MAX921CUA-T Equivalent & Substitute Parts

Part Overview

The MAX921CUA-T 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-uMAX/uSOP surface mount package. The device is classified as obsolete, making equivalent and substitute parts necessary for ongoing production and maintenance applications. Active alternatives from the same manufacturer family provide functional equivalence with enhanced availability and extended temperature range options.

Key Parameters

Parameter	MAX921CUA-T
Manufacturer	Analog Devices Inc./Maxim Integrated
Product Status	Obsolete
Package / Case	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
Supplier Device Package	8-uMAX/uSOP
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	0°C ~ 70°C
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the MAX921CUA-T is determined by the following critical parameters:

Package compatibility: 8-TSSOP/8-MSOP form factor with 0.118" (3.00mm) width
Output type: CMOS and TTL output capability
Voltage supply range: Minimum 2.5V single supply or ±1.25V dual supply operation
Input offset voltage: Maximum 10mV at 5V
Hysteresis: 50mV fixed
Propagation delay: Maximum 12µs
Quiescent current: Maximum 5µA
Compliance: ROHS3, MSL 1, REACH Unaffected

Substitute parts are grouped into two categories:

Direct Package Equivalent (8-uMAX/uSOP): MAX921CUA+T maintains identical electrical specifications and packaging, differing only in product status (Active vs. Obsolete) and packaging format (Tape & Reel).

Functional Equivalents (8-MSOP Package): LTC1440 and LTC1540 series parts provide comparable comparator functionality within the same 8-MSOP package footprint. These parts operate within overlapping voltage supply ranges and maintain the required 50mV hysteresis and CMOS/TTL output types. Differences in propagation delay, quiescent current, and temperature range are documented for application-specific evaluation.

Parameter Comparison

Parameter	MAX921CUA-T	MAX921CUA+T	LTC1440CMS8#PBF	LTC1440CMS8#TRPBF	LTC1440IMS8#PBF	LTC1440IMS8#TRPBF	LTC1540CMS8#PBF	LTC1540CMS8#TRPBF	LTC1540IMS8#PBF	LTC1540IMS8#TRPBF
Manufacturer	Analog Devices Inc./Maxim Integrated	Analog Devices Inc./Maxim Integrated	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active	Active
Package / Case	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP
Supplier Device Package	8-uMAX/uSOP	8-uMAX/uSOP	8-MSOP	8-MSOP	8-MSOP	8-MSOP	8-MSOP	8-MSOP	8-MSOP	8-MSOP
Output Type	CMOS, TTL	CMOS, TTL	CMOS, TTL	CMOS, TTL	CMOS, TTL	CMOS, TTL	CMOS, TTL	CMOS, TTL	CMOS, TTL	CMOS, TTL
Voltage - Supply, Single/Dual (±)	2.5V ~ 11V, ±1.25V ~ 5.5V	2.5V ~ 11V, ±1.25V ~ 5.5V	2V ~ 11V, ±1V ~ 5.5V	2V ~ 11V, ±1V ~ 5.5V	2V ~ 11V, ±1V ~ 5.5V	2V ~ 11V, ±1V ~ 5.5V	2V ~ 11V, ±1V ~ 5.5V	2V ~ 11V, ±1V ~ 5.5V	2V ~ 11V, ±1V ~ 5.5V	2V ~ 11V, ±1V ~ 5.5V
Voltage - Input Offset (Max)	10mV @ 5V	10mV @ 5V	10mV @ 5V	10mV @ 5V	10mV @ 5V	10mV @ 5V	12mV @ 5V	12mV @ 5V	12mV @ 5V	12mV @ 5V
Current - Output (Typ)	50mA	50mA	40mA	40mA	40mA	40mA	—	—	—	—
Current - Quiescent (Max)	5µA	5µA	4.4µA	4.4µA	4.4µA	4.4µA	680nA	680nA	710nA	710nA
CMRR, PSRR (Typ)	80dB CMRR, 80dB PSRR	80dB CMRR, 80dB PSRR	80dB CMRR, 80dB PSRR	80dB CMRR, 80dB PSRR	80dB CMRR, 80dB PSRR	80dB CMRR, 80dB PSRR	80dB CMRR, 80dB PSRR	80dB CMRR, 80dB PSRR	80dB CMRR, 80dB PSRR	80dB CMRR, 80dB PSRR
Propagation Delay (Max)	12µs	12µs	15µs	15µs	15µs	15µs	60µs	60µs	60µs	60µs
Hysteresis	50mV	50mV	50mV	50mV	50mV	50mV	50mV	50mV	50mV	50mV
Operating Temperature	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C	0°C ~ 70°C	0°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	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	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitute: MAX921CUA+T

The MAX921CUA+T is the direct equivalent to MAX921CUA-T with identical electrical specifications and package dimensions. This part is Active status with current manufacturing availability. Selection of MAX921CUA+T eliminates all technical compatibility concerns and maintains exact performance characteristics. Packaging format differs (Tape & Reel vs. standard packaging), which may affect procurement logistics but not functional performance.

Secondary Substitutes: LTC1440 Series

The LTC1440CMS8#PBF, LTC1440CMS8#TRPBF, LTC1440IMS8#PBF, and LTC1440IMS8#TRPBF parts provide functional equivalence with the following considerations:

Voltage supply range expands to 2V minimum (vs. 2.5V), providing broader operational flexibility
Propagation delay increases to 15µs maximum (vs. 12µs), acceptable for non-critical timing applications
Output current reduces to 40mA typical (vs. 50mA), requiring load impedance verification
Quiescent current improves to 4.4µA maximum (vs. 5µA)
Industrial temperature variants (LTC1440IMS8#PBF, LTC1440IMS8#TRPBF) extend operating range to -40°C ~ 85°C

Tertiary Substitutes: LTC1540 Series

The LTC1540CMS8#PBF, LTC1540CMS8#TRPBF, LTC1540IMS8#PBF, and LTC1540IMS8#TRPBF parts offer ultra-low quiescent current operation (680nA to 710nA) at the cost of significantly increased propagation delay (60µs maximum). These parts are suitable for battery-powered or low-power applications where timing constraints permit the extended delay. Input offset voltage increases to 12mV maximum. Industrial temperature variants extend operating range to -40°C ~ 85°C.

All substitute parts maintain ROHS3 compliance, MSL 1 rating, and REACH Unaffected status, ensuring regulatory alignment with the original MAX921CUA-T specification.

Frequently Asked Questions (FAQ)

Q: Can MAX921CUA+T be used as a direct replacement for MAX921CUA-T?

A: Yes. MAX921CUA+T is electrically and mechanically identical to MAX921CUA-T. The only difference is product status (Active vs. Obsolete) and packaging format (Tape & Reel). No circuit modifications are required.

Q: What is the primary difference between LTC1440 and LTC1540 series?

A: The LTC1540 series features significantly lower quiescent current (680-710nA vs. 4.4µA) but exhibits much longer propagation delay (60µs vs. 15µs). LTC1440 is preferred for timing-sensitive applications; LTC1540 is preferred for power-constrained applications.

Q: Are LTC1440 and LTC1540 parts pin-compatible with MAX921CUA-T?

A: All parts share the same 8-pin MSOP/TSSOP package footprint and pinout. Physical board-level compatibility is confirmed. Electrical performance differences must be evaluated for specific application requirements.

Q: What does the temperature grade designation mean (C vs. I)?

A: The "C" grade operates 0°C ~ 70°C (commercial); the "I" grade operates -40°C ~ 85°C (industrial). Select based on application environment requirements.

Q: What is the difference between tube and tape & reel packaging?

A: Tube packaging is manual handling format; Tape & Reel (TR) is automated assembly format. Both contain identical components. Selection depends on manufacturing process requirements.

Q: Can LTC1540 be used in applications requiring 12µs propagation delay?

A: No. LTC1540 maximum propagation delay is 60µs, which exceeds the MAX921CUA-T specification of 12µs. LTC1440 with 15µs maximum delay is the appropriate choice for timing-critical applications.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance, MSL 1 rating, and REACH Unaffected status, matching the original MAX921CUA-T regulatory requirements.

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