Electronic Components Datasheet Search |
|
NCP1200D40R2G Datasheet(PDF) 7 Page - ON Semiconductor |
|
NCP1200D40R2G Datasheet(HTML) 7 Page - ON Semiconductor |
7 / 16 page NCP1200 http://onsemi.com 7 APPLICATIONS INFORMATION INTRODUCTION The NCP1200 implements a standard current mode architecture where the switch−off time 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, auxiliary supplies etc. Due to its high−performance High−Voltage technology, the NCP1200 incorporates all the necessary components normally needed in UC384X based supplies: timing components, feedback devices, low−pass filter and self−supply. This later point emphasizes the fact that ON Semiconductor’s NCP1200 does NOT need an auxiliary winding to operate: the product is naturally supplied from the high−voltage rail and delivers a VCC to the IC. This system is called the Dynamic Self−Supply (DSS). Dynamic Self−Supply The DSS principle is based on the charge/discharge of the VCC bulk capacitor from a low level up to a higher level. We can easily describe the current source operation with a bunch of simple logical equations: POWER−ON: IF VCC < VCCOFF THEN Current Source is ON, no output pulses IF VCC decreasing > VCCON THEN Current Source is OFF, output is pulsing IF VCC increasing < VCCOFF THEN Current Source is ON, output is pulsing Typical values are: VCCOFF = 11.4 V, VCCON = 9.8 V To better understand the operational principle, Figure 15’s sketch offers the necessary light: 10.00M 30.00M 50.00M 70.00M 90.00M Current Source OFF Figure 15. The Charge/Discharge Cycle Over a 10 mF VCC Capacitor VCC ON 10.6 V Avg. Output Pulses VCCON = 9.8 V VCCOFF = 11.4 V The DSS behavior actually depends on the internal IC consumption and the MOSFET’s gate charge, Qg. If we select a MOSFET like the MTD1N60E, Qg equals 11 nC (max). With a maximum switching frequency of 48 kHz (for the P40 version), the average power necessary to drive the MOSFET (excluding the driver efficiency and neglecting various voltage drops) is: Fsw @ Qg @ Vcc with Fsw = maximum switching frequency Qg = MOSFET’s gate charge VCC = VGS level applied to the gate To obtain the final driver contribution to the IC consumption, simply divide this result by VCC: Idriver = Fsw @ Qg = 530 mA. The total standby power consumption at no−load will therefore heavily rely on the internal IC consumption plus the above driving current (altered by the driver’s efficiency). Suppose that the IC is supplied from a 400 V DC line. To fully supply the integrated circuit, let’s imagine the 4 mA source is ON during 8 ms and OFF during 50 ms. The IC power contribution is therefore: 400 V . 4 mA . 0.16 = 256 mW. If for design reasons this contribution is still too high, several solutions exist to diminish it: 1. Use a MOSFET with lower gate charge Qg 2. Connect pin through a diode (1N4007 typically) to one of the mains input. The average value on pin 8 becomes 2* Vmains PEAK p . Our power contribution example drops to: 160 mW. C3 4.7 mF 400 V + EMI Filter Adj FB CS GND Drv VCC NC HV 1 2 3 4 8 7 6 5 NCP1200 1N4007 Dstart Figure 16. A simple diode naturally reduces the average voltage on pin 8 |
Similar Part No. - NCP1200D40R2G |
|
Similar Description - NCP1200D40R2G |
|
|
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 |