LM7121IM5X Equivalent & Substitute Parts

Part Overview

The LM7121IM5X is a voltage feedback operational amplifier manufactured by Texas Instruments, housed in a SOT-23-5 surface mount package. This device is classified as obsolete, necessitating identification of equivalent and substitute components for ongoing design requirements and production continuity. The LM7121IM5X delivers a gain bandwidth product of 175 MHz with a slew rate of 1300 V/µs, operating across a supply voltage range of 4.5 V to 33 V and a temperature range of -40°C to 85°C.

Key Parameters

Parameter	Value	Unit
Amplifier Type	Voltage Feedback	—
Number of Circuits	1	—
Slew Rate	1300	V/µs
Gain Bandwidth Product	175	MHz
-3dB Bandwidth	235	MHz
Current - Input Bias	5.2	µA
Voltage - Input Offset	900	µV
Current - Supply	5.3	mA
Current - Output / Channel	71	mA
Voltage - Supply Span (Min)	4.5	V
Voltage - Supply Span (Max)	33	V
Operating Temperature	-40 to 85	°C
Mounting Type	Surface Mount	—
Package / Case	SC-74A, SOT-753	—
Supplier Device Package	SOT-23-5	—
Product Status	Obsolete	—
RoHS Status	RoHS non-compliant	—

Substitute Part Grouping Explanation

Substitution of the LM7121IM5X is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Amplifier Type: Voltage Feedback (single circuit)
Supply voltage range compatibility
Slew rate and gain bandwidth product performance envelope
Input bias current and input offset voltage specifications
Output current capability
Operating temperature range

Mechanical Compatibility Criteria:

Surface mount packaging in SOT-23-5 form factor
Pin configuration compatibility (SC-74A, SOT-753)

Substitution Categories:

Direct Manufacturer Equivalent (LM7121IM5X/NOPB): Texas Instruments part with identical base product number and packaging. Electrical parameters differ in slew rate (520 V/µs vs. 1300 V/µs), gain bandwidth product (105 MHz vs. 175 MHz), and maximum supply voltage (11 V vs. 33 V). Product status is Active with RoHS3 compliance.

Parametric Equivalent (LM7121IM5): National Semiconductor part with identical electrical specifications to the main part. Maintains 1300 V/µs slew rate, 175 MHz gain bandwidth product, and 33 V maximum supply voltage. Supplied in bulk packaging. REACH status differs (Affected vs. Unaffected).

Manufacturer Recommended Substitutes (LT1815 Series): Analog Devices LT1815CS5#TR, LT1815CS5#TRMPBF, and LT1815IS5#TRMPBF represent enhanced performance alternatives. These devices feature higher slew rate (1500 V/µs), higher gain bandwidth product (220 MHz), lower input offset voltage (200 µV vs. 900 µV), and lower input bias current (2 µA vs. 5.2 µA). All are RoHS3 compliant and Active status. Operating temperature range differs: LT1815CS5 variants operate 0°C to 70°C; LT1815IS5#TRMPBF operates -40°C to 85°C. Minimum supply voltage is 2.5 V; maximum is 11 V.

Parameter Comparison

Parameter	LM7121IM5X	LM7121IM5X/NOPB	LM7121IM5	LT1815CS5#TR	LT1815CS5#TRMPBF	LT1815CS5#TRPBF	LT1815IS5#TRMPBF
Manufacturer	Texas Instruments	Texas Instruments	National Semiconductor	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.
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)	1300	520	1300	1500	1500	1500	1500
Gain Bandwidth Product (MHz)	175	105	175	220	220	220	220
-3dB Bandwidth (MHz)	235	160	235	350	350	350	350
Current - Input Bias (µA)	5.2	5.5	5.2	2	2	2	2
Voltage - Input Offset (µV)	900	1600	900	200	200	200	200
Current - Supply (mA)	5.3	5.1	5.3	6.5	6.5	6.5	6.5
Current - Output / Channel (mA)	71	—	71	80	80	80	80
Voltage - Supply Span Min (V)	4.5	4.5	4.5	2.5	2.5	2.5	2.5
Voltage - Supply Span Max (V)	33	11	33	11	11	11	11
Operating Temperature (°C)	-40 to 85	-40 to 85	-40 to 85	0 to 70	0 to 70	0 to 70	-40 to 85
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	SC-74A, SOT-753	SC-74A, SOT-753	SC-74A, SOT-753	SOT-23-5 Thin, TSOT-23-5	SOT-23-5 Thin, TSOT-23-5	SOT-23-5 Thin, TSOT-23-5	SOT-23-5 Thin, TSOT-23-5
Supplier Device Package	SOT-23-5	SOT-23-5	SOT-23-5	TSOT-23-5	TSOT-23-5	TSOT-23-5	TSOT-23-5
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Packaging Type	—	Tape & Reel (TR)	Bulk	—	Tape & Reel (TR)	Tape & Reel (TR)	Tape & Reel (TR)

Engineering Selection Recommendations

For Direct Replacement with Active Product Status:

The LM7121IM5X/NOPB maintains the same base product number and packaging footprint. However, this variant exhibits reduced electrical performance: slew rate decreases to 520 V/µs (60% reduction), gain bandwidth product reduces to 105 MHz (40% reduction), and maximum supply voltage limits to 11 V (versus 33 V). Selection of this part requires confirmation that the reduced performance envelope meets circuit requirements. This part is RoHS3 compliant and Active status.

For Parametric Equivalence:

The LM7121IM5 (National Semiconductor) provides identical electrical specifications to the main part, maintaining 1300 V/µs slew rate, 175 MHz gain bandwidth product, and 33 V maximum supply voltage. This part is Active status but RoHS non-compliant. REACH status is Affected. Bulk packaging is supplied.

For Enhanced Performance with Full Compliance:

The LT1815 series (Analog Devices) represents manufacturer-recommended substitutes with superior electrical performance and full RoHS3 compliance. All variants feature 1500 V/µs slew rate, 220 MHz gain bandwidth product, 350 MHz -3dB bandwidth, and significantly lower input offset voltage (200 µV versus 900 µV) and input bias current (2 µA versus 5.2 µA). Maximum supply voltage is limited to 11 V.

Temperature Range Considerations:

LT1815CS5#TR, LT1815CS5#TRMPBF, LT1815CS5#TRPBF: Operating range 0°C to 70°C. Not suitable for applications requiring -40°C operation.
LT1815IS5#TRMPBF: Operating range -40°C to 85°C. Maintains full temperature compatibility with the original LM7121IM5X.

Supply Voltage Considerations:

Applications requiring supply voltages above 11 V cannot use LT1815 variants or LM7121IM5X/NOPB. The LM7121IM5 (National Semiconductor) or original LM7121IM5X support up to 33 V supply voltage.

Compliance Requirements:

For new designs or production requiring RoHS3 compliance, the LT1815 series or LM7121IM5X/NOPB are suitable. The original LM7121IM5X and LM7121IM5 are RoHS non-compliant.

Frequently Asked Questions (FAQ)

Q: Can the LM7121IM5X/NOPB be used as a direct drop-in replacement?

A: The LM7121IM5X/NOPB shares identical packaging (SOT-23-5) and pin configuration, enabling physical substitution. However, electrical performance differs significantly. Slew rate is 520 V/µs (versus 1300 V/µs), gain bandwidth product is 105 MHz (versus 175 MHz), and maximum supply voltage is 11 V (versus 33 V). Circuit validation is required to confirm performance adequacy.

Q: What is the primary advantage of LT1815 series substitutes?

A: The LT1815 series provides enhanced electrical performance with 1500 V/µs slew rate and 220 MHz gain bandwidth product. Input offset voltage is significantly lower at 200 µV (versus 900 µV), and input bias current is 2 µA (versus 5.2 µA). All variants are RoHS3 compliant and Active status. Trade-off is maximum supply voltage limited to 11 V.

Q: Which substitute is suitable for -40°C to 85°C operation?

A: The LT1815IS5#TRMPBF maintains the full -40°C to 85°C operating temperature range. The LT1815CS5 variants (LT1815CS5#TR, LT1815CS5#TRMPBF, LT1815CS5#TRPBF) operate only 0°C to 70°C and are unsuitable for extended low-temperature applications.

Q: Are all substitutes available in Tape & Reel packaging?

A: The LM7121IM5X/NOPB and all LT1815 variants are supplied in Tape & Reel (TR) packaging. The LM7121IM5 is supplied in bulk packaging only.

Q: What is the difference between LT1815CS5#TRMPBF and LT1815CS5#TRPBF?

A: Both parts are electrically identical with identical specifications. The difference is in packaging designation suffix. Both are supplied in Tape & Reel format and are RoHS3 compliant. Electrical performance, temperature range (0°C to 70°C), and supply voltage specifications are identical.

Q: Can the LM7121IM5 be used in applications requiring RoHS compliance?

A: No. The LM7121IM5 is RoHS non-compliant. For RoHS3 compliance, use LM7121IM5X/NOPB or any LT1815 variant.

Q: What is the impact of supply voltage limitation in LT1815 substitutes?

A: LT1815 series maximum supply voltage is 11 V, compared to 33 V for the original LM7121IM5X. Applications requiring supply voltages above 11 V cannot use LT1815 variants. In such cases, the LM7121IM5 (National Semiconductor) maintains 33 V maximum supply voltage with identical electrical specifications to the original part.

Q: Are there packaging footprint differences between SOT-23-5 and TSOT-23-5?

A: Both are surface mount packages with identical pin configuration and footprint compatibility. TSOT-23-5 designates a thin variant. Physical substitution on PCB layouts is compatible.

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