MAX921ESA Equivalent & Substitute Parts

Part Overview

The MAX921ESA is a comparator with integrated voltage reference manufactured by Analog Devices Inc./Maxim Integrated. This linear IC operates as a single-element comparator with CMOS and TTL output capability in an 8-SOIC surface mount package. The device is currently classified as obsolete, making equivalent and substitute parts necessary for ongoing production and maintenance applications. Active alternatives with compatible electrical and mechanical specifications are available from the same manufacturer family.

Key Parameters

Parameter	MAX921ESA
Manufacturer	Analog Devices Inc./Maxim Integrated
Package / Case	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Output Type	CMOS, TTL
Voltage - Supply, Single/Dual (±)	2.5V ~ 11V, ±1.25V ~ 5.5V
Voltage - Input Offset (Max)	10mV @ 5V
Current - Output (Typ)	50mA
Current - Quiescent (Max)	5µA
CMRR, PSRR (Typ)	80dB CMRR, 80dB PSRR
Propagation Delay (Max)	12µs
Hysteresis	50mV
Operating Temperature	-40°C ~ 85°C
Product Status	Obsolete
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitution for the MAX921ESA is determined by the following critical parameters:

Package compatibility: 8-SOIC surface mount form factor
Output type: CMOS and TTL output capability
Supply voltage range: Minimum 2.5V single supply or ±1.25V dual supply
Input offset voltage: Maximum 10mV @ 5V
Propagation delay: Maximum 12µs
Hysteresis: 50mV fixed
Operating temperature range: -40°C to 85°C
Number of elements: Single comparator with voltage reference

The MAX921ESA+ is a direct equivalent with identical electrical specifications and active product status. The LTC1440 and LTC1540 series represent functional alternatives with compatible core parameters but with variations in quiescent current, propagation delay, and operating temperature ranges. All substitute parts maintain the 8-SOIC package, CMOS/TTL output, and 50mV hysteresis specification.

Parameter Comparison

Part Number	Manufacturer	Package	Output Type	Supply Voltage	Input Offset (Max)	Output Current (Typ)	Quiescent Current (Max)	Propagation Delay (Max)	Operating Temp	Product Status	RoHS Status
MAX921ESA	Analog Devices/Maxim	8-SOIC	CMOS, TTL	2.5V~11V, ±1.25V~5.5V	10mV @ 5V	50mA	5µA	12µs	-40°C ~ 85°C	Obsolete	Non-compliant
MAX921ESA+	Analog Devices/Maxim	8-SOIC	CMOS, TTL	2.5V~11V, ±1.25V~5.5V	10mV @ 5V	50mA	5µA	12µs	-40°C ~ 85°C	Active	ROHS3 Compliant
LTC1440CS8#PBF	Analog Devices	8-SOIC	CMOS, TTL	2V~11V, ±1V~5.5V	10mV @ 5V	40mA	4.4µA	15µs	0°C ~ 70°C	Active	ROHS3 Compliant
LTC1440CS8#TRPBF	Analog Devices	8-SOIC	CMOS, TTL	2V~11V, ±1V~5.5V	10mV @ 5V	40mA	4.4µA	15µs	0°C ~ 70°C	Active	ROHS3 Compliant
LTC1440IS8#PBF	Analog Devices	8-SOIC	CMOS, TTL	2V~11V, ±1V~5.5V	10mV @ 5V	40mA	4.4µA	15µs	-40°C ~ 85°C	Active	ROHS3 Compliant
LTC1440IS8#TRPBF	Analog Devices	8-SOIC	CMOS, TTL	2V~11V, ±1V~5.5V	10mV @ 5V	40mA	4.4µA	15µs	-40°C ~ 85°C	Active	ROHS3 Compliant
LTC1540CS8#PBF	Analog Devices	8-SOIC	CMOS, TTL	2V~11V, ±1V~5.5V	12mV @ 5V	—	680nA	60µs	0°C ~ 70°C	Active	ROHS3 Compliant
LTC1540CS8#TRPBF	Analog Devices	8-SOIC	CMOS, TTL	2V~11V, ±1V~5.5V	12mV @ 5V	—	680nA	60µs	0°C ~ 70°C	Active	ROHS3 Compliant
LTC1540IS8#PBF	Analog Devices	8-SOIC	CMOS, TTL	2V~11V, ±1V~5.5V	12mV @ 5V	—	710nA	60µs	-40°C ~ 85°C	Active	ROHS3 Compliant
LTC1540IS8#TRPBF	Analog Devices	8-SOIC	CMOS, TTL	2V~11V, ±1V~5.5V	12mV @ 5V	—	710nA	60µs	-40°C ~ 85°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Replacement (Preferred): MAX921ESA+ is the primary substitute. It maintains identical electrical specifications and operating temperature range while offering active product status and ROHS3 compliance. This part is suitable for direct board-level substitution without circuit modification.

Alternative Selection - LTC1440 Series: The LTC1440CS8#PBF, LTC1440CS8#TRPBF, LTC1440IS8#PBF, and LTC1440IS8#TRPBF variants are functionally compatible with the MAX921ESA. The LTC1440IS8 variants extend the operating temperature range to -40°C ~ 85°C, matching the original specification. These parts feature slightly reduced output current (40mA vs. 50mA) and increased propagation delay (15µs vs. 12µs). All variants are ROHS3 compliant and actively produced.

Alternative Selection - LTC1540 Series: The LTC1540 family offers ultra-low quiescent current operation (680nA to 710nA) compared to the MAX921ESA (5µA), making it suitable for power-constrained applications. The LTC1540IS8 variants maintain the -40°C ~ 85°C operating temperature range. Trade-offs include increased input offset voltage (12mV vs. 10mV) and extended propagation delay (60µs vs. 12µs). All variants are ROHS3 compliant.

Packaging Considerations: Tube packaging (#PBF suffix) and Tape & Reel packaging (#TRPBF suffix) variants are available for all substitute parts. Selection depends on procurement and assembly requirements. All parts maintain the 8-SOIC surface mount form factor.

Frequently Asked Questions (FAQ)

Q: Can MAX921ESA+ be used as a direct drop-in replacement for MAX921ESA?

A: Yes. The MAX921ESA+ maintains identical electrical specifications, operating temperature range (-40°C ~ 85°C), and 8-SOIC package. The primary difference is product status (active vs. obsolete) and RoHS compliance (ROHS3 vs. non-compliant). No circuit modifications are required.

Q: What are the key differences between LTC1440 and LTC1540 series?

A: The LTC1440 series prioritizes output current capability (40mA typical) and faster propagation delay (15µs maximum). The LTC1540 series emphasizes ultra-low quiescent current (680-710nA maximum) at the expense of higher propagation delay (60µs maximum) and slightly elevated input offset voltage (12mV vs. 10mV). Select LTC1440 for timing-critical applications; select LTC1540 for power-constrained designs.

Q: Are the LTC1440CS8 and LTC1440IS8 variants interchangeable?

A: The CS8 variant operates from 0°C ~ 70°C, while the IS8 variant operates from -40°C ~ 85°C. Both share identical electrical specifications. Select IS8 for applications requiring the full -40°C ~ 85°C temperature range. Both are available in Tube (#PBF) and Tape & Reel (#TRPBF) packaging.

Q: What is the difference between #PBF and #TRPBF packaging suffixes?

A: #PBF denotes Tube packaging for manual handling and smaller quantity orders. #TRPBF denotes Tape & Reel packaging for automated assembly and higher volume production. Electrical specifications are identical; selection depends on assembly process requirements.

Q: Can LTC1540 replace MAX921ESA in all applications?

A: LTC1540 is functionally compatible but exhibits different timing characteristics. The 60µs propagation delay (vs. 12µs for MAX921ESA) makes LTC1540 unsuitable for high-speed comparison applications. LTC1540 is optimal for low-power, non-time-critical comparator functions. Verify propagation delay requirements before substitution.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts listed (MAX921ESA+, LTC1440 series, LTC1540 series) are ROHS3 compliant. The original MAX921ESA is RoHS non-compliant. Compliance status should be verified against specific procurement requirements.

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