LT1638/LT1639
1
16389fg
TYPICAL APPLICATION
DESCRIPTION
1.2MHz, 0.4V/µs
Over-The-Top Micropower
Rail-to-Rail Input and Output
Op Amps
The LT
®
1638 is a low p wer dual rail-to-rail input and output
operational amplifi er 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 amplifi er 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
fi ne 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 amplifi er. These ampli-
fi ers are reverse battery protected and draw no current
for reverse supply up to 18V.
The input range of the LT1638/LT1639 includes both sup-
plies, 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.
FEATURES
APPLICATIONS
n Operates with Inputs Above V+
n Rail-to-Rail Input and Output
n Low Power: 230μA per Amplifi er Max
n Gain Bandwidth Product: 1.2MHz
n Slew Rate: 0.4V/μs
n High Output Current: 25mA Min
n Specifi ed on 3V, 5V and ±15V Supplies
n Reverse Battery Protection to 18V
n No Supply Sequencing Problems
n High Voltage Gain: 1500V/mV
n Single Supply Input Range: –0.4V to 44V
n High CMRR: 98dB
n No Phase Reversal
n Available in 14-Lead SO, 8-Lead MSOP and DFN
Packages
n Battery- or Solar-Powered Systems
Portable Instrumentation
Sensor Conditioning
n Supply Current Sensing
n Battery Monitoring
n Micropower Active Filters
n 4mA to 20mA Transmitters
V
CC
V
CC
V1
V2
V0
–
+A
1/2 LT1638
–
+B
1/2 LT1638
V
CC
1M
1M
1M
10k
10k
V
CC
= 5V, V
CM
= 0V TO 44V, t
PD
= 27μs
1638/39 TA01
1M
Over-The-Top® Comparator with
100mV Hysteresis Centered at 0mV
Output Voltage vs Input Voltage
5V
0V
1638/39 TA02
20mV/DIV
L, LT, LTC, LTM, Over-The-Top, Linear Technology and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
LT1638/LT1639
2
16389fg
ABSOLUTE MAXIMUM RATINGS
Specifi ed Temperature Range (Note 4)
LT1638C/LT1639C ................................–40°C to 85°C
LT1638I/LT1639I ..................................–40°C to 85°C
LT1638H/LT1639H .............................–40°C to 125°C
Junction Temperature .......................................... 150°C
DD Package ...................................................... 125°C
Storage Temperature Range ...................–65°C to 150°C
DD Package .......................................–65°C to 125°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
Total Supply Voltage (V+ to V–) ................................44V
Input Differential Voltage...........................................44V
Input Current ........................................................±25mA
Output Short-Circuit Duration (Note 2) .........Continuous
Operating Temperature Range (Note 3)
LT1638C/LT1639C ................................–40°C to 85°C
LT1638I/LT1639I ..................................–40°C to 85°C
LT1638H/LT1639H .............................–40°C to 125°C
(Note 1)
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
TJMAX = 150°C, θJA = 273°C/W
1
2
3
4
8
7
6
5
TOP VIEW
N8 PACKAGE
8-LEAD PDIP
S8 PACKAGE
8-LEAD PLASTIC SO
V+
OUT B
–IN B
+IN B
A
B
OUT A
–IN A
+IN A
V–
TJMAX = 150°C, θJA = 150°C/W (N8)
TJMAX = 150°C, θJA = 190°C/W (S8)
TOP VIEW
DD PACKAGE
8-LEAD (3mm s 3mm) PLASTIC DFN
5
6
7
8
4
3
2
1OUT A
–IN A
+IN A
V
–
V
+
OUT B
–IN B
+IN B
A
B
TJMAX = 125°C, θJA = 43°C/W
UNDERSIDE METAL INTERNALLY CONNECTED TO V–
1
2
3
4
5
6
7
14
13
12
11
10
9
8
TOP VIEW
N PACKAGE
14-LEAD PDIP
S PACKAGE
14-LEAD PLASTIC SO
OUT D
–IN D
+IN D
V
–
+IN C
–IN C
OUT C
AD
BC
OUT A
–IN A
+IN A
V
+
+IN B
–IN B
OUT B
TJMAX = 150°C, θJA = 130°C/W (N)
TJMAX = 150°C, θJA = 160°C/W (S)
PIN CONFIGURATION
LT1638/LT1639
3
16389fg
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE
LT1638CMS8#PBF LT1638CMS8#TRPBF LTCY 8-Lead Plastic MSOP –40°C to 85°C
LT1638IMS8#PBF LT1638IMS8#TRPBF LTCY 8-Lead Plastic MSOP –40°C to 85°C
LT1638CDD#PBF LT1638CDD#TRPBF LAAL 8-Lead (3mm × 3mm) Plastic DFN –40°C to 85°C
LT1638IDD#PBF LT1638IDD#TRPBF LAAL 8-Lead (3mm × 3mm) Plastic DFN –40°C to 85°C
LT1638CN8#PBF LT1638CN8#TRPBF LT1638CN8 8-Lead PDIP –40°C to 85°C
LT1638IN8#PBF LT1638IN8#TRPBF LT1638IN8 8-Lead PDIP –40°C to 85°C
LT1638CS8#PBF LT1638CS8#TRPBF 1638 8-Lead Plastic SO –40°C to 85°C
LT1638IS8#PBF LT1638IS8#TRPBF 1638I 8-Lead Plastic SO –40°C to 85°C
LT1638HS8#PBF LT1638HS8#TRPBF 1638H 8-Lead Plastic SO –40°C to 125°C
LT1639CN#PBF LT1639CN#TRPBF LT1639CN 14-Lead PDIP –40°C to 85°C
LT1639IN#PBF LT1639IN#TRPBF LT1639IN 14-Lead PDIP –40°C to 85°C
LT1639CS#PBF LT1639CS#TRPBF LT1639CS 14-Lead Plastic SO –40°C to 85°C
LT1639IS#PBF LT1639IS#TRPBF LT1639IS 14-Lead Plastic SO –40°C to 85°C
LT1639HS#PBF LT1639HS#TRPBF LT1639HS 14-Lead Plastic SO –40°C to 125°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based fi nish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifi
cations, go to: http://www.linear.com/tapeandreel/
LT1638/LT1639
4
16389fg
ELECTRICAL CHARACTERISTICS
LT1638C/LT1639C, LT1638I/LT1639I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VOS Input Offset Voltage LT1638 N, S Packages
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
200 600
850
950
μV
μV
μV
LT1639 N, S Packages
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
300 700
950
1050
μV
μV
μV
LT1638 MS8 Package
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
350 900
1150
1450
μV
μV
μV
LT1638 DD Package
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
400 1100
1350
1450
μV
μV
μV
Input Offset Voltage Drift
(Note 9) LT1638/LT1639 N, S Packages
LT1638MS8, LT1638DD
l
l
2
2.5 6
7μV/°C
μV/°C
IOS Input Offset Current VCM = 44V (Note 5)
l
l
16
2.5 nA
μA
IBInput Bias Current VCM = 44V (Note 5)
VS = 0V
l
l
20
8
0.1
50
30 nA
μA
nA
Input Noise Voltage 0.1Hz to 10Hz 1 μVP-P
enInput Noise Voltage Density f = 1kHz 20 nV/√Hz
inInput Noise Current Density f = 1kHz 0.3 pA/√Hz
RIN Input Resistance Differential
Common Mode, VCM = 0V to 44V 1
1.4 2.5
5.5 MΩ
MΩ
CIN Input Capacitance 5pF
Input Voltage Range l044V
CMRR Common Mode Rejection Ratio VCM = 0V to VCC – 1V
VCM = 0V to 44V (Note 8)
l
l
88
80 98
88 dB
dB
AVOL Large-Signal Voltage Gain VS = 3V, VO = 500mV to 2.5V, RL = 10k
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
200
133
100
1500 V/mV
V/mV
V/mV
VS = 5V, VO = 500mV to 4.5V, RL = 10k
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
400
250
200
1500 V/mV
V/mV
V/mV
VOL Output Voltage Swing Low VS = 3V, No Load
VS = 3V, ISINK = 5mA
l
l
3
250 8
450 mV
mV
VS = 5V, No Load
VS = 5V, ISINK = 10mA
l
l
3
500 8
700 mV
mV
VOH Output Voltage Swing High VS = 3V, No Load
VS = 3V, ISOURCE = 5mA
l
l
2.94
2.25 2.98
2.40 V
V
VS = 5V, No Load
VS = 5V, ISOURCE = 10mA
l
l
4.94
3.8 4.98
4.0 V
V
ISC Short-Circuit Current (Note 2) VS = 3V, Short to GND
VS = 3V, Short to VCC
10
15 15
25 mA
mA
VS = 5V, Short to GND
VS = 5V, Short to VCC
15
15 20
25 mA
mA
The l denotes the specifi cations which apply over the specifi ed temperature range, otherwise specifi cations are at TA = 25°C.
VS = 3V, 0V; VS = 5V, 0V; VCM = VOUT = half supply, unless otherwise noted. (Note 4)
LT1638/LT1639
5
16389fg
LT1638C/LT1639C, LT1638I/LT1639I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
PSRR Power Supply Rejection Ratio VS = 3V to 12.5V, VCM = VO = 1V l90 100 dB
Reverse Supply Voltage IS = –100μA per Amplifi er l18 27 V
Minimum Operating Supply Voltage l2.4 2.7 V
ISSupply Current per Amplifi er
(Note 6) l
170 230
275 μA
μA
GBW Gain Bandwidth Product
(Note 5) f = 5kHz
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
650
550
500
1075 kHz
kHz
kHz
SR Slew Rate
(Note 7) AV = –1, RL = ∞
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
0.210
0.185
0.170
0.38 V/μs
V/μs
V/μs
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the specifi ed temperature range, otherwise specifi cations are at TA = 25°C.
VS = 3V, 0V; VS = 5V, 0V; VCM = VOUT = half supply, unless otherwise noted. (Note 4)
The l denotes the specifi cations which apply over the specifi ed temperature range, otherwise specifi cations are at TA = 25°C.
VS = ±15V, VCM = 0V, VOUT = 0V, unless otherwise noted. (Note 4)
LT1638C/LT1639C, LT1638I/LT1639I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VOS Input Offset Voltage LT1638 N, S Packages
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
250 800
1000
1100
μV
μV
μV
LT1639 N, S Packages
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
350 900
1100
1200
μV
μV
μV
LT1638 MS8 Package
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
400 1050
1250
1550
μV
μV
μV
LT1638 DDPackage
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
450 1250
1450
1550
μV
μV
μV
Input Offset Voltage Drift
(Note 9) LT1638/LT1639 N, S Packages
LT1638MS8, LT1638DD
l
l
2
2.5 6
7μV/°C
μV/°C
IOS Input Offset Current l16nA
IBInput Bias Current l20 50 nA
Input Noise Voltage 0.1Hz to 10Hz 1 μVP-P
enInput Noise Voltage Density f = 1kHz 20 nV/√Hz
inInput Noise Current Density f = 1kHz 0.3 pA/√Hz
RIN Input Resistance Differential
Common Mode, VCM = –15V to 14V 1 2.5
500 MΩ
MΩ
CIN Input Capacitance 4.5 pF
Input Voltage Range l–15 29 V
CMRR Common Mode Rejection Ratio VCM = –15V to 29V l80 88 dB
AVOL Large-Signal Voltage Gain VO = ±14V, RL = 10k
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
200
125
100
500 V/mV
V/mV
V/mV
VOOutput Voltage Swing No Load
IOUT = ±10mA
l
l
±14.9
±13.7 ±14.95
±14.0 V
V
LT1638/LT1639
6
16389fg
LT1638C/LT1639C, LT1638I/LT1639I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
ISC Short-Circuit Current (Note 2) Short to GND
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
25
20
15
40 mA
mA
mA
PSRR Power Supply Rejection Ratio VS = ± 1.5V to ±22V l90 100 dB
ISSupply Current per Amplifi er
l
205 280
350 μA
μA
GBW Gain Bandwidth Product f = 5kHz
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
750
650
600
1200 kHz
kHz
kHz
SR Slew Rate AV = –1, RL = ∞, VO = ±10V
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
0.225
0.2
0.18
0.4 V/μs
V/μs
V/μs
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the specifi ed temperature
range, otherwise specifi cations are at TA = 25°C. VS = ±15V, VCM = OV, VOUT = OV, unless otherwise noted. (Note 4)
The l denotes the specifi cations which apply over the full operating temperature range of –40°C ≤ TA ≤ 125°C.
VS = 3V, 0V; VS = 5V, 0V; VCM = VOUT = Half Supply unless otherwise specifi ed. (Note 4)
LT1638H/LT1639H
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VOS Input Offset Voltage LT1638S8
l
200 650
3μV
mV
LT1639S
l
300 750
3.2 μV
mV
Input Offset Voltage Drift (Note 9) l15 μV/°C
IOS Input Offset Current VCM = 44V (Note 5)
l
l
15
10 nA
μA
IBInput Bias Current VCM = 44V (Note 5)
l
l
150
100 nA
μA
Input Voltage Range l0.3 44 V
CMRR Common Mode Rejection Ratio VCM = 0.3V to VCC – 1V
VCM = 0.3V to 44V
l
l
76
72 dB
dB
AVOL Large-Signal Voltage Gain VS = 3V, VO = 500mV to 2.5V, RL = 10k
l
200
20 1500 V/mV
V/mV
VS = 5V, VO = 500mV to 4.5V, RL = 10k
l
400
35 1500 V/mV
V/mV
VOL Output Voltage Swing Low No Load
ISINK = 5mA
VS = 5V, ISINK = 10mA
l
l
l
15
900
1500
mV
mV
mV
VOH Output Voltage Swing High VS = 3V, No Load
VS = 3V, ISOURCE = 5mA
l
l
2.9
2V
V
VS = 5V, No Load
VS = 5V, ISOURCE = 10mA
l
l
4.9
3.5 V
V
PSRR Power Supply Rejection Ratio VS = 3V to 12.5V, VCM = VO = 1V l80 dB
Minimum Supply Voltage l2.7 V
Reverse Supply Voltage IS = –100μA l18 V
ISSupply Current
(Note 6) l
170 230
450 μA
μA
GBW Gain Bandwidth Product
(Note 5) f = 5kHz
l
650
350 1075 kHz
kHz
SR Slew Rate
(Note 7) AV = –1, RL = ∞
l
0.21
0.1 0.38 V/μs
V/μs
LT1638/LT1639
7
16389fg
ELECTRICAL CHARACTERISTICS
LT1638H/LT1639H
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VOS Input Offset Voltage LT1638S8
l
250 850
3.4
μV
mV
LT1639S
l
350 950
3.6
μV
mV
Input Offset Voltage Drift (Note 9) l15 μV/°C
IOS Input Offset Current l25 nA
IBInput Bias Current l250 nA
CMRR Common Mode Rejection Ratio VCM = –14.7V to 29V l72 dB
AVOL Large-Signal Voltage Gain VO = ±14V, RL = 10k
l
200
15
500 V/mV
V/mV
VOOutput Voltage Swing No Load
IOUT = ± 5mA
IOUT = ±10mA
l
l
l
±14.8
±14
±13.4
V
V
V
PSRR Power Supply Rejection Ratio VS = ±1.5V to ±22V l84 dB
Minimum Supply Voltage l±1.35 V
ISSupply Current
l
205 280
550
μA
μA
GBW Gain Bandwidth Product f = 5kHz
l
750
400
1200 kHz
kHz
SR Slew Rate AV = –1, RL = ∞, VO = ±10V,
Measured at VO = ±5V l
0.225
0.1
0.4 V/μs
V/μs
tested or QA sampled at these temperatures. The LT1638I/LT1639I are
guaranteed to meet specifi ed performance from –40°C to 85°C. The
LT1638H/LT1639H are guaranteed to meet specifi ed performance from
–40°C to 125°C.
Note 5:
VS = 5V limits are guaranteed by correlation to VS = 3V and
VS = ±15V or VS = ±22V tests.
Note 6:
VS = 3V limits are guaranteed by correlation to VS = 5V and
VS = ±15V or VS = ±22V tests.
Note 7:
Guaranteed by correlation to slew rate at VS = ±15V, and GBW at
VS = 3V and VS = ±15V tests.
Note 8:
This specifi cation implies a typical input offset voltage of 2mV at
VCM = 44V and a maximum input offset voltage of 5mV at VCM = 44V.
Note 9:
This parameter is not 100% tested.
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:
A heat sink may be required to keep the junction temperature
below absolute maximum. This depends on the power supply voltage
and how many amplifi ers 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:
The LT1638C/LT1639C are guaranteed to meet specifi ed
performance from 0°C to 70°C and are designed, characterized and
expected to meet specifi ed performance from –40°C to 85°C but not
The l denotes the specifi cations which apply over the full operating temperature range of – 40°C ≤ TA ≤ 125°C, otherwise
specifi cations are at TA = 25°C. VS = ±15V, VCM = 0V, VOUT = 0V, VSHDN = V– unless otherwise specifi ed. (Note 4)
LT1638/LT1639
8
16389fg
TYPICAL PERFORMANCE CHARACTERISTICS
Minimum Supply Voltage
Input Bias Current vs
Common Mode Voltage
Output Saturation Voltage vs
Load Current (Output High)
0.1Hz to 10Hz Noise Voltage
Noise Voltage Density vs
Frequency
SUPPLY VOLTAGE (V)
0
SUPPLY CURRENT PER AMPLIFIER (μA)
10 20 25 45
1638/39 G01
300
280
260
240
220
200
180
160
140
120
100 515 30 35 40
TA = 125°C
TA = 25°C
TA = –55°C
Supply Current vs Supply Voltage
TOTAL SUPPLY VOLTAGE (V)
0
CHANGE IN INPUT OFFSET VOLTAGE (μV)
200
400
4
1638/39 G02
0
–200
100
300
–100
–300
–400 1235
T
A
=
125°C T
A
=
–55°C
T
A
=
25°C
COMMON MODE VOLTAGE (V)
4.0
INPUT BIAS CURRENT (nA)
10000
8000
6000
60
40
20
0
–20
–40 5.6
1638/39 G03
4.4 4.8 5.2 44
T
A
=
125°C
T
A
=
–55°C
T
A
=
25°C
V
S
= 5V, 0V
FREQUENCY (Hz)
1
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
010 100 1k
1638/39 G08
INPUT NOISE CURRENT DENSITY (pA/√Hz)
TIME (SEC)
013579
NOISE VOLTAGE (400nV/DIV)
2468
1638/39 G07
10
VS = p2.5
FREQUENCY (Hz)
1
INPUT NOISE VOLTAGE DENSITY (nV/√Hz)
10 100 1k
1638/39 G09
70
60
50
40
30
20
10
0
SOURCING LOAD CURRENT (mA)
0.001
0.01
OUTPUT SATURATION VOLTAGE (V)
0.1
1
0.01 0.1 1 10
1638/39 G04
VS = ±2.5V
VOD = 30mV
TA = 125°C
TA = –55°C
TA = 25°C
SINKING LOAD CURRENT (mA)
0.001
0.001
OUTPUT SATURATION VOLTAGE (V)
0.1
0.01
1
0.01 0.1 1 10
1638/39 G05
VS = ±2.5V
VOD = 30mV
TA = 125°C
TA = –55°C
TA = 25°C
INPUT OVERDRIVE (mV)
10
OUTPUT SATURATION VOLTAGE (mV)
30
100
1638/39 G06
1
10
20 100
90
807060
50
40
0
VS = ±2.5V
NO LOAD
OUTPUT HIGH
OUTPUT LOW
Output Saturation Voltage vs
Input Overdrive
Output Saturation Voltage vs
Load Current (Output Low)
Input Noise Current Density
vs Frequency
LT1638/LT1639
9
16389fg
FREQUENCY (kHz)
OUTPUT IMPEDANCE (Ω)
10k
1k
100
10
1
0.10.1 10 100 1000
1638/39 G20
1
AV = 1
AV = 100
AV = 10
VS = ±2.5V
TYPICAL PERFORMANCE CHARACTERISTICS
PSRR vs Frequency
Output Impedance vs Frequency
Gain and Phase Shift vs
Frequency
FREQUENCY (kHz)
1
10
GAIN (dB)
PHASE SHIFT (DEG)
20
30
40
50
10 100 1000
1638/39 G12
0
–10
–20
80
60
70
40
50
60
70
80
30
20
10
0
90
100
V
S
= ±2.5V
PHASE
GAIN
FREQUENCY (kHz)
POWER SUPPLY REJECTION RATIO (dB)
90
80
70
60
50
40
30
20
10
0
–10 1 10 100 1000
1638/39 G16
VS = ±2.5V
POSITIVE SUPPLY
NEGATIVE SUPPLY
TEMPERATURE (°C)
–50
SLEW RATE (V/μs)
050 75
1638/39 G14
–25 25 100 125
RISING, VS = ±15V
RISING, VS = ±2.5V
FALLING, VS = ±2.5V
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0.25
FALLING, VS = ±15V
Slew Rate vs Temperature
Gain Bandwidth Product and
Phase Margin vs Supply Voltage
TOTAL SUPPLY VOLTAGE (V)
0
1000
GAIN BANDWIDTH PRODUCT (kHz)
1200
1500
10 20 25 45
1638/39 G15
1100
1400
1300
PHASE MARGIN (DEG)
10
30
60
20
50
40
515 30 35 40
PHASE MARGIN
GAIN BANDWIDTH
Gain Bandwidth Product and
Phase Margin vs Load Resistance
FREQUENCY (kHz)
COMMON MODE REJECTION RATIO (dB)
120
110
100
90
80
70
60
50
40
30
20 1 10 100 1000
1638/39 G18
VS = ±15V
CMRR vs Frequency
FREQUENCY (kHz)
0.1
CHANNEL SEPARATION (dB)
130
120
110
100
90
80
70
60 1 10 100
1638/39 G19
V
S
= ±15V
Channel Separation vs Frequency
TEMPERATURE (°C)
–50
GAIN BANDWIDTH PRODUCT (kHz)
1500
1400
1300
1200
1100
1000
900
800
050 75
1638/39 G13
–25 25 100 125
VS = ±15V
VS = ±2.5V
f = 1kHz
Gain Bandwidth Product vs
Temperature
LT1638/LT1639
10
16389fg
OUTPUT VOLTAGE (5V/DIV)
CHANGE IN INPUT OFFSET VOLTAGE (50μV/DIV)
1638/39 G27
–10V–20V 0V 10V 20V
R
L
=
2k
V
S
=
±15V
R
L
=
10k
R
L
=
50k
Settling Time to 0.1% vs
Output Step
Capacitive Load Handling,
Overshoot vs Capacitive Load
SETTLING TIME (μs)
0
–10
OUTPUT STEP (V)
–8
–4
–2
0
10
4
10 20 25
1638/39 G21
–6
6
8
2
515 30 35
AV = –1
AV = –1
AV = 1
AV = 1
VS = ±15V
Undistorted Output Swing
vs Frequency
Total Harmonic Distortion + Noise
vs Frequency
Total Harmonic Distortion + Noise
vs Load Resistance
Total Harmonic Distortion + Noise
vs Output Voltage
Open-Loop Gain Large-Signal Response Small-Signal Response
1638/39 G28 1638/39 G29
VS = ±15V
AV = 1
VS = ±15V
AV = 1
CL = 15pF
CAPACITIVE LOAD (pF)
OVERSHOOT (%)
100
90
80
70
60
50
40
30
20
10
010 100 1000 10000
1638/39 G22
AV = 1
AV = 5
AV = 10
VS = 5V, 0V
VCM = 2.5V
ISOURCE = 150μA
FREQUENCY (kHz)
0.1
OUTPUT SWING (VP-P)
1 10 100
1638/39 G23
35
30
25
20
15
10
5
0
DISTORTION ≤ 1%
RL = 20k
VS = ±2.5V
VS = ±15V
FREQUENCY (kHz)
THD + NOISE (%)
0.01 1 10 100
1638/39 G24
0.1
10
1
0.1
0.01
0.001
VS = 3V, 0V
VOUT = 2VP-P
VCM = 1.2V
RL = 20k
AV = –1
AV = 1
LOAD RESISTANCE TO GROUND (kΩ)
0.01
THD + NOISE (%)
0.1
1
10
0.1 10 100
1638/39 G25
0.001 1
VS = 3V TOTAL
AV = 1
VIN = 2VP-P AT 1kHz
VS = ±1.5V
VIN = ±1V
VS = 3V, 0V
VIN = 0.5V TO 2.5V
VS = 3V, 0V
VIN = 0.2V TO 2.2V
OUTPUT VOLTAGE (VP-P)
THD + NOISE (%)
10
1
0.1
0.01
0.001 023
1638/39 G26
1
RL = 10k, f = 1kHz
VCM = HALF SUPPLY
AV = –1, VS = ±1.5V
AV = –1, VS = 3V, 0V
AV = 1, VS = ±1.5V
AV = 1, VS = 3V, 0V
TYPICAL PERFORMANCE CHARACTERISTICS
LT1638/LT1639
11
16389fg
APPLICATIONS INFORMATION
Supply Voltage
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.
When operating the LT1638/LT1639 on total supplies of
10V or more, the supply must not be brought up faster
than 1V/μs. Increasing the bypass capacitor and/or add-
ing 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 Simplifi ed 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 tem-
perature 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 amplifi ers for larger capacitive loads, up to 1000pF,
at all output currents.
Optional Output Compensation for
Capacitive Loads Greater than 200pF
–
+
LT1638
V
IN
1000pF
0.22μF
150Ω
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
LT1638/LT1639
12
16389fg
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 signifi cant 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
current and with the input voltage swing between ground
and (V+ – 0.8V). See the Typical Performance Character-
istics curves.
Gain
The open-loop gain is almost independent of load when
the output is sourcing current. This optimizes perfor-
mance 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.
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 fi lter 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 fi xed current, VDIODE/R2,
will fl ow through capacitor C1, charging it linearly instead
of exponentially. The maximum slope that the circuit will
pass is equal to VDIODE divided by (R2)(C1). No matter
how fast the input changes the output will never change
any faster than the dV/dT set by the diodes and (R2)(C).
Figure 1. Lowpass Slope Limiting Filter
–
+
1/2 LT1638
C1 VOUT
1638/39 F01
R2
D2
D1
R1
VIN
FOR R1 = 10k, R2 = 100k, C1 = 1000pF
VOUT(MAX) =
d
dt
VD
(R2)(C1)
VOUT(MAX) = 0.006V/μs
d
dt
A modifi cation 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 1VP-P, 2kHz input signal with a 2V
pulse added to the sine wave; the circuit passes the 2kHz
signal but limits the slope of the pulse.
VOUT
VIN
Response of Slope Limiting Filter
Figure 2. Lowpass Slope Limiting Filter with 0 TC
1638/39 TA02
–
+
–
+
1/4 LT1639
–
+
1/4 LT1639
1/4 LT1639
D1 D2
VCC
C1
VOUT
VEE
VIN
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
VOUT =
d
dt
1.2V
(R2)(C1)
D1 TO D4 = IN4148
LT1638/LT1639
13
16389fg
SIMPLIFIED SCHEMATIC
TYPICAL APPLICATIONS
–
+
1/2 LT1638
5V
V
+
200Ω
200Ω
0.2Ω
2k
0V TO 4.3V
1638/39 F03
V
OUT
= (2Ω)(I
LOAD
)
Q1
2N3904
LOAD I
LOAD
Figure 4. Current Source
Figure 3. Positive Supply Rail Current Sense
–
+
1/2 LT1638
R1
1.2V
R1
IOUT =
LT1634-1.2
IOUT
1638/39 F04
VCC VCC
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.
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 fi xed at 1.2V generating an output
current equal to 1.2V/R1.
Q10
D5
Q9
Q1
Q7
R2
1k
R3
1k
R4
8k
Q8
Q5
–IN
+IN
Q11 Q12
D4
ONE AMPLIFIER
D2
Q2
D1
Q6
Q13 Q14
R1
6k
R5
8k
Q4
10μA
+
Q15
Q19
D3
Q3
Q16 Q18
Q22
V
+
Q17 Q20
Q21
OUT
V
–
1638/39 SS
LT1638/LT1639
14
16389fg
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
PACKAGE DESCRIPTION
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698 Rev C)
3.00 p0.10
(4 SIDES)
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
0.40 p 0.10
BOTTOM VIEW—EXPOSED PAD
1.65 p 0.10
(2 SIDES)
0.75 p0.05
R = 0.125
TYP
2.38 p0.10
14
85
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
0.00 – 0.05
(DD8) DFN 0509 REV C
0.25 p 0.05
2.38 p0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
1.65 p0.05
(2 SIDES)2.10 p0.05
0.50
BSC
0.70 p0.05
3.5 p0.05
PACKAGE
OUTLINE
0.25 p 0.05
0.50 BSC
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660 Rev F)
MSOP (MS8) 0307 REV F
0.53 p 0.152
(.021 p .006)
SEATING
PLANE
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
0.18
(.007)
0.254
(.010)
1.10
(.043)
MAX
0.22 – 0.38
(.009 – .015)
TYP
0.1016 p 0.0508
(.004 p .002)
0.86
(.034)
REF
0.65
(.0256)
BSC
0o – 6o TYP
DETAIL “A”
DETAIL “A”
GAUGE PLANE
12
34
4.90 p 0.152
(.193 p .006)
8765
3.00 p 0.102
(.118 p .004)
(NOTE 3)
3.00 p 0.102
(.118 p .004)
(NOTE 4)
0.52
(.0205)
REF
5.23
(.206)
MIN
3.20 – 3.45
(.126 – .136)
0.889 p 0.127
(.035 p .005)
RECOMMENDED SOLDER PAD LAYOUT
0.42 p 0.038
(.0165 p .0015)
TYP
0.65
(.0256)
BSC
LT1638/LT1639
15
16389fg
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
N8 1002
.065
(1.651)
TYP
.045 – .065
(1.143 – 1.651)
.130 ± .005
(3.302 ± 0.127)
.020
(0.508)
MIN
.018 ± .003
(0.457 ± 0.076)
.120
(3.048)
MIN
12 34
87 65
.255 ± .015*
(6.477 ± 0.381)
.400*
(10.160)
MAX
.008 – .015
(0.203 – 0.381)
.300 – .325
(7.620 – 8.255)
.325 +.035
–.015
+0.889
–0.381
8.255
()
NOTE:
1. DIMENSIONS ARE INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
.100
(2.54)
BSC
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)s 45o
0o– 8o TYP
.008 – .010
(0.203 – 0.254)
SO8 0303
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
1234
.150 – .157
(3.810 – 3.988)
NOTE 3
8765
.189 – .197
(4.801 – 5.004)
NOTE 3
.228 – .244
(5.791 – 6.197)
.245
MIN .160 p.005
RECOMMENDED SOLDER PAD LAYOUT
.045 p.005
.050 BSC
.030 p.005
TYP
INCHES
(MILLIMETERS)
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)
LT1638/LT1639
16
16389fg
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
PACKAGE DESCRIPTION
1
N
234
.150 – .157
(3.810 – 3.988)
NOTE 3
14 13
.337 – .344
(8.560 – 8.738)
NOTE 3
.228 – .244
(5.791 – 6.197)
12 11 10 9
567
N/2
8
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)s 45°
0° – 8° TYP
.008 – .010
(0.203 – 0.254)
S14 0502
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
.245
MIN
N
1 2 3 N/2
.160 ±.005
RECOMMENDED SOLDER PAD LAYOUT
.045 ±.005
.050 BSC
.030 ±.005
TYP
INCHES
(MILLIMETERS)
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)
S Package
14-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
N Package
14-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
N14 1103
.020
(0.508)
MIN
.120
(3.048)
MIN
.130 ± .005
(3.302 ± 0.127)
.045 – .065
(1.143 – 1.651)
.065
(1.651)
TYP
.018 ± .003
(0.457 ± 0.076)
.005
(0.127)
MIN
.255 ± .015*
(6.477 ± 0.381)
.770*
(19.558)
MAX
31 24567
8910
11
1213
14
.008 – .015
(0.203 – 0.381)
.300 – .325
(7.620 – 8.255)
.325 +.035
–.015
+0.889
–0.381
8.255
()
NOTE:
1. DIMENSIONS ARE INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
.100
(2.54)
BSC
LT1638/LT1639
17
16389fg
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
REVISION HISTORY
REV DATE DESCRIPTION PAGE NUMBER
E 06/10 Updates to Supply Voltage section 11
F 09/10 Units on x-axis of G24 changed from Hz to kHz 10
G 10/11 Updated θJA values for MS8 and DD packages in Pin Confi guration
Corrected part numbers and revised column title to Specifi ed Temperature Range in Order Information
Deleted Note 10 from Electrical Characteristics
2
3
7
(Revision history begins at Rev E)
LT1638/LT1639
18
16389fg
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 1998
LT 1011 REV G • PRINTED IN USA
RELATED PARTS
TYPICAL APPLICATION
PART NUMBER DESCRIPTION COMMENTS
LT1078/LT1079
LT2078/LT2079
Dual/Quad 55μA Max, Single Supply, Precision Op Amps Input/Output Common Mode Includes Ground, 70μV VOS(MAX)
and 2.5μV/°C Drift (Max), 200kHz GBW, 0.07V/μs Slew Rate
LT1178/LT1179
LT2178/LT2179
Dual/Quad 17μA Max, Single Supply, Precison Op Amps Input/Output Common Mode Includes Ground, 70μV VOS(MAX)
and 4μV/°C Drift (Max), 85kHz GBW, 0.04V/μs Slew Rate
LT1366/LT1367 Dual/Quad Precision, Rail-to-Rail Input and Output Op Amps 475μV VOS(MAX), 500V/mV AVOL(MIN), 400kHz GBW
LT1490/LT1491 Dual/Quad Over-The-Top Micropower, Rail-to-Rail Input and
Output Op Amps
Single Supply Input Range: –0.4V to 44V, Micropower 50μA
per Amplifi er, Rail-to-Rail Input and Output, 200kHz GBW
LT1636 Single Over-The-Top Micropower Rail-to-Rail Input and Output
Op Amp
55μA Supply Current, VCM Extends 44V above VEE,
Independent of VCC; MSOP Package, Shutdown Function
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 amplifi er
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 suffi cient current through RB to balance the
input of Amp B. Likewise, Amp A and Q1 form a closed
loop when the battery is discharging. The current through
Q1 or Q2 is proportional to the current in RS and this cur-
rent fl ows into RG and is converted into a voltage. Amp
D buffers and amplifi es the voltage across RG. Amp C
compares the output of Amp A and Amp B to determine
the polarity of current through RS. The scale factor for
VOUT with S1 open is 1V/A. With S1 closed the scale
factor is 1V/100mA and currents as low as 500μA can
be measured.
RA, 2k
Q2
2N3904
S1
S1 = OPEN, GAIN = 1
S1 = CLOSED, GAIN = 10
RA = RB
VS = 5V, 0V
10k 90.9k
VOUT
LOGIC
1638/39 F05
LOGIC HIGH (5V) = CHARGING
LOGIC LOW (0V) = DISCHARGING
RG
10k
Q1
2N3904
RS, 0.2Ω
CHARGER
VOLTAGE
RA', 2k
RB', 2k
RB, 2k
VBATT = 12V
IBATT
+
LOAD
VOUT
(RS)(RG/RA)(GAIN)
VOUT
GAIN
IBATT = = AMPS
–
+
A
1/4 LT1639
–
+
B
1/4 LT1639
–
+
C
1/4 LT1639
–
+
D
1/4 LT1639
Figure 5. Battery Monitor