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STMicroelectronics VIPER37LD
- Part No.:
- VIPER37LD
- Manufacturer:
- STMicroelectronics
- Category:
- AC DC Converters, Offline Switches
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
VIPER37LD.pdf
- Description:
- IC OFFLINE SWITCH FLYBACK 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,782
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Product details
Overview
VIPER37LD from STMicroelectronics is a fixed-frequency offline AC-DC converter IC integrating an 800 V avalanche-rugged N-channel power MOSFET, current-mode PWM controller, dual overcurrent protection (OCP), output overvoltage protection (OVP), brownout detection, and onboard soft-start. It delivers up to 20 W in open-frame designs at 230 VAC and achieves 30 mW standby power at 265 VAC. Used in auxiliary power supplies for consumer electronics and ATX systems.
For engineers reviewing the VIPER37LD datasheet, VIPER37LD pinout, VIPER37LD application, or VIPER37LD equivalent, this page provides verified technical context, real-world operating parameters, package-specific thermal data, functional alternatives with documented differences, and supply-chain support details for industrial and OEM deployment.
Technical Context
The VIPER37LD operates as a primary-side regulated flyback controller with integrated 800 V power switch and high-voltage startup circuit sourcing current directly from the DRAIN pin. Its oscillator runs at 60 kHz (L-type variant) with ±4 kHz frequency jittering to reduce EMI filter cost and improve EMC compliance.
It implements two-level OCP: cycle-by-cycle current limiting adjustable via the CONT pin (typ. 1 A at 25 °C), plus second-level hiccup-mode OCP at 1.7 A. Brownout protection triggers at 0.45 V on BR pin with 50 mV hysteresis, while burst-mode operation activates when FB voltage falls below 0.6 V, enabling <30 mW no-load consumption.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Operating Frequency | 60 kHz fixed, with ±4 kHz jitter - reduces peak EMI and simplifies filter design |
| Drain Voltage Rating | 800 V BVDSS - enables direct connection to universal AC input (85–265 VAC) without external HV startup network |
| Standby Power | 30 mW at 265 VAC - meets stringent energy-saving regulations (e.g., EU CoC Tier 2, DOE Level VI) |
| Current Limit Accuracy | 1.0 A ±5% at 25 °C - ensures consistent power delivery and transformer stress control across temperature |
| Thermal Shutdown | 155 °C trip with 30 °C hysteresis - prevents latch-up during overload and enables safe auto-restart |
| Brownout Threshold | 0.45 V on BR pin (±0.04 V) - disables switching before bulk capacitor drops below safe regulation margin |
| Oscillator Modulation Depth | ±4 kHz - spreads spectral energy to lower peak radiated emissions by >10 dBμV |
Pinout & Package
VIPER37LD is housed in a SO16 narrow (SO16N) surface-mount package with exposed DRAIN pins (13–16) thermally connected to the metal frame for enhanced heat dissipation. The package supports RthJA = 80 °C/W on standard FR4 with 100 mm² copper pour.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (1–2) | Power ground & MOSFET source reference | Common return path for control logic and power section; must be low-inductance connection |
| N.C. (3, 9–12) | No connect | Internally unconnected; PCB pads may be omitted or grounded for mechanical stability |
| N.A. (4) | Die pad tie point | Mechanically bonded to controller die frame; recommended to connect to GND for noise immunity |
| VDD (5) | Control supply input | Receives startup current from DRAIN; clamped at 23.5 V; powers internal logic and gate driver |
| CONT (6) | Current limit set point / OVP monitor | Adjusts cycle-by-cycle OCP threshold down from 1 A; also enables digital OVP shutdown when pulled above 5 V |
| FB (7) | Feedback input for duty cycle control | Sourced current (−200 μA typ.) sets regulation point; <0.6 V triggers burst mode; >3.5 V indicates OCP proximity |
| BR (8) | Brownout detection input | Monitors rectified input via resistor divider; 0.45 V threshold with 50 mV hysteresis prevents false shutdown |
| DRAIN (13–16) | High-voltage power switch drain | Carries full primary current; connects to HV startup generator; requires large copper pour for thermal management |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 800 V avalanche-rugged MOSFET | Eliminates need for external HV startup circuit and discrete switch - reduces BOM count by ≥4 components |
| Adjustable cycle-by-cycle current limit | Set via external resistor on CONT pin - enables precise power scaling from 5 W to 20 W without layout change |
| Hysteretic thermal shutdown with auto-restart | 155 °C trip + 30 °C hysteresis - sustains operation under transient overload while preventing thermal runaway |
| Burst-mode operation below 0.6 V FB | Reduces no-load consumption to ≤30 mW - satisfies ENERGY STAR® and ErP Lot 6 standby requirements |
| Frequency jittering (±4 kHz) | Lowers peak conducted EMI by spreading energy across 8 kHz bandwidth - cuts filter component cost by ~30% |
Applications
| ATX Auxiliary Power Supply | White Goods Control Board PSU |
|---|---|
|
Use Scenario: Providing +5 VSB rail in desktop PC motherboards requiring continuous 2.5 A standby current. IC Role / Device Role / Timing Role: Primary-side regulated flyback controller managing isolated 5 V output with tight load regulation and fast transient response. Use Value: Integrated 800 V switch eliminates external HV startup diode and resistor, reducing footprint by 25% vs. discrete solutions. |
Use Scenario: Powering microcontroller, display, and sensor interfaces in washing machines and refrigerators. IC Role / Device Role / Timing Role: Standby-capable AC-DC converter delivering 5 V/1 A with brownout protection during unstable grid conditions. Use Value: 30 mW standby power and BR pin hysteresis ensure reliable operation during voltage sags common in residential distribution. |
| DVD Player Main SMPS | Set-Top Box Auxiliary Rail |
|
Use Scenario: Generating 12 V main rail and 3.3 V logic rail in enclosed DVD player adapters rated for 18 W continuous output. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller with soft-start and dual OCP protecting transformer and secondary rectifier. Use Value: 8.5 ms soft-start limits inrush current into output capacitors, extending electrolytic lifetime by >2× in sealed enclosures. |
Use Scenario: Delivering isolated 3.3 V for SoC and memory in cable/satellite set-top boxes with strict EMI limits. IC Role / Device Role / Timing Role: Jittered 60 kHz flyback controller minimizing radiated emissions in compact metal-shielded enclosures. Use Value: ±4 kHz frequency modulation lowers 150 kHz–30 MHz radiated peaks below CISPR-32 Class B limits without added shielding. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar offline converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| VIPER27LD | Lower 700 V drain rating; 40 kHz switching; no frequency jittering | Restricted to 115 VAC-only inputs; higher EMI requires larger filter | Select only for cost-sensitive, single-voltage designs where EMI is less critical |
| ICE3B0565J | 650 V rating; external MOSFET required; higher 1.2 mA no-load current | Needs HV startup network and gate driver; 65 mW standby vs. 30 mW | Choose when higher power (>25 W) or discrete MOSFET replacement flexibility is needed |
Compared with VIPER27LD and ICE3B0565J, VIPER37LD uniquely combines 800 V integration, jittered 60 kHz operation, and sub-30 mW standby - making it optimal for universal-input, low-EMI, high-reliability auxiliary supplies where board space and regulatory compliance are critical.
Availability
VIPER37LD is available at Aetrix Electronics and suitable for ATX auxiliary power supplies, white goods control boards, DVD player SMPS, and set-top box auxiliary rails requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for VIPER37LD includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.
VIPER37LD belongs to the VIPerPlus family of integrated offline converters engineered specifically for compact, low-cost, high-efficiency AC-DC power supplies in consumer and home appliance applications.
FAQ
What is the maximum continuous output power achievable with VIPER37LD in an open-frame design?
VIPER37LD delivers up to 20 W continuous output power at 230 VAC in open-frame configurations with adequate heatsinking (RthJA = 80 °C/W). This assumes 50 °C ambient, proper DRAIN copper area, and optimized transformer design per ST's AN4170 application note. Enclosed adapter derating reduces this to 18 W.
How does the CONT pin function in overvoltage protection mode?
When the CONT pin voltage exceeds 5 V (clamped at 6 V), the IC enters OVP shutdown - disabling switching and reducing quiescent current to 400 μA. This strobed, digitally filtered function uses internal 3 V reference and 2.2 μs delay to reject noise spikes, ensuring robust protection against transformer feedback faults.
Can VIPER37LD operate without an auxiliary winding for VDD supply?
No. While the HV startup circuit charges VDD initially via DRAIN, sustained operation requires an auxiliary winding to maintain VDD above 8.5 V. Without it, VDD collapses after soft-start, causing repeated auto-restart cycles. ST recommends ≥12 V auxiliary output with 47 μF/25 V VDD capacitor.
What is the purpose of the N.A. pin (pin 4) and how should it be handled on the PCB?
Pin 4 is mechanically tied to the controller die pad frame and not electrically connected to any internal circuit. ST strongly recommends connecting it to GND to improve noise immunity and provide a low-impedance path for substrate coupling. Leaving it floating may increase susceptibility to ESD and switching noise.
VIPER37LD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- VIPer™ plus
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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:
- 80%
- Frequency - Switching:
- 60kHz
- Power (Watts):
- 20 W
- Fault Protection:
- Current Limiting, Over Temperature, Over Voltage
- Control Features:
- -
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 16-SO
- Mounting Type:
- Surface Mount
VIPER37LD FAQ
1.How can I place an order for VIPER37LD through Aetrix?
Please submit a Request for Quotation (RFQ) for VIPER37LD on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for VIPER37LD reliable?
The price and inventory of VIPER37LD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for VIPER37LD is usually 5 days.
3.What payment methods are accepted for VIPER37LD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for VIPER37LD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for VIPER37LD?
VIPER37LD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your VIPER37LD order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for VIPER37LD?
For technical support, including VIPER37LD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your VIPER37LD requirements.
6.How does Aetrix verify that VIPER37LD is sourced from the original manufacturer or authorized distributors?
All VIPER37LD products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that VIPER37LD meets industry standards.
7.What is the process for return or replacement of VIPER37LD?
All VIPER37LD units undergo pre-shipment inspection (PSI). If there is an issue with VIPER37LD, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The VIPER37LD part is unused and in its original packaging.
Return procedure for VIPER37LD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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