EL2125CS Equivalent & Substitute Parts

Part Overview

The EL2125CS is a voltage feedback amplifier integrated circuit manufactured by Renesas Electronics Corporation, housed in an 8-SOIC surface mount package. This device is classified as obsolete, indicating it is no longer in active production. The EL2125CS operates as a single-circuit voltage feedback amplifier with a slew rate of 185V/µs and -3dB bandwidth of 220 MHz, designed for applications requiring moderate-speed signal amplification across a wide supply voltage range of 5V to 30V.

Due to its obsolete status, locating replacement units from original inventory becomes increasingly difficult. Identifying equivalent substitute parts ensures design continuity and maintains supply chain reliability for applications currently utilizing the EL2125CS.

Key Parameters

Parameter	Value	Unit
Amplifier Type	Voltage Feedback	—
Number of Circuits	1	—
Slew Rate	185	V/µs
-3dB Bandwidth	220	MHz
Current - Input Bias	22	µA
Voltage - Input Offset	600	µV
Current - Supply	10.8	mA
Current - Output / Channel	250	mA
Voltage - Supply Span (Min)	5	V
Voltage - Supply Span (Max)	30	V
Operating Temperature Range	-45 to 85	°C
Package / Case	8-SOIC (0.154", 3.90mm Width)	—
Mounting Type	Surface Mount	—
RoHS Status	RoHS non-compliant	—

Substitute Part Grouping Explanation

Substitute parts for the EL2125CS are identified based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Critical Matching Criteria:

Amplifier Type: Voltage Feedback (single circuit configuration)
Package / Case: 8-SOIC surface mount form factor
Mounting Type: Surface Mount
Supply Voltage Range: Minimum 5V to Maximum 30V compatibility
Operating Temperature Range: Coverage of -45°C to 85°C or equivalent industrial range

Secondary Performance Parameters:

Slew Rate: 185V/µs or greater
-3dB Bandwidth: 220 MHz or greater
Input Bias Current: 22 µA or lower
Output Current Capability: 250 mA or greater

Substitute parts are grouped into two categories based on performance alignment:

Group 1 - Higher Performance Substitutes (LM7121 Series): These parts exceed the EL2125CS specifications in slew rate (1300V/µs) and bandwidth (235 MHz), with lower input bias current (5.2 µA) and improved supply current efficiency (5.3 mA). These are suitable for applications where enhanced performance is beneficial.

Group 2 - Comparable Performance Substitutes (THS4031 Series): These parts provide similar or slightly lower performance characteristics with reduced slew rate (100V/µs) and bandwidth (100 MHz). These are suitable for applications where the EL2125CS performance envelope is not fully utilized.

Parameter Comparison

Parameter	EL2125CS	LM7121IM/NOPB	LM7121IMX/NOPB	THS4031CD	THS4031CDR	THS4031ID	THS4031IDR
Manufacturer	Renesas	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments
Amplifier Type	Voltage Feedback	Voltage Feedback	Voltage Feedback	Voltage Feedback	Voltage Feedback	Voltage Feedback	Voltage Feedback
Number of Circuits	1	1	1	1	1	1	1
Slew Rate (V/µs)	185	1300	1300	100	100	100	100
-3dB Bandwidth (MHz)	220	235	235	100	100	100	100
Current - Input Bias (µA)	22	5.2	5.2	3	3	3	3
Voltage - Input Offset (µV)	600	900	900	500	500	500	500
Current - Supply (mA)	10.8	5.3	5.3	8.5	8.5	8.5	8.5
Current - Output / Channel (mA)	250	71	71	90	90	—	90
Voltage - Supply Span Min (V)	5	4.5	4.5	9	9	9	9
Voltage - Supply Span Max (V)	30	33	33	32	32	32	32
Operating Temperature (°C)	-45 to 85	-40 to 85	-40 to 85	0 to 70	0 to 70	-40 to 85	-40 to 85
Package / Case	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC
Product Status	Obsolete	Active	Active	Last Time Buy	Obsolete	Last Time Buy	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Active Production and New Designs:

The THS4031IDR is the recommended primary substitute. This part maintains active product status with ROHS3 compliance, ensuring long-term availability and regulatory alignment. The THS4031IDR operates within the extended temperature range (-40°C to 85°C), matching the EL2125CS operational envelope. While the slew rate (100V/µs) and bandwidth (100 MHz) are lower than the original part, these specifications remain suitable for applications not requiring the full performance envelope of the EL2125CS.

The LM7121IMX/NOPB provides an alternative with enhanced performance characteristics and active status. This part offers superior slew rate (1300V/µs) and bandwidth (235 MHz), with lower supply current consumption (5.3 mA). The LM7121IMX/NOPB is appropriate for applications where improved performance margins are desired or where the design can benefit from higher-speed operation.

For Existing Inventory Replacement:

The LM7121IM/NOPB offers equivalent performance to the LM7121IMX/NOPB with active product status and ROHS3 compliance. Both LM7121 variants provide superior electrical performance compared to the THS4031 series.

For Legacy System Support:

The THS4031ID maintains active status with extended temperature range coverage (-40°C to 85°C) and ROHS3 compliance, providing a path for legacy system maintenance where the lower performance envelope is acceptable.

Compliance Considerations:

All recommended substitutes are ROHS3 compliant, addressing regulatory requirements that the original EL2125CS does not meet. This compliance status is essential for applications subject to environmental regulations or customer requirements.

Frequently Asked Questions (FAQ)

Q: Can the LM7121IMX/NOPB directly replace the EL2125CS in existing designs?

A: The LM7121IMX/NOPB is mechanically compatible (8-SOIC package) and electrically compatible within the supply voltage range (4.5V to 33V encompasses the EL2125CS 5V to 30V range). However, the LM7121IMX/NOPB exhibits significantly higher slew rate (1300V/µs versus 185V/µs) and bandwidth (235 MHz versus 220 MHz). Designs must be evaluated to confirm that the enhanced performance does not introduce stability issues or require circuit modifications. The lower input bias current (5.2 µA versus 22 µA) may also affect biasing networks in some applications.

Q: What is the difference between THS4031CD, THS4031CDR, THS4031ID, and THS4031IDR?

A: These parts share identical electrical specifications but differ in product status and operating temperature range. The THS4031ID and THS4031IDR support the extended temperature range (-40°C to 85°C), matching the EL2125CS. The THS4031CD and THS4031CDR operate only from 0°C to 70°C. Additionally, THS4031IDR maintains active product status, while THS4031ID is Last Time Buy and THS4031CDR is obsolete. For new designs, THS4031IDR is the preferred choice.

Q: Why does the THS4031 series have lower bandwidth than the EL2125CS?

A: The THS4031 series is a different amplifier design with different performance characteristics. The 100 MHz bandwidth and 100V/µs slew rate represent a different performance class. Selection between the THS4031 and LM7121 series depends on application requirements. Applications not requiring the full 220 MHz bandwidth of the EL2125CS can utilize the THS4031 series effectively.

Q: Are all substitute parts RoHS compliant?

A: Yes, all recommended substitute parts are ROHS3 compliant. The original EL2125CS is RoHS non-compliant. This compliance difference is significant for applications subject to environmental regulations or customer requirements mandating RoHS compliance.

Q: What is the impact of the lower output current capability in the LM7121 series?

A: The LM7121 series provides 71 mA output current per channel, compared to 250 mA for the EL2125CS. Applications requiring the full 250 mA output current capability cannot use the LM7121 series. The THS4031 series provides 90 mA output current, which is also lower than the EL2125CS but higher than the LM7121 series. Output current requirements must be evaluated against application load specifications.

Q: Can the THS4031 series be used in applications designed for the EL2125CS?

A: The THS4031 series is mechanically and electrically compatible in terms of package and basic supply voltage requirements. However, the significantly lower bandwidth (100 MHz versus 220 MHz) and slew rate (100V/µs versus 185V/µs) may not be suitable for all applications. Applications operating near the performance limits of the EL2125CS should use the LM7121 series instead. Circuit simulation or testing is necessary to confirm suitability for specific applications.

Q: What is the significance of "Last Time Buy" status?

A: Parts designated as Last Time Buy (THS4031CD, THS4031ID) indicate that the manufacturer will discontinue production after a specified date. These parts should not be selected for new designs. For existing designs currently using these parts, transition to active-status alternatives (THS4031IDR or LM7121 series) should be planned.

Q: How do the supply voltage ranges compare?

A: The EL2125CS operates from 5V to 30V. The LM7121 series operates from 4.5V to 33V, providing slightly wider range coverage. The THS4031 series operates from 9V to 32V, which does not cover the 5V minimum of the EL2125CS. Applications requiring 5V operation cannot use the THS4031 series and must select the LM7121 series or confirm that higher minimum voltage is acceptable.

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