LF347MX Equivalent & Substitute Parts

Part Overview

The LF347MX is a J-FET input operational amplifier with four independent circuits in a 14-SOIC surface mount package, manufactured by Texas Instruments. This device is classified as obsolete but remains in stock with 17,792 units available. The LF347MX operates across a supply voltage range of 10V to 36V with a slew rate of 13V/µs and gain bandwidth product of 4 MHz, making it suitable for precision analog signal processing applications requiring low input bias current and low input offset voltage.

Due to its obsolete status, identifying equivalent and substitute parts is essential for design continuity, long-term availability assurance, and potential performance optimization in new production runs.

Key Parameters

Parameter	LF347MX Value	Unit
Amplifier Type	J-FET	—
Number of Circuits	4	—
Package / Case	14-SOIC (0.154", 3.90mm Width)	—
Mounting Type	Surface Mount	—
Slew Rate	13	V/µs
Gain Bandwidth Product	4	MHz
Current - Input Bias	50	pA
Voltage - Input Offset	5	mV
Current - Supply (x4 Channels)	7.2	mA
Current - Output / Channel	40	mA
Voltage - Supply Span (Min)	10	V
Voltage - Supply Span (Max)	36	V
Operating Temperature	0 to 70	°C
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the LF347MX is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Amplifier Type: J-FET (required for input bias current and offset voltage characteristics)
Number of Circuits: 4 (functional equivalence)
Package / Case: 14-SOIC surface mount (mechanical and thermal compatibility)
Supply Voltage Range: Minimum 10V, Maximum 36V (operational compatibility)
Slew Rate: ≥13V/µs (performance baseline)
Gain Bandwidth Product: ≥4 MHz (frequency response baseline)
Current - Input Bias: ≤50 pA (low-noise requirement)
Voltage - Input Offset: ≤5 mV (precision requirement)
Current - Output / Channel: ≥40 mA (drive capability)

Secondary Substitution Criteria:

RoHS3 Compliance (regulatory requirement)
Moisture Sensitivity Level: 1 (Unlimited) (handling and storage compatibility)
Product Status: Active preferred for long-term availability

Substitute parts are grouped into two categories: Direct Equivalents (identical base part number with different packaging or status) and Functional Equivalents (different manufacturers meeting all primary electrical and mechanical criteria).

Parameter Comparison

Part Number	Manufacturer	Amplifier Type	Slew Rate (V/µs)	GBW (MHz)	Input Bias (pA)	Input Offset (mV)	Supply Min (V)	Supply Max (V)	Output Current (mA)	Product Status
LF347MX	Texas Instruments	J-FET	13	4	50	5	10	36	40	Obsolete
LF347MX/NOPB	Texas Instruments	J-FET	13	4	50	5	10	36	—	Active
LF347D	STMicroelectronics	J-FET	16	3	20	3	44	44	40	Active
LF347DT	STMicroelectronics	J-FET	16	4	20	3	44	44	40	Active
LF247DT	STMicroelectronics	J-FET	16	4	20	3	44	44	40	Active
ADA4000-4ARZ	Analog Devices Inc.	J-FET	20	5	5	0.2	8	36	28	Active
ADA4000-4ARZ-R7	Analog Devices Inc.	J-FET	20	5	5	0.2	8	36	28	Active
TL064CDT	STMicroelectronics	J-FET	3.5	1	30	3	6	36	20	Active
TL064IDT	STMicroelectronics	J-FET	3.5	1	30	3	6	36	20	Active

Engineering Selection Recommendations

Tier 1: Direct Equivalents (Recommended for Drop-In Replacement)

LF347MX/NOPB (Texas Instruments) is the primary recommended substitute. This part maintains identical electrical specifications to the LF347MX while offering Active product status, ensuring long-term availability and manufacturing support. The packaging format (Cut Tape & Digi-Reel) provides flexibility for both prototype and production quantities. Inventory of 25,200 units supports immediate procurement.

Tier 2: Functional Equivalents with Enhanced Performance

LF347DT and LF347D (STMicroelectronics) provide J-FET amplifier functionality with improved slew rate (16V/µs vs. 13V/µs), lower input bias current (20 pA vs. 50 pA), and lower input offset voltage (3 mV vs. 5 mV). These parts are pin-compatible in 14-SOIC packages and maintain Active product status. The supply voltage specification differs (44V fixed vs. 10-36V range); applications requiring the full 10-36V range must verify compatibility with the fixed 44V specification.

LF247DT (STMicroelectronics) offers identical electrical performance to LF347DT with Tape & Reel packaging. This variant is suitable for high-volume production environments.

Tier 3: High-Performance Alternatives

ADA4000-4ARZ and ADA4000-4ARZ-R7 (Analog Devices Inc.) represent enhanced J-FET amplifiers with superior specifications: slew rate of 20V/µs, gain bandwidth product of 5 MHz, input bias current of 5 pA, and input offset voltage of 200 µV. These parts support extended operating temperature range (-40°C to 125°C) and lower minimum supply voltage (8V). Output current per channel is reduced to 28 mA. These parts are suitable for applications requiring precision and extended temperature operation.

Tier 4: General Purpose Alternatives (Limited Compatibility)

ADA4004-4ARZ (Analog Devices Inc.) and SC2902DG (onsemi) are general-purpose amplifiers with different amplifier type classification. These parts do not meet the J-FET amplifier type requirement and are not recommended as direct substitutes for the LF347MX.

TL064CDT and TL064IDT (STMicroelectronics) are J-FET amplifiers but exhibit significantly reduced performance: slew rate of 3.5V/µs and gain bandwidth product of 1 MHz. Output current per channel is limited to 20 mA. These parts are not suitable for applications requiring the LF347MX performance envelope.

Compliance and Certification:

All recommended substitute parts maintain ROHS3 compliance and Moisture Sensitivity Level 1 (Unlimited), ensuring compatibility with existing supply chain and manufacturing processes.

Frequently Asked Questions (FAQ)

Q1: Can LF347MX/NOPB be used as a direct replacement for LF347MX?

A: Yes. LF347MX/NOPB is electrically and mechanically identical to LF347MX. The primary difference is product status (Active vs. Obsolete) and packaging format (Cut Tape & Digi-Reel vs. standard). This part is the recommended substitute for immediate replacement.

Q2: What are the key differences between LF347MX and LF347DT?

A: Both are J-FET amplifiers in 14-SOIC packages with four circuits. LF347DT offers improved slew rate (16V/µs vs. 13V/µs), lower input bias current (20 pA vs. 50 pA), and lower input offset voltage (3 mV vs. 5 mV). The supply voltage specification differs: LF347DT operates at a fixed 44V, while LF347MX operates across 10-36V. Applications must verify compatibility with the fixed 44V specification before substitution.

Q3: Are ADA4000-4ARZ and LF347MX interchangeable?

A: Both are J-FET amplifiers in 14-SOIC packages with four circuits and meet the primary substitution criteria. ADA4000-4ARZ offers superior performance specifications (20V/µs slew rate, 5 MHz GBW, 5 pA input bias current, 200 µV input offset voltage) and extended operating temperature range (-40°C to 125°C). However, output current per channel is reduced to 28 mA (vs. 40 mA). Substitution is valid only if the reduced output current does not violate application requirements.

Q4: Why are TL064CDT and ADA4004-4ARZ not recommended as substitutes?

A: TL064CDT exhibits significantly reduced performance (3.5V/µs slew rate, 1 MHz GBW, 20 mA output current) and does not meet the LF347MX performance baseline. ADA4004-4ARZ is classified as a general-purpose amplifier rather than J-FET amplifier, which changes input bias current characteristics (40 nA vs. 50 pA) and does not meet the J-FET amplifier type requirement.

Q5: What packaging formats are available for substitute parts?

A: Substitute parts are available in multiple packaging formats: Tube, Cut Tape (CT) & Digi-Reel, and Tape & Reel (TR). Selection depends on procurement volume and manufacturing process requirements. Cut Tape & Digi-Reel format supports both prototype and production quantities. Tape & Reel format is optimized for high-volume automated assembly.

Q6: Are all substitute parts RoHS3 compliant?

A: Yes. All recommended substitute parts maintain ROHS3 compliance and Moisture Sensitivity Level 1 (Unlimited), ensuring compatibility with existing environmental and regulatory requirements.

Q7: What is the minimum supply voltage for substitute parts?

A: LF347MX and LF347MX/NOPB support minimum supply voltage of 10V. LF347DT and LF247DT operate at fixed 44V. ADA4000-4ARZ and ADA4000-4ARZ-R7 support minimum supply voltage of 8V. Application circuits must verify compatibility with the specific minimum supply voltage of the selected substitute part.

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