1
LTC1440/LTC1441/LTC1442
Ultralow Power Single/Dual
Comparator with Reference
V
+
R1
1.65M
1%
R2
1.13M
1%
3.3V
V
2
1
7
8
GND
OUT
LTC1440
1440 TA01
IN
+
IN
HYST
REF
3
4
5
6
+
TEMPERATURE (
C)
40
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
20
60
1440/1/2 TA02
20
0
40
80
100
SUPPLY CURRENT (
A)
V
+
= 5V
V
= GND = 0V
TYPICAL APPLICATIO
N
U
Micropower 2.9V V
CC
Threshold Detector
LTC1440 Supply Current vs Temperature
The LTC
1440/LTC1441/LTC1442 are ultralow power
single and dual comparators with built-in references. The
comparators feature less than 3.7
A supply current over
temperature (LTC1440), a 1.182V
1% reference, pro-
grammable hysteresis (LTC1440/LTC1442) and TTL/CMOS
outputs that sink and source current. The reference output
can drive a bypass capacitor of up to 0.01
F without
oscillation.
The comparators operate from a single 2V to 11V supply
or a dual
1V to
5.5V supply (LTC1440). Comparator
hysteresis is easily programmed by using two resistors
and the HYST pin (LTC1440/LTC1442). Each comparator's
input operates from the negative supply to within 1.3V of
the positive supply. The comparator output stage can
continuously source up to 40mA. By eliminating the
cross-conducting current that normally happens when the
comparator changes logic states, the power supply glitches
are eliminated.
The LTC1440 is available in 8-pin PDIP, SO and MSOP
packages. The LTC1441/LTC1442 are available in 8-pin
PDIP and SO packages.
FEATURES
DESCRIPTIO
N
U
s
Battery-Powered System Monitoring
s
Threshold Detectors
s
Window Comparators
s
Oscillator Circuits
APPLICATIO
N
S
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
s
Ultralow Quiescent Current: 2.1
A Typ (LTC1440)
s
Wide Supply Range:
Single: 2V to 11V
Dual:
1V to
5.5V
s
Input Voltage Range Includes the Negative Supply
s
Reference Output Drives 0.01
F Capacitor
s
Adjustable Hysteresis (LTC1440/LTC1442)
s
TTL/CMOS Compatible Outputs
s
12
s Propagation Delay with 10mV Overdrive
s
No Crowbar Current
s
40mA Continuous Source Current
s
Pin Compatible Upgrades for MAX921/922/923
2
LTC1440/LTC1441/LTC1442
Voltage
V
+
to V
, V
+
to GND, GND to V
...........12V to 0.3V
IN
+
, IN
, HYST ................. (V
+
+ 0.3V) to (V
0.3V)
REF ................................... (V
+
+ 0.3V) to (V
0.3V)
OUT (LTC1440) .............. (V
+
+ 0.3V) to (GND 0.3V)
OUT (LTC1441/LTC1442) ... (V
+
+ 0.3V) to (V
0.3V)
Current
IN
+
, IN
, HYST ................................................. 20mA
REF ................................................................... 20mA
OUT .................................................................. 50mA
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
OUT Short-Circuit Duration (V
+
5.5V) ...... Continuous
Power Dissipation ............................................. 500mW
Operating Temperature Range
LTC144XC .............................................. 0
C to 70
C
LTC144XI .......................................... 40
C to 85
C
Storage Temperature Range ................ 65
C to 150
C
Lead Temperature (Soldering, 10 sec).................. 300
C
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
T
JMAX
= 150
C,
JA
= 130
C/ W (N8)
T
JMAX
= 150
C,
JA
= 175
C/ W (S8)
1
2
3
4
8
7
6
5
TOP VIEW
GND
V
IN
+
IN
OUT
V
+
REF
HYST
S8 PACKAGE
8-LEAD PLASTIC SO
N8 PACKAGE
8-LEAD PDIP
ORDER PART NUMBER
ORDER PART NUMBER
LTC1440CN8
LTC1440CS8
LTC1440IN8
LTC1440IS8
LTC1440CMS8
S8 PART MARKING
MS8 PART MARKING
1440
1440I
LTBX
ORDER PART NUMBER
ORDER PART NUMBER
LTC1441CN8
LTC1441CS8
LTC1441IN8
LTC1441IS8
LTC1442CN8
LTC1442CS8
LTC1442IN8
LTC1442IS8
S8 PART MARKING
S8 PART MARKING
1441
1441I
1442
1442I
T
JMAX
= 150
C,
JA
= 130
C/ W (N8)
T
JMAX
= 150
C,
JA
= 175
C/ W (S8)
T
JMAX
= 150
C,
JA
= 130
C/ W (N8)
T
JMAX
= 150
C,
JA
= 175
C/ W (S8)
1
2
3
4
8
7
6
5
TOP VIEW
OUT A
V
IN A
+
IN A
OUT B
V
+
IN B
+
IN B
S8 PACKAGE
8-LEAD PLASTIC SO
N8 PACKAGE
8-LEAD PDIP
1
2
3
4
8
7
6
5
TOP VIEW
OUT A
V
IN A
+
IN B
OUT B
V
+
REF
HYST
S8 PACKAGE
8-LEAD PLASTIC SO
N8 PACKAGE
8-LEAD PDIP
Consult factory for Military grade parts.
V
+
= 5V, V
= GND = 0V, T
A
= 25
C unless otherwise noted.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Power Supply
V
+
Supply Voltage Range
q
2.0
11.0
V
I
CC
Supply Current
IN
+
= IN
= 80mV
LTC1440
q
2.1
3.7
A
HYST = REF (LTC1440/LTC1442)
LTC1441
q
3.5
5.7
A
LTC1442
q
3.5
5.7
A
1
2
3
4
GND
V
IN
+
IN
8
7
6
5
OUT
V
+
REF
HYST
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 150
C,
JA
= 250
C/ W
3
LTC1440/LTC1441/LTC1442
V
+
= 5V, V
= GND = 0V, T
A
= 25
C unless otherwise noted.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Comparator
V
OS
Comparator Input Offset Voltage
V
CM
= 2.5V
q
3
10
mV
I
IN
Input Leakage Current (IN
+
, IN
)
V
IN
+
= V
IN
= 2.5V
q
0.01
1.0
nA
Input Leakage Current (HYST)
q
0.02
1.0
nA
V
CM
Comparator Input Common Mode Range
q
V
V
+
1.3V
V
CMRR
Common Mode Rejection Ratio
V
to V
+
1.3V
0.1
1
mV/V
PSRR
Power Supply Rejection Ratio
V
+
= 2V to 11V
0.1
1
mV/V
NOISE
Voltage Noise
100Hz to 100kHz
100
V
RMS
V
HYST
Hysteresis Input Voltage Range
LTC1440/LTC1442
q
REF 50mV
REF
V
t
PD
Propagation Delay
C
OUT
= 100pF
Overdrive = 10mV
15
s
Overdrive = 100mV
8
s
V
OH
Output High Voltage
I
O
= 13mA
q
V
+
0.4V
V
V
OL
Output Low Voltage
I
O
= 1.8mA
LTC1440
q
GND + 0.4V
V
LTC1441/LTC1442
q
V
+ 0.4V
V
Reference
V
REF
Reference Voltage
No Load
C Temp Range
q
1.170
1.182
1.194
V
LTC1440/LTC1442
I Temp Range
q
1.164
1.200
V
No Load LTC1440 (MSOP)
C Temp Range
q
1.164
1.200
V
I
SOURCE
Reference Output Source Current
V
REF
1mV (LTC1442)
q
100
200
A
I
SINK
Reference Output Sink Current
V
REF
2.5mV (LTC1442)
10
20
A
V
REF
Reference Source Current
0
I
SOURCE
2mA (LTC1440)
q
0.8
5
mV
Reference Sink Current
0
I
SINK
10
A (LTC1440)
0.5
1.5
mV
q
5
mV
NOISE
Voltage Noise
100Hz to 100kHz
100
V
RMS
V
+
= 3V, V
= GND = 0V, T
A
= 25
C unless otherwise noted.
Power Supply
V
+
Supply Voltage Range
q
2
11
V
I
CC
Supply Current
IN
+
= IN
= 80mV
LTC1440
q
2
3.6
A
HYST = REF (LTC1440/LTC1442)
LTC1441
q
3.5
5.7
A
LTC1442
q
3.5
5.7
A
Comparator
V
OS
Comparator Input Offset Voltage
V
CM
= 1.5V
q
3
10
mV
I
IN
Input Leakage Current (IN
+
, IN
)
V
IN
+
= V
IN
= 1.5V
q
0.01
1
nA
Input Leakage Current (HYST)
q
0.02
1
nA
V
CM
Comparator Input Common Mode Range
q
V
V
+
1.3V
V
CMRR
Common Mode Rejection Ratio
V
to V
+
1.3V
0.1
1
mV/V
PSRR
Power Supply Rejection Ratio
V
+
= 2V to 11V
0.1
1
mV/V
NOISE
Voltage Noise
100Hz to 100kHz
100
V
RMS
V
HYST
Hysteresis Input Voltage Range
LTC1440/LTC1442
q
REF 50mV
REF
V
t
PD
Propagation Delay
C
OUT
= 100pF
Overdrive = 10mV
14
s
Overdrive = 100mV
5
s
V
OH
Output High Voltage
I
O
= 8mA
q
V
+
0.4V
V
V
OL
Output Low Voltage
I
O
= 0.8mA
LTC1440
q
GND + 0.4V
V
LTC1441/LTC1442
q
V
+ 0.4V
V
4
LTC1440/LTC1441/LTC1442
Comparator Response Time vs
Input Overdrive
RESPONSE TIME (
s)
1
INPUT VOLTAGE (mV)
OUTPUT VOLTAGE (V)
0
0
1
6
14
18
5
1440/1/2 G02
100
2
10
4
12
16
0
8
2
3
4
100mV
10mV
50mV
20mV
T
A
= 25
C
RESPONSE TIME (
s)
1
INPUT VOLTAGE (mV)
OUTPUT VOLTAGE (V)
100
0
1
6
4
5
1440/1/2 G01
0
2
0
10
8
2
3
4
100mV
10mV
50mV
20mV
T
A
= 25
C
Comparator Response Time vs
Input Overdrives
Comparator Short-Circuit Sink
Current vs Supply Voltage
SUPPLY VOLTAGE (V)
0
SINK CURRENT (mA)
200
180
160
140
120
100
80
60
40
20
0
8
1440/1/2 G03
2
1
3
5
7
9
4
6
10
OUT CONNECTED TO V
+
T
A
= 25
C
Comparator Short-Circuit Source
Current vs Supply Voltage
Comparator Response Time at
Low Supply Voltage
Comparator Response Time vs
Load Capacitance with 100mV
Input Overdrive
ELECTRICAL CHARACTERISTICS
The
q
denotes specifications which apply over the full operating
temperature range.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Reference
V
REF
Reference Voltage
No Load
C Temp Range
q
1.170
1.182
1.194
V
LTC1440/LTC1442
I Temp Range
q
1.164
1.200
V
No Load LTC1440 (MSOP)
C Temp Range
q
1.164
1.200
V
I
SOURCE
Reference Output Source Current
V
REF
1mV (LTC1442)
q
60
120
A
I
SINK
Reference Output Sink Current
V
REF
2.5mV (LTC1442)
10
20
A
V
REF
Reference Source Current
0
I
SOURCE
1mA (LTC1440)
q
0.8
5.5
mV
Reference Sink Current
0
I
SINK
10
A (LTC1440)
0.5
1.5
mV
q
5
mV
NOISE
Voltage Noise
100Hz to 100kHz
100
V
RMS
V
+
= 3V, V
= GND = 0V, T
A
= 25
C unless otherwise noted.
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
SUPPLY VOLTAGE (V)
0
SOURCE CURRENT (mA)
3
5
1440/1/2 G04
1
2
4
160
140
120
100
80
60
40
20
0
OUT CONNECTED TO
V
= GND = 0V
LOAD CAPACITANCE (nF)
0
RESPONSE TIME (
s)
12
10
8
6
4
2
80
1440/1/2 G05
20
40
60
100
t
PHL
t
PLH
SUPPLY VOLTAGE (V)
1.0
RESPONSE TIME (
s)
10000
1000
100
10
1
1.2
1.4
1.6
1.1
1.3
1.5
1440/1/2 G06
20mV OVERDRIVE
100mV OVERDRIVE
5
LTC1440/LTC1441/LTC1442
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
LOAD CURRENT (mA)
0
1
OUTPUT VOLTAGE HIGH (V)
2
3
4
5
10
20
30
40
1440/1/2 G07
50
60
V
+
= 5V
V
+
= 3V
V
+
= 2V
T
A
= 25
C
Comparator Output Voltage High
vs Load Current
Comparator Output Voltage Low
vs Load Current
LOAD CURRENT (mA)
0
OUTPUT VOLTAGE HIGH (V)
1.5
2.0
2.5
30
50
80
1440/1/2 G08
1.0
0.5
0
10
20
40
60
70
V
+
= 2V
V
+
= 3V
V
+
= 5V
T
A
= 25
C
LTC1440/LTC1442
Hysteresis Control
TEMPERATURE (
C)
60
SUPPLY CURRENT (
A)
6
5
4
3
2
1
100
1440/1/2 G10
20
40
20 40
80
120
0
60
140
V
+
= 5V
V
= 5V
V
+
= 5V
V
= GND = 0V
V
+
= 3V
V
= GND = 0V
LTC1440
Supply Current vs Temperature
OUTPUT LOAD CURRENT (mA)
0
1.190
1.185
1.180
1.175
1.170
1.165
1.160
1.155
1.5
2.5
1440/1/2 G11
0.5
1.0
2.0
3.0
3.5
REFERENCE OUTPUT VOLTAGE (V)
V
CC
= 5V
SOURCE
Reference Output Voltage vs
Output Load Current
OUTPUT LOAD CURRENT (
A)
0
REFERENCE OUTPUT VOLTAGE (V)
1.200
1.195
1.190
1.185
1.180
1.175
1.170
5
10
15
20
1440/1/2 G12
25
30
V
CC
= 5V
SINK
V
CC
= 2V
Reference Output Voltage vs
Output Load Current (Sink)
Reference Voltage vs
Temperature
V
REF
V
HYST
(mV)
0
POSITIVE-TO-NEGATIVE INPUT VOLTAGE (mV)
30
50
1440/1/2 G09
10
20
40
80
60
40
20
0
20
40
60
80
OUTPUT HIGH
OUTPUT LOW
TEMPERATURE (
C)
60
REFERENCE VOLTAGE (V)
1.186
1.184
1.182
1.180
1.178
1.176
1.174
1.172
1.170
100
1440/1/2 G13
20
40
20 40
80
120
0
60
140
6
LTC1440/LTC1441/LTC1442
PI
N
FU
N
CTIO
N
S
U
U
U
V
V
+
OUT A
LTC1441
1
2
3
4
8
7
6
5
IN A
+
IN A
IN B
+
IN B
OUT B
1440/1/2 PD
+
A
+
B
V
V
V
+
OUT A
LTC1442
1
2
3
4
8
7
6
5
IN A
+
IN B
REF
HYST
OUT B
1
2
3
4
8
7
6
5
IN
+
IN
HYST
REF
V
+
OUT
+
V
GND
LTC1440
+
+
A
B
LTC1440
GND (Pin 1): Ground. Connect to V
for single supply
operation.
V
(Pin 2): Negative Supply. Connect to ground for single
supply operation. Potential should be more negative than
GND.
IN
+
(Pin 3): Noninverting Comparator Input. Input com-
mon mode range from V
to V
+
1.3V. Input current
typically 10pA at 25
C.
IN
(Pin 4): Inverting Comparator Input. Input common
mode range from V
to V
+
1.3V. Input current typically
10pA at 25
C.
HYST (Pin 5): Hysteresis Input. Connect to REF if not
used. Input voltage range is from V
REF
to V
REF
50mV.
REF (Pin 6): Reference Output. 1.182V with respect
to V
. Can source up to 200
A and sink 15
A at 25
C.
Drive 0.01
F bypass capacitor without oscillation.
V
+
(Pin 7): Positive Supply. 2V to 11V.
OUT (Pin 8): Comparator CMOS Output. Swings from
GND to V
+
. Output can source up to 40mA and sink 5mA.
LTC1441
OUT A (Pin 1): Comparator A CMOS Output. Swings from
V
to V
+
. Output can source up to 40mA and sink 5mA.
V
(Pin 2): Negative Supply.
IN A
+
(Pin 3): Noninverting Input of Comparator A. Input
common mode range from V
to V
+
1.3V. Input current
typically 10pA at 25
C.
IN A
(Pin 4): Inverting Input of Comparator A. Input
common mode range from V
to V
+
1.3V. Input current
typically 10pA at 25
C.
IN B
(Pin 5): Inverting Input of Comparator B. Input
common mode range from V
to V
+
1.3V. Input current
typically 10pA at 25
C.
IN B
+
(Pin 6): Noninverting Input of Comparator B. Input
common mode range from V
to V
+
1.3V. Input current
typically 10pA at 25
C.
V
+
(Pin 7): Positive Supply. 2V to 11V.
OUT B (Pin 8): Comparator B CMOS Output. Swings from
V
to V
+
. Output can source up to 40mA and sink 5mA.
LTC1442
OUT A (Pin 1): Comparator A CMOS Output. Swings from
V
to V
+
. Output can source up to 40mA and sink 5mA.
V
(Pin 2): Negative Supply.
IN A
+
(Pin 3): Noninverting Input of Comparator A. Input
common mode range from V
to V
+
1.3V. Input current
typically 10pA at 25
C.
IN B
(Pin 4): Inverting Input of Comparator B. Input
common mode range from V
to V
+
1.3V. Input current
typically 10pA at 25
C.
HYST (Pin 5): Hysteresis Input. Connect to REF if not
used. Input voltage range is from V
REF
to V
REF
50mV.
REF (Pin 6): Reference Output. 1.182V with respect
to V
. Can source up to 200
A and sink 15
A at 25
C.
Drive 0.01
F bypass capacitor without oscillation.
V
+
(Pin 7): Positive Supply. 2V to 11V.
OUT B (Pin 8): Comparator B CMOS Output. Swings from
V
to V
+
. Output can source up to 40mA and sink 5mA.
7
LTC1440/LTC1441/LTC1442
LTC1440/LTC1441/LTC1442 are a family of micropower
comparators with built-in 1.182V reference. Features
include programmable hysteresis (LTC1440/LTC1442),
wide supply voltage range (2V to 11V) and the ability of the
reference to drive up to a 0.01
F capacitor without oscil-
lation. The comparators' CMOS outputs can source up to
40mA and the supply current glitches, that normally occur
when switching logic states, have been eliminated.
Power Supplies
The comparator family operates from a single 2V to 11V
supply. The LTC1440 includes a separate ground for the
comparator output stage, allowing a split supply ranging
from
1V to
5.5V. Connecting V
to GND on the LTC1440
will allow single supply operation. If the comparator out-
put is required to source more than 1mA, or the supply
source impedance is high, V
+
should be bypassed with a
0.1
F capacitor.
Comparator Inputs
The comparator inputs can swing from the negative sup-
ply V
to within 1.3V max of the positive supply V
+
. The
inputs can be forced 300mV below V
or above V
+
without
damage and the typical input leakage current is only
10pA.
Comparator Outputs
The LTC1440 comparator output swings between GND
and V
+
to assure TTL compatibility with a split supply. The
LTC1441 and LTC1442 outputs swing between V
and V
+
.
The outputs are capable of sourcing up to 40mA and
sinking up to 5mA while still maintaining microampere
quiescent currents. The output stage does not generate
crowbar switching currents during transitions which helps
minimize parasitic feedback through the supply pins.
Voltage Reference
The internal bandgap reference has a voltage of 1.182V
referenced to V
. The reference accuracy is 1.5% from
40
C to 85
C. It can source up to 200
A and sink up to
20
A with a 5V supply. The reference can drive a bypass
capacitor of up to 0.01
F without oscillation and by
inserting a series resistor, capacitance values up to 100
F
can be used (Figure 1).
Figure 2 shows the resistor value required for different
capacitor values to achieve critical damping. Bypassing
the reference can help prevent false tripping of the com-
parators by preventing glitches on V
+
or reference load
transients from disturbing the reference output voltage.
Figure 3 shows the bypassed reference output with a
square wave applied to the V
+
pin. Resistors R2 and R3 set
10mV of hysteresis voltage band while R1 damps the
reference response. Note that the comparator output
doesn't trip.
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
LTC144X
V
REF
R1
C1
REFERENCE
OUTPUT
1440/1/2 F01
Figure 1. Damping the Reference Output
CAPACITOR VALUE (
F)
0.001
0.1
RESISTOR VALUE (k
)
10
1000
0.01
0.1
10
1
1440/1/2 F02
1
100
Figure 2. Damping Resistance vs Bypass Capacitor Value
8
LTC1440/LTC1441/LTC1442
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
V
+
R1
430
R2
10k
C1
1
F
5V
TO
8V
OUT
V
2
1
7
8
GND
LTC1440
1440/1/2 F03a
IN
+
IN
HYST
REF
3
4
5
6
R3
2.4M
+
Figure 3a. Reference Transient Response Test Circuit
2ms/ DIV
1440/1/2 F03b
8V
V
+
5V
V
REF
OUT
Hysteresis
Hysteresis can be added to the LTC1440 by connecting a
resistor (R1) between the REF and HYST pins and a
second resistor (R2) from HYST to V
(Figure 4).
The difference between the upper and lower threshold
voltages, or hysteresis voltage band (V
HB
), is equal to twice
the voltage difference between the REF and HYST pins.
When more hysteresis is added, the upper threshold
increases the same amount as the low threshold de-
creases. The maximum voltage allowed between REF and
HYST pins is 50mV, producing a maximum hysteresis
voltage band of 100mV. The hysteresis band could vary by
2mV
/
DIV
up to 15%. If hysteresis is not wanted, the HYST pin
should be shorted to REF. Acceptable values for I
REF
range
from 0.1
A to 5
A. If 2.4M is chosen for R2, then the value
of R1 is equal to the value of V
HB
.
Figure 5. Glitch-Free Level Detector with Hysteresis
V
+
R5
430
5%
R3
15k
1%
C1
1
F
OUT
V
2
1
7
5V
V
IN
8
GND
LTC1440
1440/1/2 F05
IN
+
IN
HYST
REF
3
4
5
6
+
R2
3.4M
1%
R1
1.18M
1%
R4
2.4M
1%
6
R2
HYST
V
REF
5
R1
1440/1/2 F04
LTC1440
2
I
REF
R1 =
V
HB
(2)(I
REF
)
R2 =
I
REF
1.182V
(
)
V
HB
2
Figure 4. Programmable Hysteresis
Level Detector
The LTC1440 is ideal for use as a micropower level
detector as shown in Figure 5. R1 and R2 form a voltage
divider from V
IN
to the noninverting comparator input. R3
and R4 set the hysteresis voltage, and R5 and C1 bypass
the reference output. The following design procedure can
be used to select the component values:
1. Choose the V
IN
voltage trip level, in this example 4.65V.
Figure 3b. Reference and Comparator Output
Transient Response
9
LTC1440/LTC1441/LTC1442
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
2. Calculate the required resistive divider ratio.
Ratio = V
REF
/ V
IN
Ratio = 1.182V/4.65V = 0.254
3. Choose the required hysteresis voltage band at the
input V
HBIN
, in this example 60mV. Calculate the hyster-
esis voltage band referred to the comparator input V
HB
.
V
HB
= (V
HBIN
)(Ratio)
V
HB
= (60mV)(0.254)
V
HB
= 15.24mV
4. Choose the values for R3 and R4 to set the hysteresis.
R4 = 2.4M
R3(k
) = V
HB
= 15k
5. Choose the values for R1 and R2 to set the trip point.
R
V
I
V
A
M
R
R
V
V
V
REF
BIAS
IN
REF
HB
1
1 182
1
1 18
2
1
2
1
=
=
=
=
+
-
.
.
R
M
V
V
mV
R
M
2
1 18
4 65
1 182
15
2
1
2
3 40
=
+
-
=
.
.
.
.
Low Voltage Operation
The guaranteed minimum operating voltage is 2V or
(
1V). As the total supply voltage is reduced below 2V, the
performance degrades and the supply current falls. Both
the reference and the comparator are still functioning with
supply voltage down to 1.5V. The reference will have
slightly worse temperature coefficient. While the com-
parator would have less output drive and the propagation
delay increases. The useful input voltage range extends
from the negative supply to a little under 1V below the
positive supply, which is slightly closer to the positive rail
than the device operating from higher supply voltages.
TYPICAL APPLICATIO
N
S
U
V
+
2.6M
2-CELL
NiCd
1M
V
+
V
2
1
7
8
6
5
GND
HYST
REF
OUT
LTC1440
1440 TA06
IN
+
IN
3
4
+
20k
1.3M
1M
Low Battery Detect Operates Down to 1.5V
10
LTC1440/LTC1441/LTC1442
TYPICAL APPLICATIO
N
S
U
10-Bit 30
A A/D Converter
+
5V
5V
2N3809
1N914
32.768kHz
VN2222LL
10pF
100k
E
IN
0V TO 3V
365k*
470k
1M
10M
150k
0.033
F
POLYSTYRENE
C1
1/2 LTC1441
LT
1034
1.2V
Q
D
CLK
74C74
CONV
COMMAND
DATA
OUT
STATUS
1440/1/2 TA03
Q
1.2M
+
C2
1/2 LTC1441
74C00
74C00
74C00
74C00
*TRW-IRC MRT5/+120ppm/
C
32.768kHz "Watch Crystal" Oscillator
+V
32.768kHz
10pF
470k
1M
OUT
1440/1/2 TA05
1.2M
+
1/2
LTC1441
11
LTC1440/LTC1441/LTC1442
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 represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTIO
N
U
N8 Package
8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
N8 0695
0.005
(0.127)
MIN
0.100
0.010
(2.540
0.254)
0.065
(1.651)
TYP
0.045 0.065
(1.143 1.651)
0.130
0.005
(3.302
0.127)
0.015
(0.380)
MIN
0.018
0.003
(0.457
0.076)
0.125
(3.175)
MIN
1
2
3
4
8
7
6
5
0.255
0.015*
(6.477
0.381)
0.400*
(10.160)
MAX
0.009 0.015
(0.229 0.381)
0.300 0.325
(7.620 8.255)
0.325
+0.025
0.015
+0.635
0.381
8.255
(
)
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
1
2
3
4
0.150 0.157**
(3.810 3.988)
8
7
6
5
0.189 0.197*
(4.801 5.004)
0.228 0.244
(5.791 6.197)
0.016 0.050
0.406 1.270
0.010 0.020
(0.254 0.508)
45
0
8
TYP
0.008 0.010
(0.203 0.254)
SO8 0695
0.053 0.069
(1.346 1.752)
0.014 0.019
(0.355 0.483)
0.004 0.010
(0.101 0.254)
0.050
(1.270)
BSC
DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
*
**
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
12
LTC1440/LTC1441/LTC1442
144012fa LT/TP 0298 REV A 2K PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1996
10kHz V/F Converter
TYPICAL APPLICATIO
N
U
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1178/LT1179
Dual/Quad 17
A Precision Single Supply Op Amps
70
V Max V
OS
, 5nA Max I
BIAS
LT1351
Single 250
A, 3MHz, 200V/
s Op Amp with Shutdown
C-Load
TM
Op Amp Stable Driving Any Capacitive Load
LT1352/LT1353
Dual/Quad 250
A, 3MHz, 200V/
s Op Amps
C-Load
Op Amps Stable Driving Any Capacitive Load
LTC1443/LTC1444/LTC1445
Micropower Quad Comparator with 1% Reference
LTC1443 Has 1.182V Reference, LTC1444/LTC1445 Have
1.221V Reference and Adjustable Hysteresis
+
100pF**
50pF
2.2
F
1.2M*
10kHz TRIM
200k
10M
100k
2k*
LM334
+V
6.2V TO 12V
LT1034-1.2
LT1034-1.2
2.7M
C1
1/2 LTC1441
f
OUT
0kHz TO 10kHz
74C14
1440/1/2 TA04
0.01
F
0.1
F
INPUT
0V TO 5V
Q5
Q6
15k
2M TYP
100Hz TRIM
+
C2
1/2 LTC1441
Q1
Q8
Q2
Q3
Q4
0.47
F
Q7
= HP5082-2810
= 1N4148
= 2N2222
= 1% METAL FILM
= POLYSTYRENE
*
**
+
+
C-Load is a trademark of Linear Technology Corporation.
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
q
(408) 432-1900
FAX: (408) 434-0507
q
TELEX: 499-3977
q
www.linear-tech.com
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