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參數(shù)資料
| 型號(hào)： | LD7550 |
| 廠商： | Electronic Theatre Controls, Inc. |
| 英文描述： | Green-Mode PWM Controller |
| 中文描述： | 綠色模式PWM控制器 |
| 文件頁數(shù)： | 8/10頁 |
| 文件大?。?/td> | 216K |
| 代理商： | LD7550 |
LD7550
reduce the switching cycles under light-load or no-load
condition either by skip some switching pulses or reduce the
switching frequency.
What LD7550 used to implement the power-saving
operation is Leadtrend Technology’s own IP
2
. In such
approach, as shown in the block diagram, 2 oscillators are
implemented in LD7550. The first oscillator is to take care
the normal switching frequency, which can be set by the RT
pin through an external resistor. Under this operation mode,
as shown in Fig. 10, the 2
nd
oscillation (green-mode
oscillator) is not activated. Therefore, the rising-time and the
falling-time of the internal ramp will be constant to achieve
good stability over all temperature range. Under the
normal operation, this oscillator is dominated the switching
frequency.
8
Leadtrend Technology Corporation
LD7550-DS-00 August 2004
OSC
COMP
CS
OUT
PWM
Comparator
LEB
2R
R
R
S
Q
EN
EN=1
∑
+
+
Ramp from
Oscillator
V+
V-
Set
Reset
Green-Mode
Osc
Green-Mode Osc is not activated
under normal operation.
Fig. 10
As shown in Fig. 11, the green-mode oscillator detects the
Comp pin signal to determine if it is within the green-mode
operation. When the detected signal V+ is lower than the
green-mode threshold V
GREEN
, the green-mode oscillator is
on. The green-mode oscillator, implemented by a VCO
(voltage controlled oscillator), is a variable frequency
oscillator. The rising time of the VCO is proportional to
(V
GREEN
-V+), thus the lower voltage on V+ will generate
longer rising time on VCO as well as lower frequency on
VCO.
By using this dual-oscillator control, the green-mode
frequency can be well controlled and further to avoid the
generation of audible noise.
V+
V-
Ramp of
OSC
Green-Mode
Oscillator activated
Vgreen
Normal Mode
Green Mode
Ramp of
VCO
VCO
Level-detector
& Counter
Vgreen
V+
(V+ -Vgreen) >=0, VCO disabled
(V+ -Vgreen) <0, VCO activated
Green-Mode
Oscillator
from OSC
"Set" Signal
(to OSC & Nor gate)
Fig. 11
2
Note: Patent pending
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LD7550BL | Green-Mode PWM Controller |
| LD7550BN | Green-Mode PWM Controller |
| LD7550IL | Green-Mode PWM Controller |
| LD7550IN | Green-Mode PWM Controller |
| LD7710 | 14GHz, 40 W CW PPM FOCUSING, MINIMUM SIZE |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LD7550BBL | 制造商:Leadtrend 功能描述:Highly-integrated Green Mode PWM Controller SOT-26(PB Free) |
| LD7550BL | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Green-Mode PWM Controller |
| LD7550BN | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Green-Mode PWM Controller |
| LD7550BOBN | 制造商:Leadtrend 功能描述:PWM IC ,PDIP-8 (PB FREE) |
| LD7550IL | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Green-Mode PWM Controller |
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