Sn51dp Datasheet

From reviewing historical datasheet fragments and circuit diagrams, the SN51DP boasts the following features:

Given that Sanken has discontinued many of these older hybrid ICs, official PDFs are not always on their main site. Try these sources:

Caution: Many "SN51DP" listings online are counterfeit clones. If the price is too low (e.g., <$2), be suspicious. Authentic Sanken parts are heavy, have precise pin straightness, and include a matte finish. sn51dp datasheet

Before diving into the datasheet details, let's decode the nomenclature:

The SN51DP is generally a switching regulator IC capable of handling medium to high power. It is most commonly found in step-down (buck) converter topologies, CRT televisions (for horizontal deflection power), and industrial power modules. Given that Sanken has discontinued many of these

| Parameter | Value / Range | Remarks | |-----------|---------------|---------| | Package | DIP-6 (0.3" lead spacing) | Through-hole, also available in SMD (SN51DP-S) | | Input Diode Forward Current (IF) | 50 mA (max) | Typically driven at 5–20 mA | | Reverse Input Voltage | 6 V (max) | | | Output Blocking Voltage (VDRM) | 600 V (min) | Suitable for 110/230 VAC mains | | On-State Current (ITRMS) | 100 mA | Direct control only for tiny loads; usually drives a power triac | | Peak Surge Current (ITSM) | 1.2 A (non-repetitive) | | | Zero-Crossing Voltage | ±20 V (typical) | Activates within ~20V of AC zero crossing | | Isolation Voltage | 5000 Vrms (min) | Reinforced isolation | | Operating Temperature | -30°C to +100°C | |

The SN51DP is available in a small package, often a TSSOP (Thin Shrink Small-Outline Package) or similar, making it suitable for compact designs and portable equipment. Caution : Many "SN51DP" listings online are counterfeit

When designing with the SN51DP, the datasheet (or this compilation) emphasizes these points:

Finding an exact SN51DP replacement can be difficult. If you are repairing a board and cannot source the original, consider these cross-reference options (check pinout compatibility first):

| Part Number | Manufacturer | Notes / Differences | | :--- | :--- | :--- | | LM2576T-ADJ | Texas Instruments | 3A, 60V, but TO-220-5 pinout slightly different (Enable on pin 5 vs Compensation). Requires board mod. | | MC34063A | Onsemi / ST | Lower current (1.5A) – needs external transistor for 3A. Cheap but complex. | | Sanken SI-8050S | Sanken | Similar series, higher frequency (100kHz). Direct alternative if pin 5 function matches. | | NTE1872 | NTE Electronics | Specific replacement model for SN51DP (check NTE datasheet). |

Important: Always cross-check the pin function, not just pin count. The SN51DP pin 5 is Compensation; many modern parts use that pin for Shutdown. Connecting incorrectly will cause instability or failure.