NCP1255 Current-Mode PWM Controller for Off-line Power Supplies featuring Peak Power Excursion www.onsemi.com The NCP1255 is a highly integrated PWM controller capable of delivering a rugged and high performance offline power supply in a SOIC8 package. With a supply range up to 35 V, the controller hosts a jittered 65kHz switching circuitry operated in peak current mode 8 control. When the power on the secondary side starts to decrease, the 1 controller automatically folds back its switching frequency down to a SOIC8 minimum level of 26 kHz. As the power further goes down, the part D1, D2 SUFFIX enters skip cycle while freezing the peak current setpoint. CASE 751 To help build rugged converters, the controller features several key protective features: a brownout, a nondissipative Over Power MARKING DIAGRAM Protection for a constant maximum output current regardless of the input voltage, two latched over voltage protection inputs either 8 through a dedicated pin or via the V input and finally, the 1255x65 cc ALYW possibility to externally adjust an autorecovery timer duration. The controller architecture is arranged to authorize a transient peak 1 power excursion when the peak current hits the limit. At this point, the switching frequency is increased from 65 kHz to 130 kHz until the 1255x65 = Specific Device Code peak requirement disappears. The timer duration is then modulated as x = A, B, C or D A = Assembly Location the converter crosses a peak power excursion mode (long) or L = Wafer Lot undergoes a short circuit (short). Y = Year W = Work Week Features = PbFree Package 65kHz Fixedfrequency Currentmode Control Operation with (Note: Microdot may be in either location) 130kHz Excursion Internal and Adjustable Over Power Protection (OPP) Circuit PIN CONNECTIONS Adjustable BrownOut Protection Circuit Frequency Foldback down to 26 kHz and Skipcycle in Light Load 1 8 OPP/Latch Timer Conditions 2 7 BO FB Adjustable Slope Compensation 6 3 CS Vcc Internally Fixed 4ms Softstart 5 4 GND DRV Adjustable Timerbased Autorecovery Overload/Shortcircuit Protection (Top View) 100% to 25% Timer Reduction from Overload to Shortcircuit Fault Double V Hiccup for a Reduced Average Power in Fault Mode cc ORDERING INFORMATION Frequency Jittering in Normal and Frequency Foldback Modes See detailed ordering and shipping information in the package dimensions section on page 2 of this data sheet. Latched OVP Input for Improved Robustness and Latched OVP on V cc Up to 35V V Maximum Rating cc Extremely Low Noload Standby Power This is a PbFree Device Typical Applications Converters requiring peakpower capability such as printers power supplies, acdc adapters for game stations. Semiconductor Components Industries, LLC, 2015 1 Publication Order Number: September, 2015 Rev. 2 NCP1255/DNCP1255 Vbulk Vout OVP OPP . 1 8 2 7 BO 3 6 Eris 5 4 Eris NCP1255 ramp comp. Figure 1. Typical Application Example Table 1. PIN FUNCTION DESCRIPTION Pin No. Pin Name Function Pin Description 1 OPP/OVP Adjust the Over Power Protection. A resistive divider from the auxiliary winding to this pin sets the OPP compensation level. When brought above 3 V, the part is fully Latches off the part latched off. 2 FB Feedback pin Hooking an optocoupler collector to this pin will allow regulation. 3 CS Current sense + ramp This pin monitors the primary peak current but also offers a means compensation to introduce ramp compensation. 4 GND The controller ground. 5 DRV Driver output The drivers output to an external MOSFET gate. 6 V Supplies the controller This pin is connected to an external auxiliary voltage and supplies cc the controller. When above a certain level, the part fully latches off. 7 BO BrownOut input A voltage below the programmed level stops the controller. When above, the controller can start. 8 Timer Sets the timer duration A 22k resistor sets the duration to 200 ms. When shorted to ground or made open, this pin limits the internal current and fixes the timer duration. Table 2. ORDERING INFORMATION AND OPTIONS Controller Frequency OCP Latched OCP AutoRecovery V (V) Package Shipping BOoff 65 kHz Yes NCP1255AD65R2G No 0.6 NCP1255BD65R2G 65 kHz No Yes 0.6 SOIC8 2500 / Tape (PbFree) & Reel NCP1255CD65R2G 65 kHz Yes No 0.7 NCP1255DD65R2G 65 kHz No Yes 0.7 For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specification Brochure, BRD8011/D. www.onsemi.com 2