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SI3500-A-GMR
Skyworks Solutions Inc.
IC REG BUCK ADJ 400MA 20QFN
3159 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
- (78 Ratings)
SI3500-A-GMR
Product Overview
7971239
DiGi Electronics Part Number
SI3500-A-GMR-DGManufacturer
Skyworks Solutions Inc.
SI3500-A-GMR
Description
IC REG BUCK ADJ 400MA 20QFNInventory
3159 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-GMR 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-GMR-DG
Environmental & Export Classification
Moisture Sensitivity Level (MSL)
3 (168 Hours)
ECCN
EAR99
HTSUS
8542.39.0001
Additional Information
Standard Package
2,500
Reviews
5.0/5.0-(Show up to 5 Ratings)
December 02, 2025
配送の速さと商品品質の高さに信頼を寄せています。
December 02, 2025
Their products deliver consistent performance without excessive cost.
December 02, 2025
DiGi Electronics takes pride in providing top-quality products with punctual delivery.
December 02, 2025
Their affordable pricing doesn't compromise on sustainability—very commendable.
December 02, 2025
The affordable options from DiGi Electronics allow remote teams to scale up efficiently.
December 02, 2025
Products arrive on time and exactly as described, with no surprises.
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Frequently Asked Questions (FAQ)
What are the key risks when replacing the obsolete SI3500-A-GMR with a modern buck regulator in an existing 48V industrial power design?
Replacing the SI3500-A-GMR requires careful attention to input voltage compatibility, thermal performance, and control loop stability. Since the SI3500-A-GMR supports 42V–57V input and operates at 350kHz with non-synchronous rectification, alternatives like the Texas Instruments TPS54360 (4.5V–60V, synchronous) or Analog Devices LTC3639 (4.5V–100V, non-sync) may seem viable but introduce switching frequency mismatches that can affect EMI filtering and transient response. Additionally, the exposed pad thermal design of the 20-QFN (5x5) package must be replicated to avoid overheating—especially critical given the SI3500-A-GMR’s limited 400mA output and lack of integrated FET body diode conduction during dead time. Always validate dropout voltage and light-load efficiency under your actual load profile to prevent unexpected brownouts or thermal runaway.
Can the SI3500-A-GMR be safely used in a 24V-to-3.3V automotive application despite its 42V minimum input rating?
No—the SI3500-A-GMR has a strict minimum input voltage of 42V, making it incompatible with 24V nominal systems (which can dip below 20V during cold-crank events). Attempting to operate below 42V risks unstable regulation, premature shutdown, or device damage due to insufficient gate drive for the internal high-side MOSFET. For 24V automotive rails, consider regulators like the LM5164 (4.5V–65V input) or MAX20096 (5V–65V), which are designed for wide-input, low-voltage step-down conversion and include features like undervoltage lockout (UVLO) tuned for automotive transients. Using the SI3500-A-GMR outside its specified range violates reliability margins and may void compliance with AEC-Q100 stress test criteria.
How does the lack of synchronous rectification in the SI3500-A-GMR impact thermal design and efficiency at light loads in a remote sensor node?
The SI3500-A-GMR’s non-synchronous topology relies on an external Schottky diode for freewheeling current, which increases conduction losses—especially at light loads common in sensor nodes. This results in lower efficiency (~70–75% at 10mA) compared to synchronous alternatives like the MPQ4572 (which achieves >85% at same load). The added diode loss elevates junction temperature, requiring careful PCB copper pour under the exposed pad to meet the -40°C to 85°C operating range. In battery-powered designs, this inefficiency shortens runtime and may necessitate larger heat-spreading areas or forced airflow, increasing BOM cost and footprint. Consider adding a low-IQ synchronous replacement if quiescent current and thermal headroom are constrained.
Is it feasible to parallel two SI3500-A-GMR devices to increase output current beyond 400mA in a high-reliability industrial controller?
Paralleling SI3500-A-GMR units is not recommended due to lack of current-sharing mechanisms and tight tolerances on internal reference voltages and switching thresholds. Without master-slave synchronization or ballast resistors, one device may carry disproportionate load, leading to thermal imbalance and premature failure—particularly problematic given the part’s obsolete status and limited replacement inventory. Instead, migrate to a single higher-current regulator such as the LT8640S (4A, 3V–42V input) or use a multi-phase controller if >1A is needed. If redesign isn’t possible, external current-balancing circuitry with sense resistors and op-amps can be implemented, but this adds complexity, cost, and board space, negating the benefit of using an obsolete, low-pin-count device.
What layout considerations are critical when designing with the SI3500-A-GMR’s 20-VQFN exposed pad package to avoid solder voids and thermal throttling?
Proper thermal vias under the exposed pad of the SI3500-A-GMR are essential—use an array of 6–9 filled or tent-covered vias (0.3mm drill, 0.6mm pitch) connected to an internal ground plane to maximize heat extraction. Inadequate via count or poor solder wicking leads to hotspots that can trigger thermal shutdown even at modest loads. Keep SW node traces short and away from feedback (FB) traces to prevent noise coupling into the control loop, which can cause output instability. Also, ensure the input capacitor (rated for 63V+) is placed within 5mm of VIN and GND pins to minimize loop inductance. Given MSL 3 (168-hour floor life), follow IPC/JEDEC J-STD-033 handling procedures to avoid moisture-induced delamination during reflow, especially in humid manufacturing environments.
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-GMR CAD Models
Skyworks Solutions Inc. SI3500-A-GMR PCB symbols & footprints
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