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MUR120G , SWITCHMODE Power Rectifiers
MUR120RL ,1A 200V Ultrafast Rectifier3P , AVERAGE POWER DISSIPATION (WATTS) i , INSTANTANEOUS FORWARD CURRENT (AMPS)F(AV)FI , REVERSE CU ..
MUR130 ,1.0 AMPS. ULTRA FAST RECTIFIERSELECTRICAL CHARACTERISTICSMaximum Instantaneous Forward Voltage (Note 1) v VF(i = 1.0 Amp, T = 150° ..
MUR140 ,Fast / Super-Fast / Ultra-Fast Recovery RectifiersMAXIMUM RATINGSMUR105 110 115 120 130 140 160Rating Symbol UnitPeak Repetitive Reverse Voltage V 50 ..
MUR140RL ,1A 400V Ultrafast Rectifier2MUR120 SeriesMUR105, MUR110, MUR115, MUR12010 100T = 175°CJ7.0105.01.0100°C3.0T = 175°C 100°CJ0.12 ..
NC7SP04P5X ,TinyLogic ULP InverterNC7SP04 TinyLogic ULP InverterOctober 2001Revised March 2004NC7SP04TinyLogic ULP Inverter
NC7SP05P5X ,TinyLogic ULP Inverter (Open Drain Output)applications where battery life is criti-
1N4937RL-MUR120-NCP1200AD100R2-NCP1200AD40R2-NCP1200D60R2G-NCP1200P40-NCP1200P60.-NCP1216P133
1A 200V Ultrafast Rectifier
AND8042/D
Implementing Constant
Current Constant Voltage
AC Adapter by NCP1200
and NCP4300A
Prepared by: Hector Ng
ON Semiconductor
IntroductionThis paper describes a compact design of constant current
constant voltage (CCCV) AC adapter based on the current
mode PWM controller NCP1200 and the secondary side
feedback IC NCP4300A. By these two ICs from ON
Semiconductor, circuit design is much simplified. These
devices enable users to meet ever increasing demand of
smaller dimension and more sophisticated protection
feature of AC adapter.
On the primary side, NCP1200 is used as the PWM
controller. This current mode controller requires very few
external components and no auxiliary winding is needed to
supply this IC. In addition, NCP1200 can fulfill IEA
recommendation easily because it features a pulse skipping
low power consumption mode.
NCP4300A is a general purpose device which consists of
two operational amplifiers and a high precision voltage
reference. One of the operational amplifiers is capable of rail
to rail operation. NCP4300A is employed to provide voltage
as well as current feedback to NCP1200.
Output of the AC adapter is maintained at 5.2 V from no
load to 600 mA. Further increase in load enters constant
current output portion and output is kept at 600 mA down to
zero volt. This output characteristic assures a basic
protection against battery overcharge which is needed by a
lot of applications, for instance cellular phone AC adapter.
Circuit DescriptionCircuit and BOM of the AC adapter is shown in Figure 1
and Table 1. This design can accept universal AC input from
90 V to 264 V
inductor L1 and L2 to form the EMI filter as well as to
provide energy storage for the remaining DC to DC
converter circuit. Thanks to dynamic self supply of
NCP1200 (please refer to NCP1200 data sheet), Vcc
capacitor C7 is charged to startup voltage 11.4 V and the
power MOSFET MTD1N60E starts switching. To reduce
power consumption of NCP1200, HV pin (pin 8) is supplied
by half wave rectification through a parallel combination of
diode D6 and resistor R13. A small signal diode 1N4148 is
enough for this function because diode D6 just has to
withstand one diode drop during negative half cycle. R13 is
to equilibrate the voltages on the 1N4148 when both diodes
and high volt current source of NCP1200 are in the off state.
R12 is to set the power level at which NCP1200 goes into
pulse skipping, please refer to below section for more
details. RCD snubber R1, C1 and D3 provides the necessary
snubbing function to prevent drain voltage of MTD1N60E
to exceed 600 V
resistor R7 is very important as it limits the primary peak
current during power up. If its value is too low, the system
cannot deliver enough power during full load low AC input.
On the contrary, the transformer may go into saturation and
damages Q1 and NCP1200. Information on how to
determine value of R7 is elaborated in latter paragraph.
