SC656ULTRT LED Driver IC Equivalent & Substitute Parts

Part Overview

The SC656ULTRT is a 7-output LED driver IC manufactured by Semtech Corporation, featuring a switched capacitor (charge pump) topology with PWM dimming capability. This device is classified as a power management PMIC designed for backlight applications, operating across a 2.9V to 5.5V supply range with 25mA per-channel output current. The SC656ULTRT is currently listed as obsolete, making identification of functionally equivalent substitute components essential for ongoing design support and production continuity.

Substiute Parts

SC656ULTRT

Semtech CorporationIn Stock: 4330SC656ULTRT Datasheet

Current PartRFQ

ADP8861ACPZ-R7

Analog Devices Inc.In Stock: 2101ADP8861ACPZ-R7 Datasheet

MFR RecommendedRFQ

LM3533TMX-40/NOPB

Texas InstrumentsIn Stock: 3055LM3533TMX-40/NOPB Datasheet

MFR RecommendedRFQ

TPS60250RTET

Texas InstrumentsIn Stock: 1015TPS60250RTET Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SC656ULTRT requires matching the following core electrical and mechanical parameters:

Critical Matching Parameters:

• Number of outputs: 7 channels
• Topology: Switched capacitor (charge pump) DC-DC regulation
• Supply voltage range: Minimum 2.9V to maximum 5.5V overlap
• Output voltage capability: Support for 2.5V to 5.25V range
• Per-channel current capacity: Minimum 25mA
• Mounting type: Surface mount
• Package form factor: QFN-based packages with exposed pad

Control Interface Compatibility: The SC656ULTRT uses PWM dimming. Substitute parts may employ PWM or I2C dimming control; both are acceptable as they provide independent brightness adjustment capability.

Compliance Requirements: All substitute parts must maintain RoHS compliance status for regulatory continuity.

The three identified substitute parts (ADP8861ACPZ-R7, LM3533TMX-40/NOPB, TPS60250RTET) satisfy these core parameters while offering active product status and enhanced availability.

Parameter Comparison

Engineering Selection Recommendations

ADP8861ACPZ-R7 (Analog Devices Inc.)

This substitute maintains identical 7-output architecture and switched capacitor topology with active product status. Supply voltage range (2.5V to 5.5V) overlaps the SC656ULTRT specification. Output current capability (30mA, 60mA per channel) exceeds the original 25mA requirement. The primary design consideration is the shift from PWM to I2C dimming control, which requires firmware or control circuit modification. Package footprint differs (20-LFCSP vs. 20-VFQFN), necessitating PCB layout revision. MSL rating of 3 requires stricter moisture handling during assembly. ROHS3 compliance maintains regulatory alignment.

LM3533TMX-40/NOPB (Texas Instruments)

This substitute provides 7-output LED driver functionality with active product status and extended operating temperature range (-40°C to 125°C junction temperature). The topology combines step-up (boost) with switched capacitor regulation, enabling higher output voltage capability (40V) compared to the SC656ULTRT (2.5V to 5.25V). This topology difference makes the LM3533 suitable for applications requiring elevated output voltages. PWM dimming control matches the original device. Supply voltage range (2.7V to 5.5V) is compatible. Output current per channel (30mA) exceeds the original specification. Package format (20-DSBGA) differs from the original, requiring PCB redesign. MSL rating of 1 provides optimal moisture handling characteristics. ROHS3 compliance is maintained.

TPS60250RTET (Texas Instruments)

This substitute offers 7-output LED driver functionality with active product status and switched capacitor topology. Supply voltage range (3V to 6V) overlaps the SC656ULTRT requirement. The distinguishing feature is significantly higher per-channel output current (230mA vs. 25mA), making this device suitable for higher-power LED applications. I2C dimming control requires control interface modification. Operating frequency (750kHz) provides intermediate switching characteristics. Package format (16-WQFN) differs from the original, requiring PCB layout adjustment. MSL rating of 2 requires standard moisture control procedures. ROHS3 compliance is maintained.

Frequently Asked Questions (FAQ)

Q: Can the ADP8861ACPZ-R7 directly replace the SC656ULTRT without design changes?

A: The ADP8861ACPZ-R7 maintains the same 7-output count and switched capacitor topology, but requires control interface modification due to I2C dimming versus PWM dimming. Package footprint differs (20-LFCSP vs. 20-VFQFN), necessitating PCB layout revision. Electrical compatibility is confirmed within the specified parameter ranges.

Q: What is the primary difference between the LM3533TMX-40/NOPB and the SC656ULTRT?

A: The LM3533TMX-40/NOPB incorporates a step-up (boost) topology in addition to switched capacitor regulation, enabling 40V output voltage capability. The SC656ULTRT is limited to 2.5V to 5.25V output. Both devices support PWM dimming and 7 outputs. The LM3533 is suitable for applications requiring higher output voltages for LED strings or specialized backlight configurations.

Q: Is the TPS60250RTET suitable for low-current LED applications?

A: The TPS60250RTET is rated for 230mA per-channel output current, significantly exceeding the SC656ULTRT specification of 25mA. While the device can operate at lower currents, it is optimized for higher-power LED applications. For low-current designs, the ADP8861ACPZ-R7 or LM3533TMX-40/NOPB may provide better design efficiency.

Q: Do all substitute parts maintain RoHS compliance?

A: Yes. The SC656ULTRT is RoHS Compliant, and all three substitute parts are ROHS3 Compliant, ensuring regulatory continuity for applications subject to RoHS requirements.

Q: What packaging considerations apply when selecting a substitute?

A: The SC656ULTRT uses a 20-VFQFN package. The ADP8861ACPZ-R7 uses 20-LFCSP, the LM3533TMX-40/NOPB uses 20-DSBGA, and the TPS60250RTET uses 16-WQFN. Each package change requires PCB layout revision, including trace routing, via placement, and thermal management considerations. Consult device datasheets for specific footprint and thermal pad requirements.

Q: How do moisture sensitivity levels affect component handling?

A: The SC656ULTRT has MSL 1 (unlimited shelf life). The ADP8861ACPZ-R7 has MSL 3 (168-hour limit after moisture exposure), requiring stricter bake-out procedures before reflow soldering. The LM3533TMX-40/NOPB has MSL 1, and the TPS60250RTET has MSL 2 (1-year limit). Higher MSL ratings require adherence to IPC-A-610 moisture control standards during assembly.

Q: Can I use I2C dimming control parts as direct replacements for PWM dimming?

A: I2C and PWM dimming provide independent brightness adjustment through different control interfaces. The ADP8861ACPZ-R7 and TPS60250RTET use I2C, while the SC656ULTRT and LM3533TMX-40/NOPB use PWM. Substitution requires firmware modification or control circuit redesign to accommodate the different dimming protocol. Both methods are functionally equivalent for brightness control applications.