1671f Layout
1
LT1671
60ns, Low Power,
Single Supply, Ground-Sensing
Comparator
OVERDRIVE (mV)
0
TIME (ns)
140
120
100
80
60
40
20
10
20
30
40
1671 TA02
50
V
S
=
5V
V
STEP
= 100mV
T
A
= 25
C
R
L
= 1M
FALLING EDGE (t
PDHL
)
RISING EDGE (t
PDLH
)
Propagation Delay vs Overdrive
1MHz Crystal Oscillator
1671 TA01
+
LT1671
5V
OUTPUT
0.068
F
1671 TA01
2k
2k
2k
1MHz CRYSTAL
(AT-CUT)
, LTC and LT are registered trademarks of Linear Technology Corporation.
The LT
1671 is a low power 60ns comparator with comple-
mentary outputs and latch. The input common mode
range extends from 1.5V below the positive supply down
to the negative supply rail. Like the LT1394, LT1016 and
LT1116, this comparator has complementary outputs
designed to interface directly to TTL or CMOS logic. The
LT1671 may operate from either a single 5V supply or dual
5V supplies. Low offset voltage specifications and high
gain allow the LT1671 to be used in precision applications.
The LT1671 is designed for improved speed and stability
for a wide range of operating conditions. The output stage
provides active drive in both directions for maximum
speed into TTL, CMOS or passive loads with minimal
cross-conduction current. Unlike other fast comparators,
the LT1671 remains stable even for slow transitions
through the active region, which eliminates the need to
specify a minimum input slew rate.
The LT1671 has an internal, TTL/CMOS compatible latch
for retaining data at the outputs. The latch holds data as
long as the LATCH pin is held high. Device parameters
such as gain, offset and negative power supply current are
not significantly affected by variations in negative supply
voltage.
s
Low Power: 450
A
s
Fast: 60ns at 20mV Overdrive
85ns at 5mV Overdrive
s
Low Offset Voltage: 0.8mV
s
Operates Off Single 5V or Dual
5V Supplies
s
Input Common Mode Extends to Negative Supply
s
No Minimum Input Slew Rate Requirement
s
Complementary TTL Outputs
s
Inputs Can Exceed Supplies without Phase Reversal
s
Pin Compatible with LT1394, LT1016 and LT1116
s
Output Latch Capability
s
Available in 8-Lead MSOP and SO Packages
s
High Speed A/D Converters
s
Zero-Crossing Detectors
s
Current Sense for Switching Regulators
s
Extended Range V/F Coverters
s
Fast Pulse Height/Width Discriminators
s
High Speed Triggers
s
Line Receivers
s
High Speed Sampling Circuits
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
2
LT1671
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
(Note 1)
Total Supply Voltage (V
+
to V
) ............................... 12V
Positive Supply Voltage ............................................. 7V
Negative Supply Voltage .......................................... 7V
Differential Input Voltage .......................................
12V
Input and Latch Current (Note 2) ........................
10mA
Output Current (Continuous)(Note 2) .................
20mA
Operating Temperature Range ................ 40
C to 85
C
Specified Temperature Range (Note 3) ... 40
C to 85
C
Junction Temperature ........................................... 150
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
ORDER PART
NUMBER
LT1671CMS8
LTCT
1
2
3
4
V
+
8
7
6
5
Q OUT
Q OUT
GND
LATCH
ENABLE
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
+IN
IN
V
T
JMAX
= 150
C,
JA
= 250
C/ W
Consult factory for Military grade parts.
MS8 PART MARKING
T
JMAX
= 150
C,
JA
= 190
C/ W
S8 PART MARKING
LT1671CS8
LT1671IS8
ORDER PART
NUMBER
1671
1671I
TOP VIEW
Q OUT
Q OUT
GND
V
+
+IN
IN
V
S8 PACKAGE
8-LEAD PLASTIC SO
1
2
3
4
8
7
6
5
+
LATCH
ENABLE
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
OS
Input Offset Voltage
R
S
100
(Note 4)
0.8
2.5
mV
q
4.0
mV
V
OS
Input Offset Voltage Drift
q
4
V/
C
T
I
OS
Input Offset Current
10
100
nA
q
150
nA
I
B
Input Bias Current
(Note 5)
120
280
nA
q
350
nA
V
CMR
Input Voltage Range (Note 6)
q
5
3.5
V
Single 5V Supply
q
0
3.5
V
CMRR
Common Mode Rejection Ratio
5V
V
CM
3.5V, T
A
> 0
C
55
100
dB
5V
V
CM
3.3V, T
A
0
C
55
dB
Single 5V Supply
0V
V
CM
3.5V, T
A
> 0
C
55
100
dB
0V
V
CM
3.3V, T
A
0
C
55
dB
PSRR
Power Supply Rejection Ratio
4.6V
V
+
5.4V
q
50
85
dB
7V
V
2V
q
60
90
dB
A
V
Small Signal Voltage Gain
1V
V
OUT
2V
2500
5000
V/V
ELECTRICAL CHARACTERISTICS
The
q
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25
C.
V
+
= 5V, V
= 5V, V
OUT
(Q) = 1.4V, V
LATCH
= V
CM
= 0V unless otherwise noted.
3
LT1671
ELECTRICAL CHARACTERISTICS
The
q
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25
C.
V
+
= 5V, V
= 5V, V
OUT
(Q) = 1.4V, V
LATCH
= V
CM
= 0V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
OH
Output Voltage Swing High
V
+
4.6V, I
OUT
= 400
A
q
2.7
3.1
V
V
+
4.6V, I
OUT
= 4mA
q
2.4
3.0
V
V
OL
Output Voltage Swing Low
I
OUT
= 400
A
q
0.3
0.5
V
I
OUT
= 4mA
0.4
V
I
+
Positive Supply Current
450
800
A
q
1000
A
I
Negative Supply Current
75
200
A
q
250
A
V
IH
LATCH Pin High Input Voltage
q
2
V
V
IL
LATCH Pin Low Input Voltage
q
0.8
V
I
IL
LATCH Pin Current
V
LATCH
= 0V
q
1000
250
nA
t
PD1
Propagation Delay
V
IN
= 100mV, V
OD
= 20mV
60
80
ns
q
110
ns
t
PD2
Propagation Delay (Note 7)
V
IN
= 100mV, V
OD
= 5mV
85
100
ns
q
130
ns
t
PD
Differential Propagation Delay (Note 7)
V
IN
= 100mV, V
OD
= 5mV
15
30
ns
t
LPD
Latch Propagation Delay (Note 8)
60
ns
t
SU
Latch Setup Time (Note 8)
15
ns
t
H
Latch Hold Time (Note 8)
35
ns
t
PW
(D)
Minimum Disable Pulse Width
30
ns
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: This parameter is guaranteed to meet specified performance
through design and characterization. It has not been tested.
Note 3: The LT1671CS8 and LT1671CMS8 are guaranteed to meet
specified performance from 0
C to 70
C and are designed, characterized
and expected to meet these extended temperature limits, but are not tested
at 40
C and 85
C. The LT1671IS8 is guaranteed to meet the extended
temperature limits.
Note 4: Input offset voltage (V
OS
) is defined as the average of the two
voltages measured by forcing first one output, then the other to 1.4V.
Note 5: Input bias current (I
B
) is defined as the average of the two input
currents.
Note 6: Input voltage range is guaranteed in part by CMRR testing and in
part by design and characterization.
Note 7: t
PD
and
t
PD
cannot be measured in automatic handling
equipment with low values of overdrive. The LT1671 is 100% tested with a
100mV step and 20mV overdrive. Correlation tests have shown that t
PD
and
t
PD
limits can be guaranteed with this test, if additional DC tests are
performed to guarantee that all internal bias conditions are correct.
Propagation delay (t
PD
) is measured with the overdrive added to the actual
V
OS
. Differential propagation delay is defined as:
t
PD
= t
PDLH
t
PDHL
Note 8: Latch propagation delay (t
LPD
) is the delay time for the output to
respond when the LATCH pin is deasserted. Latch setup time (t
SU
) is the
interval in which the input signal must remain stable prior to asserting the
latch signal. Latch hold time (t
H
) is the interval after the latch is asserted in
which the input signal must remain stable.
4
LT1671
Propagation Delay vs
Load Capacitance
DIFFERENTIAL INPUT VOLTAGE (mV)
3
3
OUTPUT VOLTAGE (V)
1
2
0
1
1671 G01
2
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
V
S
=
5V
R
L
= 1M
T
A
= 125
C
T
A
= 25
C
T
A
= 55
C
Gain Characteristics
OUTPUT LOAD CAPACITANCE (pF)
0
TIME (ns)
100
90
80
70
60
50
10
20
30
40
1671 G02
50
V
S
=
5V
V
STEP
= 100mV
V
OD
= 5mV
T
A
= 25
C
R
L
= 1M
FALLING EDGE (t
PDHL
)
RISING EDGE (t
PDLH
)
Propagation Delay vs
Source Resistance
Propagation Delay vs
Input Overdrive
OVERDRIVE (mV)
0
TIME (ns)
140
120
100
80
60
40
20
10
20
30
40
1671 TA02
50
V
S
=
5V
V
STEP
= 100mV
T
A
= 25
C
R
L
= 1M
FALLING EDGE (t
PDHL
)
RISING EDGE (t
PDLH
)
SOURCE RESISTANCE (k
)
0
TIME (ns)
5
10
15
1671 G05
200
180
160
140
120
100
80
60
40
V
S
=
5V
R
L
= 1M
V
OD
= 20mV
T
A
= 25
C
STEP SIZE = 800mV
STEP SIZE = 100mV
400mV
200mV
TEMPERATURE (
C)
50
TIME (ns)
100
90
80
70
60
50
40
30
20
10
0
0
50
75
1671 G06
25
25
100
125
t
PDHL
t
PDLH
V
S
=
5V
V
STEP
= 100mV
V
OD
= 5mV
R
L
= 1M
POSITIVE SUPPLY VOLTAGE (V)
4.4
TIME (ns)
90
80
70
60
50
4.6
4.8
5.0
5.2
5.4
1671 G03
5.6
FALLING EDGE (t
PDHL
)
RISING EDGE (t
PDLH
)
V
= 5V
V
STEP
= 100mV
V
OD
= 5mV
T
A
= 25
C
R
L
= 1M
Propagation Delay vs
Positive Supply Voltage
Propagation Delay vs
Temperature
Input Bias Current vs
Temperature
Input Offset Voltage vs
Temperature
Positive Common Mode Limit vs
Temperature
TEMPERATURE (
C)
50
VOLTAGE (mV)
4
3
2
1
0
1
2
3
0
50
75
1671 G07
25
25
100
125
V
S
=
5V
R
L
= 1M
TEMPERATURE (
C)
50
INPUT BIAS CURRENT (nA)
500
400
300
200
100
0
0
50
75
1671 G08
25
25
100
125
V
CM
= 5V
V
CM
= 3.5V
V
CM
= 0V
V
S
=
5V
R
L
= 1M
TEMPERATURE (
C)
50
VOLTAGE (V)
6
5
4
3
2
1
0
0
50
75
1671 G09
25
25
100
125
V
S
=
5V
R
L
= 1M
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
5
LT1671
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
TEMPERATURE (
C)
50
INPUT VOLTAGE (V)
1
0
1
2
3
4
5
6
0
50
75
1671 G10
25
25
100
125
R
L
= 1M
V
S
= SINGLE 5V SUPPLY
V
S
=
5V
Negative Common Mode Limit vs
Temperature
OUTPUT SINK CURRENT (mA)
0
VOLTAGE (V)
12
1671 G11
4
8
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
2
6
10
14
V
S
=
5V
V
IN
= 30mV
T
A
= 25
C
T
A
= 125
C
T
A
= 55
C
OUTPUT SOURCE CURRENT (mA)
0
OUTPUT VOLTAGE (V)
12
1671 G12
4
8
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
2
6
10
14
V
S
=
5V
V
IN
= 30mV
T
A
= 25
C
T
A
= 125
C
T
A
= 55
C
Output High Voltage (V
OH
) vs
Output Source Current
Output Low Voltage (V
OL
) vs
Output Sink Current
SUPPLY VOLTAGE (V)
CURRENT (mA)
1671 G13
0.6
0.5
0.4
0.3
0.2
0.1
0
0
2
4
5
1
3
6
7
8
T
A
= 125
C
T
A
= 55
C
T
A
= 25
C
V
= 0V
V
IN
= 60mV
I
OUT
= 0
Positive Supply Current vs
V
+
Supply Voltage
Response to 15MHz
10mV Sine Wave
0V
3V
Q OUT
1V/DIV
+IN
20mV
P-P
10mV/DIV
50ns/DIV
1671 G17
SWITCHING FREQUENCY (MHz)
0.1
CURRENT (mA)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1
10
1671 G14
T
A
= 25
C
T
A
= 125
C
T
A
= 55
C
V
S
=
5V
V
STEP
=
50mV
I
OUT
= 0
Positive Supply Current vs
Switching Frequency
NEGATIVE SUPPLY VOLTAGE (V)
8
CURRENT (
A)
100
90
80
70
60
50
5
3
0
1671 G15
7
6
4
2
1
T
A
= 25
C
T
A
= 125
C
T
A
= 55
C
V
+
= 5V
V
IN
= 60mV
I
OUT
= 0
Negative Supply Current vs
V
Supply Voltage
TEMPERATURE (
C)
50
CURRENT (
A)
1.0
0.8
0.6
0.4
0.2
0
0
50
75
1671 G16
25
25
100
125
V
S
=
5V
Latch Pin Current vs Temperature
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