHOLD VOLTAGE (V)
1998 G04
0
–45 –25
35
15
55
–5
TEMPERATURE (°C)
75
95
1998 G05
0.1
35 45
55
65 75 85 95 105 115 125
TEMPERATURE (°C)
1998 G06
1998fa
4
LTC1998
TYPICAL PERFORMANCE CHARACTERISTICS
Output Low Voltage vs Load
Current
Output High Voltage vs Load
Current
OUTPUT VOLTAGE (V)
TA = 25°C
VLOGIC = VBATT = 3V
TA = 85°C
0.4
TA = 25°C
0.2
TA = –40°C
0
120
TA = 85°C
TA = 25°C
TA = –40°C
–50
–100
TA = –40°C
TA = 25°C
–150
TA = 85°C
–200
TA = 25°C
VLOGIC = VBATT
–250
0
1
2
3
4
OUTPUT SINK CURRENT (mA)
5
1998 G07
100
CURRENT (mA)
OUTPUT VOLTAGE RELATIVE TO VBATT (mV)
0.6
Output Short-Circuit Current vs
Supply Voltage
1
80
60
2
3
4
OUTPUT SOURCE CURRENT (mA)
5
1998 G08
SOURCE CURRENT,
BATTLO SHORTED TO GND
40
20
BATT = 3V
BATT = 5V
TA = 25°C
VBATT = VLOGIC
SINK CURRENT,
BATTLO SHORTED
TO VLOGIC
0
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
1998 G09
1998fa
5
LTC1998
PIN FUNCTIONS
BATT (Pin 1): Battery Voltage to be monitored. Supply
current is also drawn from this pin. Board layout should
connect this pin to the battery(+) terminal, through a trace
that does not conduct load current.
GND (Pin 2): Ground should be connected to the battery
(–) terminal through a trace that does not conduct load
return current.
VTH.A (Pin 3): Threshold Adjust Pin. Adjusts the low battery
threshold voltage, VBATT.Th = 2.5V + (VTH.A/2). VTH.A can be
supplied by a voltage source or a resistor divider.
VH.A (Pin 4): Hysteresis Adjust. Hysteresis threshold
voltage VTH2 = 2.5V + (VH.A/2). VH.A can be supplied by
a voltage source or resistor divider. VH.A must always be
programmed to a higher potential than VTH.A. Hysteresis
voltage, VHYST = VTH2 – VBATT.Th.
VLOGIC (Pin 5): Positive Supply Voltage for Output Driver.
This voltage can be driven from an external logic supply
or tied to BATT.
BATTLO (Pin 6): Output of Comparator. Low for BATT
< VBATT.Th (low battery threshold voltage). Output state
guaranteed for VBATT ≥ 1.5V.
1998fa
6
LTC1998
QUICK DESIGN GUIDE
The LTC1998 is a low battery warning indicator and is especially designed for monitoring the voltage of single-cell
Lithium-Ion batteries. The LTC1998 compares its supply
pin (BATT) to an accurate internal reference; if the battery
voltage falls below the programmed low battery threshold
voltage of the LTC1998, the battery low pin (BATTLO) will
change state, from high to low, to indicate a low battery
condition. The low battery threshold voltage is programmed
via the voltage threshold adjust pin (VTH.A). A hysteresis
adjust pin (VH.A) will add hysteresis to the programmed
value of the low battery threshold voltage.
Typical Application
Table 1: Design Equations for R1, R2, R3, Figure 1
Choose desired values for:
• VBATT.Th: Low Battery Threshold Voltage
• VHYST: Hysteresis Voltage
• IR: Max Allowable Resistor Current
Solve:
4.2V
RTOTAL = R1 + R2 + R3 =
IR
Example 1: A system using a 4.2V (fully charged) LithiumIon battery requires a low battery threshold of 2.7V, 100mV
hysteresis and can allow up to 4.2μA maximum resistor
current.
RTOTAL = 1MΩ, R1 = 786k, R2 = 66k and R3 = 148k
Choose standard 1% values.
R1 = 787k, R2 = 66.5k, R3 = 147k
1.5V TO 4.2V
+
Li-Ion
How to Calculate the External Resistor Values
R1
1%
REGULATOR
0.1μF
4
R2
1%
1
BATT
5
VH.A VLOGIC
LTC1998
3
R3
1%
VLOGIC
μP
6
VTH.A BATTLO
GND
2
1998 F01
Figure 1. Low Battery Threshold Detector with Hysteresis
⎛
⎞
5V
R1 = RTOTAL • ⎜
– 1⎟
⎝ VBATT .Th + VHYST ⎠
⎛ 5V
⎞
R2 = RTOTAL • ⎜
– 1⎟ – R1
⎝ VBATT .Th ⎠
R3 = RTOTAL – R1 – R2
1998fa
7
LTC1998
APPLICATIONS INFORMATION
LOW BATTERY THRESHOLD VOLTAGE AND
HYSTERESIS ADJUST
Low Battery Threshold Voltage Adjustment, Pin 3
The low battery threshold voltage is the battery voltage
which will trip the (BATTLO) pin high to low. It should be
adjusted via the threshold adjust pin (VTH.A). This is a high
input impedance pin that senses an externally applied
voltage and programs the low battery threshold voltage
(VBATT.Th). The VTH.A pin is designed to accommodate
voltages from 0V to 1.5V with respect to ground. This
allows the low battery threshold voltage to be set to any
voltage between 2.5V and 3.25V, that is:
VBATT .Th = 2.5V +
(VTH.A )
2
For instance, if the applied voltage at pin 3, VTH.A, is 1V
the LTC1998 will indicate a low battery condition when the
battery voltage pin (BATT) falls below 3V.
The voltage at the threshold adjust pin (VTH.A) can be set
with any voltage source. This pin allows a continuous time
adjustment, that is, the low battery threshold voltage may
be changed at any time. The high input impedance of the
VTH.A pin allows the use of a high valued resistive divider
(to minimize current drain) from the battery to set the
battery low threshold voltage, Figure 2.
+
1
BATT
Li-Ion
R1
3
R2
The simple calculations of resistor values R1 and R2 are
illustrated below. Set a value for R1 + R2. This value will
affect the max amount of current drawn from the battery
when fully charged. For instance if R1 + R2 = 1M the
resistive divider will draw 4.1μA when the battery voltage
is 4.1V. Set the desired value of VBATT.Th (this value should
be between 2.5V and 3.25V) that is the value of the battery
voltage that will trip the internal circuitry of the LTC1998
and change the state of the battery low pin (BATTLO).
⎛ 5V
⎞
Solve for R1= (R1+ R2) ⎜
– 1⎟
⎝ VBATT.Th ⎠
Example: A Lithium-Ion battery is monitored and a battery low signal should be issued when it discharges to
2.85V, that is, VBATT.Th = 2.85V; if (R1 + R2) = 1M, then
R1 = 754.38k and R2 = 245.62k. Choose the closest 1%
value of R1 = 750k and R2 = 243k. Calculate the practical
value for VBATT.Th as it will be slightly different from 2.85V,
due to the use of standard 1% resistor values.
VBATT .Th = 5V
R1 + R2
= 2.849V
R1 + (R1 + R2)
The above low battery threshold of 2.849V is guaranteed to
within 1% even though 1% resistors are used to program
the VTH.A voltage applied to Pin 3.
For sake of completeness, the voltage at Pin 3 (VTH.A) can
be easily calculated by VTH.A = VBATT.Th (R2/(R1 + R2) =
0.6972V (when VBATTERY = VBATT.Th).
VTH.A
LTC1998
2
1998 F02
Figure 2. Resistor Divider Sets Threshold
1998fa
8
LTC1998
APPLICATIONS INFORMATION
The LTC1998 has an adjustable hysteresis ranging from
10mV to 0.75V. A large hysteresis is useful in the event that
a low battery signal at the LTC1998’s BATTLO pin causes
the system to shed some battery load, thus inducing
system confusion as the partially loaded battery recovers and changes the status of Pin 6 (BATTLO). The 2.5V
to 3.25V programming window of low battery threshold
voltage includes the hysteresis. If, for instance, the low
battery threshold voltage is set to 2.5V, 750mV hysteresis can be added on top of the 2.5V. If the low battery
threshold voltage is set to 3.15V, only 100mV hysteresis
can be applied.
The programming of the hysteresis threshold adjust pin
(VH.A) is similar to the programming of the voltage threshold adjust pin (VTH.A) already described in the previous
paragraph. Pin 4 effectively adjusts the threshold voltage
at which the low battery pin (BATTLO) changes state from
low to high. This threshold (VTH2) is defined as:
VTH2
(V )
= 2.5V + H.A
2
The actual hysteresis voltage is:
It is imperative that the hysteresis threshold adjust
voltage at Pin 4 be set to a higher voltage than the low
battery threshold adjust voltage at Pin 3, at all times, to
avoid oscillation at the BATTLO output pin. The hysteresis
threshold adjust pin may be set with a voltage source or
with a resistor divider, just as with the low battery threshold
adjust pin.
Combined Control of Threshold and Hysteresis
If a resistor divider is desired, then both threshold adjust
dividers can be combined in order to save current. This
simple technique also guarantees that the hysteresis
threshold adjust voltage at Pin 4 is higher than the voltage
at the VTH.A pin, Figure 3.
+
Li-Ion
Hysteresis Adjustment, Pin 4.
R1
4
1
BATT
VH.A
LTC1998
R2
3
VTH.A
R3
1998 F03
Figure 3. Combined Resistor Divider
VHYST = VTH2 – VBATT.Th
1998fa
9
LTC1998
APPLICATIONS INFORMATION
The calculation of the resistor values R1, R2 and R3 is
quite straightforward and similar to the procedure outlined
in the previous paragraph.
VERSATILE OUTPUT DRIVER
Choose a value for the sum of R1 + R2 + R3 as well as the
values for low battery threshold and hysteresis.
The LTC1998 uses a CMOS push-pull output stage to drive
the low battery output signal. This output pin (BATTLO)
has a separate supply pin, (VLOGIC) that can be used to
provide an output voltage rail matching the VDD logic of
microprocessors. The VLOGIC pin may be tied to a voltage lower than the voltage at the BATT pin. The VLOGIC
pin may also be tied to a voltage higher than VBATT via a
series resistor greater than 10k. The output will then act
as an open-drain device.
Solve for resistor R1:
⎛ 5V
⎞
R1= (R1+ R2 + R3) ⎜
– 1⎟
⎝ VTH2 ⎠
Solve for the sum of
⎛ 5V
⎞
(R1+ R2) = (R1+ R2 + R3) ⎜
– 1⎟
⎝ VBATT.Th ⎠
then solve for R2 and R3.
Example: A system needs to detect a low battery
voltage of 3V (VBATT.Th = 3V) with 250mV hysteresis
(VTH2 = 3.25V). Set the value of the resistor divider
(R1 + R2 + R3) = 1M.
R1 = 539k, R1 + R2 = 667k, R2 = 128k, R3 = 333k.
Choose the closest 1% values, that is 536k, 332k, 127k.
Figure 4 graphically shows the function of the LTC1998 as
described above.
VLOGIC, BATTLO (Pins 5,6)
In a given application, if it is possible for BATTLO to be
shorted to GND or a supply, a series resistor should be
added to limit the short-circuit current to 5mA.
3.25V
PROGRAMMED
HYSTERESIS
THRESHOLD
PROGRAMMED
LOW BATT
THRESHOLD
2.50V
HYSTERESIS
PROGRAMMABLE
THRESHOLD RANGE
BATTERY VOLTAGE
RECOVERS UNDER
REDUCED LOAD
BATTERY
VOLTAGE
VLOGIC
BATTLO
1998 F04
Figure 4. LTC1998 Function Plot
1998fa
10
LTC1998
PACKAGE DESCRIPTION
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
0.62
MAX
2.90 BSC
(NOTE 4)
0.95
REF
1.22 REF
3.85 MAX 2.62 REF
1.4 MIN
2.80 BSC
1.50 – 1.75
(NOTE 4)
PIN ONE ID
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45
6 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
0.01 – 0.10
1.00 MAX
DATUM ‘A’
0.30 – 0.50 REF
0.09 – 0.20
(NOTE 3)
1.90 BSC
S6 TSOT-23 0302 REV B
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
1998fa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
11
LTC1998
TYPICAL APPLICATIONS
Single Li-Ion Cell Low Battery Detector
Backup Battery Switchover Circuit
VLOGIC =
1V TO 5V
VBATT =
1.5V TO 4.2V
REGULATOR
0.1μF
R1
1%
1
BATT
5
4
VH.A VLOGIC
R2
1%
LTC1998
3
R3
1%
R1
787k
1% 4
+
R2
68.1k
1% 3
Li-Ion
Li-Ion
+
MBRM120
2.5V TO 4.2V
μP
6
VTH.A BATTLO
GND
2
R3
147k
1%
VOUT
BAT54C
R4
1M
1
BATT
5
VH.A VLOGIC
Si2301
Si2301
LTC1998
VTH.A BATTLO
GND
2
BAT54C
6
+
3V
BACKUP
BATTERY
1998 TA01
SWITCHES TO BACKUP BATTERY WHEN PRIMARY FALLS BELOW 2.7V.
SWITCHES BACK TO PRIMARY WHEN VOLTAGE RECOVERS TO ≥ 2.8V
1998 TA04
Micropower 2.9V VCC Threshold
Detector with 15mV Hysteresis
High Accuracy Window Comparator
with Dual Hysteresis
3.3V
R1
715k
1% 4
R2
9.09k
1% 3
R3
274k
1%
1
VIN
BATT
5
VH.A VLOGIC
R1
619k
1% 4
LTC1998
VTH.A BATTLO
GND
2
6
OUT
R2
6.04k
1% 3
LOW THRESHOLD = 2.9V
HYSTERESIS = 15mV
R3
383k
1%
1998 TA03
Low Battery Load Reduction Circuit
R4
909k
1% 4
REGULATOR
Li-Ion
+
R1
787k
1% 4
R2
68.1k
1% 3
R3
147k
1%
Si2301
1
BATT
5
VH.A VLOGIC
CRITICAL
CIRCUITRY
R5
6.98k
1% 3
R6
76.8k
1%
LTC1998
6
VTH.A BATTLO
GND
2
NONCRITICAL
CIRCUITRY
LOW THRESHOLD = 2.7V
HYSTERESIS = 100mV
V+
1
R7
1M
BATT
5
VH.A VLOGIC
VOUT
LTC1998
VTH.A BATTLO
GND
2
6
2N7002
VOUT = V+ WHEN
2.6V ≤ VIN ≤ 3.1V
1
BATT
5
NC
VH.A VLOGIC
LTC1998
VTH.A BATTLO
GND
2
6
WINDOW LOW THRESHOLD = 2.6V
HYSTERESIS = 10mV
WINDOW HIGH THRESHOLD = 3.1V
HYSTERESIS = 10mV
1998 TA06
1998 TA05
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1440/LTC1540
Micropower Comparator with 1% Reference
1.182V ±1% Reference, ±10mV (Max) Input Offset
LTC1441/LTC1442
Micropower Dual Comparator with 1% Reference
1.182V ±1% Reference (LTC1442)
LTC1443/LTC1444/LTC1445
Micropower Quad Comparator with 1% Reference
LTC1443 has 1.182V Reference, LTC1444/LTC1445 have 1.221V
Reference and Adjustable Hysteresis
1998fa
12 Linear Technology Corporation
LT 0108 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2001
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