ANALOG DEVICES LT 1638 CS8 Datasheet

FEATURES

■

Operates with Inputs Above V

■

Rail-to-Rail Input and Output

■

Low Power: 230μA per Amplifier Max

■

Gain Bandwidth Product: 1.2MHz

■

Slew Rate: 0.4V/μs

■

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

■

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

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

U

W

U

PACKAGE/ORDER INFORMATION

ORDER

PART NUMBER

LT1638CMS8
LT1638IMS8

MS8 PART

T

= 150°C, θJA = 300°C/W (MS8)

JMAX

MARKING*

LTCY

Specified 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

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

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OS

Input Offset Voltage LT1638 N, S Packages 200 600 μV

Input Offset Voltage Drift LT1638/LT1639 N, S Packages ● 26 μV/°C
(Note 9) LT1638MS8, LT1638DD ● 2.5 7 μV/°C

I

OS

I

B

Input Offset Current ● 16 nA

Input Bias Current ● 20 50 nA

Input Noise Voltage 0.1Hz to 10Hz 1 μV

e

n

i

n

R

IN

C

IN

Input Noise Voltage Density f = 1kHz 20 nV/√Hz
Input Noise Current Density f = 1kHz 0.3 pA/√Hz
Input Resistance Differential 1 2.5 MΩ

Input Capacitance 5pF
Input Voltage Range ● 044V

CMRR Common Mode Rejection Ratio V

A

VOL

V

OL

V

OH

I

SC

Large-Signal Voltage Gain VS = 3V, VO = 500mV to 2.5V, RL = 10k 200 1500 V/mV

Output Voltage Swing Low VS = 3V, No Load ● 38 mV

Output Voltage Swing High VS = 3V, No Load ● 2.94 2.98 V

Short-Circuit Current (Note 2) VS = 3V, Short to GND 10 15 mA

= half supply, unless otherwise noted. (Note 4)

OUT

0°C ≤ TA ≤ 70°C ● 850 μV
–40°C ≤ T

≤ 85°C ● 950 μV

A

LT1639 N, S Packages 300 700 μV
0°C ≤ T

≤ 70°C ● 950 μV

A

–40°C ≤ TA ≤ 85°C ● 1050 μV
LT1638 MS8 Package 350 900 μV

0°C ≤ TA ≤ 70°C ● 1150 μV
–40°C ≤ T

≤ 85°C ● 1450 μV

A

LT1638 DD Package 400 1100 μV
0°C ≤ T

≤ 70°C ● 1350 μV

A

–40°C ≤ TA ≤ 85°C ● 1450 μV

VCM = 44V (Note 5) ● 2.5 μA

VCM = 44V (Note 5) ● 830 μA
V

= 0V 0.1 nA

S

Common Mode, VCM = 0V to 44V 1.4 5.5 MΩ

= 0V to VCC – 1V ● 88 98 dB

CM

V

= 0V to 44V (Note 8) ● 80 88 dB

CM

0°C ≤ TA ≤ 70°C ● 133 V/mV
–40°C ≤ T

≤ 85°C ● 100 V/mV

A

VS = 5V, VO = 500mV to 4.5V, RL = 10k 400 1500 V/mV
0°C ≤ T

≤ 70°C ● 250 V/mV

A

–40°C ≤ TA ≤ 85°C ● 200 V/mV

VS = 3V, I

= 5mA ● 250 450 mV

SINK

VS = 5V, No Load ● 38 mV
VS = 5V, I

VS = 3V, I

= 10mA ● 500 700 mV

SINK

= 5mA ● 2.25 2.40 V

SOURCE

VS = 5V, No Load ● 4.94 4.98 V
VS = 5V, I

VS = 3V, Short to V

= 10mA ● 3.8 4.0 V

SOURCE

CC

VS = 5V, Short to GND 15 20 mA
VS = 5V, Short to V

CC

LT1638C/LT1639C, LT1638I/LT1639I

P-P

15 25 mA

15 25 mA

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

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

PSRR Power Supply Rejection Ratio VS = 3V to 12.5V, V

Reverse Supply Voltage IS = –100μA per Amplifier ● 18 27 V
Minimum Operating Supply Voltage ● 2.4 2.7 V

I

S

Supply Current per Amplifier 170 230 μA
(Note 6)

GBW Gain Bandwidth Product f = 5kHz 650 1075 kHz

(Note 5) 0°C ≤ T

SR Slew Rate AV = –1, RL = ∞ 0.210 0.38 V/μs

(Note 7) 0°C ≤ T

The ● denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C.
VS = ±15V, VCM = 0V, V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OS

I

OS

I

B

e

n

i

n

R

IN

C

IN

CMRR Common Mode Rejection Ratio V
A

VOL

V

O

Input Offset Voltage LT1638 N, S Packages 250 800 μV

Input Offset Voltage Drift LT1638/LT1639 N, S Packages ● 26 μV/°C
(Note 9) LT1638MS8, LT1638DD ● 2.5 7 μV/°C

Input Offset Current ● 16 nA
Input Bias Current ● 20 50 nA
Input Noise Voltage 0.1Hz to 10Hz 1 μV
Input Noise Voltage Density f = 1kHz 20 nV/√Hz
Input Noise Current Density f = 1kHz 0.3 pA/√Hz
Input Resistance Differential 1 2.5 MΩ

Input Capacitance 4.5 pF
Input Voltage Range ● –15 29 V

Large-Signal Voltage Gain VO = ±14V, RL = 10k 200 500 V/mV

Output Voltage Swing No Load ● ±14.9 ±14.95 V

= 0V, unless otherwise noted. (Note 4)

OUT

= half supply, unless otherwise noted. (Note 4)

OUT

= VO = 1V ● 90 100 dB

CM

≤ 70°C ● 550 kHz

A

–40°C ≤ T

–40°C ≤ T

≤ 85°C ● 500 kHz

A

≤ 70°C ● 0.185 V/μs

A

≤ 85°C ● 0.170 V/μs

A

0°C ≤ TA ≤ 70°C ● 1000 μV
–40°C ≤ T

≤ 85°C ● 1100 μV

A

LT1639 N, S Packages 350 900 μV
0°C ≤ T

≤ 70°C ● 1100 μV

A

–40°C ≤ TA ≤ 85°C ● 1200 μV
LT1638 MS8 Package 400 1050 μV

0°C ≤ TA ≤ 70°C ● 1250 μV
–40°C ≤ T

≤ 85°C ● 1550 μV

A

LT1638 DDPackage 450 1250 μV
0°C ≤ T

≤ 70°C ● 1450 μV

A

–40°C ≤ TA ≤ 85°C ● 1550 μV

Common Mode, V

= –15V to 29V ● 80 88 dB

CM

= –15V to 14V 500 MΩ

CM

0°C ≤ TA ≤ 70°C ● 125 V/mV
–40°C ≤ T

I

OUT

≤ 85°C ● 100 V/mV

A

= ±10mA ● ±13.7 ±14.0 V

LT1638C/LT1639C, LT1638I/LT1639I

● 275 μA

LT1638C/LT1639C, LT1638I/LT1639I

P-P

4

16389fd

LT1638/LT1639

ELECTRICAL CHARACTERISTICS

range, otherwise specifications are at TA = 25°C. VS = ±15V, VCM = 0V, V

The ● denotes the specifications which apply over the specified temperature

= 0V, unless otherwise noted. (Note 4)

OUT

LT1638C/LT1639C, LT1638I/LT1639I

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I

SC

Short-Circuit Current (Note 2) Short to GND 25 40 mA

≤ 70°C ● 20 mA

0°C ≤ T

A

–40°C ≤ T

≤ 85°C ● 15 mA

A

PSRR Power Supply Rejection Ratio VS = ±1.5V to ±22V ● 90 100 dB
I

S

Supply Current per Amplifier 205 280 μA

● 350 μA

GBW Gain Bandwidth Product f = 5kHz 750 1200 kHz

≤ 70°C ● 650 kHz

0°C ≤ T

A

–40°C ≤ T

≤ 85°C ● 600 kHz

A

SR Slew Rate AV = –1, RL = ∞, VO = ±10V, 0.225 0.4 V/μs

≤ 70°C ● 0.2 V/μs

0°C ≤ T

A

–40°C ≤ TA ≤ 85°C ● 0.18 V/μs

The ● denotes the specifications which apply over the full operating temperature range of –40°C ≤ TA ≤ 125°C.
VS = 3V, 0V; VS = 5V, 0V; VCM = V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OS

I

OS

I

B

CMRR Common Mode Rejection Ratio V

A

VOL

V

OL

V

OH

PSRR Power Supply Rejection Ratio VS = 3V to 12.5V, V

I

S

GBW Gain Bandwidth Product f = 5kHz 650 1075 kHz

SR Slew Rate AV = –1, RL = ∞ 0.21 0.38 V/μs

Input Offset Voltage LT1638S8 200 650 μV

Input Offset Voltage Drift (Note 9) ● 15 μV/°C
Input Offset Current ● 15 nA

Input Bias Current ● 150 nA

Input Voltage Range ● 0.3 44 V

Large-Signal Voltage Gain VS = 3V, VO = 500mV to 2.5V, RL = 10k 200 1500 V/mV

Output Voltage Swing Low No Load ● 15 mV

Output Voltage Swing High VS = 3V, No Load ● 2.9 V

Minimum Supply Voltage ● 2.7 V
Reverse Supply Voltage IS = –100μA ● 18 V
Supply Current 170 230 μA

(Note 6)

(Note 5)

(Note 7)

= Half Supply unless otherwise specified. (Note 4)

OUT

LT1639S 300 750 μV

VCM = 44V (Note 5) ● 10 μA

VCM = 44V (Note 5) ● 100 μA

= 0.3V to VCC – 1V ● 76 dB

CM

V

= 0.3V to 44V ● 72 dB

CM

VS = 5V, VO = 500mV to 4.5V, RL = 10k 400 1500 V/mV

I

= 5mA ● 900 mV

SINK

VS = 5V, I

VS = 3V, I

= 10mA ● 1500 mV

SINK

= 5mA ● 2V

SOURCE

VS = 5V, No Load ● 4.9 V
VS = 5V, I

= 10mA ● 3.5 V

SOURCE

= VO = 1V ● 80 dB

CM

LT1638H/LT1639H

● 3mV

● 3.2 mV

● 20 V/mV

● 35 V/mV

● 450 μA

● 350 kHz

● 0.1 V/μs

16389fd

5

LT1638/LT1639

ELECTRICAL CHARACTERISTICS

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

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OS

I

OS

I

B

CMRR Common Mode Rejection Ratio V
A

VOL

V

O

PSRR Power Supply Rejection Ratio VS = ±1.5V to ±22V ● 84 dB

I

S

GBW Gain Bandwidth Product f = 5kHz 750 1200 kHz

SR Slew Rate AV = –1, RL = ∞, VO = ±10V, 0.225 0.4 V/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.

Input Offset Voltage LT1638S8 250 850 μV

LT1639S 350 950 μV

Input Offset Voltage Drift (Note 9) ● 15 μV/°C
Input Offset Current ● 25 nA
Input Bias Current ● 250 nA

= –14.7V to 29V ● 72 dB

CM

Large-Signal Voltage Gain VO = ±14V, RL = 10k 200 500 V/mV

Output Voltage Swing No Load ● ±14.8 V

I

= ±5mA ● ±14 V

OUT

I

= ±10mA ● ±13.4 V

OUT

Minimum Supply Voltage ● ±1.35 V
Supply Current 205 280 μA

Measure at V

Stresses beyond those listed under Absolute Maximum Ratings

The LT1638C/LT1639C are guaranteed to meet specified

= 0V, V

OUT

= ±5V ● 0.1 V/μs

O

= V– unless otherwise specified. (Note 4)

SHDN

LT1638H/LT1639H

● 3.4 mV

● 3.6 mV

● 15 V/mV

● 550 μA

● 400 kHz

Note 5: VS = 5V limits are guaranteed by correlation to VS = 3V and
V

= ±15V or VS = ±22V tests.

S

Note 6: V
V

S

Note 7: Guaranteed by correlation to slew rate at V
V

S

Note 8: This specification implies a typical input offset voltage of 2mV at
V

CM

Note 9: This parameter is not 100% tested.
Note 10: The θ

spreading metal. Using expanded metal area on all layers of a board
reduces this value.

= 3V limits are guaranteed by correlation to VS = 5V and

S

= ±15V or VS = ±22V tests.

= ±15V, and GBW at

= 3V and VS = ±15V tests.

= 44V and a maximum input offset voltage of 5mV at VCM = 44V.

specified for the DD package is with minimal PCB heat

JA

S

6

16389fd

W

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

TA = 125°C

TA = –55°C

TA = 25°C

VS = 5V, 0V

FREQUENCY (Hz)

1

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

10 100 1k

1638/39 G08

INPUT NOISE CURRENT DENSITY (pA/√Hz)

U

TYPICAL PERFORMANCE CHARACTERISTICS

Supply Current vs Supply Voltage

300

280

260

240

220

200

180

160

140

120

SUPPLY CURRENT PER AMPLIFIER (μA)

100

515

0

10

SUPPLY VOLTAGE (V)

TA = 125°C

TA = 25°C

T

= –55°C

A

25 45

30

20

35

40

1638/39 G01

Minimum Supply Voltage

400

300

200

100

0

–100

–200

–300

CHANGE IN INPUT OFFSET VOLTAGE (μV)

–400

TA = 25°C

TA = 125°C

1

0

TOTAL SUPPLY VOLTAGE (V)

2

T

–55°C

A =

3

4

LT1638/LT1639

Input Bias Current vs
Common Mode Voltage

5

1638/39 G02

Output Saturation Voltage vs
Load Current (Output High)

1

VS = ±2.5V
V

0.1

OUTPUT SATURATION VOLTAGE (V)

0.01

0.001

0.1Hz to 10Hz Noise Voltage

VS = ±2.5

NOISE VOLTAGE (400nV/DIV)

013579

= 30mV

OD

TA = 125°C

TA = 25°C

TA = –55°C

0.01 0.1 1 10

SOURCING LOAD CURRENT (mA)

2468

TIME (SEC)

1638/39 G04

1638/39 G07

Output Saturation Voltage vs
Load Current (Output Low)

1

VS = ±2.5V

= 30mV

V

OD

0.1

0.01

OUTPUT SATURATION VOLTAGE (V)

0.001

0.001

0.01 0.1 1 10

SINKING LOAD CURRENT (mA)

TA = 125°C

TA = 25°C

TA = –55°C

1638/39 G05

Noise Voltage Density vs
Frequency

70

60

50

40

30

20

10

INPUT NOISE VOLTAGE DENSITY (nV/√Hz)

10

0

1

10 100 1k

FREQUENCY (Hz)

1638/39 G09

Output Saturation Voltage vs
Input Overdrive

100

OUTPUT HIGH

10

OUTPUT LOW

OUTPUT SATURATION VOLTAGE (mV)

1

20 100

10

0

40

50

30

INPUT OVERDRIVE (mV)

Input Noise Current Density
vs Frequency

VS = ±2.5V
NO LOAD

807060

90

1638/39 G06

16389fd

7

LT1638/LT1639

W

U

TYPICAL PERFORMANCE CHARACTERISTICS

Gain and Phase Shift vs
Frequency

80

70

60

50

40

30

GAIN (dB)

20

10

0

–10

–20

1

GAIN

10 100 1000
FREQUENCY (kHz)

PHASE

Gain Bandwidth Product and
Phase Margin vs Supply Voltage

1500

1400

1300

1200

1100

GAIN BANDWIDTH PRODUCT (kHz)

1000

515

10

0

TOTAL SUPPLY VOLTAGE (V)

PHASE MARGIN

GAIN BANDWIDTH

25 45

30

20

VS = ±2.5V

1638/39 G12

35

40

1638/39 G15

Gain Bandwidth Product vs
Temperature

100

90

80

70

60

50

40

30

20

10

0

1500

f = 1kHz

1400

PHASE SHIFT (DEG)

1300

1200

1100

1000

900

GAIN BANDWIDTH PRODUCT (kHz)

800

–50

Gain Bandwidth Product and
Phase Margin vs Load Resistance

60

50

40

30

20

10

1500

1400

PHASE MARGIN (DEG)

1300

1200

1100

1000

900

GAIN BANDWIDTH PRODUCT (kHz)

800

1

VS = ±15V

V

= ±2.5V

S

25

0

–25

TEMPERATURE (°C)

PHASE MARGIN

GAIN BANDWIDTH
PRODUCT

LOAD RESISTANCE (kΩ)

10 100

50

VS = ±2.5V

= –1

A

V

= RG = 100k

R

F

f = 1kHz

75

100

1638/39 G13

1638/39 G17

Slew Rate vs Temperature

0.60

0.55

0.50

0.45

0.40

SLEW RATE (V/μs)

0.35

0.30

125

0.25
–50

–25

PSRR vs Frequency

60

50

40

30

20

10

0

–10

90

80

70

PHASE MARGIN (DEG)

60

50

40

30

NEGATIVE SUPPLY

20

10

0

POWER SUPPLY REJECTION RATIO (dB)

–10

1 10 100 1000

RISING, VS = ±15V

RISING, V

FALLING, V

FALLING, VS = ±15V

50

25

0

TEMPERATURE (°C)

POSITIVE SUPPLY

FREQUENCY (kHz)

= ±2.5V

S

= ±2.5V

S

75

VS = ±2.5V

100

1638/39 G14

1638/39 G16

125

CMRR vs Frequency

120

VS = ±15V

110

100

90

80

70

60

50

40

30

COMMON MODE REJECTION RATIO (dB)

20

1 10 100 1000

FREQUENCY (kHz)

8

1638/39 G18

Channel Separation vs Frequency

130

120

110

100

90

80

CHANNEL SEPARATION (dB)

70

60

0.1

1 10 100

FREQUENCY (kHz)

VS = ±15V

1638/39 G19

Output Impedance vs Frequency

10k

VS = ±2.5V

1k

100

AV = 100

10

OUTPUT IMPEDANCE (Ω)

1

0.1

0.1 10 100 1000

AV = 10

AV = 1

1

FREQUENCY (kHz)

1638/39 G20

16389fd

W

FREQUENCY (kHz)

0.1

OUTPUT SWING (V

P-P

)

1 10 100

1638/39 G23

35

30

25

20

15

10

5

0

DISTORTION ≤ 1%
R

L

= 20k

VS = ±2.5V

VS = ±15V

OUTPUT VOLTAGE (V

P-P

)

THD + NOISE (%)

10

1

0.1

0.01

0.001
023

1638/39 G26

1

RL = 10k, f = 1kHz
V

CM

= HALF SUPPLY

A

V

= –1, VS = ±1.5V

A

V

= –1, VS = 3V, 0V

A

V

= 1, VS = ±1.5V

A

V

= 1, VS = 3V, 0V

U

TYPICAL PERFORMANCE CHARACTERISTICS

LT1638/LT1639

Settling Time to 0.1% vs
Output Step

10

VS = ±15V

8

6

4

2

0

–2

OUTPUT STEP (V)

–4

–6

–8

–10

0

AV = 1

AV = –1

AV = 1

515

10

SETTLING TIME (μs)

20

AV = –1

25

Total Harmonic Distortion + Noise
vs Frequency

10

VS = 3V, 0V

= 2V

V

OUT

P-P

VCM = 1.2V

1

= 20k

R

L

0.1

30

1638/39 G21

35

Capacitive Load Handling,
Overshoot vs Capacitive Load

100

VS = 5V, 0V

90

= 2.5V

V

CM

= 150μA

I

SOURCE

80

70

60

50

40

OVERSHOOT (%)

30

20

10

0

10 100 1000 10000

AV = 1

CAPACITIVE LOAD (pF)

AV = 5

AV = 10

Total Harmonic Distortion + Noise
vs Load Resistance

10

VS = 3V TOTAL

= 1

A

V

= 2V

IN

AT 1kHz

P-P

VS = ±1.5V

= ±1V

V

IN

V

1

0.1

Undistorted Output Swing
vs Frequency

1638/39 G22

Total Harmonic Distortion + Noise
vs Output Voltage

THD + NOISE (%)

0.001

0.01

AV = –1

AV = 1

0.01 1 10 100

0.1
FREQUENCY (Hz)

1638/39 G24

THD + NOISE (%)

0.01

0.001

VS = 3V, 0V

= 0.5V TO 2.5V

V

IN

VS = 3V, 0V

= 0.2V TO 2.2V

V

IN

0.1 10 100

LOAD RESISTANCE TO GROUND (kΩ)

1

1638/39 G25

Open-Loop Gain Large-Signal Response Small-Signal Response

VS = ±15V

RL = 2k

RL = 10k

RL = 50k

CHANGE IN INPUT OFFSET VOLTAGE (50μV/DIV)

–10V–20V

OUTPUT VOLTAGE (5V/DIV)

0V

10V 20V

1638/39 G27

S

A

V

= ±15V
= 1

1638/39 G28

= ±15V

V

S

A

= 1

V

= 15pF

C

L

1638/39 G29V

16389fd

9

LT1638/LT1639

U

WUU

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.

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

D1 D2

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

Q13 Q14

R4
8k

R5
8k

Q15

Q3

D3

Q19

Q17 Q20

Q16 Q18

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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LT 0707 REV D • PRINTED IN USA

16

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

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