Download LT1116 - 12ns, Single Supply Ground-Sensing Comparator

LT1116
12ns, Single Supply
Ground-Sensing Comparator
U
FEATURES
DESCRIPTIO
■
The LT®1116 is an ultra fast (12ns) comparator designed
for sensing signals near the negative supply. The input
common mode range extends from 2.5V below the
positive supply down to the negative supply rail. Like the
LT1016, this comparator is specifically designed to
interface directly to TTL logic with complementary
outputs. The comparator may operate from either a single
5V supply or dual ±5V supplies. Tight offset voltage
specifications and high gain allow the LT1116 to be used
in precision applications.
■
■
■
■
■
■
■
■
■
Ultra Fast (12ns Typ)
Operates off Single 5V Supply or ±5V
Input Common Mode Extends to Negative Supply
No Minimum Input Slew Rate Requirement
Complementary TTL Output
Inputs Can Exceed the Positive Supply Up to 15V
without Damaging the Comparator
Low Offset Voltage
Pin-Compatible with LT1016
Output Latch Capability
Available in 8-Lead PDIP and SO Packages
U
APPLICATIO S
■
■
■
■
■
■
■
■
High Speed A/D Converters
Zero Crossing Detectors
Current Sense for Switching Regulators
Extended Range V to F Converters
Fast Pulse Height/Width Discriminators
High Speed Triggers
Line Receivers
High Speed Sampling Circuits
, LTC, LT and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
The LT1116 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 logic or passive loads, yet it has minimal
cross-conduction current. Unlike other fast comparators,
the LT1116 remains stable even for slow transitions
through the active region, which eliminates the need to
specify a minimum input slew rate.
The LT1116 has an internal, TTL 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.
U
TYPICAL APPLICATIO
LOGIC
DRIVER
M1
VIN
100mV STEP
5mV OVERDRIVE
Comparator Response Time
Fast Current Comparator for
Current Mode Switching Regulator
THRESHOLD
5V
+
LT1116
–
Q
C1
RSENSE
–
OUTPUT
VOLTAGE VOUT
1V/DIV
12ns
Q
12ns
R1
BLANKING
0
CONTROL INPUT
LT1116 • TA01
0
20
TIME (ns)
20
LT1116 • TA02
www.BDTIC.com/Linear
1116fb
1
LT1116
W W
W
AXI U
U
ABSOLUTE
RATI GS
U
U
W
PACKAGE/ORDER I FOR ATIO
(Note 1)
TOP VIEW
TOP VIEW
Supply Voltage (V +) to GND ...................................... 7V
Negative Supply Voltage (V –) ...................... –7V to GND
Voltage
Differential Input Voltage ................................... ±15V
Inputs Voltage (Either Input) ......... (V –) –0.3V to 15V
Latch Pin Voltage ........................... Equal to Supplies
Output Current (Continuous) .............................. ±20mA
Operating Temperature Range ..................... 0°C to 70°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
V+
1
+IN 2
–IN 3
+
–
V– 4
8
–
Q OUT
7
Q OUT
+IN 2
6
GND
–IN 3
5
LATCH
ENABLE
V+
1
+
–
V– 4
8
–
Q OUT
7
Q OUT
6
GND
5
LATCH
ENABLE
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 100°C, θJA = 160°C/W
N8 PACKAGE
8-LEAD PDIP
TJMAX = 100°C, θJA = 130°C/W
ORDER PART
NUMBER
ORDER PART
NUMBER
LT1116CN8
LT1116CS8
S8 PART MARKING
1116
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over full operating temperature
range, otherwise specifications are at TA = 25°C. V+ = 5V, V – = 5V, VOUT (Q) = 1.4V, LATCH = 0V. Specifications for VOS, IB, CMRR, and
Voltage Gain are valid for single supply operation, V + = 5V, V – = 0V, unless noted.
SYMBOL
PARAMETERS
CONDITIONS
VOS
Input Offset Voltage
RS ≤ 100Ω (Note 2)
MIN
TYP
MAX
UNITS
1.0
±3.0
3.5
mV
mV
●
∆VOS
∆T
Input Offset Voltage Drift
IOS
Input Offset Current
lB
µV/°C
●
5
(Note 2)
●
0.5
Input Bias Current, Sourcing
(Note 3)
●
Input Voltage Range
Arbitrary Supply Range
Single 5V Supply
●
●
V–
0
CMRR
Common Mode Rejection Ratio
–5V ≤ VCM ≤ 2.5V, VS = ±5V
0V ≤ VCM ≤ 2.5V
●
●
75
65
90
90
dB
dB
PSRR
Power Supply Rejection Ratio
Positive Supply, 4.6V ≤ V+ ≤ 5.4V
Negative Supply, –7 ≤ V – ≤ –2V
●
●
60
80
75
100
dB
dB
AV
Small Signal Voltage Gain
1V ≤ VOUT ≤ 2V
1400
3000
I+
Positive Supply Current
●
27
38
mA
I–
Negative Supply Current
●
5
7
mA
VOH
Output High Voltage
ISOURCE = 1mA
ISOURCE = 10mA
●
●
VOL
Output Low Voltage
lSINK = 4mA
ISINK = 10mA
●
2
10
2.7
2.4
2
µA
20
µA
(V+) –2.5
2.5
V
V
V/V
3.4
3.0
0.3
0.4
www.BDTIC.com/Linear
V
V
0.5
V
V
1116fb
LT1116
ELECTRICAL CHARACTERISTICS
+
The ● denotes the specifications which apply over full operating temperature
range, otherwise specifications are at TA = 25°C. V = 5V, V + = –5V, VOUT = (Q) = I .4V, LATCH = 0V, unless noted.
SYMBOL
PARAMETERS
CONDITIONS
MIN
VIH
+ Positive Latch Threshold
●
VIL
– Latch Threshold
●
IIL
Latch Input Current
VLATCH = 0V
tPD
Propagation Delay
∆VIN = 100mV, OD = 5mV (Note 4)
TYP
V
●
∆VIN = 100mV, OD = 20mV (Note 4)
Propagation Delay
UNITS
2.0
0.8
V
–20
–500
µA
12
16
18
ns
ns
10
14
16
ns
ns
3
ns
●
tPD
MAX
●
∆tPD
Differential Propagation Delay
∆VIN = 100mV, OD = 5mV (Note 4)
tSU
Latch Set-Up Time
(Note 5)
2
ns
tH
Latch Hold Time
(Note 5)
2
ns
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
reliabilty and lifetime.
Note 2: Input offset voltage is defined as the average of two offset
voltages measured by forcing first the Q output to 1.4V then forcing
the Q output to 1.4V.
Note 3: Input bias current is defined as the average of the two input
currents.
Note 4: tPD and ∆tPD cannot be measured in automatic handling
equipment with low values of overdrive. The LT1116 is sample tested with
a 1V step and 500mV overdrive. Correlation tests have shown that tPD and
∆tPD can be guaranteed with this test if additional DC tests are performed
to verify internal bias conditions are correct. For low overdrive conditions
VOS is added to the measured overdrive.
Note 5: Input latch set-up time, tSU, is the interval in which the input signal
must be stable prior to asserting the latch signal. The hold time,
tH, is the interval after the latch is asserted in which the input signal must
be stable.
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Gain CharacteristIcs
5.0
4.5
25
VS = ±5V
IOUT = 0
20
TJ = 25°C
STEP SIZE = 100mV
20
16
TJ = –55°C
15
DELAY (ns)
TJ = 25°C
2.0
tPDLH
10
tPDHL
1.5
tPDLH
12
10
8
6
5
1.0
4
0.5
0
–2.5
tPDHL
14
3.0
2.5
STEP = 100mV, OVERDRIVE = 5mV
18
3.5
DELAY (ns)
OUTPUT VOLTAGE (V)
4.0
TJ = 125°C
Propagation Delay
vs Load Capacitance
Propagation Delay vs Overdrive
2
0
–1.5
1.5
– 0.5 0 0.5
DIFFERENTIAL INPUT VOLTAGE (mV)
2.5
LT1116 • TPC01
0
10
30
40
20
OVERDRIVE VOLTAGE (mV)
50
0
0
LT1116 • TPC02
www.BDTIC.com/Linear
10
30
40
20
OUTPUT LOAD CAPACITANCE (pF)
50
LT1116 • TPC03
1116fb
3
LT1116
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Propagation Delay
vs Source Resistance
80
Propagation Delay
vs Temperature
Propagation Delay
vs Positive Supply
25
VS = ±5V, OVERDRIVE = 20mV
30
STEP = 100mV
OVERDRIVE = 5mV
25 CLOAD = 10pF
VS = ±5V
70
20
60
400mV
40
200mV
30
20
tPDHL
RISING OUTPUT
15
DELAY (ns)
50
DELAY (ns)
DELAY (ns)
STEP SIZE = 800mV
tPDLH
FALLING OUTPUT
10
tPDHL
15
tPDLH
10
20
STEP SIZE = 100mV
5
5
10
0
0.5
0
1.0
2.0
2.5
1.5
SOURCE RESISTANCE (kΩ)
0
3.0
4.4
5.4
4.8
5.0
5.2
4.6
POWER SUPPLY VOLTAGE (V)
LT1116 • TPC04
4.5
OUTPUT VOLTAGE (V)
100
2
90
TIME (ns)
80
70
0
–2
60
–4
40
10k
100k
1M
FREQUENCY (Hz)
–6
50
100
–50 –25
25
75
0
JUNCTION TEMPERATURE (°C)
10M
LT1116 • TPC07
VS = ±5V, VIN = 30mV
30
0.6
CURRENT (mA)
TJ = 25°C
0.3
2
4 6 8 10 12 14 16 18 20
OUTPUT SOURCE CURRENT (mA)
LT1116 • TPC09
Positive Supply Current
50
POSITIVE SUPPLY CURRENT
20
15
V– = 0
40
30
20
TJ = 125°C
NEGATIVE SUPPLY CURRENT
TJ = 25°C
10
5
0.1
TJ = –55°C
0
0
2
4 6 8 10 12 14 16 18 20
OUTPUT SINK CURRENT (mA)
LT1116 • TPC10
4
0
60
10
TJ = 125°C
0.2
2.0
1.0
25
0.4
TJ = –55°C
2.5
Supply Current vs Temperature
TJ = –55°C
TJ = 25°C
3.0
125
35
0.7
0.5
3.5
LT1116 • TPC08
Output Low Voltage (VOL)
0.8
TJ = 125°C
4.0
1.5
CURRENT (mA)
REJECTION RATIO (dB)
5.0
4
50
VOLTAGE (V)
Output High Voltage (VOH)
Latch Set-Up Time
6
VIN = 2VP-P
VS = ±5V
TJ = 25°C
110
LT1116 • TPC06
LT1116 • TPC05
Common Mode Rejection
120
0
–50 –30 –10 10 30 50 70 90 110 130
JUNCTION TEMPERATURE (°C)
5.6
0
–60 –40 –20 0 20 40 60 80 100 120 140
JUNCTION TEMPERATURE (°C)
0
0
LT1116 • TPC11
www.BDTIC.com/Linear
6
2
4
POSITIVE SUPPLY VOLTAGE (V)
8
LT1116 • TPC12
1116fb
LT1116
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Positive Supply Current
Input Bias Current
10
45
40
INPUT BIAS CURRENT (µA)
TJ = 125°C
TJ = 25°C
CURRENT (mA)
35
30
TJ = –55°C
25
20
15
10
Positive Common Mode Limit
5
TJ = 25°C
VS = ±5V
COMMON MODE VOLTAGE (V)
50
0
–10
– 20
– 30
VS = ±5V
4
3
2
1
5
0
1
10
SWITCHING FREQUENCY (MHz)
– 40
100
–6
–4
0
–2
INPUT VOLTAGE (V)
LT1116 • TPC13
2
0
– 60 – 40 –20 0 20 40 60 80 100 120 140
JUNCTION TEMPERATURE (°C)
4
LT1116 • TPC15
LT1116 • TPC14
Negative Common Mode Limit
Latch Pin Threshold
Latch Pin Current*
2.6
300
–1
2.2
250
–2
1.8
0
–3
OUTPUT LATCHED
1.4
1.0
–4
CURRENT (µA)
VOLTAGE (V)
COMMON MODE VOLTAGE (V)
VS = 5V, OV
OUTPUT UNAFFECTED
0.6
–5
VS = ±5V
–6
– 60 –40 –20 0 20 40 60 80 100 120 140
JUNCTION TEMPERATURE (°C)
VS = ±5V
200
150
100
50
0.2
50
100
–50 –25
25
75
0
JUNCTION TEMPERATURE (°C)
*CURRENT COMES OUT OF LATCH PIN
BELOW THRESHOLD
125
0
50
100
–50 –25
25
75
0
JUNCTION TEMPERATURE (°C)
LT1116 • TPC17
LT1116 • TPC16
125
LT1116 • TPC18
W
UW
TI I G DIAGRA S
VOD
LATCH
ENABLE
tH
tSU
VIN
∆VIN
VIN
tPD
tPD
VOUT
VOUT
LT1116 • TD01
LT1116 • TD02
www.BDTIC.com/Linear
1116fb
5
LT1116
U
W
U U
APPLICATIO S I FOR ATIO
Common Mode Considerations
The LT1116 is specified for a common mode range of 0V
to 2.5V with a single 5V supply, and –5V to 2.5V with ±5V
supplies. The common mode range is defined as the DC
input for which the output responds correctly to small
changes in the input differential. Input signals can exceed
the positive common mode limit up to the 15V absolute
maximum rating without damaging the comparator. There
will, however, be an increase in propagation delay of up to
10ns when the input signal switches back into the
common mode range. When input signals fall below the
negative common mode limit, the internal PN diode formed
with the substrate can turn on (resulting in significant
charge flow throughout the die). A Schottky clamp diode,
between the input and the negative rail, speeds up recovery from negative overdrive by preventing the substrate
diode from turning on. The zero crossing detector in
Figure 1 demonstrates the use of a fast clamp diode.
Recovery, from 500mV overdrive below V –, for this circuit
is approximately 18ns.
Input Characteristics
Each input to the LT1116 is buffered with a fast PNP
follower—input bias current therefore does not vary
significantly throughout the common mode range. When
either input exceeds the positive common mode limit, the
bias current drops to zero. Inputs that fall more than one
diode and drop below V – will forward bias the substrate or
clamp diode, causing large input current to flow.
Single ended input resistance is about 5MΩ, and remains
roughly constant over the input common mode range. The
common mode resistance is about 2.5MΩ with zero
differential input voltage, and does not change
significantly with the absolute value of differential input.
Effective input capacitance, typically 5pF, is determined by
measuring the resulting change in propagation delay for a
1kΩ change in source resistance.
Latch Pin Dynamics
The internal latch uses local regenerative feedback to
shorten set-up and hold times. Driving the latch pin high
retains the output state. The latch pin floats to a high state
when disconnected, so it must be driven low for
flow-through operation. The set-up time required to
guarantee detecting a given transition of the inputs is 2ns.
The inputs must also remain stable for a 2ns hold time
after latch is asserted. New data will appear at the output
approximately 10ns to 12ns after the latch goes low. The
latch pin has no built-in hysteresis, and is designed to be
driven from TTL or CMOS logic gates.
Additional Information
Linear Technology’s Application Note 13 provides an
extensive discussion of design techniques for high speed
comparators.
Single Supply Crystal Oscillator 10MHZ to 15MHz
10 TO 15MHz
AT CUT
1kΩ
Fast Zero Crossing Detector
5V
5V
RS
50Ω
5V
Q
+
CABLE
+
VIN
1N5712
RT
50Ω
Q
LT1116
–
LT1116
1kΩ
–
Q
–
–
Q
OUTPUT
24pF
2kΩ
LT1116 • AI01
Figure 1. The Zero Crossing Detector Terminates the
Transmission Line At Its 50Ω Characteristic Impedance. Negative
Inputs Should Not Fall Below –2V to keep the Signal Current
Within the Clamp Diode’s Maximum Forward Rating. Positive
Inputs Should not Exceed the Devices Absolute Maximum Ratings
nor the Power Rating on the Terminating Resistor
6
LT1116 • AI02
Figure 2. This Single Supply Crystal Oscillator Utilizes Crystals
From 10MHz To 15MHz Without Component Changes
www.BDTIC.com/Linear
1116fb
LT1116
U
W
U U
APPLICATIO S I FOR ATIO
High Speed Adaptive Trigger Circuit
Line receivers often require an adaptive trigger to
compensate for variations in signal amplitude and DC
offsets. The circuit in Figure 3 triggers on 2mV to 200mV
signals from 100Hz to 10MHz from a single 5V rail. The
trigger level is the average of the input signal’s positive and
negative peaks stored on 0.005µF capacitors. Pairs of
NPN and PNP transistors are used instead of diodes to
temperature compensate the peak detector.
5pF
5V
3kΩ
1%
1kΩ
CABLE
VIN
200Ω
1kΩ
4R
200Ω
5V
To achieve single supply operation, the input signal must
be shifted into the pre-amplifier’s common mode range.
The input amplifier A1 adds a 1V level shift, while A2
provides a gain of 20 for high frequency signals.
Capacitors C1 and C2 insure that low frequency signals
see unity gain. Bandwidth limiting in A1 and A2 does not
affect triggering because the adaptive trigger threshold
varies ratiometrically to maintain circuit output.
5V
5V
–
A1
LT1191
+
0.005µF
500pF
A2
LT1192
+
5V
3MΩ
+
–
0.005µF
3MΩ
A3
LT1006
–
47µF
1000pF
R
100Ω
1kΩ
50Ω
C1
100µF
3kΩ
1%
C2
0.1µF
500Ω
5V
0.1µF
+
NPN = 2N3904
PNP = 2N3906
Q
LT1116
–
–
Q
TRIGGER
OUT
LT1116 • AI03
Figure 3. Fast Single Supply Adaptive Trigger
www.BDTIC.com/Linear
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.
1116fb
7
LT1116
U
PACKAGE DESCRIPTIO
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
0.300 – 0.325
(7.620 – 8.255)
0.045 – 0.065
(1.143 – 1.651)
(
8
7
6
5
1
2
3
4
0.255 ± 0.015*
(6.477 ± 0.381)
+0.035
0.325 –0.015
+0.889
8.255
–0.381
0.130 ± 0.005
(3.302 ± 0.127)
0.065
(1.651)
TYP
0.009 – 0.015
(0.229 – 0.381)
0.400*
(10.160)
MAX
)
0.100
(2.54)
BSC
0.125
(3.175) 0.020
MIN (0.508)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
N8 1098
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.053 – 0.069
(1.346 – 1.752)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.014 – 0.019
(0.355 – 0.483)
TYP
*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
8
7
6
5
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
SO8 1298
1
2
3
4
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1016
10ns Precision Comparator
Complementary Outputs with Latch, LT1116 Pinout
LT1394
7ns Single Supply Comparator
6mA, 100MHz Toggle Rate, LT1116 Pinout
LT1671
60ns Single Supply Comparator
450µA, 0.8mV Offset, LT1116 Pinout
LT1713/LT1714
7ns Single/Dual Comparator
Rail-to-Rail Input and Output, 2.7V to + 5.5V Operation
LT1715
4ns Dual Comparator
Independent Input/Output Supplies, 150MHz Toggle Rate
LT1719
4.5ns Single Supply Comparator
Independent Input/Output Supplies, 3V/5V
LT1720/LT1721
4.5ns Dual/Quad Comparator
4mA per Comparator, Input 100mV Below V –, 3V/5V
8
www.BDTIC.com/Linear
Linear Technology Corporation
1116fb
LT 0306 REV B • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507
●
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2006