SC4911IMSTRT Equivalent & Substitute Parts

Part Overview

The SC4911IMSTRT is a multi-topology DC-DC controller IC manufactured by Semtech Corporation, designed for boost, flyback, and SEPIC regulator applications with positive, isolation-capable output configurations. This device operates as a transistor driver for step-up and step-up/step-down topologies in an 8-MSOP surface mount package.

The SC4911IMSTRT is classified as obsolete. Identifying equivalent substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications currently utilizing this controller.

Key Parameters

Parameter	SC4911IMSTRT
Manufacturer	Semtech Corporation
Category	Power Management (PMIC)
Output Type	Transistor Driver
Function	Step-Up, Step-Up/Step-Down
Output Configuration	Positive, Isolation Capable
Topology	Boost, Flyback, SEPIC
Number of Outputs	1
Output Phases	1
Voltage - Supply (Vcc/Vdd)	6V ~ 16V
Frequency - Switching	200kHz
Duty Cycle (Max)	65%
Control Features	Current Limit, Frequency Control
Operating Temperature	-40°C ~ 125°C (TJ)
Mounting Type	Surface Mount
Package / Case	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
Product Status	Obsolete
RoHS Status	RoHS Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the SC4911IMSTRT are identified based on the following critical parameters that determine functional compatibility:

Output Type: Transistor Driver
Function: Step-Up, Step-Up/Step-Down capability
Output Configuration: Positive, Isolation Capable
Topology Support: Boost, Flyback, and related converter types
Package Compatibility: 8-pin surface mount (8-MSOP or equivalent 8-TSSOP)
Supply Voltage Range: Overlap with 6V ~ 16V input specification
Control Features: Current Limit capability
Surface Mount Technology: Consistent with original mounting requirements

The UCC25705DGK qualifies as a substitute based on these parameters. It maintains the same output type, function, output configuration, and package form factor. Both devices support the required topologies and include current limit control features. The substitute operates within a compatible supply voltage range (8.2V ~ 15V) that overlaps the original specification.

Parameter Comparison

Parameter	SC4911IMSTRT	UCC25705DGK
Manufacturer	Semtech Corporation	Unitrode
Output Type	Transistor Driver	Transistor Driver
Function	Step-Up, Step-Up/Step-Down	Step-Up, Step-Up/Step-Down
Output Configuration	Positive, Isolation Capable	Positive, Isolation Capable
Topology	Boost, Flyback, SEPIC	Boost, Flyback, Forward Converter
Number of Outputs	1	1
Output Phases	1	1
Voltage - Supply (Vcc/Vdd)	6V ~ 16V	8.2V ~ 15V
Frequency - Switching	200kHz	1MHz
Duty Cycle (Max)	65%	93%
Control Features	Current Limit, Frequency Control	Current Limit
Operating Temperature	-40°C ~ 125°C (TJ)	-40°C ~ 85°C (TA)
Mounting Type	Surface Mount	Surface Mount
Package / Case	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
Product Status	Obsolete	Active
RoHS Status	RoHS Compliant	Not specified

Engineering Selection Recommendations

The UCC25705DGK is an active product from Unitrode, providing supply chain continuity for applications currently using the obsolete SC4911IMSTRT. Both devices share identical package form factors (8-MSOP) and mounting technology, enabling direct physical replacement in PCB layouts.

The substitute maintains core functional compatibility across output type, function, output configuration, and topology support. The supply voltage range of the UCC25705DGK (8.2V ~ 15V) overlaps substantially with the original specification (6V ~ 16V), covering the majority of typical application requirements. Both devices include current limit control features.

Design validation is required for applications operating at the lower end of the original supply voltage range (below 8.2V) or at the upper temperature limit (above 85°C ambient), as the substitute has a reduced maximum junction temperature specification compared to the original device.

Frequently Asked Questions (FAQ)

Q: Can the UCC25705DGK be used as a direct replacement for the SC4911IMSTRT?

A: The UCC25705DGK is functionally compatible as a substitute. Both devices are 8-pin surface mount transistor drivers supporting step-up and step-up/step-down topologies with positive, isolation-capable outputs. Physical package compatibility is confirmed. Design review is necessary for applications at the lower supply voltage boundary (below 8.2V) or elevated operating temperatures.

Q: What are the key differences between these two controllers?

A: The primary differences are switching frequency (200kHz vs. 1MHz), maximum duty cycle (65% vs. 93%), maximum operating temperature (125°C vs. 85°C), and topology support (SEPIC included in original vs. Forward Converter in substitute). The substitute offers higher frequency operation and greater duty cycle flexibility.

Q: Are there supply voltage compatibility concerns?

A: The UCC25705DGK operates from 8.2V to 15V, while the SC4911IMSTRT operates from 6V to 16V. Applications requiring supply voltages below 8.2V or above 15V require alternative solutions or design modification.

Q: Is the package footprint identical?

A: Both devices use 8-pin surface mount packages with 0.118" (3.00mm) width specifications. PCB layout compatibility is confirmed for direct substitution.

Q: What is the product status difference?

A: The SC4911IMSTRT is obsolete, making the active UCC25705DGK the recommended path for new designs and ongoing production support.

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