LT1122CS8 Equivalent & Substitute Parts

Part Overview

The LT1122CS8 is a J-FET operational amplifier manufactured by Analog Devices Inc., designed for single-circuit applications in 8-SOIC surface mount packaging. This linear amplifier operates across a supply voltage range of 10V to 36V with an operating temperature range of -40°C to 85°C. The device is currently in active product status with ROHS3 compliance and unlimited moisture sensitivity rating.

Substitute parts are identified when equivalent electrical performance and mechanical compatibility are required due to inventory constraints, design flexibility, or packaging format preferences while maintaining functional equivalence within specified parameter tolerances.

Key Parameters

Parameter	Value	Unit
Amplifier Type	J-FET	—
Number of Circuits	1	—
Slew Rate	75	V/µs
Gain Bandwidth Product	13	MHz
Current - Input Bias	12	pA
Voltage - Input Offset	130	µV
Current - Supply	7.8	mA
Voltage - Supply Span (Min)	10	V
Voltage - Supply Span (Max)	36	V
Operating Temperature	-40 to 85	°C
Package / Case	8-SOIC (0.154", 3.90mm Width)	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution logic for the LT1122CS8 is based on the following critical parameters that determine functional equivalence:

Primary Substitution Criteria:

Amplifier Type: J-FET configuration
Number of Circuits: Single circuit (1)
Package / Case: 8-SOIC form factor with 0.154" width and 3.90mm width specification
Mounting Type: Surface Mount compatibility
Slew Rate: 75V/µs minimum performance
Gain Bandwidth Product: 13 MHz minimum
Supply Voltage Range: Minimum 10V to maximum 36V overlap
Operating Temperature: Extended range -40°C to 85°C preferred

Packaging Format Variants: The LT1122CS8#PBF represents the same electrical device in tube packaging format, providing direct substitution with identical electrical specifications and performance characteristics.

Cross-Manufacturer Alternatives: Texas Instruments TLE2081ACDR and TLE2081CDR devices provide J-FET amplifier functionality in 8-SOIC packaging with compatible supply voltage ranges and operating temperatures, though with different slew rate and bandwidth characteristics.

Limited Compatibility Substitutes: Analog Devices AD744 series devices (AD744JRZ-REEL, AD744JRZ-REEL7, AD744KRZ, AD744KRZ-REEL7) maintain J-FET amplifier architecture and 8-SOIC packaging but operate within a reduced temperature range (0°C to 70°C) and lower minimum supply voltage (9V).

Parameter Comparison

Part Number	Manufacturer	Amplifier Type	Slew Rate (V/µs)	Gain Bandwidth (MHz)	Input Bias (pA)	Input Offset (µV)	Supply Current (mA)	Supply Min (V)	Supply Max (V)	Temp Range (°C)	Package
LT1122CS8	Analog Devices	J-FET	75	13	12	130	7.8	10	36	-40 to 85	8-SOIC
LT1122CS8#PBF	Analog Devices	J-FET	75	13	12	130	7.8	10	36	-40 to 85	8-SOIC
AD744JRZ-REEL	Analog Devices	J-FET	75	13	30	300	3.5	9	36	0 to 70	8-SOIC
AD744JRZ-REEL7	Analog Devices	J-FET	75	13	30	300	3.5	9	36	0 to 70	8-SOIC
AD744KRZ	Analog Devices	J-FET	75	13	30	250	3.5	9	36	0 to 70	8-SOIC
AD744KRZ-REEL7	Analog Devices	J-FET	75	13	30	250	3.5	9	36	0 to 70	8-SOIC
TLE2081ACDR	Texas Instruments	J-FET	45	10	20	470	1.7	4.5	38	0 to 70	8-SOIC

Engineering Selection Recommendations

Direct Substitution (Identical Electrical Performance):

LT1122CS8#PBF is the direct equivalent of LT1122CS8, differing only in packaging format (tube versus standard). Both devices maintain identical electrical specifications, operating parameters, and performance characteristics. Selection between these variants depends solely on packaging and handling requirements for manufacturing processes.

Conditional Substitution (Reduced Operating Temperature Range):

AD744 series devices (AD744JRZ-REEL, AD744JRZ-REEL7, AD744KRZ, AD744KRZ-REEL7) provide functional substitution for applications operating within the 0°C to 70°C temperature range. These devices maintain J-FET amplifier architecture, 8-SOIC packaging, and equivalent slew rate and bandwidth specifications. However, the reduced operating temperature range excludes these parts from applications requiring -40°C to 85°C performance. Input bias current and input offset voltage specifications differ from the primary device.

Limited Substitution (Reduced Performance Parameters):

TLE2081ACDR from Texas Instruments provides J-FET amplifier functionality in 8-SOIC packaging with extended supply voltage range (4.5V to 38V). This device exhibits reduced slew rate (45V/µs versus 75V/µs) and lower gain bandwidth product (10 MHz versus 13 MHz), limiting applicability to designs not requiring the full performance envelope of the LT1122CS8. Operating temperature range is restricted to 0°C to 70°C.

Compliance and Regulatory Status:

All listed substitute parts maintain ROHS3 compliance, unlimited moisture sensitivity rating (MSL 1), and REACH unaffected status, ensuring regulatory equivalence for applications with environmental and compliance requirements.

Frequently Asked Questions (FAQ)

Q: Can LT1122CS8#PBF be used as a direct replacement for LT1122CS8?

A: Yes. LT1122CS8#PBF is electrically identical to LT1122CS8. The designation difference indicates packaging format only (tube packaging for #PBF variant). All electrical specifications, performance parameters, and operating characteristics are equivalent. Selection depends on manufacturing process requirements and packaging handling procedures.

Q: What are the key differences between LT1122CS8 and AD744 series devices?

A: The primary differences are operating temperature range and input bias current specifications. LT1122CS8 operates from -40°C to 85°C with 12 pA input bias current, while AD744 series devices operate from 0°C to 70°C with 30 pA input bias current. AD744 devices also exhibit lower supply current (3.5 mA versus 7.8 mA). These differences restrict AD744 substitution to applications within the narrower temperature range.

Q: Is TLE2081ACDR a suitable substitute for LT1122CS8?

A: TLE2081ACDR provides partial substitution with limitations. Both devices are J-FET amplifiers in 8-SOIC packaging with compatible supply voltage ranges. However, TLE2081ACDR exhibits reduced slew rate (45V/µs versus 75V/µs) and lower gain bandwidth product (10 MHz versus 13 MHz). Operating temperature range is restricted to 0°C to 70°C. Substitution is appropriate only for applications not requiring the full performance specifications of the LT1122CS8.

Q: What packaging formats are available for LT1122 devices?

A: The LT1122 base product is available in 8-SOIC surface mount packaging. Packaging format variants include standard tape and reel (TR) format and tube packaging. The #PBF designation indicates lead-free, RoHS-compliant tube packaging. Selection between packaging formats depends on manufacturing equipment compatibility and component handling requirements.

Q: Are all substitute parts RoHS compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance status, ensuring regulatory equivalence for applications with environmental and compliance requirements. All devices are also REACH unaffected and carry unlimited moisture sensitivity rating (MSL 1).

Q: What is the minimum supply voltage requirement for each substitute?

A: LT1122CS8 requires minimum 10V supply voltage. AD744 series devices operate with minimum 9V supply voltage. TLE2081ACDR operates with minimum 4.5V supply voltage. Applications requiring operation below 9V must use TLE2081ACDR. Applications requiring operation below 4.5V cannot use any of these devices.

Q: How do input bias current specifications affect circuit design?

A: Input bias current determines the input impedance and affects circuit performance in high-impedance applications. LT1122CS8 specifies 12 pA input bias current, while AD744 series devices specify 30 pA. TLE2081ACDR specifies 20 pA. Lower input bias current is preferred for high-impedance signal sources. Applications sensitive to input bias current effects should verify compatibility before substitution.

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