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FEATURES
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LT1638/LT1639 1.2MHz, 0.4V/s Over-The-TopTM Micropower Rail-to-Rail Input and Output Op Amps DESCRIPTION
The LT (R)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 on the standard 14-pin PDIP and surface mount packages. The LT1638/LT1639 op amps operate on all single and split supplies with a total voltage of 2.5V to 44V drawing only 170A 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 even when the inputs are 22V 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.
Operates with Inputs Above V + Rail-to-Rail Input and Output Low Power: 230A per Amplifier Max Gain Bandwidth Product: 1.2MHz Slew Rate: 0.4V/s High Output Current: 25mA Min Specified on 3V, 5V and 15V Supplies Reverse Battery Protection to 18V No Supply Sequencing Problems High Voltage Gain: 1500V/mV Single Supply Input Range: - 0.4V to 44V High CMRR: 98dB No Phase Reversal
APPLICATIONS
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Battery- or Solar-Powered Systems Portable Instrumentation Sensor Conditioning Supply Current Sensing Battery Monitoring Micropower Active Filters 4mA to 20mA Transmitters
, LTC and LT are registered trademarks of Linear Technology Corporation. Over-The-Top is a trademark of Linear Technology Corporation.
TYPICAL APPLICATION
Over-The-Top Comparator with 100mV Hysteresis Centered at 0mV
10k V1 VCC 1M 1M VCC VCC
Output Voltage vs Input Voltage
5V
+
A 1/2 LT1638
+
B 1/2 LT1638 1M V0
-
10k V2 1M
-
0V
1638/39 TA01
VCC = 5V, VCM = 0V TO 44V, tPD = 27s
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1638/39 TA02
1
LT1638/LT1639
ABSOLUTE MAXIMUM RATINGS
Total Supply Voltage (V + to V -) .............................. 44V Input Differential Voltage ......................................... 44V Input Current ...................................................... 25mA Output Short-Circuit Duration (Note 2) ......... Continuous Operating Temperature Range ................ - 40C to 85C
PACKAGE/ORDER INFORMATION
TOP VIEW
TOP VIEW OUT A -IN A +IN A V- 1 2 3 4 8 7 6 5 V+ OUT B -IN B +IN B
OUT A -IN A +IN A V-
1 2 A 3 B 4
MS8 PACKAGE 8-LEAD PLASTIC MSOP
TJMAX = 150C, JA = 250C/ W (MS8)
N8 PACKAGE 8-LEAD PDIP
TJMAX = 150C, JA = 130C/ W (N8) TJMAX = 150C, JA = 190C/ W (S8)
ORDER PART NUMBER LT1638CMS8 MS8 PART MARKING LTCY
Consult factory for Military grade parts.
ORDER PART NUMBER LT1638CN8 LT1638IN8 LT1638CS8 LT1638IS8
S8 PART MARKING 1638 1638I
ELECTRICAL CHARACTERISTICS
VS = 3V, 0V; VS = 5V, 0V; VCM = VOUT = half supply, TA = 25C, unless otherwise noted. (Note 3)
SYMBOL VOS PARAMETER Input Offset Voltage CONDITIONS LT1638 N, S Packages 0C TA 70C - 40C TA 85C LT1639 N, S Packages 0C TA 70C - 40C TA 85C LT1638C MS8 Package 0C TA 70C - 40C TA 85C LT1638/LT1639 N, S Packages LT1638CMS8 VCM = 44V (Note 4) MIN
q q
IOS
Input Offset Voltage Drift (Note 7) Input Offset Current
2
U
U
W
WW U
W
(Note 1)
Specified Temperature Range (Note 3) .. - 40C to 85C Junction Temperature ........................................... 150C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
TOP VIEW
8 7 6 5 V+ OUT B -IN B +IN B
OUT A -IN A +IN A V+ +IN B
1 2 3 4 5 6 7 B C A D
14 OUT D 13 -IN D 12 +IN D 11 V - 10 +IN C 9 8 - IN C OUT C
S8 PACKAGE 8-LEAD PLASTIC SO
-IN B OUT B
N PACKAGE 14-LEAD PDIP
S PACKAGE 14-LEAD PLASTIC SO
TJMAX = 150C, JA = 110C/ W (N) TJMAX = 150C, JA = 150C/ W (S)
ORDER PART NUMBER LT1639CN LT1639IN LT1639CS LT1639IS
TYP 200
300
q q
350
q q q q q q
2 2.5 1
MAX 600 850 950 700 950 1050 900 1150 1250 6 7 6 2.5
UNITS V V V V V V V V V V/C V/C nA A
LT1638/LT1639 ELECTRICAL CHARACTERISTICS
VS = 3V, 0V; VS = 5V, 0V; VCM = VOUT = half supply, TA = 25C, unless otherwise noted. (Note 3)
SYMBOL IB PARAMETER Input Bias Current CONDITIONS VCM = 44V (Note 4) VS = 0V 0.1Hz to 10Hz f = 1kHz f = 1kHz Differential Common Mode, VCM = 0V to 44V
q q q
MIN
Input Noise Voltage en in RIN CIN CMRR AVOL Input Noise Voltage Density Input Noise Current Density Input Resistance Input Capacitance Input Voltage Range Common Mode Rejection Ratio Large-Signal Voltage Gain
TYP 20 8 0.1 1 20 0.3 2.5 5.5 5
MAX 50 30
UNITS nA A nA VP-P nV/Hz pA/Hz M M pF V dB dB V/mV V/mV V/mV V/mV V/mV V/mV mV mV mV mV V V V V mA mA mA mA dB V V A A kHz kHz kHz V/s V/s V/s
1 1.4 0 88 80 200 133 100 400 250 200
44 98 88 1500
VCM = 0V to VCC - 1V VCM = 0V to 44V (Note 8) VS = 3V, VO = 500mV to 2.5V, RL = 10k 0C TA 70C - 40C TA 85C VS = 5V, VO = 500mV to 4.5V, RL = 10k 0C TA 70C - 40C TA 85C VS = 3V, No Load VS = 3V, ISINK = 5mA VS = 5V, No Load VS = 5V, ISINK = 10mA VS = 3V, No Load VS = 3V, ISOURCE = 5mA VS = 5V, No Load VS = 5V, ISOURCE = 10mA VS = 3V, Short to GND VS = 3V, Short to VCC VS = 5V, Short to GND VS = 5V, Short to VCC VS = 3V to 12.5V, VCM = VO = 1V IS = - 100A per Amplifier
q q q q q q q q q q q q q q
1500
VOL
Output Voltage Swing Low
VOH
Output Voltage Swing High
ISC
Short-Circuit Current (Note 2)
PSRR
Power Supply Rejection Ratio Reverse Supply Voltage Minimum Operating Supply Voltage Supply Current per Amplifier (Note 5) Gain Bandwidth Product (Note 4) Slew Rate (Note 6)
q q q q
2.94 2.25 4.94 3.8 10 15 15 15 90 18
3 250 3 500 2.98 2.40 4.98 4.0 15 25 20 25 100 27 2.4 170
8 450 8 700
IS GBW
2.7 230 275
f = 1kHz 0C TA 70C - 40C TA 85C AV = - 1, RL = 0C TA 70C - 40C TA 85C
q q q q
650 550 500 0.210 0.185 0.170
1075
SR
0.38
3
LT1638/LT1639 ELECTRICAL CHARACTERISTICS
SYMBOL VOS PARAMETER Input Offset Voltage
VS = 15V, VCM = 0V, VOUT = 0V, TA = 25C, unless otherwise noted. (Note 3)
MIN
q q
IOS IB en in RIN CIN CMRR AVOL
Input Offset Voltage Drift (Note 7) Input Offset Current Input Bias Current Input Noise Voltage Input Noise Voltage Density Input Noise Current Density Input Resistance Input Capacitance Input Voltage Range Common Mode Rejection Ratio Large-Signal Voltage Gain
CONDITIONS LT1638 N, S Packages 0C TA 70C - 40C TA 85C LT1639 N, S Packages 0C TA 70C - 40C TA 85C LT1638C MS8 Package 0C TA 70C - 40C TA 85C LT1638/LT1639 N, S Packages LT1638CMS8
TYP 250
350
q q
400
q q q q q q
0.1Hz to 10Hz f = 1kHz f = 1kHz Differential Common Mode, VCM = - 15V to 14V
q
2 2.5 1 20 1 20 0.3 2.5 500 4.5
MAX 800 1000 1100 900 1100 1200 1050 1250 1350 6 7 6 50
UNITS V V V V V V V V V V/C V/C nA nA VP-P nV/Hz pA/Hz M M pF V dB V/mV V/mV V/mV V V mA mA mA dB
1
- 15 80 200 125 100 14.9 13.7 25 20 15 90 88 500
29
VCM = -15V to 29V VO = 14V, RL = 10k 0C TA 70C - 40C TA 85C No Load IOUT = 10mA Short to GND 0C TA 70C - 40C TA 85C VS = 1.5V to 22V
q q q q q q q q q
VOL ISC
Output Voltage Swing Short-Circuit Current (Note 2)
14.95 14.0 40
PSRR IS GBW
Power Supply Rejection Ratio Supply Current per Amplifier Gain Bandwidth Product
100 205 280 350
A A kHz kHz kHz V/s V/s V/s
f = 1kHz 0C TA 70C - 40C TA 85C AV = - 1, RL = , VO = 10V, 0C TA 70C - 40C TA 85C
q q q q
750 650 600 0.225 0.2 0.18
1200
SR
Slew Rate
0.4
The q denotes specifications which apply over the full specified temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. 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 are guaranteed to meet 0C to 70C specifications and are designed, characterized and expected to meet the extended temperature limits, but are not tested at - 40C and 85C. The LT1638I/LT1639I are guaranteed to meet the extended temperature limits.
Note 4: VS = 5V limits are guaranteed by correlation to VS = 3V and VS = 15V tests. Note 5: VS = 3V limits are guaranteed by correlation to VS = 5V and VS = 15V tests. Note 6: Guaranteed by correlation to slew rate at VS = 15V and GBW at VS = 3V and VS = 15V tests. Note 7: This parameter is not 100% tested. Note 8: The spec implies a typical offset voltage at VCM = 44 of 2mV and a maximum offset voltage at VCM = 44 of 5mV.
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LT1638/LT1639 TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Supply Voltage
300 280 260 240 220 200 180 160 140 120 100 0 5 10 15 20 25 30 35 SUPPLY VOLTAGE (V) 40 45 TA = -55C TA = 25C TA = 125C
CHANGE IN INPUT OFFSET VOLTAGE (V)
SUPPLY CURRENT PER AMPLIFIER (A)
200 100 0 -100 -200 -300 TA = 25C TA = 125C TA = -55C
INPUT BIAS CURRENT (nA)
Output Saturation Voltage vs Load Current (Output High)
1 1
TA = 125C 0.1 TA = 25C
0.1 TA = 25C
TA = 125C
OUTPUT SATURATION VOLTAGE (mV)
OUTPUT SATURATION VOLTAGE (V)
OUTPUT SATURATION VOLTAGE (V)
VS = 2.5V VOD = 30mV
TA = -55C
0.01 0.001
0.01 0.1 1 SOURCING LOAD CURRENT (mA)
0.1Hz to 10Hz Noise Voltage
70
INPUT NOISE VOLTAGE DENSITY (nV/Hz)
INPUT NOISE CURRENT DENSITY (pA/Hz)
VS = 2.5
NOISE VOLTAGE (400nV/DIV)
0
1
2
3
456 TIME (SEC)
7
UW
1638/39 G01
Minimum Supply Voltage
400 300 10000 8000 6000
Input Bias Current vs Common Mode Voltage
VS = 5V, 0V
60 40 20 0 -20
TA = -55C
TA = 125C TA = 25C
- 400
0
1 3 4 2 TOTAL SUPPLY VOLTAGE (V)
5
1638/39 G02
-40 4.0
4.4 5.2 5.6 4.8 COMMON MODE VOLTAGE (V)
44
1638/39 G03
Output Saturation Voltage vs Load Current (Output Low)
100 VS = 2.5V VOD = 30mV
Output Saturation Voltage vs Input Overdrive
VS = 2.5V NO LOAD OUTPUT HIGH
10
0.01 TA = -55C
OUTPUT LOW
10
0.001 0.001
1 0.01 0.1 1 SINKING LOAD CURRENT (mA) 10
1638/39 G05
0 10 20 30 40 50 60 70 80 90 100 INPUT OVERDRIVE (mV)
1638/39 G06
1638/39 G04
Noise Voltage Density vs Frequency
4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0
Input Noise Current Density vs Frequency
60 50 40 30 20 10 0 1 10 100 FREQUENCY (Hz) 1k
1638/39 G09
8
9
10
1
10 100 FREQUENCY (Hz)
1k
1638/39 G08
1638/39 G07
5
LT1638/LT1639 TYPICAL PERFORMANCE CHARACTERISTICS
Gain and Phase Shift vs Frequency
80 70 60 PHASE 50
GAIN (dB)
VS = 2.5V
GAIN BANDWIDTH PRODUCT (kHz)
40 30 20 10 0 GAIN
60 50 40 30 20 10 1 10 100 FREQUENCY (kHz) 0 1000
1638/39 G12
VS = 15V 1200 1100 1000 900 800 -50 -25
SLEW RATE (V/s)
-10 -20
Gain Bandwidth Product and Phase Margin vs Supply Voltage
1500 60
POWER SUPPLY REJECTION RATIO (dB)
GAIN BANDWIDTH PRODUCT (kHz)
1400 PHASE MARGIN 1300 GAIN BANDWIDTH
50
GAIN BANDWIDTH PRODUCT (kHz)
1200
1100
1000 0 5 10 15 20 25 30 35 40 TOTAL SUPPLY VOLTAGE (V)
CMRR vs Frequency
120
COMMON MODE REJECTION RATIO (dB)
110 100 90 80 70 60 50 40 30 20 1
VS = 15V
CHANNEL SEPARATION (dB)
110 100 90 80 70 60 0.1
OUTPUT IMPEDANCE ()
10 100 FREQUENCY (kHz)
6
UW
1638/39 G15 1638/39 G18
Gain Bandwith Product vs Temperature
100 90 80 70
PHASE SHIFT (DEG)
Slew Rate vs Temperature
0.60 0.55 0.50 RISING, VS = 2.5V 0.45 0.40 0.35 0.30 0.25 -50 -25 FALLING, VS = 2.5V FALLING, VS = 15V
1500 f = 1kHz 1400 1300
RISING, VS = 15V
VS = 2.5V
50 0 75 25 TEMPERATURE (C)
100
125
50 25 0 75 TEMPERATURE (C)
100
125
1638/39 G13
1638/39 G14
Gain Bandwidth Product and Phase Margin vs Load Resistance
1500 1400 1300 PHASE MARGIN 1200 1100 1000 900 800 1 10 LOAD RESISTANCE (k) GAIN BANDWIDTH PRODUCT 30 20 10 0 -10 100
1638/39 G17
PSRR vs Frequency
60 50
PHASE MARGIN (DEG)
90 80 70 60 50 40 30 20 10 0 -10 1 10 100 FREQUENCY (kHz) 1000
1638/39 G16
VS = 2.5V AV = -1 RF = RG = 100k f = 1kHz
VS = 2.5V
PHASE MARGIN (DEG)
40
POSITIVE SUPPLY
40
30
NEGATIVE SUPPLY
20
10 45
Channel Separation vs Frequency
130 120 1k VS = 15V 10k
Output Impedance vs Frequency
VS = 2.5V AV = 10
100
AV = 100
10 AV = 1 1
1000
1 10 FREQUENCY (kHz)
100
1638/39 G19
0.1 0.1
1
10 100 FREQUENCY (kHz)
1000
1638/39 G20
LT1638/LT1639 TYPICAL PERFORMANCE CHARACTERISTICS
Settling Time to 0.1% vs Output Step
10 8 6 VS = 15V AV = 1 AV = -1 100 90 80 VS = 5V, 0V VCM = 2.5V ISOURCE = 150A
OUTPUT SWING (VP-P)
OUTPUT STEP (V)
OVERSHOOT (%)
4 2 0 -2 -4 -6 -8 -10 0 5 AV = 1
AV = -1
20 15 10 25 SETTLING TIME (s)
Total Harmonic Distortion + Noise vs Frequency
10 VS = 3V, 0V VOUT = 2VP-P VCM = 1.2V RL = 20k
1
THD + NOISE (%)
THD + NOISE (%)
VS = 1.5V VIN = 1V 0.1 VS = 3V, 0V VIN = 0.5V TO 2.5V VS = 3V, 0V VIN = 0.2V TO 2.2V
THD + NOISE (%)
0.1
0.01
AV = -1 AV = 1
0.001 0.01
0.1
1 10 FREQUENCY (Hz)
Open-Loop Gain
CHANGE IN INPUT OFFSET VOLTAGE (50V/DIV)
VS = 15V
RL = 2k RL = 10k RL = 50k
-20V
-10V 10V 0V OUTPUT VOLTAGE (5V/DIV)
UW
30
1638/39 G21
1638/39 G24
Capacitive Load Handling, Overshoot vs Capacitive Load
35 30 25 20 15 10 5
Undistorted Output Swing vs Frequency
VS = 15V DISTORTION 1% RL = 20k
70 60 50 40 30 20 10 0 AV = 1 AV = 10 AV = 5
VS = 2.5V
35
10
100 1000 CAPACITIVE LOAD (pF)
10000
1638/39 G22
0 0.1
1 10 FREQUENCY (kHz)
100
1638/39 G23
Total Harmonic Distortion + Noise vs Load Resistance
10 VS = 3V TOTAL AV = 1 VIN = 2VP-P AT 1kHz 1
1 10
Total Harmonic Distortion + Noise vs Output Voltage
RL = 10k, f = 1kHz VCM = HALF SUPPLY A V = -1, VS = 1.5V AV = -1, VS = 3V, 0V AV = 1, VS = 1.5V AV = 1, VS = 3V, 0V
0.1
0.01
0.01
100
0.001 0.1
0.001
1 10 LOAD RESISTANCE TO GROUND (k)
100
0
2 1 OUTPUT VOLTAGE (VP-P)
3
1638/39 G26
1638/39 G25
Large-Signal Response
Small-Signal Response
VS = 15V AV = 1
20V
1638/39 G27
1638/39 G28
VS = 15V AV = 1 CL = 15pF
1638/39 G29
7
LT1638/LT1639
APPLICATIONS INFORMATION
Supply Voltage The positive supply pin of the LT1638/LT1639 should be bypassed with a small capacitor (typically 0.1F) within an inch of the pin. When driving heavy loads an additional 4.7F 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 70C, when operating the LT1638/LT1639 on total supplies of 10V or more, the supply must not be brought up faster than 1V/s. Increasing 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 600V. 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 8A 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 as much as 22V below V - by an internal 1k resistor in series with each input and a diode from the input to the negative supply. The input stage of the LT1638/LT1639 incorporates phase reversal protection to prevent the output from phase reversing for inputs up to 22V 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 0.22F capacitor in series with a 150 resistor between the output and ground will compensate these amplifiers for larger capacitive loads, up to 1000pF, at all output currents. 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 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 current and with the input voltage swing between ground and (V + - 0.8V). See the Typical Performance Characteristics curves.
8
U
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LT1638/LT1639
APPLICATIONS INFORMATION
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.
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, VDIODE/R2, will flow 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).
D1 D2
R1 VIN
R2 C1
+
1/2 LT1638 VOUT
VD d = V dt OUT(MAX) (R2)(C1) FOR R1 = 10k, R2 = 100k, C1 = 1000pF d V = 0.006V/s dt OUT(MAX)
-
1638/39 F01
Figure 1. Lowpass Slope Limiting Filter
VOUT
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 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. The application in Figure 3 utilizes the Over-The-Top capabilities of the LT1638. The 0.2 resistor senses the load current while the op amp and NPN transistor form a closed loop making the collector current of Q1
U
W
U
U
U
VCC R5 100k
+
1/4 LT1639 D1 R3 100k D2
-
LT1634-1.2V
-
R1 1k VIN C1 R4 100k R2 1/4 LT1639 VOUT
+
LT1634-1.2V D4
D3
-
1/4 LT1639
FOR R2 = 50k, C1 = 500pF, MAXIMUM SLOPE = 0.048V/s 1.2V d = V dt OUT (R2)(C1)
+
R6 100k
1638/39 F02
VEE
Response of Slope Limiting Filter
VIN
1638/39 TA02
Figure 2. Lowpass Slope Limiting Filter with 0TC
9
LT1638/LT1639
TYPICAL APPLICATIONS
proportional 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+ 200 5V 0.2 200 LOAD ILOAD VOUT = (2)(ILOAD)
LT1634-1.2
+
1/2 LT1638 Q1 2N3904 0V TO 4.3V 2k
1638/39 F03
-
Figure 3. Positive Supply Rail Current Sense
SI PLIFIED SCHE ATIC
V+ Q1 D1 R1 6k Q4 - IN Q17 Q20 OUT Q16 Q15 Q9 Q10 Q13 Q14 Q21 Q18 R3 1k 10A +IN Q7 Q8 Q11 Q12 R2 1k D2 Q2 D3 Q3 Q22
+
Q5
Q6
ONE AMPLIFIER
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
MS8 Package 8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.040 0.006 (1.02 0.15) 0.007 (0.18) 0.021 0.006 (0.53 0.015) 0 - 6 TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) TYP 0.192 0.004 (4.88 0.10) 0.118 0.004** (3.00 0.102) 0.034 0.004 (0.86 0.102) 0.118 0.004* (3.00 0.102) 8 76 5
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
10
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D4
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.
VCC VCC R1
+
1/2 LT1638 IOUT = 1.2V R1 IOUT
1638/39 F04
-
Figure 4. Current Source
W
W
Q19
D5
R4 8k
R5 8k V-
1638/39 SS
0.006 0.004 (0.15 0.102)
MSOP (MS8) 1197
1
23
4
LT1638/LT1639
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
N8 Package 8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.300 - 0.325 (7.620 - 8.255) 0.045 - 0.065 (1.143 - 1.651) 0.130 0.005 (3.302 0.127) 0.400* (10.160) MAX 8 7 6 5
0.009 - 0.015 (0.229 - 0.381)
0.065 (1.651) TYP 0.125 (3.175) 0.020 MIN (0.508) MIN 0.018 0.003 (0.457 0.076)
(
+0.035 0.325 -0.015 +0.889 8.255 -0.381
)
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP
0.016 - 0.050 0.406 - 1.270
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.300 - 0.325 (7.620 - 8.255)
0.130 0.005 (3.302 0.127) 0.020 (0.508) MIN
0.009 - 0.015 (0.229 - 0.381) +0.035 0.325 -0.015 +0.889 8.255 -0.381 0.005 (0.125) MIN 0.100 0.010 (2.540 0.254)
(
)
0.125 (3.175) MIN
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254)
0.053 - 0.069 (1.346 - 1.752) 0 - 8 TYP
0.050 (1.270) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 0.016 - 0.050 0.406 - 1.270 0.014 - 0.019 (0.355 - 0.483)
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.
U
0.255 0.015* (6.477 0.381)
1
2
3
4
N8 1197
0.100 0.010 (2.540 0.254)
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.053 - 0.069 (1.346 - 1.752) 0.004 - 0.010 (0.101 - 0.254) 8 0.189 - 0.197* (4.801 - 5.004) 7 6 5
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) TYP
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
SO8 0996
1
2
3
4
N Package 14-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.045 - 0.065 (1.143 - 1.651) 0.770* (19.558) MAX 14 13 12 11 10 9 8
0.065 (1.651) TYP 0.018 0.003 (0.457 0.076)
0.255 0.015* (6.477 0.381)
1
2
3
4
5
6
7
N14 1197
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
S Package 14-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.004 - 0.010 (0.101 - 0.254) 14 13 0.337 - 0.344* (8.560 - 8.738) 12 11 10 9 8
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
S14 0695
1
2
3
4
5
6
7
11
LT1638/LT1639
TYPICAL APPLICATION
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 loop when the battery is discharging. The current through Q1 or Q2 is proportional to the current in R S and this current flows into RG and is converted into a voltage. Amp D buffers and amplifies 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 500A can be measured.
CHARGER VOLTAGE
RS, 0.2
IBATT
LOAD
IBATT =
VOUT V = OUT AMPS (RS)(RG /RA)(GAIN) GAIN
RELATED PARTS
PART NUMBER
LT1078/LT1079 LT2078/LT2079 LT1178/LT1179 LT2178/LT2179 LT1366/LT1367 LT1490/LT1491 LT1636
DESCRIPTION
Dual/Quad 55A Max, Single Supply, Precision Op Amps Dual/Quad 17A Max, Single Supply, Precison Op Amps Dual/Quad Precision, Rail-to-Rail Input and Output Op Amps Dual/Quad Over-The-Top Micropower, Rail-to-Rail Input and Output Op Amps Single Over-The-Top Micropower Rail-to-Rail Input and Output Op Amp
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
U
+
RA, 2k
+
A 1/4 LT1639
Q1 2N3904
RA', 2k
+
C 1/4 LT1639 LOGIC
-
-
RB, 2k
+
B 1/4 LT1639
Q2 2N3904
LOGIC HIGH (5V) = CHARGING LOGIC LOW (0V) = DISCHARGING
RB', 2k VBATT = 12V
-
RG 10k S1 10k
+
D 1/4 LT1639 VOUT
-
90.9k
1638/39 F05
S1 = OPEN, GAIN = 1 S1 = CLOSED, GAIN = 10
RA = RB VS = 5V, 0V
Figure 5. Battery Monitor
COMMENTS
Input/Output Common Mode Includes Ground, 70V VOS(MAX) and 2.5V/C Drift (Max), 200kHz GBW, 0.07V/s Slew Rate Input/Output Common Mode Includes Ground, 70V VOS(MAX) and 4V/C Drift (Max), 85kHz GBW, 0.04V/s Slew Rate 475V VOS(MAX), 500V/mV AVOL(MIN), 400kHz GBW Single Supply Input Range: - 0.4V to 44V, Micropower 50A per Amplifier, Rail-to-Rail Input and Output, 200kHz GBW 55A Supply Current, VCM Extends 44V above VEE, Independent of VCC; MSOP Package, Shutdown Function
16389f LT/TP 1098 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1998

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