LM385Z-1.2/LFT4 Equivalent & Substitute Parts

Part Overview

The LM385Z-1.2/LFT4 is a shunt voltage reference IC manufactured by Texas Instruments, designed for precision voltage reference applications requiring a fixed 1.235V output. This through-hole component operates across the 0°C to 70°C temperature range and delivers 20 mA output current with ±2.43%/+2.02% tolerance. The part is Active status and ROHS3 compliant, making it suitable for modern electronic designs. Substitute parts are identified when equivalent electrical performance and mechanical compatibility are maintained within the specified parameter ranges.

Key Parameters

Parameter	Value
Reference Type	Shunt
Output Type	Fixed
Voltage - Output (Min/Fixed)	1.235V
Current - Output	20 mA
Tolerance	-2.43%, +2.02%
Temperature Coefficient	150ppm/°C
Noise - 10Hz to 10kHz	60µVrms
Current - Cathode	15 µA
Operating Temperature	0°C ~ 70°C (TA)
Mounting Type	Through Hole
Package / Case	TO-92-3 (TO-226AA)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the LM385Z-1.2/LFT4 are classified based on strict adherence to the following electrical and mechanical parameters:

Critical Matching Parameters:

Reference Type: Shunt
Output Type: Fixed
Voltage - Output: 1.235V
Current - Output: 20 mA
Package / Case: TO-92-3 (TO-226AA)
Mounting Type: Through Hole
RoHS Status: ROHS3 Compliant

Allowable Variation Parameters:

Tolerance: Must accommodate the original specification range or tighter
Temperature Coefficient: Lower values indicate improved stability
Current - Cathode: Variations within operational limits
Operating Temperature: Must support at minimum the original range

Parts are grouped into three categories: Parametric Equivalent (identical electrical specifications), Direct Manufacturer (functionally equivalent with minor parameter variations), and Manufacturer Recommended (enhanced performance alternatives).

Parameter Comparison

Parameter	LM385Z-1.2/LFT4 (Main)	LM385Z-1.2/LFT3	LM385Z-1.2RPG	LM285Z-1.2RAG	LM385BZ-1.2RAG	LT1004CZ-1.2#TRPBF
Manufacturer	Texas Instruments	Texas Instruments	onsemi	onsemi	onsemi	Analog Devices Inc.
Reference Type	Shunt	Shunt	Shunt	Shunt	Shunt	Shunt
Output Type	Fixed	Fixed	Fixed	Fixed	Fixed	Fixed
Voltage - Output	1.235V	1.235V	1.235V	1.235V	1.235V	1.235V
Current - Output	20 mA	20 mA	20 mA	20 mA	20 mA	20 mA
Tolerance	-2.43%, +2.02%	-2.43%, +2.02%	-2.4%, +2.01%	±1%	±1%	±0.03%
Temperature Coefficient	150ppm/°C	150ppm/°C	80ppm/°C Typical	80ppm/°C Typical	80ppm/°C Typical	20ppm/°C Typical
Noise - 10Hz to 10kHz	60µVrms	60µVrms	60µVrms	60µVrms	60µVrms	60µVrms
Current - Cathode	15 µA	15 µA	20 µA	20 µA	20 µA	10 µA
Operating Temperature	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	-40°C ~ 85°C	0°C ~ 70°C	0°C ~ 70°C
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Active	Active	Active	Active	Active	Active

Engineering Selection Recommendations

LM385Z-1.2/LFT3 (Parametric Equivalent): Identical electrical and mechanical specifications to the main part. Both manufactured by Texas Instruments with matching tolerance, temperature coefficient, and operating range. Selection between LM385Z-1.2/LFT4 and LM385Z-1.2/LFT3 depends on packaging tape configuration availability and inventory requirements.

LM385Z-1.2RPG (Direct Manufacturer): Manufactured by onsemi with equivalent core specifications. Tolerance of -2.4%/+2.01% is within acceptable substitution range. Temperature coefficient of 80ppm/°C provides improved thermal stability compared to the main part. Cathode current of 20 µA is within operational limits. All compliance certifications match the original specification.

LM285Z-1.2RAG (Manufacturer Recommended): onsemi product with tighter tolerance of ±1% and improved temperature coefficient of 80ppm/°C. Extended operating temperature range of -40°C to 85°C exceeds the original 0°C to 70°C specification. Suitable for applications requiring enhanced performance and wider temperature operation. All regulatory compliance maintained.

LM385BZ-1.2RAG (Manufacturer Recommended): onsemi product with ±1% tolerance and 80ppm/°C temperature coefficient. Operating temperature range matches the original specification at 0°C to 70°C. Provides improved tolerance performance while maintaining identical thermal and mechanical characteristics. ROHS3 compliant.

LT1004CZ-1.2#TRPBF (Manufacturer Recommended): Analog Devices Inc. product with superior tolerance of ±0.03% and exceptional temperature coefficient of 20ppm/°C. Lowest cathode current at 10 µA. Represents highest precision alternative for applications demanding stringent voltage reference accuracy. All compliance requirements satisfied.

Frequently Asked Questions (FAQ)

Q: Can LM385Z-1.2/LFT3 be used as a direct replacement for LM385Z-1.2/LFT4?

A: Yes. Both parts are manufactured by Texas Instruments with identical electrical specifications, tolerance, temperature coefficient, and operating temperature range. The difference lies in packaging tape configuration (CT designation). Mechanical and electrical compatibility is complete.

Q: What is the primary difference between LM385Z-1.2RPG and the main part?

A: The LM385Z-1.2RPG is manufactured by onsemi rather than Texas Instruments. It maintains the same 1.235V output, 20 mA current, and TO-92-3 package. The temperature coefficient is improved at 80ppm/°C versus 150ppm/°C, and tolerance is -2.4%/+2.01% versus -2.43%/+2.02%. These variations remain within acceptable substitution parameters.

Q: When should LM285Z-1.2RAG or LM385BZ-1.2RAG be selected over the main part?

A: These parts offer tighter tolerance of ±1% compared to the main part's -2.43%/+2.02%. Selection is appropriate when applications require improved voltage reference accuracy. LM285Z-1.2RAG additionally supports extended temperature operation from -40°C to 85°C.

Q: Is LT1004CZ-1.2#TRPBF suitable for all applications using LM385Z-1.2/LFT4?

A: LT1004CZ-1.2#TRPBF maintains identical output voltage, current, and package specifications. It provides superior performance with ±0.03% tolerance and 20ppm/°C temperature coefficient. Mechanical compatibility is complete. Selection depends on application precision requirements and cost considerations.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance status, matching the regulatory requirement of the main part.

Q: Do all substitute parts use the same TO-92-3 package?

A: Yes. All substitute parts use the TO-92-3 (TO-226AA) through-hole package with formed leads, ensuring mechanical compatibility with existing PCB designs and assembly processes.

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