DPA424SN

The DPA424SN is one member of the DPA424 series.The following transparent or built-in features are also provided:soft-start, cycle skipping down to zero load and hysteretic thermal shutdown. In addition, all critical parameters (i.e.current limit, frequency, PWM gain) have tight temperature and absolute tolerance, to simplify design and optimize system cost.

Features of the DPA424SN are:(1)eliminates all external current sensing circuitry; (2)built-in auto-restart for output overload/open loop protection; (3)pin selectable 300/400 kHz fixed frequency; (4)wide input (line) voltage range: 16-75 VDC; (5)source connected tab reduces emi; (6)line under-voltage (UV) detection: meets ETSI standards; (7)line overvoltage (OV) shutdown protection; (8)low cost synchronous rectification: line UV/OV shut down limits gate drive voltage range from transformer winding; (9)fully integrated soft-start for minimum stress/overshoot; (10)externally programmable current limit; (11)supports forward or flyback topology; (12)cycle skipping: regulation to zero load without pre-load; (13)hysteretic thermal shutdown for automatic fault recovery.

The absolute maximum ratings of the DPA424SN can be summarized as:(1)drain voltage:-0.3 to 220V;(2)storage temperature:-65 to 150;(3)lead temperature:+260;(4)operating junction temperature:-40 to 150;(5)control current:100 mA.It is recommended that the forward converter transformer be designed for maximum operating flux swing of 1500 Gauss and a peak flux density of 3500 Gauss. When operating at the maximum current limit of the selected DPA-Switch (during overload conditions), neither magnetic component (transformer and output inductor) should be allowed to saturate. When a larger device than necessary has been selected, reducing the internal current limit close to the operating peak current limits overload power and minimizes the size of the secondary components.The current limit is externally set by resistor R3 to just above the drain current level needed for maximum load regulation to limit the maximum overload power of the converter. The externally programmable current limit feature also allows a larger DPA-Switch family member to be selected. Using the X pin, the current limit can be adjusted to the same level.