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VIPER25LD
STMicroelectronics
IC OFFLINE SWITCH FLYBACK 16SO
1450 Pcs New Original In Stock
Converter Offline Flyback Topology 136kHz 16-SO
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*Quantity
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Minimum 1
5.0 / 5.0
- (344 Ratings)
VIPER25LD
Product Overview
8151827
DiGi Electronics Part Number
VIPER25LD-DGManufacturer
STMicroelectronics
VIPER25LD
Description
IC OFFLINE SWITCH FLYBACK 16SOInventory
1450 Pcs New Original In Stock
Converter Offline Flyback Topology 136kHz 16-SO
Quantity
Minimum 1
Minimum 1
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VIPER25LD Technical Specifications
Category
Power Management (PMIC), AC DC Converters, Offline Switches
Packaging
Tube
Series
VIPer™ plus
Product Status
Active
Output Isolation
Isolated
Internal Switch(s)
Yes
Voltage - Breakdown
800V
Topology
Flyback
Voltage - Start Up
14 V
Voltage - Supply (Vcc/Vdd)
8.5V ~ 23.5V
Duty Cycle
-
Frequency - Switching
136kHz
Power (Watts)
20 W
Fault Protection
Current Limiting, Over Temperature, Over Voltage
Control Features
-
Operating Temperature
-40°C ~ 150°C (TJ)
Package / Case
16-SOIC (0.154", 3.90mm Width)
Supplier Device Package
16-SO
Mounting Type
Surface Mount
Base Product Number
VIPER25
Datasheet & Documents
HTML Datasheet
VIPER25LD-DG
Environmental & Export Classification
RoHS Status
ROHS3 Compliant
Moisture Sensitivity Level (MSL)
3 (168 Hours)
REACH Status
REACH Unaffected
ECCN
EAR99
HTSUS
8542.39.0001
Additional Information
Other Names
497-19251
VIPER25LD-DG
Standard Package
50
Alternative Parts
PART NUMBER
MANUFACTURER
QUANTITY AVAILABLE
DiGi PART NUMBER
UNIT PRICE
SUBSTITUTE TYPE
Reviews
5.0/5.0-(Show up to 5 Ratings)
December 02, 2025
物流安排非常合理，每次都能準時收到貨，後續的支援也令人滿意。
December 02, 2025
每次購買都看到商品包裝完整，產品耐用，長時間使用後仍然性能穩定。
December 02, 2025
Their manufacturing process results in top-tier products.
December 02, 2025
Their support staff is knowledgeable and responsive, making troubleshooting post-purchase issues easy.
December 02, 2025
Reliable tracking and sturdy packaging—these are the marks of a truly professional company.
December 02, 2025
Efficient inventory management at Di Digi Electronics helps streamline operations across the board.
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Frequently Asked Questions (FAQ)
Can the VIPER25LD replace a VIPER12AD in an existing 12W offline flyback design without major circuit changes, and what risks should I evaluate?
The VIPER25LD can potentially replace the VIPER12AD in a 12W flyback design due to its higher 20W capability and compatible 136kHz switching frequency, but critical evaluation is required. Key risks include differences in internal MOSFET on-resistance (RDS(on)), gate drive characteristics, and feedback loop dynamics—even though both use current-mode control. The VIPER25LD has a higher startup voltage (14V vs. ~10–12V for VIPER12AD), which may delay startup under low-line conditions. Additionally, its higher peak current limit could saturate smaller transformers designed for the VIPER12AD. Always revalidate transformer design, verify startup behavior across input ranges (85–265VAC), and test transient response to avoid instability or overstress.
What are the thermal management trade-offs when using the VIPER25LD in a compact 16-SO package for a 15W industrial power supply operating at 70°C ambient?
The VIPER25LD’s 16-SO package has limited thermal dissipation compared to larger DIP or PowerSO variants, making junction temperature control critical in high-ambient environments. At 15W output with ~85% efficiency, the IC may dissipate 2–3W, pushing TJ close to or beyond 125°C at 70°C ambient without proper layout. Mitigate this by using a solid ground plane under the package, thermal vias to inner layers, and minimizing copper isolation around the IC. Avoid placing heat-sensitive components nearby. Monitor TJ using the thermal shutdown threshold (typically 160°C) as a hard limit—prolonged operation near this point accelerates aging. Consider derating output power by 10–15% if natural convection cooling is the only option.
How does the VIPER25LD’s built-in 800V MOSFET impact reliability in surge-prone applications like outdoor LED drivers, and should I add external TVS protection?
While the VIPER25LD’s 800V breakdown voltage provides margin against typical line surges (e.g., IEC 61000-4-5 Class 2), real-world transients—especially in outdoor or industrial settings—can exceed this during lightning-induced events. The internal MOSFET is robust but not immune to cumulative stress from repeated surges below the breakdown threshold. For mission-critical or high-reliability applications, always include an external TVS diode (e.g., SMAJ400A or P6KE400CA) on the bulk capacitor rail and consider an input filter with an MOV. This reduces peak voltage stress on the IC and extends field life. Without such protection, latent damage may accumulate, leading to premature failure during seasonal surge events.
Is the VIPER25LD suitable for replacing a Power Integrations TNY280GN in a 18W isolated flyback adapter, and what design modifications are necessary?
Replacing the TNY280GN with the VIPER25LD is feasible but requires careful redesign due to architectural differences. The TNY280GN uses a TOPSwitch-style hysteretic control with integrated frequency jitter, while the VIPER25LD employs fixed-frequency PWM at 136kHz with current-mode control. This affects EMI signature, loop compensation, and transformer design. You’ll likely need to adjust the feedback network (optocoupler/ TL431 circuit) and possibly increase primary inductance to match the VIPER25LD’s higher switching frequency. Also, the VIPER25LD requires a dedicated Vcc supply above 8.5V during operation, unlike the TNY280GN’s auto-restart behavior. Validate no-load consumption, cross-regulation (if multi-output), and conducted EMI to ensure compliance.
What precautions should I take when designing a PCB for the VIPER25LD to avoid false triggering of its over-temperature protection during high-duty-cycle operation?
False over-temperature (OTP) triggering in the VIPER25LD often stems from poor thermal coupling between the IC and ambient, or localized heating from adjacent components. Ensure the 16-SO package is mounted on a sufficiently sized copper pour with multiple thermal vias connecting to an internal ground plane. Keep high-current traces (drain, source, output rectifier) away from the IC to prevent conductive heating. Avoid placing the VIPER25LD near hot components like bridge rectifiers or output diodes. Use thermal relief pads cautiously—they can impede heat flow. During testing, monitor case temperature (TC) with a thermocouple; if TC exceeds 110°C under steady load, revisit layout or consider airflow enhancement. Remember, the OTP threshold is internal to the die and responds to TJ, not ambient, so effective heat sinking is non-negotiable for reliable operation.
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.
VIPER25LD CAD Models
STMicroelectronics VIPER25LD PCB symbols & footprints
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