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PDF LD7577JA Data sheet ( Hoja de datos )
| Número de pieza | LD7577JA | |
| Descripción | High Voltage Green-Mode PWM Controller | |
| Fabricantes | Leadtrend | |
| Logotipo |  |
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LD7577JA
8/16/2010
High Voltage Green-Mode PWM Controller with
Brown-Out Protection
Rev. 00b
General Description
The LD7577JA integrated several functions of protections,
and EMI-improved solution in a SOP-7, SOP-8/or DIP-8
package. It minimizes the component counts and the
circuit space, and it’s perfect for the low cost of
applications.
It provides functions of low startup current, green-mode
power-saving operation, leading-edge blanking of the
current sensing and internal slope compensation. Also,
the LD7577JA features more protections like OLP (Over
Load Protection), OVP (Over Voltage Protection), and
brownout protection to prevent the circuit being damaged
from the abnormal conditions.
Features
z High-Voltage (500V) Startup Circuit
z Current Mode Control
z Non-Audible-Noise Green Mode Control
z UVLO (Under Voltage Lockout)
z LEB (Leading-Edge Blanking) on CS Pin
z Internal Frequency Trembling
z Internal Slope Compensation
z Internal Over Current compensation
z OVP (Over Voltage Protection) on Vcc
z AC Input OVP (Over Voltage Protection)
z OLP (Over Load Protection)
z Brownout Protection
z 500mA Driving Capability
Furthermore, the LD7577JA features frequency trembling
to suppress the noise and is an excellent solution for EMI
filter design.
Applications
z Switching AC/DC Adaptor and Battery Charger
z Open Frame Switching Power Supply
z LCD Monitor/TV Power
Typical Application
AC
input
EMI
Filter
*
HV VCC OUT
LD7577JA
BNO
CS
GND COMP
*
*See Application Information
photocoupler
TL431
Leadtrend Technology Corporation
LD7577JA-DS-00b August 2010
1
www.leadtrend.com.tw
Free Datasheet http://www.datasheet4u.com/
1 page  
Electrical Characteristics
(TA = +25°C unless otherwise stated, VCC=15.0V)
PARAMETER
CONDITIONS
High-Voltage Supply (HV Pin)
High-Voltage Current Source
Off-State Leakage Current
VCC< UVLO(on), HV=500V
VCC> UVLO(off), HV=500V
Supply Voltage (Vcc Pin)
Startup Current
Operating Current
(with 1nF load on OUT pin)
VCOMP=0V,Fsw=65KHz
VCOMP=3V,Fsw=65KHz
OLP Tripped
OVP Tripped
UVLO (off)
UVLO (on)
OVP Level
Voltage Feedback (Comp Pin)
Short Circuit Current
Open Loop Voltage
VCOMP=0V
COMP pin open
Green Mode Threshold VCOMP
Burst Mode Threshold VCOMP
Current Sensing (CS Pin)
Maximum Input Voltage(Vcs_off)
Leading Edge Blanking Time
COMP >1.9V
COMP <1.9V
Input impedance
Delay to Output
Oscillator for Switching Frequency
Frequency
Trembling Frequency
FSW=65KHz
Green Mode Frequency
Modulation Frequency
Temp. Stability
FSW=65KHz
FSW=65KHz
Voltage Stability
VCC=11V-25V
LD7577JA
MIN TYP MAX UNITS
0.5 1.0 1.5 mA
35 μA
320 μA
3.3 mA
3.6 mA
0.78 mA
0.88 mA
9.0
10.0 11.0
V
15.0 16.0 17.0 V
26.5 28.0 29.5 V
1.5 2.2 mA
5.8 V
2.35 V
1.4 V
0.80 0.85 0.90 V
320 nS
750 nS
1 MΩ
100 nS
60 65 70 KHz
±4 KHz
22 KHz
86 Hz
5%
1%
Leadtrend Technology Corporation
LD7577JA-DS-00b August 2010
5
www.leadtrend.com.tw
Free Datasheet http://www.datasheet4u.com/
5 Page 
LD7577JA
VCC
OUT
LD7577JA
CS
GND
250ns
blanking
time
Can be removed if the negative
spike is not over spec. (-0.3V).
Fig. 16
Fig. 17
Oscillator and Switching Frequency
The switching frequency of the LD7577JA is fixed as
65KHz internally to provide the optimized operations by
considering the EMI performance, thermal treatment,
component sizes and transformer design.
Frequency Trembling
The LD7577JA is implemented an adjustable frequency
Trembling function which provides the power supply
designers to choose the optimized EMI performance and
lowest system cost. The Trembling frequency is fixed
internally ±4KHz which is incorporated with the 65KHz
switching frequency.
Internal Slope Compensation
Stability is crucial for current mode control when it
operates at more than 50% of duty-cycle. To stabilize the
control loop, the slope compensation is required in the
traditional UC384X design by injecting the ramp signal
from the RT/CT pin through a coupling capacitor. In the
LD7577JA, the internal slope compensation circuit has
been implemented to simplify the external circuit design.
On/Off Control
Pulling COMP pin below 1.2V will turn off the LD7577JA
and disable the gate output pin of the LD7577JA. The
off-mode will be released when the pull-low signal at
COMP pin is removed.
Dual-Oscillator Green-Mode Operation
Lots of topologies have been implemented in different
chips for the green-mode or power saving requirements
such as “burst-mode control”, “skipping-cycle mode”,
“variable off-time control “…etc. The basic operation
theory of all these approaches intends to reduce the
switching cycles under light-load or no-load condition
either by skipping some switching pulses or by reducing
the switching frequency.
Leadtrend Technology Corporation
LD7577JA-DS-00b August 2010
11
www.leadtrend.com.tw
Free Datasheet http://www.datasheet4u.com/
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet LD7577JA.PDF ] | |
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