LT1671
60ns, Low Power,
Single Supply, Ground-Sensing
Comparator
FEATURES
s
s
DESCRIPTIO
s
s
s
s
s
s
s
s
s
Low Power: 450
µ
A
Fast: 60ns at 20mV Overdrive
85ns at 5mV Overdrive
Low Offset Voltage: 0.8mV
Operates Off Single 5V or Dual
±5V
Supplies
Input Common Mode Extends to Negative Supply
No Minimum Input Slew Rate Requirement
Complementary TTL Outputs
Inputs Can Exceed Supplies without Phase Reversal
Pin Compatible with LT1394, LT1016 and LT1116
Output Latch Capability
Available in 8-Lead MSOP and SO Packages
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s
s
s
s
s
s
s
s
High Speed A/D Converters
Zero-Crossing Detectors
Current Sense for Switching Regulators
Extended Range V/F Coverters
Fast Pulse Height/Width Discriminators
High Speed Triggers
Line Receivers
High Speed Sampling Circuits
TYPICAL APPLICATIO
5V
2k
1MHz CRYSTAL
(AT-CUT)
Propagation Delay vs Overdrive
140
120
100
V
S
=
±5V
V
STEP
= 100mV
T
A
= 25°C
R
L
= 1M
1MHz Crystal Oscillator
TIME (ns)
80
FALLING EDGE (t
PDHL
)
60
40
20
+
2k
LT1671
OUTPUT
–
2k
0.068µF
1671 TA01
1671 TA01
0
U
RISING EDGE (t
PDLH
)
10
20
30
OVERDRIVE (mV)
40
50
1671 TA02
U
U
1
LT1671
ABSOLUTE
MAXIMUM
RATINGS
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
PACKAGE/ORDER INFORMATION
TOP VIEW
1
+IN
2
–IN
3
V
–
4
V
+
8
7
6
5
Q OUT
Q OUT
GND
LATCH
ENABLE
ORDER PART
NUMBER
LT1671CMS8
MS8 PART MARKING
LTCT
+IN 2
–IN 3
V
–
4
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 250°C/ W
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 190°C/ W
Consult factory for Military grade parts.
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
V
OS
∆V
OS
∆T
I
OS
I
B
V
CMR
CMRR
PARAMETER
Input Offset Voltage
Input Offset Voltage Drift
Input Offset Current
q
CONDITIONS
R
S
≤
100Ω (Note 4)
q
q
Input Bias Current
Input Voltage Range (Note 6)
(Note 5)
q
q
q
Single 5V Supply
Common Mode Rejection Ratio
– 5V
≤
V
CM
≤
3.5V, T
A
> 0°C
– 5V
≤
V
CM
≤
3.3V, T
A
≤
0°C
Single 5V Supply
0V
≤
V
CM
≤
3.5V, T
A
> 0°C
0V
≤
V
CM
≤
3.3V, T
A
≤
0°C
PSRR
A
V
Power Supply Rejection Ratio
Small Signal Voltage Gain
4.6V
≤
V
+
≤
5.4V
– 7V
≤
V
–
≤
– 2V
1V
≤
V
OUT
≤
2V
2
–
+
U
U
W
W W
U
W
(Note 1)
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
TOP VIEW
V
+
1
8 Q OUT
7 Q OUT
6 GND
5
LATCH
ENABLE
ORDER PART
NUMBER
LT1671CS8
LT1671IS8
S8 PART MARKING
1671
1671I
MIN
TYP
0.8
4
10
120
MAX
2.5
4.0
UNITS
mV
mV
µV/°C
100
150
280
350
3.5
3.5
nA
nA
nA
nA
V
V
dB
dB
dB
dB
dB
dB
V/V
–5
0
55
55
55
55
100
100
85
90
5000
q
q
50
60
2500
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
V
OH
V
OL
I
+
I
–
V
IH
V
IL
I
IL
t
PD1
t
PD2
∆t
PD
t
LPD
t
SU
t
H
t
PW
(D)
PARAMETER
Output Voltage Swing High
Output Voltage Swing Low
Positive Supply Current
q
CONDITIONS
V
+
≥
4.6V, I
OUT
= 400µA
V
+
≥
4.6V, I
OUT
= 4mA
I
OUT
= – 400µA
I
OUT
= – 4mA
q
q
q
MIN
2.7
2.4
TYP
3.1
3.0
0.3
0.4
450
75
MAX
UNITS
V
V
0.5
800
1000
200
250
0.8
V
V
µA
µA
µA
µA
V
V
nA
ns
ns
ns
ns
ns
ns
ns
ns
ns
Negative Supply Current
q
LATCH Pin High Input Voltage
LATCH Pin Low Input Voltage
LATCH Pin Current
Propagation Delay
Propagation Delay (Note 7)
Differential Propagation Delay (Note 7)
Latch Propagation Delay (Note 8)
Latch Setup Time (Note 8)
Latch Hold Time (Note 8)
Minimum Disable Pulse Width
V
LATCH
= 0V
∆V
IN
= 100mV, V
OD
= 20mV
q
q
q
q
2
– 1000
– 250
60
85
80
110
100
130
30
∆V
IN
= 100mV, V
OD
= 5mV
q
∆V
IN
= 100mV, V
OD
= 5mV
15
60
– 15
35
30
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.
3
LT1671
TYPICAL PERFORMANCE CHARACTERISTICS
Gain Characteristics
5.0
4.5
4.0
OUTPUT VOLTAGE (V)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
–3
50
60
100
T
A
= 125°C
T
A
= 25°C
T
A
= – 55°C
TIME (ns)
TIME (ns)
–2
–1
1
2
0
DIFFERENTIAL INPUT VOLTAGE (mV)
Propagation Delay vs
Input Overdrive
140
120
100
V
S
=
±5V
V
STEP
= 100mV
T
A
= 25°C
R
L
= 1M
TIME (ns)
TIME (ns)
200mV
120
100
80
STEP SIZE = 100mV
TIME (ns)
80
FALLING EDGE (t
PDHL
)
60
40
20
RISING EDGE (t
PDLH
)
0
10
20
30
OVERDRIVE (mV)
Input Offset Voltage vs
Temperature
4
3
2
VOLTAGE (mV)
500
V
S
=
±5V
R
L
= 1M
INPUT BIAS CURRENT (nA)
400
1
0
–1
–2
300
VOLTAGE (V)
–3
–50 –25
50
0
75
25
TEMPERATURE (°C)
4
U W
V
S
=
±5V
R
L
= 1M
3
1671 G01
Propagation Delay vs
Load Capacitance
90
FALLING EDGE (t
PDHL
)
Propagation Delay vs
Positive Supply Voltage
90
FALLING EDGE (t
PDHL
)
80
RISING EDGE (t
PDLH
)
70
V
–
= –5V
V
STEP
= 100mV
V
OD
= 5mV
T
A
= 25°C
R
L
= 1M
4.4
4.6
4.8
5.0
5.2
5.4
POSITIVE SUPPLY VOLTAGE (V)
5.6
1671 G03
80
RISING EDGE (t
PDLH
)
70
V
S
=
±5V
V
STEP
= 100mV
V
OD
= 5mV
T
A
= 25°C
R
L
= 1M
0
10
20
30
40
OUTPUT LOAD CAPACITANCE (pF)
50
1671 G02
60
50
Propagation Delay vs
Source Resistance
200
180
160
140
100
Propagation Delay vs
Temperature
90
t
PDHL
t
PDLH
V
S
=
±5V
R
L
= 1M
V
OD
= 20mV
T
A
= 25°C
STEP SIZE = 800mV
400mV
80
70
60
50
40
30
20
10
V
S
=
±5V
V
STEP
= 100mV
V
OD
= 5mV
R
L
= 1M
60
40
50
1671 TA02
40
0
5
10
SOURCE RESISTANCE (kΩ)
15
1671 G05
0
–50 –25
50
0
75
25
TEMPERATURE (°C)
100
125
1671 G06
Input Bias Current vs
Temperature
6
V
S
=
±5V
R
L
= 1M
Positive Common Mode Limit vs
Temperature
V
S
=
±5V
R
L
= 1M
5
4
3
2
200
V
CM
= –5V
V
CM
= 0V
100
1
V
CM
= 3.5V
100
125
0
–50 –25
50
0
75
25
TEMPERATURE (°C)
100
125
0
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
1671 G07
1671 G08
1671 G09
LT1671
TYPICAL PERFORMANCE CHARACTERISTICS
Negative Common Mode Limit vs
Temperature
1
R
L
= 1M
0
V
S
= SINGLE 5V SUPPLY
INPUT VOLTAGE (V)
0.8
0.7
0.6
VOLTAGE (V)
0.5
0.4
0.3
0.2
T
A
= 25°C
T
A
= –55°C
T
A
= 125°C
V
S
=
±5V
V
IN
= 30mV
OUTPUT VOLTAGE (V)
–1
–2
–3
–4
–5
–6
–50 –25
V
S
=
±5V
50
0
75
25
TEMPERATURE (°C)
Positive Supply Current vs
V
+
Supply Voltage
0.6
0.5
3.5
V
–
= 0V
V
IN
= –60mV
I
OUT
= 0
CURRENT (mA)
CURRENT (mA)
CURRENT (µA)
0.4
0.3
T
A
= 125°C
0.2
0.1
0
T
A
= 25°C
T
A
= –55°C
0
1
2
6
4
3
5
SUPPLY VOLTAGE (V)
Latch Pin Current vs Temperature
1.0
V
S
=
±5V
0.8
CURRENT (µA)
0.6
0.4
0.2
0
–50 –25
50
0
75
25
TEMPERATURE (°C)
U W
100
1671 G10
Output Low Voltage (V
OL
) vs
Output Sink Current
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0
2
4
6
8
10
12
14
Output High Voltage (V
OH
) vs
Output Source Current
V
S
=
±5V
V
IN
= –30mV
T
A
= 125°C
T
A
= –55°C
T
A
= 25°C
0.1
0
125
0
2
OUTPUT SINK CURRENT (mA)
1671 G11
4
8
6
10
12
OUTPUT SOURCE CURRENT (mA)
14
1671 G12
Positive Supply Current vs
Switching Frequency
100
V
S
=
±5V
V
STEP
=
±50mV
I
OUT
= 0
3.0
2.5
2.0
T
A
= 125°C
1.5
1.0
T
A
= 25°C
0.5
0
T
A
= –55°C
Negative Supply Current vs
V
–
Supply Voltage
V
+
= 5V
V
IN
= –60mV
I
OUT
= 0
90
80
70
T
A
= 125°C
T
A
= 25°C
60
T
A
= –55°C
50
–8
–7 –6 –5 –4 –3 –2 –1
NEGATIVE SUPPLY VOLTAGE (V)
0
7
8
0.1
1
SWITCHING FREQUENCY (MHz)
10
1671 G14
1671 G13
1671 G15
Response to 15MHz
±10mV
Sine Wave
+IN
20mV
P-P
10mV/DIV
3V
Q OUT
1V/DIV
0V
50ns/DIV
1671 G17
100
125
1671 G16
5
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