Electronic Components Datasheet Search |
|
NCP1217AP100G Datasheet(PDF) 8 Page - ON Semiconductor |
|
NCP1217AP100G Datasheet(HTML) 8 Page - ON Semiconductor |
8 / 19 page NCP1217, NCP1217A www.onsemi.com 8 APPLICATION INFORMATION Introduction The NCP1217 implements a standard current mode architecture where the switch−off event is dictated by the peak current setpoint. This component represents the ideal candidate where low part−count is the key parameter, particularly in low−cost AC/DC adapters, TV power supplies, etc. Due to its high−performance High−Voltage technology, the NCP1217 incorporates all the necessary components normally needed in UC384X based supplies: timing components, feedback devices, low−pass filter and startup device but also enhances the original component by offering: 1) an externally triggerable latchoff 2) ramp compensation and finally, 3) short−circuit protection. Due to its high−voltage current source, ON Semiconductor’s NCP1217 does not need an external startup resistance but supplies the startup current directly from the high−voltage rail. On the other hand, more and more applications are requiring low no−load standby power, e.g. for AC/DC adapters, VCRs, etc. UC384X series have a lot of difficulty to reduce the switching losses at low power levels. NCP1217 elegantly solves this problem by skipping unwanted switching cycles at a user−adjustable power level. By ensuring that skip cycles take place at low peak current, the device ensures quiet, noise−free operation: Current−Mode Operation: As the UC384X series, the NCP1217 features a well−known current mode control architecture which provides superior input audio− susceptibility compared to traditional voltage−mode controllers. Primary current pulse−by−pulse checking together with a fast over current comparator offers greater security in the event of a difficult fault condition, e.g. a saturating transformer. Ramp Compensation: By inserting a resistor between the current−sense (CS) pin and the actual sense resistor, it becomes possible to inject a given amount of ramp compensation since the internal saw tooth clock is routed to the CS pin. Subharmonic oscillations in Continuous Conduction Mode (CCM) can thus be compensated via a single resistor. Adjustable Skip Cycle Level: By offering the ability to tailor the level at which the skip cycle takes place, the designer can make sure that the skip operation only occurs at low peak current. This point guarantees a noise−free operation with cheap transformers. Skip cycle offers a proven mean to reduce the standby power in no or light loads situations. Wide Switching−Frequency Offer: Three different options are available: 65 kHz – 100 kHz–133 kHz. Depending on the application, the designer can pick up the right device to help reducing magnetics or improve the EMI signature before reaching the 150 kHz starting point. Overcurrent Protection (OCP): By continuously monitoring the VCC auxiliary winding voltage, NCP1217 enters burst mode as soon as the power supply undergoes an overload: when the VCC voltage goes down until it crosses the undervoltage lockout level (VCCmin). When the NCP1217 reaches this level (typically 7.6 V), it stops the switching pulses until the VCC pin voltage reaches VCClatch (5.6 V). At VCClatch, the NCP1217 attempts to restart. As soon as the default disappears, the power supply resumes operation. Overvoltage Protection (OVP): If pin1 is brought to a level higher than the internal 3.2 V reference voltage, the controller is permanently shut down until the user cycles the VCC OFF and ON again. This allows the building of efficient and low−cost over voltage protection circuits. Wide Duty−Cycle Operation: Wide mains operation requires a large duty−cycle excursion. The NCP1217 can go up to 74% typically. Low Standby−Power: If SMPS naturally exhibit a good efficiency at nominal load, they begin to be less efficient when the output power demand diminishes. By skipping unneeded switching cycles, the NCP1217 drastically reduces the power wasted during light load conditions. In no−load conditions, the NPC1217 allows the total standby power to easily reach next International Energy Agency (IEA) recommendations. No Acoustic Noise While Operating: Instead of skipping cycles at high peak currents, the NCP1217 waits until the peak current demand falls below a user−adjustable 1/3 of the maximum limit. As a result, cycle skipping can take place without having a singing transformer … You can thus select cheap magnetic components free of noise problems. External MOSFET Connection: By leaving the external MOSFET external to the IC, you can select avalanche proof devices, which in certain cases (e.g. low output powers), let you work without an active clamping network. Also, by controlling the MOSFET gate signal flow, you have an option to slow down the device commutation, therefore reducing the amount of ElectroMagnetic Interference (EMI). SPICE Model: A dedicated model to run transient cycle−by−cycle simulations is available but also an averaged version to help you closing the loop. Ready−to−use templates can be downloaded in OrCAD’s Pspice and INTUSOFT’s IsSpice from ON Semiconductor web site, NCP1217 related section. |
Similar Part No. - NCP1217AP100G |
|
Similar Description - NCP1217AP100G |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |