KF347 Equivalent & Substitute Parts Reference

Part Overview

The KF347 is a J-FET operational amplifier integrated circuit manufactured by onsemi, configured as a 4-circuit amplifier in a 14-pin DIP package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The KF347 operates across a ±18V supply range (36V total span) with a 4 MHz gain-bandwidth product and 13V/µs slew rate, suitable for precision analog signal processing applications requiring low input bias current (50 pA) and low input offset voltage (5 mV).

Key Parameters

Parameter	Value	Unit
Amplifier Type	J-FET	—
Number of Circuits	4	—
Slew Rate	13	V/µs
Gain Bandwidth Product	4	MHz
Current - Input Bias	50	pA
Voltage - Input Offset	5	mV
Current - Supply	7.2	mA
Voltage - Supply Span	36	V
Operating Temperature	0 to 70	°C
Package / Case	14-DIP (0.300", 7.62mm)	—
Mounting Type	Through Hole	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the KF347 is determined by strict alignment of electrical and mechanical parameters. The primary substitution criteria are:

Critical Parameters for Substitution:

Amplifier Type: J-FET (maintains input impedance and bias current characteristics)
Number of Circuits: 4 (functional equivalence)
Package / Case: 14-DIP (0.300", 7.62mm) (mechanical compatibility)
Slew Rate: 13V/µs (signal fidelity)
Gain Bandwidth Product: 4 MHz (frequency response)
Voltage - Supply Span: 36V (power supply compatibility)
Operating Temperature: 0°C to 70°C (thermal envelope)

Substitute parts are grouped into two categories:

Direct Substitutes (Electrical and Mechanical Equivalence): Parts that match all critical parameters, including J-FET amplifier type, 4-circuit configuration, 4 MHz bandwidth, 13V/µs slew rate, and 36V supply span. These include LF347BN/NOPB and LF347N/NOPB.

Compatible Substitutes (Functional Equivalence with Parameter Variations): Parts that maintain 4-circuit J-FET configuration and 14-DIP package but exhibit variations in secondary parameters such as slew rate, supply span, or input bias current. These include TL084ACN, LF347BN, LF347N, and TL084CN.

Limited Compatibility Substitutes (Different Amplifier Type): Parts with different amplifier types (General Purpose instead of J-FET) that share the 4-circuit, 14-DIP package configuration. These include TL3474ACN, OP497GPZ, and TL3474CN. These are suitable only when J-FET characteristics are not required.

Parameter Comparison

Part Number	Manufacturer	Amplifier Type	Slew Rate (V/µs)	GBW (MHz)	Input Bias (pA)	Input Offset (mV)	Supply Span (V)	Status	RoHS
KF347	onsemi	J-FET	13	4	50	5	36	Obsolete	—
TL084ACN	Texas Instruments	J-FET	13	3	30	3	10–30	Active	ROHS3
LF347BN	onsemi	J-FET	13	4	50	3	36	Obsolete	Non-compliant
LF347BN/NOPB	Texas Instruments	J-FET	13	4	50	3	36	Active	ROHS3
LF347N	STMicroelectronics	J-FET	16	4	20	3	44	Obsolete	ROHS3
LF347N/NOPB	Texas Instruments	J-FET	13	4	50	5	36	Active	ROHS3
TL084CN	STMicroelectronics	J-FET	16	3	20	3	6–36	Obsolete	ROHS3
TL3474ACN	Texas Instruments	General Purpose	13	4	100 nA	1	4–36	Last Time Buy	ROHS3
TL3474CN	Texas Instruments	General Purpose	13	4	100 nA	1	4–36	Last Time Buy	ROHS3
OP497GPZ	Analog Devices Inc.	General Purpose	0.15	0.5	60	0.08	4–40	Active	ROHS3

Engineering Selection Recommendations

For Direct Replacement (Preferred):

Select LF347BN/NOPB (Texas Instruments) or LF347N/NOPB (Texas Instruments) when full electrical and mechanical compatibility is required. Both parts maintain J-FET amplifier type, 4-circuit configuration, 4 MHz gain-bandwidth product, 13V/µs slew rate, and 36V supply span. Both are Active status products with ROHS3 compliance, ensuring long-term availability and regulatory compliance.

For Active Status Requirement:

If product status is a selection criterion, TL084ACN (Texas Instruments, Active) provides J-FET amplifier functionality with 14-DIP package compatibility. Note that TL084ACN operates within a 10–30V supply span (narrower than KF347's 36V) and has a 3 MHz gain-bandwidth product (lower than KF347's 4 MHz). Verify supply voltage requirements before selection.

For Automotive or AEC-Q100 Applications:

TL084CN (STMicroelectronics) carries AEC-Q100 qualification and Automotive grade designation. This part exhibits 16V/µs slew rate and 3 MHz gain-bandwidth product with a 6–36V supply span, providing broader supply compatibility than the KF347.

For General Purpose Applications Without J-FET Requirements:

TL3474ACN or TL3474CN (Texas Instruments) are suitable when J-FET input characteristics are not critical. Both are General Purpose amplifiers with 4 MHz gain-bandwidth product, 13V/µs slew rate, and 4–36V supply span. These parts are in Last Time Buy status; verify availability before design commitment.

Not Recommended:

OP497GPZ (Analog Devices Inc.) exhibits significantly different electrical characteristics (0.15V/µs slew rate, 0.5 MHz gain-bandwidth product) and is suitable only for applications with relaxed frequency response requirements.

Frequently Asked Questions (FAQ)

Q1: Can I use TL084ACN as a direct replacement for KF347?

TL084ACN shares the J-FET amplifier type and 4-circuit 14-DIP package configuration. However, it operates within a 10–30V supply span compared to KF347's 36V span, and has a 3 MHz gain-bandwidth product versus KF347's 4 MHz. Use TL084ACN only if your circuit operates within the 10–30V range and does not require 4 MHz bandwidth.

Q2: What is the difference between LF347BN and LF347BN/NOPB?

LF347BN/NOPB is the Texas Instruments version with Active product status and ROHS3 compliance. The onsemi LF347BN is Obsolete and RoHS non-compliant. For new designs, select LF347BN/NOPB.

Q3: Why does LF347N have a 44V supply span while KF347 has 36V?

LF347N (STMicroelectronics) is specified with a 44V supply span, providing broader supply voltage tolerance. This is a parameter variation that does not prevent substitution but indicates the part can operate at higher supply voltages. Verify your circuit design operates within the specified range.

Q4: Is OP497GPZ suitable for high-speed applications?

No. OP497GPZ has a 0.15V/µs slew rate and 0.5 MHz gain-bandwidth product, significantly lower than KF347's 13V/µs and 4 MHz. Use OP497GPZ only for low-frequency, low-speed applications.

Q5: Can I use TL3474ACN in place of KF347?

TL3474ACN is a General Purpose amplifier, not a J-FET amplifier. It shares the 4-circuit 14-DIP package, 4 MHz gain-bandwidth product, and 13V/µs slew rate. Use TL3474ACN only if your application does not require J-FET input characteristics (high input impedance, low input bias current). Note that TL3474ACN is in Last Time Buy status.

Q6: What does "Last Time Buy" status mean?

Last Time Buy indicates the manufacturer will no longer produce the part after a specified date. Parts in this status have limited availability. Verify stock and lead times before committing to designs using Last Time Buy components.

Q7: Are all substitute parts available in the same package?

Yes. All substitute parts listed are available in 14-DIP (0.300", 7.62mm) Through Hole packages, ensuring mechanical compatibility with KF347 PCB layouts.

Q8: Which substitute offers the best long-term availability?

LF347BN/NOPB and LF347N/NOPB (both Texas Instruments, Active status) offer the best long-term availability. Active status indicates ongoing production and support.

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