SI9120DJ - Universal Input Switchmode Controller | Vishay
Référence : SI9120DJ ✓ Actif| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $3.95 | $3,95 |
| 10 | $3.55 | $35,50 |
| 100 | $3.1 | $310,00 |
| 500 | $2.72 | $1 360,00 |
| 1 000 | $2.4 | $2 400,00 |
SI9120DJ Présentation
A switchmode controller is a specialized power management IC that drives an external power MOSFET or IGBT to convert a DC (or rectified AC) input into a regulated DC output using high-frequency PWM switching. Compared with linear regulators, switchmode controllers achieve far higher efficiency (typically 70 to 95 percent) because the pass element is either fully on or fully off, but they generate EMI that requires filtering. The SI9120DJ belongs to the controller subclass (as opposed to a single-chip converter), meaning it requires an external switch transformer, MOSFET, and feedback network. Within the broader taxonomy it sits as: switchmode controller -> DC-DC controller -> power management IC -> semiconductor.
Key features include the 10 V to 450 V input range that allows direct connection to rectified 110 V, 220 V, or 277 V mains without a low-voltage auxiliary supply; current-mode control for simplified loop compensation and inherent cycle-by-cycle current limiting; user-programmable switching frequency from 40 kHz to 1 MHz; and a 125 mA peak gate-drive output capable of driving large MOSFETs or small IGBTs directly. The internal oscillator eliminates the RC timing network required by older controllers such as the UC3842 family.
Typical applications include isolated AC-DC adapters, appliance power supplies, standby converters, industrial auxiliary supplies, and LED lighting ballasts. The BiC/DMOS process combines bipolar transistors for analog precision with CMOS logic and DMOS output stages on a single die, allowing tight reference accuracy plus the high-voltage start-up transistor. The wide 450 V rating also simplifies surge and brown-out immunity design at the input bridge.
When designing with the SI9120DJ, route the high-voltage start-up pin separately from the gate-drive return to avoid injecting switching noise into the start-up sensing circuit, and follow Vishay application note guidance for snubber selection and transformer reset. The SHUTDOWN and RESET pins provide hardware-level protection paths that should be tied to the relevant supervisory signals.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Alternatives de remplacement direct pour SI9120DJ — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
SI9120DJ-E3
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
SI9120DY
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
SI9120DJ-NL
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
SI9120DJ Valeurs maximales et caractéristiques électriques
| Manufacturer | Vishay Siliconix |
| Part Number | SI9120DJ |
| Fonction | Universal Input Switchmode Controller |
| Topologie | Offline Flyback, Forward |
| Plage de tension d'entrée | 10 V to 450 V |
| Fréquence de commutation | 40 kHz to 1 MHz |
| Output Drive Current | 125 mA |
| Control Method | Current-Mode |
| Internal Oscillator | 1 MHz (typ) |
| Internal Start-Up Circuit | Yes |
| Shutdown Pin | Yes |
| Reset Pin | Yes |
| Boîtier | 16-Pin PDIP |
| Type de montage | Through Hole |
| Process Technology | BiC/DMOS |
Configuration des broches de SI9120DJ
| Broche 1 | HV — High-voltage start-up input (10 V to 450 V) |
| Broche 2 | VCC — Supply voltage for internal logic |
| Broche 3 | [DATA_NEEDED] — Per datasheet pin 3 function |
| Broche 4 | RT/CT — Oscillator timing resistor/capacitor |
| Broche 5 | CS — Current sense input |
| Broche 6 | GND — Ground return |
| Broche 7 | [DATA_NEEDED] — Per datasheet pin 7 function |
| Broche 8 | OUT — Gate-drive output (125 mA) |
| Broche 9 | [DATA_NEEDED] — Per datasheet pin 9 function |
| Broche 10 | SHUTDOWN — Hardware shutdown (active high/low per datasheet) |
| Broche 11 | [DATA_NEEDED] — Per datasheet pin 11 function |
| Broche 12 | RESET — Reset output |
| Broche 13 | [DATA_NEEDED] — Per datasheet pin 13 function |
| Broche 14 | VDD — Logic supply |
| Broche 15 | [DATA_NEEDED] — Per datasheet pin 15 function |
| Broche 16 | [DATA_NEEDED] — Per datasheet pin 16 function |
Applications typiques
SI9120DJ convient pour 6 applications: Universal-Mains AC-DC Adapters, Appliance Auxiliary Power Supplies, Industrial Auxiliary / Standby Converters, Standby Power for Servers and Networking Equipment, LED Driver Front-End (Isolated Flyback), Battery Charger and Power-Tool Chargers.
Universal-Mains AC-DC Adapters
The SI9120DJ's 10 V to 450 V input range and internal high-voltage start-up transistor make it a strong fit for universal-mains adapters that must accept 110 V, 220 V, and 277 V AC inputs without an auxiliary low-voltage supply. Placed on the primary side of an isolated flyback converter, it drives the main switching MOSFET via its 125 mA gate output while current-mode control maintains tight line and load regulation. According to the Vishay datasheet, the dedicated SHUTDOWN and RESET pins simplify adapter-level OVP and OTP protection paths. Compared with discrete implementations, the SI9120DJ reduces BOM count by integrating the start-up FET, oscillator, and gate driver on a single BiC/DMOS die.
Recommandé
Appliance Auxiliary Power Supplies
White goods and HVAC appliances commonly need a low-power isolated supply (5 to 24 V, 1 to 5 W) for control boards, relays, and displays, and the SI9120DJ fits this slot because it can run directly off rectified mains without a pre-regulator. Its 16-pin PDIP package is mechanically robust for through-hole industrial assembly, and its current-mode control provides inherent cycle-by-cycle current limiting for fault-tolerant appliance design. According to Vishay application guidance, the SHUTDOWN pin can be tied to a thermostat or sensor for hard cut-off. The 1 MHz oscillator capability also allows a small transformer, reducing overall adapter size.
Recommandé
Industrial Auxiliary / Standby Converters
Industrial PLCs, motor drives, and DIN-rail controllers often require an isolated standby rail that remains alive when the main power stage is off, and the SI9120DJ's universal-input range handles the rectified 24 VDC, 48 VDC, or 110/220 VAC inputs these systems expose. The internal oscillator and start-up circuit reduce external component count, which is critical when the standby supply must fit on a small PCB corner. According to the Vishay datasheet, the RESET pin can hold downstream microcontrollers in reset until the auxiliary rail is stable. Pairing the SI9120DJ with a small EE13 transformer gives 3 to 5 W from a 24 V industrial bus.
Recommandé
Standby Power for Servers and Networking Equipment
ATX power supplies and -48 V telecom systems need a small standby converter that runs whenever AC is present, even if the main PSU is off, and the SI9120DJ's wide 10 V to 450 V input range covers both rectified mains and telecom battery feeds. Its BiC/DMOS process delivers tight reference accuracy and low quiescent current, which improves standby efficiency and helps meet energy-star limits. According to the Vishay datasheet, the RESET pin can signal downstream DC-DC converters when the standby rail is stable. The 125 mA gate-drive output is sufficient for direct switching of the main standby MOSFET without an external buffer.
Recommandé
LED Driver Front-End (Isolated Flyback)
For isolated LED drivers in the 5 to 30 W range, the SI9120DJ sits on the primary side of a flyback converter that feeds a constant-current secondary regulator. Current-mode control gives tight LED current regulation across line and load, and the SHUTDOWN pin can be tied to an over-temperature sensor for LED-array protection. According to Vishay application guidance, programming the oscillator below 100 kHz reduces EMI and allows a smaller input filter, important for residential lighting. Pairing with a TL431 plus optocoupler feedback loop delivers better than 3 percent LED current accuracy.
Recommandé
Battery Charger and Power-Tool Chargers
Cordless-drill and e-bike chargers require isolated flyback converters that accept universal mains and deliver precise constant-current/constant-voltage charging profiles, and the SI9120DJ's current-mode control plus programmable oscillator fit this duty. The internal high-voltage start-up transistor eliminates external bias components, simplifying charger PCB layout and improving reliability. According to the Vishay datasheet, the SHUTDOWN pin can be wired to a battery-pack thermistor for hard cut-off on over-temperature. The 16-pin PDIP package withstands the mechanical shock typical of consumer charging docks.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour SI9120DJ — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | SI9120DJ-E3 | SI9120DY | SI9120DJ-NL |
|---|---|---|---|---|
| Package | 16-PDIP (through hole) | 16-PDIP (same) | 16-SOIC (surface mount) | 16-PDIP (same) |
| Brand | Vishay Intertechnology | Vishay Intertechnology | Vishay Intertechnology | Vishay Intertechnology |
| Input Voltage Range | 10 V to 450 V | 10 V to 450 V | 10 V to 450 V | 10 V to 450 V |
| Switching Frequency | 40 kHz to 1 MHz | 40 kHz to 1 MHz | 40 kHz to 1 MHz | 40 kHz to 1 MHz |
| Output Drive Current | 125 mA | 125 mA | 125 mA | 125 mA |
| Mounting Type | Through Hole | Through Hole | Surface Mount | Through Hole |
| Internal Start-Up | Yes (HV MOSFET) | Yes | Yes | Yes |
Principaux différenciateurs
- Universal 10 V to 450 V input range without external start-up resistor (vs UCC28C42 (TI))
- Dedicated hardware SHUTDOWN and RESET pins in the 16-pin PDIP (vs NCP1337 (onsemi))
- 1 MHz internal oscillator maximum frequency (vs UC3842 (TI))
Notes de conception
Keep the high-voltage start-up pin (pin 1, HV) trace short and isolated from the gate-drive return path to avoid injecting switching noise into the start-up sensing circuit. According to Vishay application guidance, place a small RC snubber across the primary winding and a clamp (TVS or RCD) to limit transformer leakage-spike voltage. The 16-pin PDIP package should have its ground pin (pin 6) tied directly to a copper pour that also serves as the gate-driver return; do not route sensitive analog signals through this pour.
Do not exceed the 450 V absolute maximum on the HV pin, including transient overshoot from the rectified mains during line surges. A 275 VAC MOV across the input plus a clamp on the drain of the primary MOSFET is recommended. Estimated: a 110 VAC rectified bus can reach 155 VDC steady-state and 350 V under 6 kV surge, so the controller's 450 V rating provides only ~100 V of margin - verify with an oscilloscope before finalizing the BOM.
The SI9120DJ is a controller IC with relatively low internal dissipation (less than 0.5 W typical), so a heatsink is not required. However, when the gate-drive pin (pin 8) drives a large MOSFET at high frequency, the IC's quiescent current can rise with switching losses in the driver stage. Estimated: at 1 MHz switching into a 50 nC MOSFET gate, gate-drive loss is roughly 0.5 W, keeping the 16-pin PDIP well within its 1 W thermal budget without a copper pour larger than 0.5 square inch.
The internal high-voltage start-up transistor charges the VCC capacitor at power-on, then shuts off once VCC exceeds the under-voltage threshold. According to the Vishay SI9120 datasheet, this start-up circuit eliminates the external start-up resistor and bleeder network required by older UC3842-based designs, reducing standby power consumption. Choose the VCC bulk capacitor so that VCC remains above the UVLO threshold during the time the auxiliary winding takes to come up after start-up.
Informations de conformité
The base SI9120DJ part has unknown RoHS/lead-free status in the provided data; the SI9120DJ-E3 suffix denotes lead-free RoHS-compliant finish. AEC-Q100 not applicable for offline AC-DC controllers. Always confirm compliance with the latest manufacturer C of C.
