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參數(shù)資料
| 型號： | SG5841 |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | Highly Integrated Green-Mode PWM Controller |
| 中文描述： | 高度集成的綠色模式PWM控制器 |
| 文件頁數(shù)： | 10/14頁 |
| 文件大?。?/td> | 506K |
| 代理商： | SG5841 |
Product Specification
Highly Integrated Green-Mode PWM Controller
Constant Output Power Limit
SG5841/J
System General Corp.
Version 1.3.1 (IAO33.0017.B6)
- 10 -
www.sg.com.tw www.fairchildsemi.com
September 20, 2007
When the SENSE voltage across the sense resistor, R
S
,
reaches the threshold voltage, around 0.85V, the output
GATE drive is turned off after delay t
PD
. This delay
introduces additional current, proportional to t
PD
V
IN
/ L
P
.
The delay is nearly constant regardless of the input voltage
V
IN
. Higher input voltage results in larger additional
current and the output power limit is higher than under low
input line voltage. To compensate this variation for a wide
AC input range, a sawtooth power-limiter (saw limiter) is
designed to solve the unequal power-limit problem. The
saw
limiter is designed as a positive ramp signal (V
limit_ramp
)
and fed to the inverting input of the OCP comparator. This
results in a lower current limit at high-line inputs than at
low-line inputs.
V
DD
Over-Voltage Clamping
V
DD
over-voltage clamping has been built in to prevent
damage due to abnormal conditions. Once the V
DD
voltage is over the V
DD
over-voltage clamping voltage
(V
DD-CLAMP
) and lasts for t
D-VDDCLAMP
, the PWM pulses are
disabled until the V
DD
voltage drops below the V
DD
over-voltage clamping voltage.
Thermal Protection
An NTC thermistor R
NTC
in series with a resistor R
A
can
be connected from pin RT to ground. A constant current
I
RT
is output from pin RT. The voltage on the RT pin can
be expressed as V
RT
= I
RT
× (R
NTC
+ R
A
), in which I
RT
= 2
x (1.3V / R
I
). At high ambient temperature, R
NTC
is
smaller, such that V
RT
decreases. When V
RT
is less than
0.62V, the PWM is completely turned off.
Limited Power Control
The FB voltage increases every time the output of the
power supply is shorted or over loaded. If the FB voltage
remains higher than a built-in threshold longer than t
D-OLP
,
PWM output is turned off. As PWM output is turned off,
the supply voltage V
DD
begins decreasing.
When V
DD
goes below the turn-off threshold (e.g., 10V)
the controller is totally shut down. V
DD
is charged up to
the turn-on threshold voltage of 16V through the start-up
resistor until PWM output is restarted. This protection
feature remains activated as long as the over-loading
condition persists. This prevents the power supply from
overheating due to over loading conditions.
Noise Immunity
Noise on the current sense or control signal may cause
significant pulse width jitter, particularly in the
continuous-conduction mode. Slope compensation helps
alleviate this problem. Good placement and layout
practices should be followed. Avoiding long PCB traces
and component leads, locating compensation and filter
components near to the SG5841/J, and increasing the
power MOS gate resistance improves performance.
)
(K
I
R
115
.
1
OLP
-
D
(ms)
t
Ω
×
=
----------------- (2)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SG5841DZ | Highly Integrated Green-Mode PWM Controller |
| SG5841J | Highly Integrated Green-Mode PWM Controller |
| SG5841JSZ | Highly Integrated Green-Mode PWM Controller |
| SG5841SZ | Highly Integrated Green-Mode PWM Controller |
| SG5842ASZ | Highly Integrated Green-Mode PWM Controller |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SG5841CDZ | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| SG5841CSZ | 功能描述:電流型 PWM 控制器 Green-Mode PWM Controller 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(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| SG5841DY | 功能描述:電壓模式 PWM 控制器 HI-INTEGRD GRN-MODE PWM CONTROLLER RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| SG5841DZ | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 Highly-Integrated Grn Mode PWM Cntrl RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| SG5841J | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Highly Integrated Green-Mode PWM Controller |
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