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PDF SD4851 Data sheet ( Hoja de datos )
| Número de pieza | SD4851 | |
| Descripción | PRIMARY SIDE POWER CONTROLLER | |
| Fabricantes | Silan Microelectronics | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de SD4851 (archivo pdf) en la parte inferior de esta página. Total 11 Páginas | ||
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SD4851
PRIMARY SIDE POWER CONTROLLER WITH BUILT-IN HIGH VOLTAGE
MOSFET
DESCRIPTION
SD4851 is primary side power controller with built-in high voltage
MOSFET. It senses the output voltage indirectly by using the
auxiliary wind of the power transformer. It adopts Pulse Frequency
Modulation (PFM) technology for flyback power supply controller.
SD4851 provides accurate constant voltage, constant current
(CV/CC) regulation for higher efficiency and higher reliability.
By using SD4851 for flyback power controller, Few peripheral
components are needed, the Opto-coupler and secondary control
circuitry is not needed and the loop compensation circuitry for
maintaining stability is also unnecessary.
DIP-8A-300-2.54
FEATURES
* Lower start-up current
* Primary side control for Constant Voltage (CV) and Constant
Current (CC)
* Leading edge blanking
* Pulse-Frequency Modulation
* Overvoltage protection
* Undervoltage lockout
* Over temperature protection
* Built-in high voltage MOSFET
* Cycle by cycle current limiting
* Open Loop Protection
* Cable drop compensation
* Peak current compensation
APPLICATIONS
* Chargers for Cell Phones
* Adapters
* MP3 and Other Portable Apparatus
* Standby Power Supply
HANGZHOU SILAN MICROELECTRONICS CO.,LTD
Http: //www.silan.com.cn
REV:1.0 2009.04.27
Page 1 of 11
1 page  
SD4851
FUNCTION DESCRIPTION
SD4851 is designed for off-line SMPS, consisting of high voltage MOSFET, cable compensation and peak
current compensation without opto-coupler. SD4851 provides constant voltage/constant current (CV/CC) output
through primary current and auxiliary voltage. It adopts PFM technology and accurate constant voltage/constant
current (CV/CC) control loop for higher stability and efficiency.
A whole work period of SD4851 can be divided into two period sections:
When MOSFET is on, primary current is detected by sample resistor and voltage at pin FB is negative, load is
powered by output capacitor and output voltage VO decreases.
When primary current exceeds the limit, MOSFET is off and voltage at pin FB is detected. Output capacitor is
powered by secondary current and VO increases. MOSFET is on again after stop for TCV and hold for TCC.
And then, it comes to peak current detect again.
1. Under Voltage Lockout and Self-Start
At the beginning, the capacitor connected to pin VCC is charged via start resistor by high voltage DC bus and the
circuit start to work if voltage at Vcc is 16V. The output is shutdown if there is any protection during normal
operation and Vcc is decreased because of no powering of auxiliary winding. The whole control circuit is
shutdown if voltage at Vcc is 8V below to lower current dissipation and the capacitor is recharged for restarting.
2. Driver Circuit
The driver circuit is powered by VCC.
When VGATE＝1, the power MOSFET is on. When VGATE＝0, the power MOSFET is off. It is recommended to
set TLEB＝0.7μs to avoid error trigger caused by burr.
HANGZHOU SILAN MICROELECTRONICS CO.,LTD
Http: //www.silan.com.cn
REV:1.0 2009.04.27
Page 5 of 11
5 Page 
PACKAGE OUTLINE
DIP-8A-300-2.54
SD4851
UNIT: mm
MOS DEVICES OPERATE NOTES:
Electrostatic charges may exist in many things. Please take following preventive measures to prevent effectively
the MOS electric circuit as a result of the damage which is caused by discharge:
z The operator must put on wrist strap which should be earthed to against electrostatic.
z Equipment cases should be earthed.
z All tools used during assembly, including soldering tools and solder baths, must be earthed.
z MOS devices should be packed in antistatic/conductive containers for transportation.
Disclaimer :
• Silan reserves the right to make changes to the information herein for the improvement of the design and performance
without further notice!
• All semiconductor products malfunction or fail with some probability under special conditions. When using Silan products
in system design or complete machine manufacturing, it is the responsibility of the buyer to comply with the safety
standards strictly and take essential measures to avoid situations in which a malfunction or failure of such Silan products
could cause loss of body injury or damage to property.
• Silan will supply the best possible product for customers!
HANGZHOU SILAN MICROELECTRONICS CO.,LTD
Http: //www.silan.com.cn
REV:1.0 2009.04.27
Page 11 of 11
11 Page | ||
| Páginas | Total 11 Páginas | |
| PDF Descargar | [ Datasheet SD4851.PDF ] | |
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