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參數(shù)資料
| 型號： | NCP1200D |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | PWM Current-Mode Controller for Universal Off-Line Supplies Featuring Low Standby Power |
| 中文描述： | PWM電流模式控制器的通用離線用品，具有低待機功耗 |
| 文件頁數(shù)： | 7/16頁 |
| 文件大?。?/td> | 136K |
| 代理商： | NCP1200D |
NCP1200A
http://onsemi.com
7
APPLICATION INFORMATION
Introduction
The NCP1200A implements a standard current mode
architecture where the switchoff time is dictated by the
peak current setpoint. This component represents the ideal
candidate where low partcount is the key parameter,
particularly in lowcost ACDC adapters, auxiliary
supplies, etc. Due to its highperformance HighVoltage
technology, the NCP1200A incorporates all the necessary
components normally needed in UC384X based supplies:
timing components, feedback devices, lowpass filter and
selfsupply. This later point emphasizes the fact that
ON Semiconductor’s NCP1200A does NOT need an
auxiliary winding to operate: the product is naturally
supplied from the highvoltage rail and delivers a V
CC
to the
IC. This system is called the Dynamic SelfSupply (DSS).
Dynamic SelfSupply
The DSS principle is based on the charge/discharge of the
V
CC
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:
POWERON: IF V
CC
< VCC
H
THEN Current Source is
ON, no output pulses
IF V
CC
decreasing > VCC
L
THEN Current Source is OFF,
output is pulsing
IF V
CC
increasing < VCC
H
THEN Current Source is ON,
output is pulsing
Typical values are: VCC
H
= 12 V, VCC
L
= 10 V
To better understand the operational principle, Figure 15’s
sketch offers the necessary light:
Figure 15. The charge/discharge cycle over a
10 F V
CC
capacitor
10.0 M
30.0 M
50.0 M
70.0 M
90.0 M
V
CC
Current
Source
OFF
ON
OUTPUT PULSES
V
ripple
= 2 V
UVLO
H
= 12 V
UVLO
L
= 10 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 MTP2N60E, Qg max equals
22 nC. With a maximum switching frequency of 68 kHz for
the P60 version, the average power necessary to drive the
MOSFET (excluding the driver efficiency and neglecting
various voltage drops) is:
F
SW
Qg
V
CC
with
F
SW
= maximum switching frequency
Qg = MOSFET’s gate charge
V
CC
= V
GS
level applied to the gate
To obtain the final IC current, simply divide this result by
V
CC
: I
driver
= F
SW
Qg = 1.5 mA. The total standby power
consumption at noload 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 350 VDC line. The current flowing through
pin 8 is a direct image of the NCP1200A consumption
(neglecting the switching losses of the HV current source).
If ICC2 equals 2.3 mA @ T
J
= 25
°
C, then the power
dissipated (lost) by the IC is simply: 350 x 2.3 m = 805 mW.
For design and reliability reasons, it would be interesting to
reduce this source of wasted power which increases the die
temperature. This can be achieved by using different
methods:
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
VMAINS(peak)
becomes
contribution example drops to: 223 x 2.3 m = 512
mW. If a resistor is installed between the mains and
the diode, you further force the dissipation to
migrate from the package to the resistor. The
resistor value should account for lowline startups.
3. Permanently force the V
CC
level above VCC
H
with
an auxiliary winding. It will automatically
disconnect the internal startup source and the IC
will be fully selfsupplied from this winding.
Again, the total power drawn from the mains will
significantly decrease. Make sure the auxiliary
voltage never exceeds the 16 V limit.
2
. Our power
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PDF描述 |
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| NCP1200AD100R2 | PWM Current-Mode Controller for Universal Off-Line Supplies Featuring Low Standby Power |
| NCP1200AD100R2G | PWM Current-Mode Controller for Universal Off-Line Supplies Featuring Low Standby Power |
| NCP1200AD40R2 | PWM Current-Mode Controller for Universal Off-Line Supplies Featuring Low Standby Power |
| NCP1200 | PWM Current-Mode Controller for Low-Power Universal Off-Line Supplies |
| NCP1200D100R2 | PWM Current-Mode Controller for Low-Power Universal Off-Line Supplies |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCP1200D100R | 制造商:Rochester Electronics LLC 功能描述: 制造商:ON Semiconductor 功能描述: |
| NCP1200D100R2 | 功能描述:電流型 PWM 控制器 100KHz Current Mode RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1200D100R2G | 功能描述:電流型 PWM 控制器 100KHz Current Mode SMPS PWM RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1200D100R2G | 制造商:ON Semiconductor 功能描述:Pulse Width Modulation (PWM) Controller |
| NCP1200D40R2 | 功能描述:電流型 PWM 控制器 40KHz Current Mode RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
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