LM2661M/NOPB Equivalent & Substitute Parts

Part Overview

The LM2661M/NOPB is a charge pump switching regulator IC manufactured by Texas Instruments, designed for power management applications requiring positive or negative fixed output voltage conversion. This device operates as a ratiometric regulator with a single output capable of delivering 100mA across input voltage ranges of 1.5V to 5.5V. The part is classified as obsolete, necessitating identification of active equivalent alternatives for new designs and ongoing production requirements.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Category	Power Management (PMIC)
Topology	Charge Pump
Output Configuration	Positive or Negative
Number of Outputs	1
Voltage - Input (Min)	1.5V
Voltage - Input (Max)	5.5V
Voltage - Output (Min/Fixed)	-Vin, 2Vin, Vin/2
Current - Output	100mA
Frequency - Switching	5kHz, 40kHz
Operating Temperature	-40°C ~ 85°C (TA)
Package / Case	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the LM2661M/NOPB is determined by strict alignment with the following critical parameters:

Primary Substitution Criteria:

Package / Case: 8-SOIC (0.154", 3.90mm Width)
Mounting Type: Surface Mount
Topology: Charge Pump
Output Configuration: Positive or Negative
Number of Outputs: 1
Voltage - Input Range: 1.5V to 5.5V
Current - Output: 100mA
RoHS Status: ROHS3 Compliant

Secondary Compatibility Factors:

Voltage - Output (Min/Fixed): Must support -Vin and 2Vin at minimum
Operating Temperature Range: Extended range (-40°C ~ 85°C) preferred for industrial applications
Switching Frequency: 5kHz to 80kHz acceptable range

The substitute parts identified below meet all primary criteria. Variations in switching frequency and output voltage options (Vin/2 availability) are noted in the parameter comparison table.

Parameter Comparison

Parameter	LM2661M/NOPB	LM2660M/NOPB	MAX660CSA+	MAX660CSA+T	MAX660ESA+	MAX660ESA+T
Manufacturer	Texas Instruments	Texas Instruments	Analog Devices Inc./Maxim Integrated	Analog Devices Inc./Maxim Integrated	Analog Devices Inc./Maxim Integrated	Analog Devices Inc./Maxim Integrated
Product Status	Obsolete	Active	Active	Active	Active	Active
Voltage - Input (Min)	1.5V	1.5V	1.5V	1.5V	1.5V	1.5V
Voltage - Input (Max)	5.5V	5.5V	5.5V	5.5V	5.5V	5.5V
Voltage - Output (Min/Fixed)	-Vin, 2Vin, Vin/2	-Vin, 2Vin, Vin/2	-Vin, 2Vin	-Vin, 2Vin	-Vin, 2Vin	-Vin, 2Vin
Current - Output	100mA	100mA	100mA	100mA	100mA	100mA
Frequency - Switching	5kHz, 40kHz	5kHz, 40kHz	10kHz, 80kHz	10kHz, 80kHz	10kHz, 80kHz	10kHz, 80kHz
Operating Temperature	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TJ)	0°C ~ 70°C (TA)	0°C ~ 70°C (TA)	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TA)
Package / Case	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Packaging Option	-	Tube	Tube	Cut Tape (CT) & Digi-Reel®	Tube	Cut Tape (CT) & Digi-Reel®
Inventory Availability	3020 Pcs	2356 Pcs	1410 Pcs	12700 Pcs	7051 Pcs	25440 Pcs

Engineering Selection Recommendations

Primary Recommendation: LM2660M/NOPB

The LM2660M/NOPB from Texas Instruments is the direct active equivalent to the obsolete LM2661M/NOPB. This part maintains identical electrical specifications including switching frequency (5kHz, 40kHz), output voltage options (-Vin, 2Vin, Vin/2), and operating temperature range (-40°C ~ 85°C). Both parts share the same base product number lineage and package configuration. The LM2660M/NOPB is classified as active with 2356 units in stock, making it the preferred substitution path for designs currently using the LM2661M/NOPB.

Secondary Recommendations: MAX660 Series (Analog Devices Inc./Maxim Integrated)

The MAX660 family provides functional equivalence with the following considerations:

MAX660ESA+ and MAX660ESA+T: These variants support the full operating temperature range (-40°C ~ 85°C) matching the LM2661M/NOPB. The MAX660ESA+T offers the highest inventory availability (25440 units) with Cut Tape and Digi-Reel packaging options. Switching frequency operates at 10kHz and 80kHz, which differs from the original 5kHz and 40kHz specification but remains within acceptable charge pump regulator operating ranges.
MAX660CSA+ and MAX660CSA+T: These variants operate within a restricted temperature range (0°C ~ 70°C), limiting their applicability to designs not requiring extended temperature performance. Selection of these parts is appropriate only for applications with ambient temperature constraints within this range.

Key Differentiation: All MAX660 variants support -Vin and 2Vin output configurations but do not include the Vin/2 option available on the LM2661M/NOPB and LM2660M/NOPB. Designs dependent on Vin/2 output must use the LM2660M/NOPB.

Compliance Status: All recommended substitutes maintain ROHS3 compliance and MSL Level 1 (Unlimited) moisture sensitivity rating, ensuring compatibility with standard manufacturing and storage protocols.

Frequently Asked Questions (FAQ)

Q: Can the MAX660 series directly replace the LM2661M/NOPB in all applications?

A: The MAX660 series provides functional equivalence for applications requiring -Vin and 2Vin output configurations. However, designs utilizing the Vin/2 output option must use the LM2660M/NOPB, as MAX660 variants do not support this output ratio. Additionally, MAX660CSA+ and MAX660CSA+T variants are limited to 0°C ~ 70°C operation and are unsuitable for applications requiring -40°C ~ 85°C performance.

Q: What is the difference between MAX660ESA+ and MAX660ESA+T?

A: Both parts are electrically identical. The primary difference is packaging: MAX660ESA+ is supplied in Tube format, while MAX660ESA+T is supplied in Cut Tape (CT) and Digi-Reel format. Selection depends on assembly line requirements and inventory management preferences. The MAX660ESA+T offers significantly higher stock availability (25440 units versus 7051 units).

Q: Are there switching frequency implications when substituting with MAX660 variants?

A: The LM2661M/NOPB operates at 5kHz and 40kHz switching frequencies, while MAX660 variants operate at 10kHz and 80kHz. Both frequency ranges are standard for charge pump regulators and do not affect functional compatibility. Higher switching frequencies in the MAX660 may result in reduced EMI in some applications but require verification of PCB layout and filtering adequacy for specific designs.

Q: Is the LM2660M/NOPB a complete drop-in replacement?

A: Yes. The LM2660M/NOPB is the active equivalent of the obsolete LM2661M/NOPB with identical electrical specifications, package configuration, and output voltage options. No design modifications are required for substitution.

Q: What packaging options are available for high-volume production?

A: For high-volume assembly, the MAX660ESA+T in Cut Tape and Digi-Reel format is recommended, offering the highest inventory availability (25440 units) and compatibility with automated tape-and-reel handling systems. The LM2660M/NOPB is available in Tube packaging (2356 units).

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All recommended substitutes—LM2660M/NOPB, MAX660CSA+, MAX660CSA+T, MAX660ESA+, and MAX660ESA+T—are ROHS3 compliant with MSL Level 1 (Unlimited) moisture sensitivity rating, meeting standard environmental and regulatory requirements.

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