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Vishay Siliconix SI9120DY-E3
- Part No.:
- SI9120DY-E3
- Manufacturer:
- Vishay Siliconix
- Category:
- AC DC Converters, Offline Switches
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SI9120DY-E3.pdf
- Description:
- IC OFFLINE SW MULT TOP 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,563
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Product details
Overview
SI9120DY-E3 from Vishay Siliconix is a universal-input, current-mode switchmode controller IC designed for off-line flyback and forward power converters. It supports 10–450 VDC input, delivers 125 mA peak output drive, integrates a 1 MHz oscillator, and operates across −40 °C to +85 °C in SOIC-16 package - enabling compact, high-efficiency 30 W AC/DC adapters and industrial power supplies.
For engineers reviewing the SI9120DY-E3 datasheet, SI9120DY-E3 pinout, SI9120DY-E3 application, or SI9120DY-E3 equivalent, key selection criteria include its wide-input-range HV pre-regulator, internal start-up circuit, undervoltage lockout (8.1 V), 1.2 V current-sense threshold, and CMOS push-pull output capable of driving MOSFETs with Qg up to 25 nC.
Technical Context
The SI9120DY-E3 implements current-mode PWM control using a CMOS-based error amplifier and comparator architecture, with a dedicated high-voltage DMOS input stage on +VIN (Pin 1) enabling direct connection to rectified AC mains. Its internal oscillator frequency (40 kHz–1 MHz) is set by an external resistor between OSC IN (Pin 9) and OSC OUT (Pin 10), while DISCHARGE (Pin 15) must be tied to −VIN for normal operation.
Control logic includes latched SHUTDOWN/RESET functionality with defined truth table behavior, a 4 V reference output (VREF, Pin 11), and a 1.2 V current-sense threshold (SENSE, Pin 7). The pre-regulator provides constant-current start-up until VCC reaches 8.6 V, then transitions to regulated mode, with UVLO activation at 8.1 V to ensure stable gate drive before switching begins.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 10–450 VDC - enables single-controller operation from universal AC mains (85–265 VAC) through industrial DC bus inputs without external step-down. |
| Oscillator Frequency | 40 kHz to 1 MHz - adjustable via ROSC; 100 kHz typical with 330 kΩ resistor - balances efficiency, EMI, and transformer size in flyback designs. |
| Output Drive Current | 125 mA source/sink - sufficient to directly drive MOSFET gates (e.g., IRF820, BUZ78) with Qg ≤ 25 nC at 100 kHz, minimizing external driver complexity. |
| Current-Sense Threshold | 1.2 V (typical) - sets overcurrent protection point; allows precise primary-side current limiting without secondary sensing components. |
| VCC Operating Range | 9.5–13.5 V - defines stable bias window; internal pre-regulator maintains VCC during start-up and regulates it to ~8.6 V if no external supply is present. |
| Undervoltage Lockout | 8.1 V (typical) - prevents erratic operation during brown-out or incomplete start-up; hysteresis ensures clean re-enable above 8.9 V. |
| Reference Output Voltage | 4.0 V ±2% - precision internal voltage reference for error amplifier feedback; bypassed externally to stabilize loop compensation. |
Pinout & Package
SI9120DY-E3 is housed in a 16-pin SOIC (Narrow) package per JEDEC MS-012, with 1.27 mm pitch, 10.0 mm × 4.0 mm body, and thermal impedance θJA = 140 °C/W. Pins 2 and 3 are omitted (NC). Package meets RoHS-compliant lead (Pb)-free requirements.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| +VIN (1) | High-voltage input | Accepts 10–450 VDC; powers internal pre-regulator; requires series resistor (>10 kΩ) above 250 V to limit dissipation. |
| BIAS (16) | Bias current reference | Connects to −VIN via 390 kΩ resistor to set analog section bias current (~15 µA) and pull-up strength for SHUTDOWN/RESET. |
| FB (4) | Error amplifier inverting input | Receives optocoupler feedback signal; closed-loop regulation adjusts duty cycle to maintain output voltage stability. |
| COMP (5) | Error amplifier output | Provides compensation node for Type II/III networks; high-impedance output interfaces directly with oscillator ramp input. |
| SENSE (7) | Current-sense input | Monitors primary-side current via sense resistor; triggers PWM shutdown when voltage exceeds 1.2 V threshold. |
| OUTPUT (8) | CMOS push-pull driver output | Drives external MOSFET gate; 20 Ω typical RON, 75 ns rise/fall time into 500 pF - optimized for fast switching with low gate charge devices. |
| SHUTDOWN (12) | Digital control input | Latched or unlatched disable control; internal current-source pull-up; low state forces OUTPUT low; logic compatible with 0–VCC levels. |
| −VIN (6) | Power ground reference | System return for +VIN, BIAS, SENSE, and internal circuits; not connected to earth or chassis ground in isolated topologies. |
Key Features
| Feature | Design Value |
|---|---|
| Universal input range (10–450 VDC) | Eliminates need for separate controllers per input voltage class - supports global AC/DC adapter and industrial SMPS designs with one BOM item. |
| Integrated HV pre-regulator with start-up current source | Enables self-biasing from rectified line without auxiliary winding; constant-current start-up charges VCC capacitor reliably across full input range. |
| Current-mode PWM control with 1.2 V sense threshold | Provides inherent cycle-by-cycle current limiting, improves transient response, and simplifies loop compensation versus voltage-mode alternatives. |
| 125 mA CMOS output driver | Directly drives medium-power MOSFETs (Qg ≤ 25 nC); reduces bill-of-materials and layout area compared to discrete driver stages. |
| Latched SHUTDOWN/RESET logic | Allows robust fault recovery: simultaneous low on both pins latches OFF state until RESET returns high - prevents spurious restarts during overvoltage/overload events. |
Applications
| AC/DC Adapters | Industrial Power Supplies |
|---|---|
|
Use Scenario: 12 V/2.5 A universal-input offline adapter for networking equipment. IC Role / Device Role / Timing Role: Primary-side PWM controller implementing discontinuous conduction mode (DCM) flyback topology with opto-coupled feedback. Use Value: Enables compact 30 W design with <1.5 mA quiescent current, meeting Level VI efficiency requirements without auxiliary bias winding. |
Use Scenario: 24 V/1.25 A DIN-rail mounted power supply for PLC I/O modules. IC Role / Device Role / Timing Role: Off-line forward converter controller managing synchronous rectification timing and input surge tolerance. Use Value: Wide 10–450 VDC input range accommodates unregulated industrial DC buses (e.g., 277 VDC lighting systems) and rectified 3-phase inputs. |
| LED Driver Modules | Medical Auxiliary Supplies |
|
Use Scenario: Constant-current LED driver for commercial signage operating from 120/277 VAC line. IC Role / Device Role / Timing Role: Primary-side regulated flyback controller with valley-switching optimization for low EMI and high PF. Use Value: Internal 1 MHz oscillator and fast 75 ns output switching minimize transformer size and improve thermal performance in enclosed fixtures. |
Use Scenario: Isolated 5 V/1 A auxiliary supply for patient-monitor sensor interface boards. IC Role / Device Role / Timing Role: Safety-isolated flyback controller with reinforced creepage/clearance compliance via external transformer design. Use Value: Undervoltage lockout (8.1 V) and latchable SHUTDOWN ensure fail-safe shutdown during input brown-out or overtemperature conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switchmode controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC3842BD1R2G (ON Semiconductor) | Fixed 52 kHz frequency, 16 V max VCC, no integrated HV start-up - requires external bias network. | Best suited for lower-input-voltage (<265 VAC) applications where cost sensitivity outweighs design simplicity. | Choose UC3842BD1R2G only when designing for fixed-frequency operation below 200 VDC input and when external start-up circuitry is acceptable. |
| ICE2A265 (Infineon) | Integrated 650 V MOSFET, fixed 65 kHz frequency, higher integration but no programmable oscillator or latched shutdown. | Targeted at cost-optimized, low-component-count flybacks up to 25 W - lacks SI9120DY-E3's wide input flexibility and precision current-sense threshold. | Prefer ICE2A265 for ultra-compact, low-power consumer adapters where integrated FET eliminates gate driver layout; avoid for >30 W or wide-input industrial use. |
Compared with UC3842BD1R2G and ICE2A265, the SI9120DY-E3 uniquely combines universal 10–450 VDC input capability, programmable oscillator (40 kHz–1 MHz), latched fault protection, and self-starting HV pre-regulator - making it the only option among the three suitable for high-reliability, wide-input industrial SMPS without external HV bias components.
Availability
SI9120DY-E3 is available at Aetrix Electronics and suitable for AC/DC adapters, industrial power supplies, and LED driver modules requiring stable component supply and long-term lifecycle support despite its end-of-life status.
Supply support for SI9120DY-E3 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
Vishay Siliconix is a global semiconductor manufacturer specializing in discrete power MOSFETs, diodes, optoelectronics, and analog ICs, with emphasis on high-voltage, high-reliability solutions.
The SI9120DY-E3 belongs to Vishay's universal-input switchmode controller product line, engineered specifically for high-efficiency, low-noise off-line power conversion in space-constrained industrial and medical applications.
FAQ
What is the maximum recommended input voltage for SI9120DY-E3, and how is overvoltage protection implemented?
The SI9120DY-E3 supports a maximum +VIN rating of 450 VDC. Overvoltage protection is not internally implemented; instead, safe operation above 250 VDC requires an external series resistor (10 kΩ for 250–380 V, 15 kΩ for 380–450 V) on Pin 1 to limit pre-regulator power dissipation. The device relies on external clamping or system-level protection for transients beyond this range. SI9120DY-E3 itself does not include built-in overvoltage shutdown or crowbar circuitry.
Does SI9120DY-E3 require an external oscillator capacitor, and how is frequency set?
No, the SI9120DY-E3 does not require an external oscillator capacitor. Its frequency is set solely by an external resistor (ROSC) connected between OSC IN (Pin 9) and OSC OUT (Pin 10); typical values range from 25 kΩ to 1 MΩ to achieve 40 kHz–1 MHz. DISCHARGE (Pin 15) must be tied to −VIN for internal oscillator operation. SI9120DY-E3 uses a ring-oscillator architecture with no timing capacitor dependency.
Can SI9120DY-E3 drive a MOSFET with 50 nC gate charge?
No, SI9120DY-E3 is rated for MOSFETs with gate charge up to 25 nC at 100 kHz. Driving a 50 nC device would exceed its 125 mA output drive capability, resulting in slow switching, increased losses, and potential thermal failure. For higher-Qg MOSFETs, an external gate driver is required. SI9120DY-E3's 75 ns rise/fall times are validated only for loads ≤500 pF, consistent with ≤25 nC gate charge at typical VGS.
What is the function of the BIAS pin (Pin 16) on SI9120DY-E3, and what resistor value is required?
The BIAS pin (Pin 16) sets bias current for all analog sections and internal pull-ups on SHUTDOWN/RESET. A 390 kΩ resistor must be connected from BIAS to −VIN (Pin 6) to establish nominal 15 µA bias current. Omitting this resistor or using incorrect value degrades error amplifier gain, oscillator stability, and logic input thresholds. SI9120DY-E3 will not operate correctly without this external bias network.
Is SI9120DY-E3 still in active production, and what is its lifecycle status?
No, SI9120DY-E3 is End-of-Life (EOL); its Last Available Purchase Date was December 31, 2014. However, Aetrix Electronics maintains legacy inventory with full traceability and offers lifecycle coordination support, including obsolescence forecasting and cross-reference guidance. SI9120DY-E3 remains suitable for repair, maintenance, and legacy production runs where form-fit-function compatibility is critical.
SI9120DY-E3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay Siliconix
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Output Isolation:
- Isolated
- Internal Switch(s):
- No
- Voltage - Breakdown:
- -
- Topology:
- Flyback, Forward
- Voltage - Start Up:
- -
- Voltage - Supply (Vcc/Vdd):
- 9.5V ~ 13.5V
- Duty Cycle:
- 50%
- Frequency - Switching:
- 40kHz ~ 1MHz
- Power (Watts):
- -
- Fault Protection:
- -
- Control Features:
- -
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 16-SOIC
- Mounting Type:
- Surface Mount
SI9120DY-E3 FAQ
1.How can I place an order for SI9120DY-E3 through Aetrix?
Please submit a Request for Quotation (RFQ) for SI9120DY-E3 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 SI9120DY-E3 reliable?
The price and inventory of SI9120DY-E3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI9120DY-E3 is usually 5 days.
3.What payment methods are accepted for SI9120DY-E3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI9120DY-E3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SI9120DY-E3?
SI9120DY-E3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SI9120DY-E3 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 SI9120DY-E3?
For technical support, including SI9120DY-E3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI9120DY-E3 requirements.
6.How does Aetrix verify that SI9120DY-E3 is sourced from the original manufacturer or authorized distributors?
All SI9120DY-E3 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 SI9120DY-E3 meets industry standards.
7.What is the process for return or replacement of SI9120DY-E3?
All SI9120DY-E3 units undergo pre-shipment inspection (PSI). If there is an issue with SI9120DY-E3, 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 SI9120DY-E3 part is unused and in its original packaging.
Return procedure for SI9120DY-E3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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