LF253D Equivalent & Substitute Parts

Part Overview

The LF253D is a J-FET operational amplifier integrated circuit manufactured by STMicroelectronics, configured as a dual-channel amplifier in an 8-SOIC surface mount package. This device is classified as obsolete, indicating discontinued production and limited availability. The LF253D operates across a wide supply voltage range of 6V to 36V with a slew rate of 16V/µs and gain bandwidth product of 4 MHz, making it suitable for applications requiring high input impedance and low input bias current characteristics inherent to J-FET input stages.

Due to its obsolete status, sourcing the LF253D presents supply chain challenges. Equivalent and substitute parts are necessary to maintain design continuity, ensure long-term component availability, and support ongoing production requirements. Substitute devices must maintain electrical compatibility within the specified parameter tolerances while offering active product status and reliable supply channels.

Key Parameters

Parameter	Value	Unit
Amplifier Type	J-FET	—
Number of Circuits	2	—
Slew Rate	16	V/µs
Gain Bandwidth Product	4	MHz
Current - Input Bias	20	pA
Voltage - Input Offset	3	mV
Current - Supply (per Channel)	1.4	mA
Current - Output per Channel	40	mA
Voltage - Supply Span (Min)	6	V
Voltage - Supply Span (Max)	36	V
Operating Temperature Range	-40 to 105	°C
Package / Case	8-SOIC (0.154", 3.90mm Width)	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the LF253D is determined by electrical and mechanical compatibility across critical parameters. The primary substitution criteria are:

Electrical Compatibility Parameters:

Amplifier Type: J-FET input stage required for equivalent input impedance and bias current characteristics
Number of Circuits: Dual-channel configuration (2 circuits)
Supply Voltage Range: Minimum 6V and maximum 36V to ensure operation across the original specification
Slew Rate: 16V/µs or greater to maintain signal fidelity
Gain Bandwidth Product: 4 MHz or greater for frequency response equivalence
Input Bias Current: 20 pA or lower for low-bias applications
Output Current per Channel: 40 mA or greater for load driving capability

Mechanical Compatibility Parameters:

Package Type: 8-SOIC surface mount package with 0.154" (3.90mm) width
Mounting Type: Surface mount configuration for PCB compatibility

Compliance Parameters:

RoHS3 Compliance: Required for regulatory alignment
Moisture Sensitivity Level: MSL 1 (Unlimited) for handling and storage compatibility

Substitute parts are grouped into two categories: direct electrical equivalents from STMicroelectronics (LF253DT) and functionally compatible alternatives from Analog Devices (AD648 and AD706 series). The AD648 series maintains J-FET input characteristics with reduced performance specifications, while the AD706 series represents general-purpose amplifiers with different input stage topology.

Parameter Comparison

Parameter	LF253D	LF253DT	AD648JRZ	AD648JRZ-REEL	AD648JRZ-REEL7	AD648KRZ	AD706ARZ	AD706ARZ-REEL	AD706ARZ-REEL7	AD706JRZ	AD706JRZ-REEL
Amplifier Type	J-FET	J-FET	J-FET	J-FET	J-FET	J-FET	General Purpose	General Purpose	General Purpose	General Purpose	General Purpose
Number of Circuits	2	2	2	2	2	2	2	2	2	2	2
Slew Rate (V/µs)	16	16	1.8	1.8	1.8	1.8	0.15	0.15	0.15	0.15	0.15
Gain Bandwidth Product (MHz)	4	4	1	1	1	1	0.8	0.8	0.8	0.8	0.8
Current - Input Bias (pA)	20	20	5	5	5	3	50	50	50	50	50
Voltage - Input Offset (mV)	3	3	0.75	0.75	0.75	0.3	0.03	0.03	0.03	0.03	0.03
Current - Supply (mA)	1.4	1.4	0.34	0.34	0.34	0.34	0.75	0.75	0.75	0.75	0.75
Current - Output per Channel (mA)	40	40	15	15	15	15	15	15	15	15	15
Voltage - Supply Span Min (V)	6	6	9	9	9	9	4	4	4	4	4
Voltage - Supply Span Max (V)	36	36	36	36	36	36	36	36	36	36	36
Operating Temperature (°C)	-40 to 105	-40 to 105	0 to 70	0 to 70	0 to 70	0 to 70	-40 to 85	-40 to 85	-40 to 85	0 to 70	0 to 70
Package / Case	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitute: LF253DT

The LF253DT from STMicroelectronics is the direct equivalent to the LF253D. This part maintains identical electrical specifications across all critical parameters including slew rate (16V/µs), gain bandwidth product (4 MHz), input bias current (20 pA), and output current capability (40 mA per channel). The LF253DT is manufactured in the same 8-SOIC package and carries active product status with significantly higher inventory availability (72,138 units). Both parts are ROHS3 compliant with MSL 1 rating. The LF253DT is available in Cut Tape and Digi-Reel packaging options, providing supply chain flexibility. This substitution requires no circuit redesign or performance compromise.

Secondary Substitutes: AD648 Series (AD648JRZ, AD648JRZ-REEL, AD648JRZ-REEL7, AD648KRZ)

The AD648 series from Analog Devices represents J-FET input amplifiers with reduced performance specifications. These devices maintain the J-FET input topology, dual-channel configuration, and 8-SOIC package compatibility. However, the AD648 series exhibits lower slew rate (1.8V/µs versus 16V/µs), reduced gain bandwidth product (1 MHz versus 4 MHz), and lower output current capability (15 mA versus 40 mA per channel). The AD648 series requires minimum supply voltage of 9V compared to 6V for the LF253D, restricting operation in lower voltage applications. The AD648KRZ variant offers improved input offset voltage (300 µV) and input bias current (3 pA) specifications. These parts are suitable for applications where the reduced performance specifications are acceptable and where J-FET input characteristics are required.

Tertiary Substitutes: AD706 Series (AD706ARZ, AD706ARZ-REEL, AD706ARZ-REEL7, AD706JRZ, AD706JRZ-REEL)

The AD706 series from Analog Devices represents general-purpose operational amplifiers with different input stage topology. These devices do not employ J-FET input stages and therefore exhibit significantly different input characteristics. The AD706 series shows substantially lower slew rate (0.15V/µs), reduced gain bandwidth product (0.8 MHz), and higher input bias current (50 pA). The AD706 series is suitable only for applications where J-FET input characteristics are not critical and where the reduced performance specifications are acceptable. The AD706ARZ variants support extended operating temperature range (-40°C to 85°C), while AD706JRZ variants operate from 0°C to 70°C.

Compliance and Availability Considerations

All substitute parts maintain ROHS3 compliance and MSL 1 moisture sensitivity rating, ensuring regulatory alignment and handling compatibility with the original LF253D. The LF253DT offers the highest inventory availability and represents the recommended substitution path. The AD648 and AD706 series provide alternative sourcing channels with active product status, supporting long-term supply chain resilience.

Frequently Asked Questions (FAQ)

Q: Can the LF253DT be used as a direct replacement for the LF253D without circuit modification?

A: Yes. The LF253DT is electrically and mechanically identical to the LF253D across all specified parameters. No circuit redesign is required. The primary difference is product status: LF253DT is active with higher availability, while LF253D is obsolete.

Q: What are the key differences between the LF253D and AD648 series?

A: The AD648 series maintains J-FET input topology but exhibits reduced performance: slew rate of 1.8V/µs (versus 16V/µs), gain bandwidth product of 1 MHz (versus 4 MHz), and output current of 15 mA per channel (versus 40 mA). The AD648 requires minimum 9V supply voltage compared to 6V for the LF253D. These differences may impact applications requiring high-speed signal processing or low-voltage operation.

Q: Are the AD706 series parts suitable replacements for the LF253D?

A: The AD706 series represents general-purpose amplifiers with different input stage topology. These parts do not employ J-FET input stages and exhibit significantly reduced performance specifications. The AD706 series is suitable only for applications where J-FET input characteristics are not required and where reduced slew rate (0.15V/µs) and gain bandwidth product (0.8 MHz) are acceptable.

Q: What packaging options are available for substitute parts?

A: All substitute parts are available in 8-SOIC surface mount package with 0.154" (3.90mm) width, matching the LF253D footprint. Packaging variants include Tube, Cut Tape (CT), and Cut Tape with Digi-Reel options. Selection depends on procurement and assembly requirements.

Q: Do all substitute parts meet RoHS3 compliance?

A: Yes. All listed substitute parts are ROHS3 compliant and carry MSL 1 (Unlimited) moisture sensitivity rating, matching the compliance profile of the LF253D.

Q: What is the operating temperature range difference between LF253D and substitute parts?

A: The LF253D operates from -40°C to 105°C. The LF253DT maintains this range. The AD648 series operates from 0°C to 70°C, restricting use in extended temperature applications. The AD706ARZ variants support -40°C to 85°C, while AD706JRZ variants operate from 0°C to 70°C. Application temperature requirements should guide substitution selection.

Q: Which substitute part offers the best supply chain availability?

A: The LF253DT offers the highest inventory availability at 72,138 units in stock, compared to 3,200 units for the obsolete LF253D. This makes LF253DT the recommended substitution for long-term supply chain continuity.

Q: Can the AD648 and AD706 series be used interchangeably?

A: No. The AD648 series employs J-FET input stages while the AD706 series uses general-purpose input stages. These represent different device classes with distinct electrical characteristics. Selection depends on specific application requirements for input impedance, bias current, and frequency response.

Q: What supply voltage range is supported by each substitute part?

A: LF253D and LF253DT support 6V to 36V. AD648 series supports 9V to 36V, restricting operation below 9V. AD706 series supports 4V to 36V, allowing operation at lower voltages. Application supply voltage requirements should guide substitution selection.

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