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Analog Devices Inc. LT1638IN8#PBF
- Part No.:
- LT1638IN8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1638IN8#PBF.pdf
- Description:
- IC OPAMP GP 2 CIRCUIT 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,793
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Product details
Overview
LT1638IN8#PBF from Analog Devices (formerly Linear Technology) is a dual rail-to-rail input and output operational amplifier with Over-The-Top® capability, enabling operation with inputs up to 44V above the negative supply - including above V+. It delivers 1.2MHz gain bandwidth, 0.4V/µs slew rate, and 25mA output drive while consuming only 170µA per amplifier at 2.5V–44V total supply. It is widely used in battery monitoring and high-side current sensing where input voltage exceeds V+.
For engineers reviewing the LT1638IN8#PBF datasheet, LT1638IN8#PBF pinout, LT1638IN8#PBF application, or LT1638IN8#PBF equivalent, key selection criteria include its reverse-battery protection to 18V, single-supply input range of –0.4V to 44V, rail-to-rail output swing within 3mV of rails, 98dB CMRR, and guaranteed operation from –40°C to 85°C in the 8-lead PDIP package.
Technical Context
The LT1638IN8#PBF integrates dual NPN/PNP input stages enabling seamless Over-The-Top operation: when inputs exceed V+, the Schottky-clamped NPN stage activates, maintaining functionality up to 44V common-mode voltage independent of supply. Its phase reversal protection prevents false outputs during negative overvoltage events.
Internally compensated for unity-gain stability, it drives capacitive loads up to 1000pF with optional RC compensation (150Ω + 0.22µF), and supports split or single supplies from 2.5V to 44V total. Input bias current remains below 50nA across the full common-mode range, and large-signal voltage gain reaches 1500V/mV at ±15V supplies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Bandwidth Product | 1.2MHz - enables stable closed-loop operation up to ~1MHz with moderate gain, suitable for sensor signal conditioning and active filtering. |
| Slew Rate | 0.4V/µs - supports clean 10kHz full-scale output swings up to 4Vpp without distortion in low-power systems. |
| Supply Current per Amplifier | 170µA - allows continuous operation for years on coin-cell batteries in portable instrumentation. |
| Input Common-Mode Range | –0.4V to 44V - permits direct high-side sensing of 44V bus voltages with 3V or 5V logic-compatible supplies. |
| Output Drive Capability | ±25mA - drives 200Ω loads directly, eliminating need for external buffers in transducer interface circuits. |
| CMRR | 98dB - rejects power supply noise and ground bounce in noisy industrial environments. |
| Reverse Battery Protection | 18V - survives accidental reverse connection in automotive and solar-battery systems without damage or current draw. |
Pinout & Package
LT1638IN8#PBF is housed in an 8-lead plastic DIP (N8) package with through-hole mounting, 0.300" wide body, and JEDEC-standard pinout. Thermal resistance θJA = 150°C/W enables operation up to 85°C ambient without heatsinking under typical load conditions.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OUT A) | Amplifier A output | Rail-to-rail sourcing/sinking up to ±25mA; swing within 3mV of V– and 20mV of V+ at no load. |
| 2 (–IN A) | Inverting input A | Protected by internal 1kΩ series resistor and clamp diode to V–; handles –0.4V to 44V common-mode. |
| 3 (+IN A) | Non-inverting input A | Same protection and voltage range as Pin 2; phase reversal protected for inputs below V–. |
| 4 (V–) | Negative supply | Reference for both amplifiers; underside metal pad in DFN variant internally connected to V–. |
| 5 (+IN B) | Non-inverting input B | Independent input stage identical to Pin 3; supports dual-channel differential or independent sensing. |
| 6 (–IN B) | Inverting input B | Identical electrical behavior to Pin 2; enables dual-opamp configurations like instrumentation amps. |
| 7 (OUT B) | Amplifier B output | Electrically identical to Pin 1; supports dual-output functions such as dual feedback or matched gain paths. |
| 8 (V+) | Positive supply | Bypass with 0.1µF capacitor within 1 inch; supports total supply voltages from 2.5V to 44V. |
Key Features
| Feature | Design Value |
|---|---|
| Over-The-Top® Input Operation | Enables direct sensing of voltages > V+ (up to 44V above V–), eliminating level-shifting ICs in high-side current monitors. |
| Rail-to-Rail Input and Output | Full dynamic range utilization with 3V or 5V supplies - maximizes ADC resolution in low-voltage data acquisition. |
| Reverse Battery Protection | Draws <1nA under –18V reverse supply - prevents system damage and battery drain in field-deployed equipment. |
| No Supply Sequencing Requirement | Operates safely with V+ applied before or after V– - simplifies power-up sequencing in multi-rail embedded systems. |
| Phase Reversal Protection | Prevents output inversion when inputs fall below V–, ensuring reliable comparator-like behavior in fault-detection circuits. |
Applications
| Battery Monitoring | High-Side Current Sensing |
|---|---|
Use Scenario: Real-time monitoring of 12V–48V lead-acid or Li-ion battery packs in UPS and portable medical devices. IC Role / Device Role / Timing Role: Precision voltage follower and buffer for ADC input, rejecting common-mode ripple while tracking cell voltage. Use Value: Input range extends to –0.4V to 44V, allowing direct measurement of battery voltage referenced to system ground without isolation or resistive dividers. | Use Scenario: Measuring load current on positive supply rail of motor drivers or DC-DC converters. IC Role / Device Role / Timing Role: High-side current sense amplifier with gain set by external resistors, driving analog front-end or microcontroller ADC. Use Value: Over-The-Top capability enables sensing at V+ while powered from same rail - eliminates need for isolated supplies or level shifters. |
| Micropower Active Filters | 4mA–20mA Transmitter Interface |
Use Scenario: Low-frequency anti-aliasing and noise-rejection filters in wireless sensor nodes powered by energy harvesters. IC Role / Device Role / Timing Role: Dual op-amp configured as Sallen-Key low-pass filter with unity-gain stability and minimal quiescent current. Use Value: 170µA per amplifier enables multi-pole filtering with sub-1mA total supply current - critical for battery lifetime extension. | Use Scenario: Converting DAC output or sensor voltage into industry-standard 4mA–20mA loop current for PLC and SCADA systems. IC Role / Device Role / Timing Role: Voltage-to-current converter using one amplifier for error amplification and second for current mirror control. Use Value: Rail-to-rail output ensures full 20mA compliance across 0–24V loop supply range; reverse-battery protection guards against field wiring errors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual rail-to-rail op amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1638CS8#PBF | Same silicon die, but in 8-lead SOIC package (S8); θJA = 190°C/W vs 150°C/W for PDIP. | Preferred for surface-mount production; slightly lower thermal performance in high-power-density layouts. | Select LT1638CS8#PBF for automated assembly; LT1638IN8#PBF remains optimal for prototyping, through-hole legacy designs, and thermal-limited board areas. |
| AD8602ARZ | Lower supply current (120µA), higher GBW (8MHz), but no Over-The-Top capability; max input voltage limited to V+ + 0.3V. | Unsuitable for high-side sensing above V+; requires level-shifting circuitry for >V+ inputs. | Choose AD8602ARZ only for low-noise, high-speed signal conditioning where input stays within rail limits; LT1638IN8#PBF is irreplaceable for true Over-The-Top use cases. |
Compared with LT1638CS8#PBF, LT1638IN8#PBF offers superior thermal dissipation in through-hole layouts and mechanical robustness for vibration-prone environments; compared with AD8602ARZ, LT1638IN8#PBF uniquely supports input voltages exceeding V+, making it essential for battery stack monitoring and industrial power rail sensing where level shifters add cost and error.
Availability
LT1638IN8#PBF is available at Aetrix Electronics and suitable for battery monitoring, high-side current sensing, micropower active filters, and 4mA–20mA transmitter interfaces requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for LT1638IN8#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for the LT1638 family. Linear Technology pioneered precision analog ICs with emphasis on ruggedness, rail-to-rail performance, and application-specific architectures.
The LT1638 product line was designed specifically for micropower, high-voltage-input industrial and automotive signal conditioning - emphasizing Over-The-Top operation, reverse-battery survival, and guaranteed performance from –40°C to 85°C in legacy through-hole packages.
FAQ
What is the maximum input voltage the LT1638IN8#PBF can tolerate relative to V–?
The LT1638IN8#PBF supports a common-mode input voltage range from –0.4V to 44V relative to V–, regardless of V+ value. This Over-The-Top® capability allows inputs to exceed V+ by up to 44V – V+, enabling direct high-side sensing in 48V systems powered from 3.3V or 5V supplies. Absolute maximum rating is 44V differential and common-mode, verified per datasheet Section "Absolute Maximum Ratings".
Does the LT1638IN8#PBF require external compensation for driving capacitive loads?
The LT1638IN8#PBF is internally compensated for unity-gain stability and drives up to 200pF capacitively without external components. For loads >200pF (up to 1000pF), optional compensation using a 150Ω resistor in series with a 0.22µF capacitor from output to ground is required - confirmed in "Applications Information" section of the LT1638/LT1639 datasheet (Rev. G).
What is the guaranteed operating temperature range for the LT1638IN8#PBF?
The LT1638IN8#PBF is specified and guaranteed over –40°C to +85°C ambient temperature (Industrial grade, denoted by 'I' suffix). This is explicitly stated in the "Order Information" table and "Absolute Maximum Ratings" section of the official datasheet (16389fg), and applies to all electrical characteristics unless otherwise noted.
How does reverse battery protection work in the LT1638IN8#PBF?
Under reverse supply conditions (V+ < V–), the LT1638IN8#PBF draws less than 1nA total supply current and sustains no damage up to –18V reverse voltage. This is achieved via internal protection circuitry that disables conduction paths - documented in "Applications Information" and verified in absolute maximum ratings. No external components are needed for this protection.
Can the LT1638IN8#PBF be used in single-supply configurations with rail-to-rail input and output?
Yes - the LT1638IN8#PBF is fully specified for single-supply operation from 2.5V to 44V total voltage. Its rail-to-rail input accepts signals from –0.4V to V+ + 43.6V, and rail-to-rail output swings within 3mV of V– and 20mV of V+ at no load. Performance is validated at 3V, 5V, and ±15V supplies per Electrical Characteristics tables.
LT1638IN8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- General Purpose
- Number of Circuits:
- 2
- Output Type:
- Rail-to-Rail
- Slew Rate:
- 0.4V/µs
- Gain Bandwidth Product:
- 1.2 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 20 nA
- Voltage - Input Offset:
- 250 µV
- Current - Supply:
- 205µA (x2 Channels)
- Current - Output / Channel:
- 40 mA
- Voltage - Supply Span (Min):
- 2.5 V
- Voltage - Supply Span (Max):
- 44 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1638IN8#PBF FAQ
1.How can I place an order for LT1638IN8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1638IN8#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LT1638IN8#PBF reliable?
The price and inventory of LT1638IN8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1638IN8#PBF is usually 5 days.
3.What payment methods are accepted for LT1638IN8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1638IN8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1638IN8#PBF?
LT1638IN8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1638IN8#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LT1638IN8#PBF?
For technical support, including LT1638IN8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1638IN8#PBF requirements.
6.How does Aetrix verify that LT1638IN8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1638IN8#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LT1638IN8#PBF meets industry standards.
7.What is the process for return or replacement of LT1638IN8#PBF?
All LT1638IN8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1638IN8#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LT1638IN8#PBF part is unused and in its original packaging.
Return procedure for LT1638IN8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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