A3955SLB Equivalent & Substitute Parts

Part Overview

The A3955SLB is a bipolar motor driver IC manufactured by Allegro MicroSystems, designed for stepper motor control applications. This device integrates control and power stage functionality in a 16-SOIC package, supporting step resolutions from full step to 1/8 microstepping. The A3955SLB is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and new design implementations.

Substiute Parts

A3955SLB

Allegro MicroSystemsIn Stock: 2105A3955SLB Datasheet

Current PartRFQ

TB6560AHQ,8

Toshiba Semiconductor and StorageIn Stock: 1000362TB6560AHQ,8 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

The TB6560AHQ,8 qualifies as a functional substitute based on the following core electrical and mechanical compatibility criteria:

Matching Parameters:

• Bipolar stepper motor driver architecture
• Fully integrated control and power stage function
• Parallel interface for logic control
• Supply voltage range: 4.5V ~ 5.5V (identical)
• Step resolution support: 1, 1/2, 1/4, 1/8 (minimum requirement met; TB6560 extends to 1/16)
• Output configuration: Half Bridge topology (TB6560 provides 4 bridges vs. 2 in A3955SLB, enabling dual-motor or higher-current applications)

Differences Requiring Design Consideration:

• Output current: TB6560AHQ,8 rated at 3A vs. A3955SLB at 1.5A
• Load voltage range: TB6560AHQ,8 supports 4.5V ~ 34V vs. A3955SLB at 4.5V ~ 50V
• Package: TB6560AHQ,8 uses 25-HZIP (through-hole) vs. A3955SLB in 16-PowerSOIC (surface mount)
• Technology: TB6560AHQ,8 uses Power MOSFET vs. A3955SLB using Bipolar technology
• Operating temperature: TB6560AHQ,8 rated -30°C ~ 85°C (TA) vs. A3955SLB at -20°C ~ 150°C (TJ)
• Product status: TB6560AHQ,8 is active; RoHS3 compliant

Parameter Comparison

Engineering Selection Recommendations

For Obsolete Part Replacement: The TB6560AHQ,8 is the designated manufacturer-recommended substitute for the A3955SLB. Selection of this alternative is appropriate when:

• Active product status is required for new procurement and long-term supply assurance
• RoHS3 compliance is mandated by regulatory or customer requirements
• PCB redesign to accommodate through-hole mounting (25-HZIP) is feasible
• Load voltage requirements do not exceed 34V
• Operating temperature range of -30°C ~ 85°C (TA) satisfies application needs

Design Considerations:

• The TB6560AHQ,8 output current rating of 3A exceeds the A3955SLB specification of 1.5A, allowing for higher motor torque or dual-motor configurations
• The extended step resolution to 1/16 microstepping in the TB6560 provides finer motion control if required
• Load voltage limitation to 34V in the TB6560 versus 50V in the A3955SLB must be evaluated against motor supply specifications
• Parallel interface compatibility ensures logic-level control signals remain unchanged

Frequently Asked Questions (FAQ)

Q: Can the TB6560AHQ,8 directly replace the A3955SLB without PCB modifications?

A: No. The TB6560AHQ,8 uses a 25-HZIP through-hole package versus the A3955SLB's 16-PowerSOIC surface-mount package. PCB layout redesign is required. Pin configuration and signal assignments must be verified against respective datasheets before implementation.

Q: What is the impact of the higher output current rating (3A vs. 1.5A) on motor selection?

A: The TB6560AHQ,8's 3A rating allows operation with stepper motors requiring higher phase currents. Existing motors rated for 1.5A maximum phase current remain compatible. Motor selection is not constrained by the substitute's higher capability.

Q: Does the TB6560AHQ,8 support the same step resolution modes as the A3955SLB?

A: Yes. The TB6560AHQ,8 supports 1, 1/2, 1/4, and 1/8 step resolutions, matching the A3955SLB. The TB6560 additionally supports 1/16 microstepping, which is optional and does not affect compatibility with existing firmware or control logic.

Q: Are there temperature range implications for the substitution?

A: The A3955SLB operates to 150°C junction temperature; the TB6560AHQ,8 operates to 85°C ambient temperature. These use different measurement bases. Applications requiring sustained operation above 85°C ambient may require thermal analysis to confirm the TB6560 remains within safe operating limits.

Q: What is the significance of the load voltage difference (50V vs. 34V)?

A: The A3955SLB supports motor supply voltages up to 50V; the TB6560AHQ,8 is rated to 34V. If the application requires motor supply voltages exceeding 34V, the TB6560AHQ,8 is not suitable. Verify motor supply specifications before substitution.

Q: Is RoHS3 compliance a functional requirement or a regulatory requirement?

A: RoHS3 compliance is a regulatory requirement for products sold in the European Union and certain other markets. The A3955SLB is RoHS non-compliant; the TB6560AHQ,8 is RoHS3 compliant. Substitution is necessary for regulatory compliance in restricted markets.