LT6700-1/LT6700-2/LT6700-3
Micropower, Low Voltage,
SOT-23, Dual Comparator
with 400mV Reference
U
FEATURES
■
■
■
■
■
■
■
■
■
■
■
■
DESCRIPTIO
Low Quiescent Current: 6.5µA Typ at 5V
Wide Supply Range: 1.4V to 18V
400mV Reference ±2% Accuracy Over Temperature
Input Range Includes Ground
Over-The-Top® Input Range
Over-The-Top Open-Collector Outputs
Internal Hysteresis: 6.5mV Typ
Low Input Bias Current: ±10nA Max
40mA Typical Output Sink Current
Supports Wired-AND Connections
Choice of Input Polarities: LT6700-1/LT6700-2/
LT6700-3
Low Profile (1mm) SOT-23 (ThinSOTTM) Package
U
APPLICATIO S
■
■
■
■
■
■
The comparators each have one input available externally,
the other inputs are connected internally to the reference.
The comparator outputs are open collector and the output
load can be referred to any voltage up to 18V, independent
of supply voltage. The output stage sinking capability is
guaranteed greater than 5mA over temperature.
The three versions of the part differ by the polarity of the
available comparator inputs. The LT6700-1 has one inverting input and one noninverting input, making it suitable for use as a window comparator. The LT6700-2 has
two inverting inputs and the LT6700-3 has two noninverting inputs. All versions are offered in commercial, industrial and automotive temperature ranges.
Battery-Powered System Monitoring
Threshold Detectors
Window Comparators
Relay Driving
Optoisolator Driving
Industrial Control Systems
Handheld Instruments
, LTC and LT are registered trademarks of Linear Technology Corporation.
Over-The-Top is a registered trademark of Linear Technology.
ThinSOT is a trademark of Linear Technology Corporation.
U
■
The LT®6700-1/LT6700-2/LT6700-3 combine two micropower, low voltage comparators with a 400mV reference in the 6-lead SOT-23 package. Operating with supplies
from 1.4V up to 18V, the devices draw only 6.5µA typical,
making them ideal for low voltage system monitoring.
Hysteresis is included in the comparators, easing design
requirements to insure stable output operation.
TYPICAL APPLICATIO
Micropower Battery Monitor
VBATT
1.4V (MIN)
3V (NOM)
Comparator Thresholds
vs Temperature
5
LT6700-3
4
+
1M
ALKALINE
AA CELLS
63.4k
VBATT > 1.6V
–
VR = 400mV
REFERENCE
–
3
406
404
6
+
+
1M
COMP B
VS
COMP A
1
VBATT > 2V
+
0.1µF
261k
2
6700123 TA01
MONITOR CONSUMES ~10µA
HYSTERESIS IS APPROXIMATELY
2% OF TRIP VOLTAGE
THRESHOLD VOLTAGE (mV)
1M
#1A
#1B
#2A
#2B
RISING INPUT
402
400
398
396
FALLING INPUT
394
TWO TYPICAL PARTS
392 COMP A AND B
VS = 5V
390
–60 –40 –20 0 20 40 60 80 100 120
TEMPERATURE (°C)
6700123 TA02
6700123fb
1
LT6700-1/LT6700-2/LT6700-3
W W
W
AXI U
U
ABSOLUTE
RATI GS (Note 1)
Total Supply Voltage (VS to GND) ........................ 18.5V
Input Voltage (+IN, –IN)
(Note 3) ..................................... 18.5V to (GND – 0.3V)
Output Voltage (OUT) ................ 18.5V to (GND – 0.3V)
Output Short-Circuit Duration (Note 2) ........... Indefinite
Input Current (Note 3) ....................................... –10mA
Operating Temperature Range (Note 4)
LT6700CS6-1/-2/-3 ............................ – 40°C to 85°C
LT6700IS6-1/-2/-3 ............................. – 40°C to 85°C
LT6700HS6-1/-2/-3 .......................... – 40°C to 125°C
Specified Temperature Range (Note 5)
LT6700CS6-1/-2/-3 ............................ – 40°C to 85°C
LT6700IS6-1/-2/-3 ............................. – 40°C to 85°C
LT6700HS6-1/-2/-3 .......................... – 40°C to 125°C
Maximum Junction Temperature ......................... 150°C
Storage Temperature Range ................... – 65°C to 150°
Lead Temperature (Soldering, 10 sec).................. 300°C
U
U
W
PACKAGE/ORDER I FOR ATIO
TOP VIEW
OUTA 1
TOP VIEW
6 OUTB
TOP VIEW
OUTA 1
6 OUTB
OUTA 1
6 OUTB
GND 2
5 VS
GND 2
5 VS
GND 2
5 VS
+INA 3
4 –INB
–INA 3
4 –INB
+INA 3
4 +INB
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
TJMAX = 150°C, θJA = 230°C/W
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
TJMAX = 150°C, θJA = 230°C/W
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
TJMAX = 150°C, θJA = 230°C/W
ORDER PART
NUMBER
S6 PART
MARKING*
ORDER PART
NUMBER
S6 PART
MARKING*
ORDER PART
NUMBER
S6 PART
MARKING*
LT6700CS6-1
LT6700IS6-1
LT6700HS6-1
LTK7
LT6700CS6-2
LT6700IS6-2
LT6700HS6-2
LTADL
LT6700CS6-3
LT6700IS6-3
LT6700HS6-3
LTADM
*The temperature grades are identified by a label on the shipping container. Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
TA = 25°C, unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VTH(R)
Rising Input Threshold Voltage
RL = 100k, VO = 2V Swing
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
394
395
393
392
400
400
400
400
406
405
407
408
mV
mV
mV
mV
RL = 100k, VO = 2V Swing
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
386
387
385
384
393.5
393.5
393.5
393.5
401
400
402
403
mV
mV
mV
mV
VS = 1.4V, 5V, 12V, 18V, RL = 100k, VO = 2V Swing
3.5
6.5
9.5
mV
VTH(F)
HYS
Falling Input Threshold Voltage
HYS = VTH(R) – VTH(F)
6700123fb
2
LT6700-1/LT6700-2/LT6700-3
ELECTRICAL CHARACTERISTICS
TA = 25°C, unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
IB
Input Bias Current
VS = 1.4V, 18V, VIN = VS
VS = 1.4V, VIN = 18V
VS = 1.4V, 18V, VIN = 0.1V
VOL
Output Low Voltage
10mV Input Overdrive
VS = 1.4V, IOUT = 0.5mA
VS = 1.6V, IOUT = 3mA
VS = 5V, IOUT = 5mA
MIN
TYP
MAX
UNITS
±0.01
±0.01
±4
±10
±10
±10
nA
nA
nA
55
60
70
200
200
200
mV
mV
mV
0.01
0.01
0.8
0.8
µA
µA
IOFF
Output Leakage Current
VS = 1.4V, 18V, VOUT = VS, VIN = 40mV Overdrive
VS = 1.4V, VOUT = 18V, VIN = 40mV Overdrive
tPD(HL)
High-to-Low Propagation Delay
VS = 5V, 10mV Input Overdrive, RL = 10k,
VOL = 400mV
29
µs
tPD(LH)
Low-to-High Propagation Delay
VS = 5V, 10mV Input Overdrive, RL = 10k,
VOH = 0.9 • VS
18
µs
tr
Output Rise Time
VS = 5V, 10mV Input Overdrive, RL = 10k
VO = (0.1 to 0.9) • VS
2.2
µs
tf
Output Fall Time
VS = 5V, 10mV Input Overdrive, RL = 10k
VO = (0.1 to 0.9) • VS
0.22
µs
IS
Supply Current
No Load Current
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
5.7
6.5
6.9
7.1
10.0
11.0
12.5
13.0
µA
µA
µA
µA
The ● denotes the specifications which apply over the temperature range of 0°C ≤ TA ≤ 70°C, unless otherwise specified (Notes 4, 5).
SYMBOL
PARAMETER
CONDITIONS
VTH(R)
Rising Input Threshold Voltage
RL = 100k, VO = 2V Swing
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
●
●
●
●
RL = 100k, VO = 2V Swing
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
●
●
●
●
VTH(F)
Falling Input Threshold Voltage
MIN
TYP
MAX
UNITS
391.0
392.5
390.0
389.0
409.0
407.5
410.0
411.0
mV
mV
mV
mV
383.5
384.5
382.5
381.5
403.5
402.5
404.5
405.5
mV
mV
mV
mV
3
11
mV
HYS
HYS = VTH(R) – VTH(F)
VS = 1.4V, 5V, 12V, 18V, RL = 100k, VO = 2V Swing ●
IB
Input Bias Current
VS = 1.4V, 18V, VIN = VS
VS = 1.4V, VIN = 18V
VS = 1.4V, 18V, VIN = 0.1V
●
●
●
±15
±15
±15
nA
nA
nA
VOL
Output Low Voltage
10mV Input Overdrive
VS = 1.4V, IOUT = 0.5mA
VS = 1.6V, IOUT = 3mA
VS = 5V, IOUT = 5mA
●
●
●
250
250
250
mV
mV
mV
IOFF
Output Leakage Current
VS = 1.4V, 18V, VOUT = VS, VIN = 40mV Overdrive
VS = 1.4V, VOUT = 18V, VIN = 40mV Overdrive
●
●
1
1
µA
µA
IS
Supply Current
No Load Current
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
●
●
●
●
13.0
14.0
15.5
16.0
µA
µA
µA
µA
6700123fb
3
LT6700-1/LT6700-2/LT6700-3
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the temperature range of
–40°C ≤ TA ≤ 85°C, unless otherwise specified (Notes 4, 5).
SYMBOL
VTH(R)
VTH(F)
PARAMETER
Rising Input Threshold Voltage
Falling Input Threshold Voltage
HYS
IB
HYS = VTH(R) – VTH(F)
Input Bias Current
VOL
Output Low Voltage
IOFF
Output Leakage Current
IS
Supply Current
CONDITIONS
RL = 100k, VO = 2V Swing
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
RL = 100k, VO = 2V Swing
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
VS = 1.4V, 5V, 12V, 18V, RL = 100k, VO = 2V Swing
VS = 1.4V, 18V, VIN = VS
VS = 1.4V, VIN = 18V
VS = 1.4V, 18V, VIN = 0.1V
10mV Input Overdrive
VS = 1.4V, IOUT = 0.1mA
VS = 1.6V, IOUT = 3mA
VS = 5V, IOUT = 5mA
VS = 1.4V, 18V, VOUT = VS, VIN = 40mV Overdrive
VS = 1.4V, VOUT = 18V, VIN = 40mV Overdrive
No Load Current
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
MIN
TYP
MAX
UNITS
●
●
●
●
390
392
389
388
410
408
411
412
mV
mV
mV
mV
●
●
●
●
382.5
383.5
381.5
380.5
2
404.5
403.5
405.5
406.5
11.5
±15
±15
±15
mV
mV
mV
mV
mV
nA
nA
nA
●
●
250
250
250
1
1
mV
mV
mV
µA
µA
●
●
●
●
14.0
15.0
16.5
17.0
µA
µA
µA
µA
●
●
●
●
●
●
●
The ● denotes the specifications which apply over the temperature range of –40°C ≤ TA ≤ 125°C, unless otherwise specified (Notes 4, 5).
SYMBOL
VTH(R)
VTH(F)
PARAMETER
Rising Input Threshold Voltage
Falling Input Threshold Voltage
HYS
IB
HYS = VTH(R) – VTH(F)
Input Bias Current
VOL
Output Low Voltage
IOFF
Output Leakage Current
IS
Supply Current
CONDITIONS
RL = 100k, VO = 2V Swing
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
RL = 100k, VO = 2V Swing
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
VS = 1.4V, 5V, 12V, 18V, RL = 100k, VO = 2V Swing
VS = 1.4V, 18V, VIN = VS
VS = 1.4V, VIN = 18V
VS = 1.4V, 18V, VIN = 100mV
10mV Input Overdrive
VS = 1.4V, IOUT = 0.1mA
VS = 1.6V, IOUT = 3mA
VS = 5V, IOUT = 5mA
VS = 1.4V, 18V, VOUT = VS, VIN = 40mV Overdrive
VS = 1.4V, VOUT = VS, VIN = 40mV Overdrive
No Load Current
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
MIN
LT6700H
TYP
MAX
UNITS
●
●
●
●
390
392
389
388
411
410
412
413
mV
mV
mV
mV
●
●
●
●
381.5
382.5
380.5
379.5
2
405.5
404.5
406.5
407.5
13.5
±45
±45
±50
mV
mV
mV
mV
mV
nA
nA
nA
●
●
250
250
250
1
1
mV
mV
mV
µA
µA
●
●
●
●
16.0
17.0
18.5
19.0
µA
µA
µA
µA
●
●
●
●
●
●
●
6700123fb
4
LT6700-1/LT6700-2/LT6700-3
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those beyond which the life of the
device may be impaired.
Note 2: A heat sink may be required to keep the junction temperature
below the absolute maximum rating when the output is shorted
indefinitely.
Note 3: The inputs are protected by ESD diodes to the ground. If the input
voltage exceeds –0.3V below ground, the input current should be limited
to less than 10mA.
Note 4: The LT6700CS6-1/-2/-3 and LT6700IS6-1/-2/-3 are guaranteed
functional over the operating temperature range of – 40°C to 85°C. The
LT6700HS6-1/-2/-3 are guaranteed functional over the operating
temperature range of –40°C to 125°C.
Note 5: The LT6700CS6-1/-2/-3 are guaranteed to meet the specified
performance from 0°C to 70°C. The LT6700CS6-1/-2/-3 are designed,
characterized and expected to meet specified performance from – 40°C to
85°C but are not tested or QA sampled at these temperatures. The
LT6700IS6-1/-2/-3 are guaranteed to meet specified performance from
–40°C to 85°C. The LT6700HS6-1/-2/-3 are guaranteed to meet specified
performance from –40°C to 125°C.
U
U
U
PI FU CTIO S
LT6700-1
–INB 4
VS
VS
5
5
LT6700-2
COMP B
–
–INB 4
VS
COMP B
–
+INB 4
VS
–
400mV
REFERENCE
COMP A
+
400mV
REFERENCE
–
6700123 PF01
1 OUTA
GND
OUTA (Pin 1): Open-Collector Output of Comparator Section A. This pin provides drive for up to 40mA of load
current. Off-state voltage may be as high as 18V above
GND (Pin 2), regardless of VS used.
GND (Pin 2): Ground. This pin is also the low side return
of the internal 400mV reference.
INA (Pin 3): External Input for Comparator Section A. The
voltage on this pin can range from –0.3V to 18V with
respect to GND (Pin 2) regardless of VS used. The input is
noninverting for the LT6700-1 and LT6700-3, and inverting for the LT6700-2. The other section A comparator
input is internally connected to the 400mV reference.
+INA 3
2
GND
6700123 PF02
VS
COMP A
–
1 OUTA
–INA 3
2
VS
COMP A
+
1 OUTA
+INA 3
6 OUTB
+
–
COMP B
+
6 OUTB
6 OUTB
+
400mV
REFERENCE
5
LT6700-3
+
2
6700123 PF03
GND
INB (Pin 4): External Input for Comparator Section B. The
voltage on this pin can range from –0.3V to 18V with
respect to GND (Pin 2) regardless of VS used. The input is
noninverting for the LT6700-3, and inverting for the
LT6700-1 and LT6700-2. The other section B comparator
input is internally connected to the 400mV reference.
VS (Pin 5): Comparator Core Supply Voltage. The parts are
characterized for operation with 1.4V ≤ VS ≤ 18V with
respect to GND (Pin 2).
OUTB (Pin 6): Open-Collector Output of Comparator Section B. This pin provides drive for up to 40mA of load
current. Off-state voltage may be as high as 18V above
GND (Pin 2), regardless of VS used.
6700123fb
5
LT6700-1/LT6700-2/LT6700-3
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Distribution of Rising Input
Threshold Voltage
VS = 5V
TA = 25°C
14
12
10
8
6
4
18
12
10
8
6
4
14
12
10
8
6
4
2
2
0
0
388
390
392
394
396
398
400
FALLING INPUT THRESHOLD VOLTAGE (mV)
0
6700123 G01
401
400
#2
#3
399
398
397
#4
403.0
402.5
402.0
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
401.5
401.0
400.5
400.0
399.5
396
–60 –40 –20 0 20 40 60 80 100 120
TEMPERATURE (°C)
399.0
–60 –40 –20 0 20 40 60 80 100 120
TEMPERATURE (°C)
6700123 G04
6700123 G05
9
8
6
5
8
8.8
TA = 25°C
TA = 85°C
TA = 125°C
TA = –55°C
402.5
402.0
401.5
401.0
400.5
400.0
399.5
399.0
2
4
8 10 12 14
6
SUPPLY VOLTAGE (V)
16
18
6700123 G06
Hysteresis vs Temperature
10
HYSTERESIS (mV)
HYSTERESIS (mV)
403.0
Hysteresis vs Supply Voltage
10
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
TA = 25°C
TA = 85°C
9
TA = 125°C
TA = –55°C
8
HYSTERESIS (mV)
Hysteresis vs Temperature
10
FOUR TYPICAL PARTS
9 VS = 5V
#1
#2
8
#3
#4
7
5.6
6.4
7.2
HYSTERESIS (mV)
Rising Input Threshold Voltage
vs Supply Voltage
RISING INPUT THRESHOLD VOLTAGE (mV)
#1
402
4.8
6700123 G03
Rising Input Threshold Voltage
vs Temperature
RISING INPUT THRESHOLD VOLTAGE (mV)
403
FOUR TYPICAL PARTS
VS = 5V
4
6700123 G02
Rising Input Threshold Voltage
vs Temperature
404
VS = 5V
TA = 25°C
16
14
2
394
396
398
400
402
404
406
RISING INPUT THRESHOLD VOLTAGE (mV)
RISING INPUT THRESHOLD VOLTAGE (mV)
Distribution of Hysteresis
20
VS = 5V
TA = 25°C
16
PERCENT OF UNITS (%)
PERCENT OF UNITS (%)
16
18
PERCENT OF UNITS (%)
18
Distribution of Falling Input
Threshold Voltage
7
6
5
7
6
5
4
4
4
3
3
3
2
–60 –40 –20 0 20 40 60 80 100 120
TEMPERATURE (°C)
2
–60 –40 –20 0 20 40 60 80 100 120
TEMPERATURE (°C)
2
6700123 G07
6700123 G08
2
4
8 10 12 14
6
SUPPLY VOLTAGE (V)
16
18
6700123 G09
6700123fb
6
LT6700-1/LT6700-2/LT6700-3
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Quiescent Supply Current
vs Supply Voltage
Minimum Supply Voltage
1
10
TA = 125°C
TA = –55°C
9 NO LOAD CURRENT
–1
–2
–3
TA = 25°C
TA = 85°C
TA = 125°C
TA = –55°C
–4
–5
0.9
1.1
1.5
1.3
1.7
SUPPLY VOLTAGE (V)
8
7
6
4
1.4 3.4 5.4 7.4 9.4 11.4 13.4 15.4 17.4
SUPPLY VOLTAGE (V)
10
1
0.001
100
0.01
0.1
1
10
OUTPUT SINK CURRENT (mA)
Below Ground Input Bias Current
Low Level Input Bias Current
VS = 18V
–0.3V < VIB < 0V
TA = 25°C
TA = 85°C
TA = 125°C
TA = –55°C
10
CURRENT IS GOING INTO THE DEVICE
0
–1
–2
VS = 18V
0V < VIB < 1V
TA = 25°C
TA = 85°C
TA = 125°C
TA = –55°C
–4
–5
–6
1
–0.3
High Level Input Bias Current
1
–3
CURRENT IS GOING OUT OF THE DEVICE
–7
–0.2
–0.1
INPUT VOLTAGE (V)
0
6700123 G16
0
100
10
CURRENT IS POSITIVE GOING
2 INTO THE DEVICE
100
0.01
0.1
1
10
OUTPUT SINK CURRENT (mA)
6700123 G15
3
INPUT BIAS CURRENT (nA)
1000
10
6700123 G14
6700123 G13
10000
100
TA = 85°C
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
1
0.001
100
INPUT BIAS CURRENT (nA)
0.01
0.1
1
10
OUTPUT SINK CURRENT (mA)
100
1.4
1000
TA = 25°C
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
10
0.4 0.6 0.8 1.0 1.2
SUPPLY VOLTAGE (V)
Supply Current
vs Output Sink Current
1000
TA = –40°C
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
0.2
0
6700123 G12
Supply Current
vs Output Sink Current
1000
INPUT BIAS CURRENT (nA)
0
6700123 G11
Supply Current
vs Output Sink Current
1
0.001
20
10
6700123 G10
100
30
5
1.9
TA = 25°C
TA = 85°C
TA = 125°C
TA = –55°C
40
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
THRESHOLD SHIFT (mV)
0
TA = 25°C
TA = 85°C
Start-Up Supply Current
50
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
INPUT VOLTAGE (V)
1
6700123 G17
1
0.1
VS = 18V
0.01 VIB > 1V
TA = 25°C
TA = 85°C
TA = 125°C
0.001
1
3
5
7
9 11 13
INPUT VOLTAGE (V)
15
17
6700123 G18
6700123fb
7
LT6700-1/LT6700-2/LT6700-3
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Output Saturation Voltage
vs Output Sink Current
Output Saturation Voltage
vs Output Sink Current
1000
100
10
1
0.001
0.01
0.1
1
10
OUTPUT SINK CURRENT (mA)
100
10
1
0.001
100
1000
TA = 25°C
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
OUTPUT SATURATION VOLTAGE (mV)
TA = –40°C
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
OUTPUT SATURATION VOLTAGE (mV)
OUTPUT SATURATION VOLTAGE (mV)
1000
0.01
0.1
1
10
OUTPUT SINK CURRENT (mA)
6700123 G19
70
50
40
30
VS = 5V
TA = 25°C
TA = 85°C
TA = 125°C
TA = –55°C
10
0
0
2
4
8 10 12 14
6
OUTPUT VOLTAGE (V)
16
50
TA = 25°C
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
40
30
20
10
2
0
20
RISE AND FALL TIME (µs)
LH NONINV
HL NONINV
LH INV
HL INV
30
4
8 10 12 14
6
OUTPUT VOLTAGE (V)
16
20
60
80
40
INPUT OVERDRIVE (mV)
100
6700123 G25
VS = 5V
TA = 25°C
TA = 85°C
TA = 125°C
TA = –55°C
0.01
18
0
2
4
6
8 10 12 14
OUTPUT VOLTAGE (V)
VS = 5V
CL = 20pF
TA = 25°C
RISE
6700123 G24
FALL
VIN
10mV/DIV
AC
0.1
0.01
0.1
18
VO(NINV)
5V/DIV
DC
VO(INV)
5V/DIV
DC
10
1
16
Noninverting and Inverting
Comparators’ Propagation Delay
10
0
0.1
Rise and Fall Times
vs Output Pull-Up Resistor
40
0
1
6700123 G23
100
50
6700123 G21
0.001
0
18
100
Output Leakage Current
60
Propagation Delay
vs Input Overdrive
TA = 25°C
0.01
0.1
1
10
OUTPUT SINK CURRENT (mA)
10
6700123 G22
60
10
1
0.001
100
OUTPUT LEAKAGE CURRENT (nA)
70
SHORT-CIRCUIT CURRENT (mA)
SHORT-CIRCUIT CURRENT (mA)
80
20
100
Output Short-Circuit Current
80
60
TA = 85°C
VS = 1.4V
VS = 5V
VS = 12V
VS = 18V
6700123 G20
Output Short-Circuit Current
PROPAGATION DELAY (µs)
Output Saturation Voltage
vs Output Sink Current
1
10
100
OUTPUT PULL-UP RESISTOR (kΩ)
1000
20µs/DIV
VS = 5V
TA = 25°C
RLOAD = 10k CONNECTED TO VS
VIN(OVERDRIVE) = 10mV OVER THE INPUT
VOLTAGE THRESHOLDS
67000123 G27
6700123 G26
6700123fb
8
LT6700-1/LT6700-2/LT6700-3
U
W
U U
APPLICATIO S I FOR ATIO
The LT6700-1/LT6700-2/LT6700-3 devices are a family of
dual micropower comparators with a built-in 400mV reference. Features include wide supply voltage range (1.4V
to 18V), Over-The-Top input and output range, 2% accurate rising input threshold voltage and 6.5mV typical builtin hysteresis. The comparator’s open-collector outputs
can sink up to 40mA typical.
Internal Reference
Each of the comparator sections has one input available
externally, with the three versions of the part differing by
the polarity of those available inputs (i.e., inverting or
noninverting). The other comparator inputs are connected
internally to the 400mV reference. The rising input threshold voltage of the comparators is designed to be equal to
that of the reference (i.e., ≈ 400mV). The reference voltage
is established with respect to the device GND connection.
Hysteresis
Each comparator has built-in 6.5mV (typical) hysteresis to
simplify designs, insure stable operation in the presence
of noise at the inputs, and to reject supply rail noise that
might be induced by state change load transients. The
hysteresis is designed such that the falling input threshold
voltage is nominally 393.5mV. External positive feedback
circuitry can be employed with noninverting comparator
inputs to increase effective hysteresis if desired, but such
circuitry will provide an apparent effect on both the rising
and falling input thresholds (the actual internal thresholds
remain unaffected).
Comparator Inputs
A comparator input can swing from ground to 18V,
regardless of the supply voltage used. The typical input
current for inputs well above threshold (i.e., >800mV) is
a few pA leaking into an input. With decreasing input
voltage, a small bias current begins to be drawn out of the
input, reaching a few nA when at ground potential. The
input may be forced 100mV below ground without causing
an improper output, though some additional bias current
will begin to flow from the parasitic ESD input protection
diode. Inputs driven further negative than 100mV below
ground will not cause comparator malfunction or damage
(provided the current is limited to 10mA), but the accuracy
of the reference cannot be guaranteed, in which case the
output state of the alternate comparator may be effected.
Comparator Outputs
The comparator outputs are open collector and capable of
sinking 40mA typical. Load currents are directed out the
GND pin of the part. The output off-state voltage may range
between –0.3V and 18V with respect to ground, regardless
of the supply voltage used. As with any open-collector
device, the outputs may be tied together to implement
wire-AND logic functions.
Power Supplies
The comparator family core circuitry operates from a
single 1.4V to 18V supply. A minimum 0.1µF bypass
capacitor is required between the VS pin and GND. When
an output load is connected to the supply rail near the part
and the output is sinking more than 5mA, a 1µF bypass
capacitor is recommended. In instances where the supply
is relatively “soft” (such as with small batteries) and
susceptible to load steps, an additional 47Ω series decoupling resistor can further improve isolation of supply
transients from the VS pin.
Flexible Window Comparator
Using the LT6700-1 as shown in the circuits of Figure 1,
the wire-AND configuration permits high accuracy window functions to be implemented with a simple 3-resistor
voltage divider network. The section A comparator provides the VL trip-point and the section B comparator
provides the VH trip-point, with the built-in hysteresis
providing about 1.7% recovery level at each trip point to
prevent output chatter.
For designs that are to be optimized to detect departure
from a window limit, the nominal resistor divider values
are selected as follows (refer to the resistor designators
shown on the first circuit of Figure 1):
R1 ≤ 400k (this sets the divider current >> IB of inputs)
R2 = R1 • (0.98 • VH/VL – 1)
R3 = R1 • (2.5 • VH – 0.98 • VH/VL)
6700123fb
9
LT6700-1/LT6700-2/LT6700-3
U
W
U U
APPLICATIO S I FOR ATIO
3.3V Supply Monitor
5V Supply Monitor
3.3V
5V
VL
R3
301k
R1
40.2k
VOUT
5
VS
1
3
+INA OUTA
R2
6.04k 4
487k
33k
VS
LT6700-1
–INB OUTB
GND
VH
6
2
5
VS
1
3
+INA OUTA
LT6700-1
6.04k
4
VOUT
HIGH = (3.1V < VS < 3.5V)
40.2k
0.1µF
33k
–INB OUTB
GND
6
VOUT
HIGH = (4.7V < VS < 5.3V)
0.1µF
2
HYSTERESIS ZONES
APPROXIMATELY
2% OF TRIP VOLTAGE
6700123 F01
Figure 1. Simple Window Comparator
To create window functions optimized for detecting entry
into a window (i.e. where the output is to indicate a
“coming into spec” condition, as with the examples in
Figure 1), the nominal resistor values are selected as
follows:
0.1µF
1.4V TO 18V
(IS ≈ 10µA)
2 • VREF
RSET
499k
LT6700-1
R1 ≤ 400k (this sets the divider current >> IB of inputs)
R2 = R1 • (1.02 • VH/VL – 1)
5
VS
3
1
+INA OUTA
4
3.3µF
RTH
T
499k
–INB OUTB
GND
220k
220k*
T < TSET
6 10k
3.3µF
2
6700123 F02
R3 = R1 • (2.54 • VH – 1.02 • VH/VL)
The worst-case variance of the trip-points is related to the
specified threshold limits of the LT6700 device and the
basic tolerance of divider resistors used. For resistor
tolerance RTOL (e.g. 0.01 for 1%), the worst-case trippoint voltage (either VH or VL) deviations can be predicted
as follows (italicized values are taken from the datasheet,
expressed in volts):
Max dev VTRIP↑ = ±VTRIPnom • {2 • RTOL • [(VTRIPnom – 0.4)
/ VTRIPnom] + 1.25 • (VTH(R)max – VTH(R)min)}
Max dev VTRIP↓ = ±VTRIPnom • {2 • RTOL • [(VTRIPnom – 0.39)
/ VTRIPnom] + 1.27 • (VTH(F)max – VTH(F)min)}
Generating an External Reference Signal
In some applications, it would be advantageous to have
access to a signal that is directly related to the internal
400mV reference, even though the reference itself is not
available externally. This can be accomplished to a reasonable degree by using an inverting comparator section as a
“bang-bang” servo, establishing a nominal voltage, on an
integration capacitor, that is scaled to the reference. This
method is used in Figure 2, where the reference level has
RTH = 1M (e.g., YSI 44015, 1.00MΩ AT 25°C)
RSET = RTH AT TSET
*RESISTANCE MAY REQUIRE OPTIMIZATION FOR OPERATION
OVER INTENDED RTH AND VSUPPLY RANGES
HYSTERESIS ZONE ≈0.4°C
Figure 2. Micropower Thermostat/Temperature Alarm
been doubled to drive a resistor bridge. The section B
output cycles on and off to swing the section B input
between its hysteresis trip points as the load capacitor
charges and discharges in a shallow, controlled fashion.
The multiplied reference signal also contains ripple that is
the hysteresis multiplied by the same factor, so additional
filtering is performed at the sense node of the bridge to
prevent comparator chatter in the section A comparator,
which is performing the actual conditional decision for the
circuit.
Instrumentation Grade Pulse Width Modulator (PWM)
Comparators with hysteresis are frequently employed to
make simple oscillator structures, and the LT6700 lends
itself nicely to forming a charge-balancing PWM function.
The circuit shown in Figure 3 forms a PWM that is intended
to transmit an isolated representation of a voltage differ6700123fb
10
LT6700-1/LT6700-2/LT6700-3
U
W
U U
APPLICATIO S I FOR ATIO
ence, rather like an isolated instrumentation amplifier. The
section B comparator is used to generate a 2V reference
supply level for the CMOS NOT gate (inverter), which
serves as the precision switch element for the charge
balancer. The heart of the charge balancer is the section A
comparator, which is detecting slight charge or discharge
states on the 0.22µF “integration” capacitor as it remains
balanced at ≈400mV by feedback through the NOT gate.
The input sense voltage, VIN, is converted to an imbalance
current that the NOT gate duty cycle is continually correcting for, thus the digital waveform at the section A comparator output is a PWM representation of VIN with respect
to the 2V “full scale.” In this particular circuit, the PWM
information drives the LED of an optocoupler, allowing the
VIN information to be coupled across a dielectric barrier.
As an additional option to the circuit, the feedback loop can
be broken and a second optocoupler employed to provide
the charge balance management. This configuration allows for clocking the comparator output (externally to this
circuit) and providing synchronous feedback such that a
simple ∆Σ voltage-to-frequency conversion can be formed
if desired. Approximately 11-bit accuracy and noise performance was observed in a one second integration period
for duty factors from 1% to 99%.
U
W
U U
APPLICATIO S I FOR ATIO
3V/5V
3V NOM (IS < 3mA)
Lithium
COIN CELL
10k**
VIN
0V TO 2V
–
750Ω
1
22µF
+
0.1µF
470Ω
5 • VREF = 2V
NC7S14
10k
+
412k*
3
309k*
4
0.22µF††
100k*
100k*
MOC-207
5
VS
1
+INA OUTA
LT6700-1
309k*
–INB OUTB
GND
2
PWM OUT
(OR ∆Σ SENSE)
6
10k
10k
6 10k
2
5
3V/5V
†
0.1µF
750**
6
1
MOC-207**
*1% METAL FILM
**DELETE FOR PWM MODE
†
CONNECT FOR PWM MODE
††
OPTIMIZED FOR 2kHz ∆Σ SAMPLING, fPWM(MAX) ≈ 0.6kHz
6700123 F03
5
2
∆Σ
SAMPLE
IN
Figure 3. Isolated PWM or ∆Σ Converter
6700123fb
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
LT6700-1/LT6700-2/LT6700-3
U
PACKAGE DESCRIPTIO
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
2.80 BSC
1.4 MIN
3.85 MAX 2.62 REF
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
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
1.90 BSC
0.09 – 0.20
(NOTE 3)
S6 TSOT-23 0302
U
TYPICAL APPLICATIO S
PowerPathTM Controller
48V Status Monitor
B0520LW
“WART” INPUT
3.3V NOM
+
VSUPPLY
1.6V MIN
3V NOM
Si2301DS
33k
10k
VL
LED OFF
1k
1M
VOUT
3
VIN
7.87k
3
VIN
VS
1
+INA OUTA
VWART > 3.1V
R2
150k
R1
249k
+INB OUTB
GND
6
2
VBATT > 2V
1µF
3V/5V
–INB OUTB
GND
27k
33k
1
6
2
5
6
2 0.1µF
HYSTERESIS ZONES
APPROXIMATELY
2% OF TRIP VOLTAGE
5.1V
CMPZ5231B
–
VOUT
LOW = (39V < VIN < 70V)
MOC-207
10k
LT6700-3
4
5
VS
1
+INA OUTA
LT6700-1
4
5
+
VH
LED ON
+
ALKALINE
AA CELLS
100k
1M
22V
CMPZ5251B
1.74M
6700123 TA03
6700123 TA04
R1 = 400k/(VBATT AT LOW – 0.4)
R2 = 400k/(VBATT AT MAX – 0.4)
HYSTERESIS ZONES APPROXIMATELY 2% OF TRIP VOLTAGE
PowerPath IS A TRADEMARK OF LINEAR TECHNOLOGY CORPORATION
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1017/LT1018
Micropower Dual Comparator
1.1V (Min) Supply Voltage, ±1.4mV (Max) Input Offset
LTC1441/LTC1442
Micropower Dual Comparator with 1% Reference
1.182 ±1% Reference, ±10mV (Max) Input Offset
LTC1998
Micropower Comparator for Battery Monitoring
2.5µA Typ Supply Current, Adjustable Threshold and Hysteresis
6700123fb
12
Linear Technology Corporation
LT/TP 0104 1K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2003