that incorporates a precision current sense amplifier, an
integrated voltage reference and a comparator. Two ver-
sions of the LT6108 are available. The LT6108-1 has a
latching comparator and the LT6108-2 has a non-latching
comparator. In addition, the current sense amplifier and
comparator inputs and outputs are directly accessible. The
amplifier gain and comparator trip point are configured
by external resistors. The open-drain comparator output
allows for easy interface to other system components.
The overall propagation delay of the LT6108 is typically only
1.4µs, allowing for quick reaction to overcurrent condi-
tions. The 1MHz bandwidth allows the LT6108 to be used
for error detection in critical applications such as motor
control. The high threshold accuracy of the comparator,
combined with the ability to latch the comparator, ensures
the LT6108 can capture high speed events.
The LT6108 is fully specified for operation from –40°C to
125°C, making it suitable for industrial and automotive
applications. The LT6108 is available in the small 8-lead
MSOP and 8-lead DFN packages.
L,
LT, LTC, LTM, TimerBlox, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
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Current Sense Amplifier
– Fast Step Response: 500ns
– Low Offset Voltage: 125µV Maximum
– Low Gain Error: 0.2% Maximum
Internal 400mV Precision Reference
Internal Comparator
– Fast Response Time: 500ns
– Total Threshold Error: ±1.25% Maximum
– Latching or Non-Latching Comparator Option
Wide Supply Range: 2.7V to 60V
Supply Current: 450µA
Low Shutdown Current: 5µA Maximum
Specified for –40°C to 125°C Temperature Range
Available in 8-Lead MSOP and 8-Lead (2mm
×
3mm)
DFN Packages
Overcurrent and Fault Detection
Current Shunt Measurement
Battery Monitoring
Motor Control
Automotive Monitoring and Control
Remote Sensing
Industrial Control
APPLICATIONS
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n
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TYPICAL APPLICATION
Circuit Fault Protection with Very Fast Latching Load Disconnect
12V
6.2V*
1k
100
SENSEHI SENSELO
V
+
3.3V
1k
2N2700
10k
RESET
EN/RST
OUTC
INC
1.6k
610812 TA01a
Response to Overcurrent Event
TO LOAD
0.1
0.1µF
V
OUT
6.04k
IRF9640
V
LOAD
10V/DIV
0V
I
LOAD
200mA/DIV
0mA
V
OUTC
5V/DIV 0V
250mA DISCONNECT
OUTA
LT6108-1
250mA DISCONNECT
V
–
*CMH25234B
5µs/DIV
610812 TA01b
610812fa
1
LT6108-1/LT6108-2
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Total Supply Voltage (V
+
to V
–
) .................................60V
Maximum Voltage
(SENSELO, SENSEHI, OUTA) ............................... V
+
+ 1V
Maximum V
+
– (SENSELO or SENSEHI) ....................33V
Maximum EN, EN/RST Voltage .................................60V
Maximum Comparator Input Voltage ........................60V
Maximum Comparator Output Voltage......................60V
Input Current (Note 2) ..........................................–10mA
SENSEHI, SENSELO Input Current ....................... ±10mA
Differential SENSEHI or SENSELO Input Current ..±2.5mA
Amplifier Output Short-Circuit Duration (to V
–
) .. Indefinite
Operating Temperature Range (Note 3)
LT6108I ................................................–40°C to 85°C
LT6108H ............................................ –40°C to 125°C
Specified Temperature Range (Note 3)
LT6108I ................................................–40°C to 85°C
LT6108H ............................................ –40°C to 125°C
Maximum Junction Temperature .......................... 150°C
Storage Temperature Range .................. –65°C to 150°C
MSOP Lead Temperature (Soldering, 10 sec)........ 300°C
PIN CONFIGURATION
LT6108-1
SENSELO
EN/RST
OUTC
V
–
1
2
3
4
TOP VIEW
8
7
6
5
SENSEHI
V
+
OUTA
INC
LT6108-2
SENSELO
EN
OUTC
V
–
1
2
3
4
TOP VIEW
8
7
6
5
SENSEHI
V
+
OUTA
INC
MS8 PACKAGE
8-LEAD PLASTIC MSOP
θ
JA
= 163°C/W,
θ
JC
= 45°C/W
TOP VIEW
SENSELO 1
EN/RST 2
OUTC 3
V
–
4
9
8 SENSEHI
7 V
+
6 OUTA
5 INC
MS8 PACKAGE
8-LEAD PLASTIC MSOP
θ
JA
= 163°C/W,
θ
JC
= 45°C/W
TOP VIEW
SENSELO 1
EN 2
OUTC 3
V
–
4
9
8 SENSEHI
7 V
+
6 OUTA
5 INC
DCB PACKAGE
8-LEAD (2mm
×
3mm) PLASTIC DFN
θ
JA
= 64°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 9) IS V
–
, PCB CONNECTION OPTIONAL
DCB PACKAGE
8-LEAD (2mm
×
3mm) PLASTIC DFN
θ
JA
= 64°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 9) IS V
–
, PCB CONNECTION OPTIONAL
610812fa
2
LT6108-1/LT6108-2
ORDER INFORMATION
LEAD FREE FINISH
LT6108AIMS8-1#PBF
LT6108IMS8-1#PBF
LT6108AHMS8-1#PBF
LT6108HMS8-1#PBF
LT6108AIMS8-2#PBF
LT6108IMS8-2#PBF
LT6108AHMS8-2#PBF
LT6108HMS8-2#PBF
TAPE AND REEL
LT6108AIMS8-1#TRPBF
LT6108IMS8-1#TRPBF
LT6108AHMS8-1#TRPBF
LT6108HMS8-1#TRPBF
LT6108AIMS8-2#TRPBF
LT6108IMS8-2#TRPBF
LT6108AHMS8-2#TRPBF
LT6108HMS8-2#TRPBF
PART MARKING*
LTFND
LTFND
LTFND
LTFND
LTFNG
LTFNG
LTFNG
LTFNG
PACKAGE DESCRIPTION
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
SPECIFIED TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 125°C
–40°C to 125°C
–40°C to 85°C
–40°C to 85°C
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
Lead Free Finish
TAPE AND REEL (MINI)
LT6108IDCB-1#TRMPBF
LT6108HDCB-1#TRMPBF
LT6108IDCB-2#TRMPBF
LT6108HDCB-2#TRMPBF
TAPE AND REEL
LT6108IDCB-1#TRPBF
LT6108HDCB-1#TRPBF
LT6108IDCB-2#TRPBF
LT6108HDCB-2#TRPBF
PART MARKING*
LFNF
LFNF
LFNH
LFNH
PACKAGE DESCRIPTION
8-Lead (2mm
×
3mm) Plastic DFN
8-Lead (2mm
×
3mm) Plastic DFN
8-Lead (2mm
×
3mm) Plastic DFN
SPECIFIED TEMPERATURE RANGE
–40°C to 85°C
–40°C to 125°C
–40°C to 85°C
–40°C to 125°C
8-Lead (2mm
×
3mm) Plastic DFN
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
610812fa
3
LT6108-1/LT6108-2
ELECTRICAL CHARACTERISTICS
SYMBOL
V
+
I
S
PARAMETER
Supply Voltage Range
Supply Current (Note 4)
V
+
= 2.7V, R
IN
= 1k, V
SENSE
= 5mV
V
+
= 60V, R
IN
= 1k, V
SENSE
= 5mV
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 12V, V
PULLUP
= V
+
, V
EN
= V
EN/RST
= 2.7V, R
IN
= 100Ω,
R
OUT
= R1 + R2 = 10k, gain = 100, R
C
= 25.5k, C
L
= C
LC
= 2pF unless otherwise noted. (See Figure 3)
,
CONDITIONS
l
MIN
2.7
TYP
450
550
3
MAX
60
650
950
5
7
11
13
UNITS
V
µA
µA
µA
µA
µA
µA
µA
nA
nA
V
Supply Current in Shutdown
V
+
= 2.7V, V
EN/RST
= 0V, R
IN
= 1k, V
SENSE
= 0.5V
l
V
+
= 60V, V
EN/RST
= 0V, R
IN
= 1k, V
SENSE
= 0.5V
l
7
–200
–100
l
l
l
l
EN/RST Pin Current
EN Pin Current
V
IH
V
IL
V
IH
V
IL
V
OS
EN/RST Pin Input High
EN/RST Pin Input Low
EN Pin Input High
EN Pin Input Low
Input Offset Voltage
V
EN/RST
= 0V, V
+
= 60V (LT6108-1 Only)
V
EN
= 0V, V
+
= 60V (LT6108-2 Only)
V
+
= 2.7V to 60V (LT6108-1 Only)
V
+
= 2.7V to 60V (LT6108-1 Only)
V
+
= 2.7V to 60V (LT6108-2 Only)
V
+
= 2.7V to 60V (LT6108-2 Only)
V
SENSE
= 5mV, LT6108A
V
SENSE
= 5mV, LT6108
V
SENSE
= 5mV, LT6108A
V
SENSE
= 5mV, LT6108
V
SENSE
= 5mV
V
+
= 2.7V to 60V
l
1.9
0.8
1.9
0.8
–125
–350
–250
–450
±0.8
60
±5
300
350
125
350
250
450
V
V
V
µV
µV
µV
µV
µV/°C
nA
nA
nA
mA
dB
dB
dB
dB
dB
mV
Current Sense Amplifier
l
l
l
∆V
OS
/∆T
I
B
I
OS
I
OUTA
PSRR
CMRR
Input Offset Voltage Drift
Input Bias Current
(SENSELO, SENSEHI)
Input Offset Current
Output Current (Note 5)
Power Supply Rejection Ratio
(Note 6)
Common Mode Rejection Ratio
V
+
= 2.7V to 60V
l
1
120
114
110
103
500
–0.08
127
125
125
V
+
= 2.7V to 60V
l
V
+
= 36V, V
SENSE
= 5mV, V
ICM
= 2.7V to 36V
V
+
= 60V, V
SENSE
= 5mV, V
ICM
= 27V to 60V
l
V
SENSE(MAX)
Full-Scale Input Sense Voltage
(Note 5)
Gain Error (Note 7)
R
IN
= 500Ω
V
+
= 2.7V to 12V
V
+
= 12V to 60V, V
SENSE
= 5mV to 100mV, MS8 Package
V
+
= 12V to 60V, V
SENSE
= 5mV to 100mV, DFN Package
V
+
= 2.7V, V
SENSE
= 100mV, R
OUT
= 2k
V
+
= 60V, V
SENSE
= 100mV
V
+
= 2.7V, V
SENSE
= 27mV
V
+
= 12V, V
SENSE
= 120mV
I
OUT
= 1mA
I
OUT
= 100µA
V
+
= 2.7V, V
SENSE
= 24mV Step, Output Rising Edge
V
+
= 12V to 60V, V
SENSE
= 100mV Step, Output Rising Edge
V
SENSE
= 10mV to 100mV, R
OUT
= 2k
l
l
l
l
l
l
l
–0.2
–0.3
2.5
27
0
0
%
%
%
V
V
SENSELO Voltage (Note 8)
Output Swing High (V
+
to V
OUTA
)
BW
t
r
t
SETTLE
Signal Bandwidth
Input Step Response (to 50% of
Final Output Voltage)
Settling Time to 1%
0.2
0.5
1
140
500
500
2
V
V
MHz
kHz
ns
ns
µs
610812fa
4
LT6108-1/LT6108-2
ELECTRICAL CHARACTERISTICS
SYMBOL
V
TH(R)
(Note 9)
V
HYS
V
OL
PARAMETER
Rising Input Threshold Voltage
V
HYS
= V
TH(R)
– V
TH(F)
Comparator Input Bias Current
Output Low Voltage
High to Low Propagation Delay
Output Fall Time
t
RESET
t
RPW
Reset Time
Valid
RST
Pulse Width
LT6108-1 Only
LT6108-1 Only
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 12V, V
PULLUP
= V
+
, V
EN
= V
EN/RST
= 2.7V, R
IN
= 100Ω,
R
OUT
= R1 + R2 = 10k, gain = 100, R
C
= 25.5k, C
L
= C
LC
= 2pF unless otherwise noted. (See Figure 3)
,
CONDITIONS
V
+
= 2.7V to 60V, LT6108A
V
+
= 2.7V to 60V, LT6108
V
+
= 2.7V to 60V
V
INC
= 0V, V
+
= 60V
I
OUTC
= 500µA, V
+
= 2.7V
l
l
l
l
MIN
395
392
3
–50
TYP
400
400
10
60
3
0.5
0.08
0.5
MAX
405
408
15
150
220
UNITS
mV
mV
mV
nA
mV
mV
µs
µs
µs
µs
Reference and Comparator
5mV Overdrive
100mV Overdrive
2
15
µs
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
reliability and lifetime.
Note 2:
Input and output pins have ESD diodes connected to ground. The
SENSEHI and SENSELO pins have additional current handling capability
specified as SENSEHI, SENSELO Input Current.
Note 3:
The LT6108I is guaranteed to meet specified performance from
–40°C to 85°C. LT6108H is guaranteed to meet specified performance
from –40°C to 125°C.
Note 4:
Supply current is specified with the comparator output high. When
the comparator output goes low the supply current will increase by 75µA
typically.
Note 5:
The full-scale input sense voltage and the maximum output
current must be considered to achieve the specified performance.
Note 6:
Supply voltage and input common mode voltage are varied while
amplifier input offset voltage is monitored.
Note 7:
The specified gain error does not include the effect of external
resistors R
IN
and R
OUT
. Although gain error is only guaranteed between
12V and 60V, similar performance is expected for V
+
< 12V, as well.
Note 8:
Refer to SENSELO, SENSEHI Range in the Applications
Information section for more information.
Note 9:
The input threshold voltage which causes the output voltage of the
comparator to transition from high to low is specified. The input voltage
which causes the comparator output to transition from low to high is
the magnitude of the difference between the specified threshold and the
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