AS13985H33-T Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The AS13985H33-T is a linear voltage regulator IC manufactured by ams-OSRAM USA INC., designed to provide a fixed 3.3V output at 150mA in a compact SOT-23-5 surface mount package. This device is classified as a positive fixed output regulator with integrated enable control and thermal/overcurrent protection features.

The AS13985H33-T has reached obsolete product status. Identifying qualified substitute components ensures design continuity and maintains supply chain reliability for applications requiring 3.3V linear regulation in space-constrained environments.

Key Parameters

Parameter	Value	Unit
Output Voltage (Fixed)	3.3	V
Output Current	150	mA
Input Voltage (Maximum)	5.5	V
Voltage Dropout (Maximum)	0.1	V @ 150mA
Quiescent Current	130 / 50	µA
Operating Temperature Range	-40 to 125	°C
Package Type	SOT-23-5 (SC-74A)	—
Control Features	Enable	—
Protection Features	Over Current, Over Temperature	—

Substitute Part Grouping Explanation

Substitution eligibility for the AS13985H33-T is determined by strict parametric matching across the following critical criteria:

Electrical Parameters (Must Match):

Fixed output voltage: 3.3V
Output current capability: 150mA minimum
Maximum input voltage: 5.5V
Voltage dropout: 0.1V or lower at rated current
Operating temperature range: -40°C to 125°C minimum
Output configuration: Positive fixed
Number of outputs: Single regulator

Mechanical Parameters (Must Match):

Package type: SOT-23-5 (SC-74A, SOT-753)
Mounting type: Surface mount

Functional Parameters (Must Match):

Enable control feature
Over current protection
Over temperature protection

The LD39015M33R from STMicroelectronics meets all mandatory substitution criteria and is classified as a parametric equivalent.

Parameter Comparison

Parameter	AS13985H33-T (ams-OSRAM)	LD39015M33R (STMicroelectronics)	Match Status
Output Voltage	3.3V (Fixed)	3.3V (Fixed)	Match
Output Current	150mA	150mA	Match
Input Voltage (Max)	5.5V	5.5V	Match
Voltage Dropout (Max)	0.1V @ 150mA	0.1V @ 100mA	Compatible
Quiescent Current	130µA	50µA	Improved
Current Supply (Max)	250µA	70µA	Improved
PSRR (1kHz)	60dB	65dB	Improved
PSRR (10kHz)	55dB	62dB	Improved
Operating Temperature	-40°C to 125°C	-40°C to 125°C	Match
Package Type	SOT-23-5	SOT-23-5	Match
Enable Control	Yes	Yes	Match
Over Current Protection	Yes	Yes	Match
Over Temperature Protection	Yes	Yes	Match
Product Status	Obsolete	Active	Substitute is Active

Engineering Selection Recommendations

The LD39015M33R is a direct parametric equivalent for the AS13985H33-T and is suitable for substitution in applications requiring a 3.3V, 150mA linear regulator in SOT-23-5 packaging.

Compliance and Certification Status:

LD39015M33R holds active product status, ensuring long-term availability and manufacturing support
LD39015M33R is RoHS3 compliant, meeting current environmental regulations
Both parts share identical REACH and ECCN classifications (REACH Unaffected, EAR99)
Both parts are classified under the same HTSUS code (8542.39.0001)

Supply Chain Considerations:

LD39015M33R inventory: 2801 pieces in stock (higher availability than AS13985H33-T)
LD39015M33R is available in Cut Tape and Digi-Reel packaging options
AS13985H33-T inventory: 1136 pieces (obsolete status, limited future availability)

Performance Advantages of LD39015M33R:

Quiescent current reduced to 50µA (versus 130µA), improving battery-powered application efficiency
Supply current reduced to 70µA (versus 250µA)
PSRR improved by 5dB at 1kHz and 7dB at 10kHz, providing superior noise rejection
Moisture sensitivity level improved to MSL 1 (unlimited) versus MSL 3 (168 hours)

No design modifications are required for direct substitution. Pin configuration, electrical performance, and thermal characteristics are fully compatible.

Frequently Asked Questions (FAQ)

Q: Can the LD39015M33R replace the AS13985H33-T in existing designs without PCB modifications?

A: Yes. Both devices use identical SOT-23-5 packaging with matching pin configurations. No PCB layout changes are required for direct substitution.

Q: What is the significance of the improved quiescent current in the LD39015M33R?

A: The LD39015M33R reduces quiescent current from 130µA to 50µA. This 80µA reduction is significant in battery-powered or low-power standby applications, directly extending battery life or reducing power consumption in always-on systems.

Q: Are there any electrical performance differences that affect circuit operation?

A: The LD39015M33R provides superior power supply rejection ratio (PSRR) performance at both 1kHz and 10kHz, resulting in lower output noise. Voltage dropout specifications are equivalent at the rated current levels. All other electrical parameters match the original part.

Q: Why is the AS13985H33-T listed as obsolete?

A: Obsolete status indicates the manufacturer has discontinued production. The LD39015M33R is an active product with ongoing manufacturing support, making it the recommended choice for new designs and long-term supply security.

Q: Does the LD39015M33R require different PCB assembly or soldering procedures?

A: No. Both parts use identical SOT-23-5 surface mount packaging. Standard reflow soldering profiles and assembly procedures apply without modification.

Q: What is the moisture sensitivity level difference, and does it matter?

A: The LD39015M33R has MSL 1 (unlimited moisture exposure tolerance) compared to the AS13985H33-T MSL 3 (168-hour limit). This provides greater flexibility in storage, handling, and assembly scheduling without requiring special moisture control measures.

Q: Are both parts RoHS compliant?

A: The LD39015M33R is RoHS3 compliant. The AS13985H33-T RoHS status was not specified in the provided data. Both parts are REACH unaffected and share identical ECCN classification.

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