ZR285R03STZ Equivalent & Substitute Parts

Part Overview

The ZR285R03STZ is a shunt voltage reference IC manufactured by Diodes Incorporated, designed to provide a fixed 2.5V output with ±3% tolerance. This through-hole TO-92 package component operates across the industrial temperature range of -40°C to 85°C and delivers 20 mA output current. The product is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for ongoing production and repair applications.

Key Parameters

Parameter	Value
Reference Type	Shunt
Output Type	Fixed
Voltage - Output (Min/Fixed)	2.5V
Current - Output	20 mA
Tolerance	±3%
Temperature Coefficient	90ppm/°C
Noise - 10Hz to 10kHz	60µVrms
Current - Cathode	20 µA
Operating Temperature	-40°C ~ 85°C (TA)
Mounting Type	Through Hole
Package / Case	TO-226-3, TO-92-3 (TO-226AA) Formed Leads
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the ZR285R03STZ is determined by strict alignment of the following electrical and mechanical parameters:

Output Voltage: Must be 2.5V fixed
Output Current: Must be 20 mA
Reference Type: Must be Shunt
Package: Must be TO-92-3 (TO-226-3) with formed leads for through-hole mounting
Operating Temperature Range: Must support -40°C to 85°C minimum
Tolerance: ±3% or better (±1.5% acceptable as tighter specification)

Substitute parts are grouped into two categories based on tolerance specification:

Category A - ±3% Tolerance (Direct Electrical Match):

LM385LPR-2-5 (Texas Instruments)
LM385Z-2.5/LFT1 (National Semiconductor)
LM385Z-2.5/LFT2 (Texas Instruments)

Category B - ±1.5% Tolerance (Superior Performance):

LM285LPR-2-5 (Texas Instruments)
LM285LPRE3-2-5 (Texas Instruments)
LM285Z-2.5/LFT7 (National Semiconductor)
LM285Z-2.5RAG (onsemi)
LM285Z-2.5RPG (onsemi)
LM385BLPR-2-5 (Texas Instruments)
LM385BZ-2.5/LFT7 (Texas Instruments)

All listed substitutes maintain TO-92-3 package compatibility and through-hole mounting configuration.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Tolerance	Temp Coefficient	Operating Temp	Product Status	Package
ZR285R03STZ	Diodes Incorporated	2.5V	20 mA	±3%	90ppm/°C	-40°C ~ 85°C	Obsolete	TO-92-3
LM385LPR-2-5	Texas Instruments	2.5V	20 mA	±3%	20ppm/°C	0°C ~ 70°C	Active	TO-92-3
LM385Z-2.5/LFT1	National Semiconductor	2.5V	20 mA	±3%	150ppm/°C	0°C ~ 70°C	Active	TO-92-3
LM385Z-2.5/LFT2	Texas Instruments	2.5V	20 mA	±3%	150ppm/°C	0°C ~ 70°C	Active	TO-92-3
LM285LPR-2-5	Texas Instruments	2.5V	20 mA	±1.5%	20ppm/°C	-40°C ~ 85°C	Active	TO-92-3
LM285LPRE3-2-5	Texas Instruments	2.5V	20 mA	±1.5%	20ppm/°C	-40°C ~ 85°C	Active	TO-92-3
LM285Z-2.5/LFT7	National Semiconductor	2.5V	20 mA	±1.5%	150ppm/°C	-40°C ~ 85°C	Active	TO-92-3
LM285Z-2.5RAG	onsemi	2.5V	20 mA	±1.5%	80ppm/°C	-40°C ~ 85°C	Active	TO-92-3
LM285Z-2.5RPG	onsemi	2.5V	20 mA	±1.5%	80ppm/°C	-40°C ~ 85°C	Active	TO-92-3
LM385BLPR-2-5	Texas Instruments	2.5V	20 mA	±1.5%	20ppm/°C	0°C ~ 70°C	Active	TO-92-3
LM385BZ-2.5/LFT7	Texas Instruments	2.5V	20 mA	±1.5%	150ppm/°C	0°C ~ 70°C	Active	TO-92-3

Engineering Selection Recommendations

For Direct Replacement (Matching ±3% Tolerance and Full Temperature Range):

LM285LPR-2-5 or LM285LPRE3-2-5 from Texas Instruments are the primary recommendations. Both are active products with ROHS3 compliance, maintain the -40°C to 85°C operating range, and deliver superior temperature coefficient performance (20ppm/°C typical versus 90ppm/°C of the original). These parts are available in high inventory quantities.

For Extended Temperature Range Applications:

LM285Z-2.5/LFT7 (National Semiconductor) or LM285Z-2.5RAG and LM285Z-2.5RPG (onsemi) provide ±1.5% tolerance with full -40°C to 85°C support. The onsemi variants offer improved temperature coefficient (80ppm/°C) compared to National Semiconductor (150ppm/°C).

For Restricted Temperature Range (0°C to 70°C):

LM385LPR-2-5, LM385Z-2.5/LFT1, or LM385Z-2.5/LFT2 are suitable only when the application does not require operation below 0°C or above 70°C. These maintain ±3% tolerance matching the original specification.

All recommended substitutes are ROHS3 compliant and carry EAR99 ECCN classification matching the original part.

Frequently Asked Questions (FAQ)

Q: Can LM385 series parts substitute for the ZR285R03STZ?

A: Yes, LM385 series parts with 2.5V fixed output and 20 mA current rating are electrically compatible. However, operating temperature range varies by specific part number. LM385LPR-2-5, LM385Z-2.5/LFT1, and LM385Z-2.5/LFT2 operate only to 0°C to 70°C, which is narrower than the original -40°C to 85°C range. Verify application temperature requirements before selection.

Q: What is the difference between ±3% and ±1.5% tolerance parts?

A: Tolerance defines the maximum deviation of output voltage from the nominal 2.5V specification. ±3% allows ±75mV deviation (2.425V to 2.575V), while ±1.5% allows ±37.5mV deviation (2.4375V to 2.5625V). Applications requiring tighter voltage regulation should use ±1.5% parts. Both are electrically compatible with the original circuit.

Q: Are all substitute parts in the same TO-92-3 package?

A: Yes. All listed substitutes use TO-92-3 (TO-226-3) package with formed leads, maintaining identical through-hole mounting compatibility with the ZR285R03STZ.

Q: Which substitute offers the best temperature stability?

A: LM285LPR-2-5 and LM285LPRE3-2-5 from Texas Instruments provide the lowest temperature coefficient at 20ppm/°C typical, compared to 90ppm/°C of the original part. This results in superior voltage stability across the operating temperature range.

Q: Can I use LM285 parts in place of LM385 parts?

A: Yes, LM285 and LM385 series are cross-compatible when output voltage and current ratings match. The primary difference is temperature coefficient and operating temperature range. LM285 variants generally offer better temperature stability and wider operating ranges.

Q: What is the significance of the part number suffix (e.g., /LFT7, /LFT1)?

A: The suffix indicates packaging and tape configuration. /LFT7 and /LFT1 denote different tape formats for automated assembly. These are packaging variants of the same electrical device and do not affect circuit performance.

Q: Are all substitutes ROHS3 compliant?

A: Yes. All active substitute parts listed carry ROHS3 compliance certification, matching the environmental compliance status of the original ZR285R03STZ.

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