Available in 14-Lead SO, 8-Lead MSOP and DFN
Packages
+
U
APPLICATIO S
■
Battery- or Solar-Powered Systems
Portable Instrumentation
Sensor Conditioning
■
Supply Current Sensing
■
Battery Monitoring
■
Micropower Active Filters
■
4mA to 20mA Transmitters
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Over-The-Top is a registered trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
LT1638/LT1639
1.2MHz, 0.4V/μs
Over-The-Top Micropower
Rail-to-Rail Input and Output
Op Amps
U
DESCRIPTIO
The LT®1638 is a low power dual rail-to-rail input and output
operational amplifier available in the standard 8-pin PDIP and
SO packages as well as the 8-lead MSOP package. The
LT1639 is a low power quad rail-to-rail input and output
operational amplifier offered in the standard 14-pin PDIP and
surface mount packages. For space limited applications the
LT1638 is available in a 3mm x 3mm x 0.8mm dual fine pitch
leadless package (DFN).
The LT1638/LT1639 op amps operate on all single and
split supplies with a total voltage of 2.5V to 44V drawing
only 170μA of quiescent current per amplifier. These
amplifiers are reverse battery protected and draw no
current for reverse supply up to 18V.
The input range of the LT1638/LT1639 includes both
supplies, and a unique feature of this device is its capability
to operate over the top with either or both of its inputs
above V+. The inputs handle 44V, both differential and
common mode, independent of supply voltage. The input
stage incorporates phase reversal protection to prevent
false outputs from occurring when the inputs are below
the negative supply. Protective resistors are included in
the input leads so that current does not become excessive
when the inputs are forced below the negative supply. The
LT1638/LT1639 can drive loads up to 25mA and still
maintain rail-to-rail capability. The op amps are unity-gain
stable and drive all capacitive loads up to 1000pF when
optional output compensation is used.
TYPICAL APPLICATIO
Over-The-Top® Comparator with
100mV Hysteresis Centered at 0mV
10k
V1
10k
V2
1M
V
CC
+
A
1/2 LT1638
–
1M
V
= 5V, VCM = 0V TO 44V, tPD = 27μs
CC
1M
U
Output Voltage vs Input Voltage
V
CC
V
1M
CC
+
B
1/2 LT1638
–
V0
1638/39 TA01
5V
0V
20mV/DIV
1638/39 TA02
16389fd
1
LT1638/LT1639
1
2
3
4
OUT A
–IN A
+IN A
V
–
8
7
6
5
V+
OUT B
–IN B
+IN B
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
A
B
TOP VIEW
S PACKAGE
14-LEAD PLASTIC SO
N PACKAGE
14-LEAD PDIP
1
2
3
4
5
6
7
14
13
12
11
10
9
8
A
B
C
OUT A
–IN A
+IN A
V
+
+IN B
–IN B
OUT B
OUT D
–IN D
+IN D
V
–
+IN C
– IN C
OUT C
D
WW
W
ABSOLUTE MAXIMUM RATINGS
U
(Note 1)
Total Supply Voltage (V+ to V–) .............................. 44V
Input Differential Voltage ......................................... 44V
Input Current ...................................................... ±25mA
Storage Temperature Range ................. –65°C to 150°C
DD Package ...................................... –65°C to 125°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER
PART NUMBER
TOP VIEW
1
OUT A
2
–IN A
+IN A
N8 PACKAGE
8-LEAD PDIP
A
3
–
4
V
T
= 150°C, θJA = 150°C/W (N8)
JMAX
= 150°C, θJA = 190°C/W (S8)
T
JMAX
+
8
V
7
OUT B
6
–IN B
B
5
+IN B
S8 PACKAGE
8-LEAD PLASTIC SO
LT1638CN8
LT1638IN8
LT1638CS8
LT1638IS8
LT1638HS8
S8 PART MARKING
1638
1638I
1638H
ORDER
PART NUMBER
TOP VIEW
LT1638CDD
+
8
V
OUT B
7
–IN B
6
B
+IN B
5
LT1638IDD
–IN A
+IN A
1OUT A
2
A
3
–
V
4
DD PART MARKING*
8-LEAD (3mm × 3mm) PLASTIC DFN
T
JMAX
UNDERSIDE METAL INTERNALLY CONNECTED TO V
DD PACKAGE
= 125°C, θJA = 160°C/W (NOTE 10)
–
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/
*The temperature grades are identified by a label on the shipping container.
2
LAAL
ORDER
PART NUMBER
LT1639CN
LT1639IN
LT1639CS
LT1639IS
LT1639HS
T
= 150°C, θJA = 130°C/W (N)
JMAX
= 150°C, θJA = 160°C/W (S)
T
JMAX
Consult LTC Marketing for parts specified with wider operating temperature ranges.
16389fd
LT1638/LT1639
ELECTRICAL CHARACTERISTICS
The ●denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C.
V
= 3V, 0V; VS = 5V, 0V; VCM = V
S
SYMBOLPARAMETERCONDITIONSMINTYPMAXUNITS
V
OS
Input Offset VoltageLT1638 N, S Packages200600μV
Input Offset Voltage DriftLT1638/LT1639 N, S Packages●26 μV/°C
(Note 9)LT1638MS8, LT1638DD●2.57μV/°C
I
OS
I
B
Input Offset Current●16nA
Input Bias Current●2050nA
Input Noise Voltage0.1Hz to 10Hz1μV
e
n
i
n
R
IN
C
IN
Input Noise Voltage Densityf = 1kHz20nV/√Hz
Input Noise Current Densityf = 1kHz0.3pA/√Hz
Input ResistanceDifferential12.5MΩ
Input Capacitance5pF
Input Voltage Range●044V
CMRRCommon Mode Rejection RatioV
A
VOL
V
OL
V
OH
I
SC
Large-Signal Voltage GainVS = 3V, VO = 500mV to 2.5V, RL = 10k2001500V/mV
Output Voltage Swing LowVS = 3V, No Load●38mV
Output Voltage Swing HighVS = 3V, No Load●2.942.98V
Short-Circuit Current (Note 2)VS = 3V, Short to GND1015mA
= half supply, unless otherwise noted. (Note 4)
OUT
0°C ≤ TA ≤ 70°C●850μV
–40°C ≤ T
≤ 85°C●950μV
A
LT1639 N, S Packages300700μV
0°C ≤ T
≤ 70°C●950μV
A
–40°C ≤ TA ≤ 85°C●1050μV
LT1638 MS8 Package350900μV
0°C ≤ TA ≤ 70°C●1150μV
–40°C ≤ T
≤ 85°C●1450μV
A
LT1638 DD Package4001100μV
0°C ≤ T
≤ 70°C●1350μV
A
–40°C ≤ TA ≤ 85°C●1450μV
VCM = 44V (Note 5)●2.5μA
VCM = 44V (Note 5)●830μA
V
= 0V0.1nA
S
Common Mode, VCM = 0V to 44V1.45.5MΩ
= 0V to VCC – 1V●8898dB
CM
V
= 0V to 44V (Note 8)●8088dB
CM
0°C ≤ TA ≤ 70°C●133V/mV
–40°C ≤ T
≤ 85°C●100V/mV
A
VS = 5V, VO = 500mV to 4.5V, RL = 10k4001500V/mV
0°C ≤ T
≤ 70°C●250V/mV
A
–40°C ≤ TA ≤ 85°C●200V/mV
VS = 3V, I
= 5mA●250450mV
SINK
VS = 5V, No Load●38mV
VS = 5V, I
VS = 3V, I
= 10mA●500700mV
SINK
= 5mA●2.252.40V
SOURCE
VS = 5V, No Load●4.944.98V
VS = 5V, I
VS = 3V, Short to V
= 10mA●3.84.0V
SOURCE
CC
VS = 5V, Short to GND1520mA
VS = 5V, Short to V
CC
LT1638C/LT1639C, LT1638I/LT1639I
P-P
1525mA
1525mA
16389fd
3
LT1638/LT1639
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C.
VS = 3V, 0V; VS = 5V, 0V; VCM = V
SYMBOLPARAMETERCONDITIONSMINTYPMAXUNITS
PSRRPower Supply Rejection RatioVS = 3V to 12.5V, V
The ● denotes the specifications which apply over the full operating temperature range of –40°C ≤ TA≤ 125°C, otherwise
specifications are at TA = 25°C. VS = ±15V, VCM = 0V, V
SYMBOLPARAMETERCONDITIONSMINTYPMAXUNITS
V
OS
I
OS
I
B
CMRRCommon Mode Rejection RatioV
A
VOL
V
O
PSRRPower Supply Rejection RatioVS = ±1.5V to ±22V●84dB
I
S
GBWGain Bandwidth Productf = 5kHz7501200kHz
SRSlew RateAV = –1, RL = ∞, VO = ±10V,0.2250.4V/μs
Note 1:
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: A heat sink may be required to keep the junction temperature
below absolute maximum. This depends on the power supply voltage
and how many amplifiers are shorted.
Note 3: The LT1638C/LT1639C and LT1638I/LT1639I are guaranteed
functional over the operating temperature range of –40°C to 85°C. The
LT1638H/LT1639H are guaranteed functional over the operating
temperature range of – 40°C to 125°C.
Note 4:
performance from 0°C to 70°C and are designed, characterized and
expected to meet specified performance from –40°C to 85°C but not
tested or QA sampled at these temperatures. The LT1638I/LT1639I are
guaranteed to meet specified performance from –40°C to 85°C. The
LT1638H/LT1639H are guaranteed to meet specified performance from
–40°C to 125°C.
The positive supply pin of the LT1638/LT1639 should be
bypassed with a small capacitor (typically 0.1μF) within an
inch of the pin. When driving heavy loads an additional
4.7μF electrolytic capacitor should be used. When using
split supplies, the same is true for the negative supply pin.
The LT1638/LT1639 are protected against reverse battery
voltages up to 18V. In the event a reverse battery condition
occurs, the supply current is less than 1nA.
The LT1638/LT1639 can be shut down by removing V+. In
this condition the input bias current is less than 0.1nA,
even if the inputs are 44V above the negative supply.
At temperatures greater than 70°C, when operating the
LT1638/LT1639 on total supplies of 10V or more, the
supply must not be brought up faster than 1V/μs. Increas-
ing the bypass capacitor and/or adding a small resistor in
series with the supply will limit the rise time.
Inputs
The LT1638/LT1639 have two input stages, NPN and PNP
(see the Simplified Schematic), resulting in three distinct
operating regions as shown in the Input Bias Current vs
Common Mode typical performance curve.
For input voltages about 0.8V or more below V+, the PNP
input stage is active and the input bias current is typically
–20nA. When the input common mode voltage is within
0.5V of the positive rail, the NPN stage is operating and the
input bias current is typically 40nA. Increases in temperature will cause the voltage at which operation switches
from the PNP input stage to the NPN input stage to move
towards V+. The input offset voltage of the NPN stage is
untrimmed and is typically 600μV.
A Schottky diode in the collector of each NPN transistor
allow the LT1638/LT1639 to operate over the top, with
either or both of its inputs above V+. At about 0.3V above
V+ the NPN input transistor is fully saturated and the input
bias current is typically 8μA at room temperature. The
input offset voltage is typically 2mV when operating above
V+. The LT1638/LT1639 will operate with its inputs 44V
above V– regardless of V+.
The inputs are protected against excursions of 2V below
V– by an internal 1k resistor in series with each input and
a diode from the input to the negative supply. If the inputs
can go more than 2V below V–, an additional external
resistor is required. A 10k resistor will protect the input
–
against excursions as much as 10V below V
. The input
stage of the LT1638/LT1639 incorporates phase reversal
protection to prevent the output from phase reversing for
inputs below V–. There are no clamping diodes between
the inputs and the maximum differential input voltage is
44V.
Output
The output of the LT1638/LT1639 can swing within 20mV
of the positive rail with no load, and within 3mV of the
negative rail with no load. When monitoring voltages
within 20mV of the positive rail or within 3mV of the
negative rail, gain should be taken to keep the output from
clipping. The LT1638/LT1639 are capable of sinking and
sourcing over 40mA on ±15V supplies; sourcing current
capability is reduced to 20mA at 5V total supplies as noted
in the electrical characteristics.
The LT1638/LT1639 are internally compensated to drive
at least 200pF of capacitance under any output loading
conditions. A 0.22μF capacitor in series with a 150Ω
resistor between the output and ground will compensate
these amplifiers for larger capacitive loads, up to 1000pF,
at all output currents.
Optional Output Compensation for
Capacitive Loads Greater than 200pF
V
+
IN
LT1638
–
0.22μF
150Ω
1000pF
Distortion
There are two main contributors of distortion in op amps:
output crossover distortion as the output transitions from
sourcing to sinking current and distortion caused by
16389fd
10
LT1638/LT1639
–
+
–
+
1/4 LT1639
–
+
1/4 LT1639
1/4 LT1639
D1D2
V
CC
C1
V
OUT
V
EE
V
IN
R5
100k
R6
100k
1638/39 F02
LT1634-1.2V
R3
100k
R4
100k
R2
R1
1k
D3
D4
LT1634-1.2V
FOR R2 = 50k, C1 = 500pF,
MAXIMUM SLOPE = 0.048V/μs
V
OUT
=
d
dt
1.2V
(R2)(C1)
D1 TO D4 = IN4148
U
WUU
APPLICATIONS INFORMATION
nonlinear common mode rejection. If the op amp is operating inverting there is no common mode induced distortion. If the op amp is operating in the PNP input stage
(input is not within 0.8V of V+), the CMRR is very good,
typically 98dB. When the LT1638 switches between input
stages there is significant nonlinearity in the CMRR. Lower
load resistance increases the output crossover distortion,
but has no effect on the input stage transition distortion.
For lowest distortion the LT1638/LT1639 should be operated single supply, with the output always sourcing
U
TYPICAL APPLICATIONS
With 1.2MHz bandwidth, Over-The-Top capability, reverse-battery protection and rail-to-rail input and output
features, the LT1638/LT1639 are ideal candidates for
general purpose applications.
The lowpass slope limiting filter in Figure 1 limits the
maximum dV/dT (not frequency) that it passes. When the
input signal differs from the output by one forward diode
drop, D1 or D2 will turn on. With a diode on, the voltage
across R2 will be constant and a fixed current, V
will flow through capacitor C1, charging it linearly instead
of exponentially. The maximum slope that the circuit will
pass is equal to V
divided by (R2)(C1). No matter
DIODE
how fast the input changes the output will never change
any faster than the dV/dT set by the diodes and (R2)(C).
DIODE
/R2,
current and with the input voltage swing between ground
and (V+ – 0.8V). See the Typical Performance Characteristics curves.
Gain
The open-loop gain is almost independent of load when
the output is sourcing current. This optimizes performance in single supply applications where the load is
returned to ground. The typical performance curve of
Open-Loop Gain for various loads shows the details.
d
V
OUT(MAX)
dt
FOR R1 = 10k, R2 = 100k, C1 = 1000pF
d
V
OUT(MAX)
dt
A modification of this application is shown in Figure 2
using references instead of diodes to set the maximum
slope. By using references, the slope is independent of
temperature. A scope photo shows a 1V
signal with a 2V pulse added to the sine wave; the circuit
passes the 2kHz signal but limits the slope of the pulse.
D1
D2
V
IN
V
D
=
(R2)(C1)
= 0.006V/μs
Figure 1. Lowpass Slope Limiting Filter
R2
R1
+
C1
1/2 LT1638
–
P-P
V
OUT
1638/39 F01
, 2kHz input
Response of Slope Limiting Filter
V
OUT
V
IN
1638/39 TA02
Figure 2. Lowpass Slope Limiting Filter with 0 TC
11
16389fd
LT1638/LT1639
U
TYPICAL APPLICATIONS
The application in Figure 3 utilizes the Over-The-Top
capabilities of the LT1638. The 0.2Ω resistor senses the
load current while the op amp and NPN transistor form a
closed loop making the collector current of Q1
propor
tional to the load current. As a convenient monitor,
the 2k load resistor converts the current into a voltage. The
positive supply rail, V
+
, is not limited to the 5V supply of
the op amp and could be as high as 44V.
+
V
200Ω
5V
0.2Ω
200Ω
LOAD
I
LOAD
+
1/2 LT1638
–
V
OUT
= (2Ω)(I
LOAD
Q1
2N3904
0V TO 4.3V
2k
1638/39 F03
)
Figure 3. Positive Supply Rail Current Sense
WW
SI PLIFIED SCHE ATIC
The Figure 4 application uses the LT1638 in conjunction
with the LT1634 micropower shunt reference. The supply
current of the op amp also biases the reference. The drop
across resistor R1 is fixed at 1.2V generating an output
current equal to 1.2V/R1.
V
CC
LT1634-1.2
+
1/2 LT1638
–
Figure 4. Current Source
V
CC
R1
I
OUT
1638/39 F04
I
OUT
1.2V
=
R1
Q1
R1
6k
Q4
+
10μA
Q5
ONE AMPLIFIER
–IN
+IN
+
Q22
Q21
OUT
1638/39 SS
V
–
V
16389fd
Q2
D2
D1
R2
1k
Q7
R3
1k
Q6
D4
D5
Q8
Q9
Q10
Q11 Q12
Q13Q14
R4
8k
R5
8k
Q15
Q3
D3
Q19
Q17Q20
Q16Q18
12
PACKAGE DESCRIPTION
0.675 ±0.05
U
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698)
LT1638/LT1639
R = 0.115
TYP
0.38 ± 0.10
85
3.5 ±0.05
1.65 ±0.05
(2 SIDES)2.15 ±0.05
PACKAGE
OUTLINE
0.25 ± 0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
2.38 ±0.05
(2 SIDES)
0.50
BSC
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON TOP AND BOTTOM OF PACKAGE
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660)
0.889 ± 0.127
(.035 ± .005)
5.23
(.206)
MIN
0.42 ± 0.038
(.0165 ± .0015)
TYP
RECOMMENDED SOLDER PAD LAYOUT
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
3.20 – 3.45
(.126 – .136)
0.65
(.0256)
BSC
GAUGE PLANE
0.18
(.007)
0.254
(.010)
DETAIL “A”
DETAIL “A”
0° – 6° TYP
0.53 ± 0.152
(.021 ± .006)
3.00 ±0.10
(4 SIDES)
0.75 ±0.05
SEATING
PLANE
1.65 ± 0.10
(2 SIDES)
0.00 – 0.05
3.00 ± 0.102
(.118 ± .004)
(NOTE 3)
4.90 ± 0.152
(.193 ± .006)
(.043)
0.22 – 0.38
(.009 – .015)
TYP
0.25 ± 0.05
BOTTOM VIEW—EXPOSED PAD
8
7
6
12
3
1.10
MAX
0.65
(.0256)
BSC
2.38 ±0.10
(2 SIDES)
5
4
14
0.50 BSC
0.52
(.0205)
REF
3.00 ± 0.102
(.118 ± .004)
(NOTE 4)
0.86
(.034)
REF
0.127 ± 0.076
(.005 ± .003)
MSOP (MS8) 0204
(DD) DFN 1203
16389fd
13
LT1638/LT1639
U
PACKAGE DESCRIPTION
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
.300 – .325
(7.620 – 8.255)
.065
(1.651)
.008 – .015
(0.203 – 0.381)
+.035
.325
–.015
+0.889
8.255
()
–0.381
NOTE:
1. DIMENSIONS ARE
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
INCHES
MILLIMETERS
TYP
.045 – .065
(1.143 – 1.651)
.100
(2.54)
BSC
N8 Package
(0.457 ± 0.076)
.130 ± .005
(3.302 ± 0.127)
.120
(3.048)
MIN
.018 ± .003
.020
(0.508)
MIN
N8 1002
.255 ± .015*
(6.477 ± 0.381)
.400*
(10.160)
MAX
87 6
12
3
5
4
NOTE:
1. DIMENSIONS IN
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE
MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL
NOT EXCEED .006" (0.15mm)
INCHES
(MILLIMETERS)
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.050 BSC
.245
MIN
.030
±
.005
TYP
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
(0.254 – 0.508)
.008 – .010
(0.203 – 0.254)
(0.406 – 1.270)
× 45°
.016 – .050
.045 ±.005
±
.005
.160
0°– 8° TYP
.228 – .244
(5.791 – 6.197)
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.189 – .197
(4.801 – 5.004)
8
1
NOTE 3
7
2
5
6
.150 – .157
(3.810 – 3.988)
NOTE 3
3
4
.004 – .010
(0.101 – 0.254)
.050
(1.270)
SO8 0303
BSC
14
16389fd
PACKAGE DESCRIPTION
U
N Package
14-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
14
.255 ± .015*
(6.477 ± 0.381)
1213
.770*
(19.558)
MAX
11
LT1638/LT1639
8910
(7.620 – 8.255)
(0.203 – 0.381)
8.255
()
NOTE:
1. DIMENSIONS ARE
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
.050 BSC
N
.245
MIN
123 N/2
.300 – .325
.008 – .015
+.035
.325
–.015
+0.889
–0.381
2
.130 ± .005
(3.302 ± 0.127)
.020
(0.508)
MIN
.005
(0.127)
MIN
INCHES
MILLIMETERS
.120
(3.048)
MIN
S Package
14-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.045 ±.005
.160 ±.005
.228 – .244
(5.791 – 6.197)
31
.045 – .065
(1.143 – 1.651)
.100
(2.54)
BSC
14
N
6
.337 – .344
NOTE 3
11
7
.065
(1.651)
TYP
.018 ± .003
(0.457 ± 0.076)
N14 1103
10
8
9
.150 – .157
(3.810 – 3.988)
N/2
NOTE 3
5
4
(8.560 – 8.738)
13
12
.030 ±.005
TYP
RECOMMENDED SOLDER PAD LAYOUT
NOTE:
1. DIMENSIONS IN
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE
MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS
SHALL NOT EXCEED .006" (0.15mm)
INCHES
(MILLIMETERS)
1
.010 – .020
(0.254 – 0.508)
.008 – .010
(0.203 – 0.254)
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.
× 45°
.016 – .050
(0.406 – 1.270)
.053 – .069
(1.346 – 1.752)
0° – 8° TYP
.014 – .019
(0.355 – 0.483)
TYP
3
2
4
.050
(1.270)
BSC
5
7
6
.004 – .010
(0.101 – 0.254)
S14 0502
16389fd
15
LT1638/LT1639
TYPICAL APPLICATION
U
The battery monitor in Figure 5 also demonstrates the
LT1638’s ability to operate with its inputs above the
positive rail. In this application, a conventional amplifier
would be limited to a battery voltage between 5V and
ground, but the LT1638 can handle battery voltages as
high as 44V. When the battery is charging, Amp B senses
the voltage drop across RS. The output of Amp B causes
Q2 to drain sufficient current through RB to balance the
input of Amp B. Likewise, Amp A and Q1 form a closed
CHARGER
VOLTAGE
RS, 0.2Ω
I
BATT
LOAD
I
= = AMPS
BATT
(RS)(RG/RA)(GAIN)
RA, 2k
+
A
2k
R
A
',
1/4 LT1639
–
RB, 2k
+
B
= 12V
V
OUT
GAIN
1/4 LT1639
–
R
2k
B
',
+
V
BATT
V
OUT
loop when the battery is discharging. The current through
Q1 or Q2 is proportional to the current in RS and this
current flows into R
D buffers and amplifies the voltage across R
and is converted into a voltage. Amp
G
. Amp C
G
compares the output of Amp A and Amp B to determine
the polarity of current through R
V
with S1 open is 1V/A. With S1 closed the scale factor
OUT
. The scale factor for
S
is 1V/100mA and currents as low as 500μA can be
measured.
Q1
2N3904
+
Q2
2N3904
R
G
10k
S1
S1 = OPEN, GAIN = 1
S1 = CLOSED, GAIN = 10
10k
C
1/4 LT1639
–
LOGIC HIGH (5V) = CHARGING
LOGIC LOW (0V) = DISCHARGING
+
D
1/4 LT1639
–
90.9k
= R
R
A
B
VS = 5V, 0V
1638/39 F05
LOGIC
V
OUT
Figure 5. Battery Monitor
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