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SI3500-A-GM
Skyworks Solutions Inc.
IC REG BUCK ADJ 400MA 20QFN
2114 Pcs New Original In Stock
Buck Switching Regulator IC Positive, Isolation Capable Adjustable 1.8V 1 Output 400mA 20-VQFN Exposed Pad
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5.0 / 5.0
- (498 Ratings)
SI3500-A-GM
Product Overview
8006105
DiGi Electronics Part Number
SI3500-A-GM-DGManufacturer
Skyworks Solutions Inc.
SI3500-A-GM
Description
IC REG BUCK ADJ 400MA 20QFNInventory
2114 Pcs New Original In Stock
Buck Switching Regulator IC Positive, Isolation Capable Adjustable 1.8V 1 Output 400mA 20-VQFN Exposed Pad
Quantity
Minimum 1
Minimum 1
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SI3500-A-GM Technical Specifications
Category
Power Management (PMIC), Voltage Regulators - DC DC Switching Regulators
Packaging
-
Series
-
Product Status
Obsolete
Function
Step-Down
Output Configuration
Positive, Isolation Capable
Topology
Buck
Output Type
Adjustable
Number of Outputs
1
Voltage - Input (Min)
42V
Voltage - Input (Max)
57V
Voltage - Output (Min/Fixed)
1.8V
Voltage - Output (Max)
12V
Current - Output
400mA
Frequency - Switching
350kHz
Synchronous Rectifier
No
Operating Temperature
-40°C ~ 85°C (TA)
Mounting Type
Surface Mount
Package / Case
20-VQFN Exposed Pad
Supplier Device Package
20-QFN (5x5)
Base Product Number
SI3500
Datasheet & Documents
HTML Datasheet
SI3500-A-GM-DG
Environmental & Export Classification
Moisture Sensitivity Level (MSL)
3 (168 Hours)
ECCN
EAR99
HTSUS
8542.39.0001
Additional Information
Other Names
336-1844-5
SI3500AGM
Standard Package
60
Reviews
5.0/5.0-(Show up to 5 Ratings)
December 02, 2025
돈이 아깝지 않은 만족스러운 구매 경험입니다.
December 02, 2025
Die freundliche und engagierte Kundenbetreuung von DiGi Electronics schafft ein vertrauensvolles Geschäftsklima.
December 02, 2025
Die Website ist sehr übersichtlich, was den Bestellprozess vereinfacht.
December 02, 2025
Customer service was proactive in checking on my satisfaction post-purchase.
December 02, 2025
The website's search filter options are very helpful in narrowing down choices.
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Frequently Asked Questions (FAQ)
Can the SI3500-A-GM be safely replaced with a modern buck regulator like the TPS54360 in a 48V industrial power supply design, and what are the key risks in doing so?
Replacing the obsolete SI3500-A-GM with the TPS54360 requires careful evaluation of input voltage compatibility, thermal performance, and control loop stability. While the TPS54360 supports up to 60V input and offers higher efficiency, it uses a different feedback architecture and requires external compensation—unlike the SI3500-A-GM’s internal compensation. This introduces risk in transient response and EMI behavior, especially in noise-sensitive industrial environments. Additionally, the TPS54360 lacks the SI3500-A-GM’s isolation-capable output configuration, which may affect grounding strategies in floating output applications. Always validate layout parasitics and perform full load-step testing before deployment.
What are the critical layout considerations when designing a PCB with the SI3500-A-GM to avoid thermal shutdown or premature failure in a high-ambient-temperature enclosure?
The SI3500-A-GM’s 20-VQFN exposed pad package relies heavily on proper PCB thermal management. Inadequate copper area under the thermal pad or insufficient via stitching can cause localized hotspots, triggering thermal shutdown even below the 85°C ambient rating. To mitigate this, use a minimum of nine 0.3mm thermal vias connected to an internal ground plane, and extend the top-layer copper pour beyond the package footprint. Avoid placing high-impedance analog traces near the switching node (LX pin), as the 350kHz switching frequency can couple noise into feedback circuits. Thermal imaging during prototype validation is strongly recommended, especially in enclosed systems with limited airflow.
Is it safe to operate the SI3500-A-GM near its maximum input voltage (57V) in a telecom application with frequent voltage surges, and how does this impact long-term reliability?
Operating the SI3500-A-GM continuously near its 57V absolute maximum input voltage significantly increases stress on internal MOSFETs and increases the risk of latent failures due to voltage transients common in telecom power systems (e.g., from inductive loads or lightning-induced surges). Although the part is rated for 57V, Skyworks typically derates such devices to 80% of max in rugged applications—meaning 45.6V is a safer long-term ceiling. For surge-prone environments, add a TVS diode (e.g., SMAJ58A) at the input and consider a pre-regulator stage. Continuous operation at 57V may also accelerate electromigration in the die, reducing MTBF despite appearing functional during initial testing.
How does the absence of synchronous rectification in the SI3500-A-GM affect efficiency and heat dissipation compared to newer alternatives like the LM5164, and when might this become a design-limiting factor?
The SI3500-A-GM uses an asynchronous buck topology, which results in higher conduction losses through the external Schottky diode during the freewheeling phase—especially at low output voltages (e.g., 1.8V) and light loads. This leads to efficiency drops of 10–15% compared to synchronous alternatives like the LM5164, which integrates a low-RDS(on) MOSFET for rectification. In battery-powered or thermally constrained systems, this inefficiency translates directly into increased junction temperature and reduced runtime. If your design requires >85% efficiency at 400mA load or operates in ambient temperatures above 70°C, the SI3500-A-GM may not meet thermal targets without aggressive heatsinking, making a synchronous replacement necessary despite its obsolescence.
Can the SI3500-A-GM be used in a redundant power architecture where two regulators share a common load, and what isolation or current-sharing mechanisms are required to prevent backfeeding?
The SI3500-A-GM is not designed for direct parallel operation due to lack of current-sharing control and precise output voltage matching. Attempting to connect two SI3500-A-GM outputs together without isolation can cause one regulator to source current into the other during startup or transient conditions, leading to reverse current flow and potential damage—even though the part is labeled 'isolation capable,' this refers to output referencing, not backfeed protection. To implement redundancy, use ORing diodes (e.g., SBRT5U40P1) at each output or adopt active ideal diode controllers. Alternatively, consider a modern PMIC with built-in load-sharing features. Without such measures, unequal feedback thresholds (±2% typical) will cause significant current imbalance, overloading one device and compromising system reliability.
Quality Assurance (QC)
DiGi ensures the quality and authenticity of every electronic component through professional inspections and batch sampling, guaranteeing reliable sourcing, stable performance, and compliance with technical specifications, helping customers reduce supply chain risks and confidently use components in production.
SI3500-A-GM CAD Models
Skyworks Solutions Inc. SI3500-A-GM PCB symbols & footprints
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