LT1638 - 1.2MHz, 0.4V/μs Over-The-Top Micropower Rail-to-Rail Input and Output Op Amps


  • 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

Typical Application

LT1638 Typical Application
LT1638 Typical Application


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.


CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
LT1638CDD#PBF 3x3 DFN-8 DD C 05-08-1698 Yes
LT1638CDD#TRPBF 3x3 DFN-8 DD C 05-08-1698 Yes
LT1638CMS8#PBF MS-8 MS8 C 05-08-1660 Yes
LT1638CMS8#TRPBF MS-8 MS8 C 05-08-1660 Yes
LT1638CN8#PBF N-8 N C 05-08-1510 (N8) Yes
LT1638CS8#PBF SO-8 S8 C 05-08-1610 (S8) Yes
LT1638CS8#TRPBF SO-8 S8 C 05-08-1610 (S8) Yes
LT1638HS8#PBF SO-8 S8 H 05-08-1610 (S8) Yes
LT1638HS8#TRPBF SO-8 S8 H 05-08-1610 (S8) Yes
LT1638IDD#PBF 3x3 DFN-8 DD I 05-08-1698 Yes
LT1638IDD#TRPBF 3x3 DFN-8 DD I 05-08-1698 Yes
LT1638IMS8#PBF MS-8 MS8 I 05-08-1660 Yes
LT1638IMS8#TRPBF MS-8 MS8 I 05-08-1660 Yes
LT1638IN8#PBF N-8 N I 05-08-1510 (N8) Yes
LT1638IS8#PBF SO-8 S8 I 05-08-1610 (S8) Yes
LT1638IS8#TRPBF SO-8 S8 I 05-08-1610 (S8) Yes

LT1638 Package Drawing
LT1638 Package Drawing
LT1638 Package Drawing
LT1638 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
LT1638CDD#PBF 3x3 DFN-8 C $3.39 $2.40 Yes
LT1638CDD#TRPBF 3x3 DFN-8 C $2.45 Yes
LT1638CMS8#PBF MS-8 C $3.00 $2.30 Yes
LT1638CMS8#TRPBF MS-8 C $2.36 Yes
LT1638CN8#PBF N-8 C $2.50 $1.95 Yes
LT1638CS8#PBF SO-8 C $2.60 $2.05 Yes
LT1638CS8#TRPBF SO-8 C $2.11 Yes
LT1638HS8#PBF SO-8 H $3.05 $2.65 Yes
LT1638HS8#TRPBF SO-8 H $2.71 Yes
LT1638IDD#PBF 3x3 DFN-8 I $4.07 $2.88 Yes
LT1638IDD#TRPBF 3x3 DFN-8 I $2.93 Yes
LT1638IMS8#PBF MS-8 I $3.65 $2.55 Yes
LT1638IMS8#TRPBF MS-8 I $2.61 Yes
LT1638IN8#PBF N-8 I $2.85 $2.40 Yes
LT1638IS8#PBF SO-8 I $2.95 $2.55 Yes
LT1638IS8#TRPBF SO-8 I $2.61 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC594A LT1638CDD | Dual, Over-The-Top, Micropower, Rail-to-Rail Input and Output Op Amp in DFN Package $50.00
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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

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