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PDF LD7752 Data sheet ( Hoja de datos )
| Número de pieza | LD7752 | |
| Descripción | Green-Mode PWM Controller | |
| Fabricantes | Leadtrend | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LD7752 (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
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LD7752
01/16/2013
Green-Mode PWM Controller with HV Start-Up Circuit and
Soft Start time Adjustment
REV. 00
General Description
The LD7752 brings high performance, highly integrated
functions, protections and EMI-improve solution. It’s an
ideal solution for those cost-sensitive system, reducing
component count and overall system cost.
The LD7752 features high voltage startup circuit,
minimum loss and green-mode power-saving operation,
leading-edge blanking of the current sensing and internal
slope compensation. They also consist of more
protections of OLP (Over Load Protection) and OVP (Over
Voltage Protection) to prevent the circuit from damage
under abnormal conditions.
Furthermore, the proprietary frequency swapping function
can reduce the noise and help the power circuit designers
to enhance EMI performance with fewer components and
less developing time.
Features
High-Voltage Startup Circuit
UVLO (Under Voltage Lockout)
LEB (Leading-Edge Blanking) on CS Pin
Internal Frequency swapping
Internal Slope Compensation
Internal OCP Compensation
OVP (Over Voltage Protection) on Vcc Pin
OLP (Over Load Protection)
+250mA/-500mA Driving Capability
Soft-Driving
Soft Start Time and Grouping Frequency Adjustment
Applications
LCD Monitor/TV Power
Switching AC/DC Adaptor and Battery Charger
Open Frame Switching Power Supply
Typical Application
AC EMI
input Filter
HV VCC
CT OUT
LD7752
*
CS
GND COMP
photocoupler
Leadtrend Technology Corporation
LD7752-DS-00 January 2013
1
www.leadtrend.com.tw
1 page  
Electrical Characteristics
(TA = +25C unless otherwise stated, VCC=15.0V)
PARAMETER
CONDITIONS
High-Voltage Supply (HV Pin, HV MOS process)
High-Voltage Current Source
VCC < UVLO(on)
Off-State Leakage Current
VCC > UVLO(off), HV=500V
Supply Voltage (VCC Pin)
Startup Current
VCC=15V, HV=500V
Operating Current
(with 1nF load on OUT pin)
VCOMP=0V
VCOMP=3V
OLP tripped
OVP tripped, VCC=OVP
UVLO (OFF)
UVLO (ON)
OVP Level
.
Voltage Feedback (COMP Pin)
Short Circuit Current
Open Loop Voltage
VCOMP=0V
COMP pin open
Fixed Frequency Mode Threshold
VCOMP()
Green Mode Threshold VCOMP()
25kHz
Burst Mode Threshold VCOMP
Current Sensing (CS Pin)
VCS-OFF
VCS-MIN
Leading Edge Blanking Time
Delay to Output
Oscillator for Switching Frequency
Frequency
Temp. Stability()
Voltage Stability()
(VCC =11V-25V)
Green Mode Frequency
65kHz
Frequency Swapping
65kHz
Maximum Duty
LD7752
MIN TYP MAX UNITS
1.1 1.3 1.5 mA
15 A
100 150 200
0.55
2.0
230
230
7.0 8.0 9.0
15.0 16.0 17.0
27.0 28.0 29.0
A
mA
mA
A
A
V
V
V
0.15 0.17 0.19
5.10 5.30 5.50
2.5
2.1
1.65
mA
V
V
V
V
0.80 0.85 0.90
0.60 0.65
0.7
250
100
V
V
ns
ns
62.0 65.0 68.0
5
1
25
4.0
75
kHz
%
%
kHz
kHz
%
Leadtrend Technology Corporation
LD7752-DS-00 January 2013
5
www.leadtrend.com.tw
5 Page 
LD7752
OVP (Over Voltage Protection) on Vcc -
Auto Recovery
The maximum VGS ratings of the power MOSFETs are
mostly set at 30V. To prevent the VGS from damage in
fault condition, LD7752 is embedded with OVP function
on Vcc. Once the Vcc voltage rises above OVP
threshold, it shuts down output gate drive circuit
simultaneously and disable the switching of the power
MOSFET until the next UVLO(on) is reached.
The LD7752 possess auto-recoverable Vcc OVP
functions. The OVP condition usually comes with
open-loop of feedback. Before it’s released, the Vcc will
trip to OVP level and shutdown the output again. The
Vcc works in hiccup mode. Fig. 12 shows its operation.
Otherwise, soon as the OVP condition is removed, the
Vcc level will be resumed and the output will
automatically return to the normal operation.
VCC
OVP Level
OVP Tripped
from being false-triggered by the current through the
gate-to-drain capacitor CGD. Therefore, the MOSFET is
always pulled low and placed in the off-state no matter
when the gate resistor is disconnected or opened.
It is recommended to add an
resistor on the power circuit.
OUT
LD7752
CS
GND
Rg
R8
An internal pull-low resistor is built in here to
prevent from floating.
Fig. 13
UVLO(on)
UVLO(off)
Vbulk
OUT
t
Switching
Non-Switching
Fig. 12
Switching
t
Pull-Low Resistor on the Gate Pin of
MOSFET
The LD7752 consists of an anti-floating resistor on the
OUT pin to protect the output from abnormally operation
or false triggering of MOSFET. Even so, we still
recommend adding an external one at the MOSFET
gate terminal to provide more protection in case of
disconnection of gate resistor RG during power-on.
OUT
LD7752
i Cgd dVbulk
dt
Cgd
Rg
R8
CS
GND
This resistor is to prevent the MOSFET
from false triggering by the current
through Cgd in case Rg is disconnected.
Fig. 14
In single-fault condition, as shown in Fig. 13, the resistor
R8 can provide a discharge path to avoid the MOSFET
Leadtrend Technology Corporation
LD7752-DS-00 January 2013
11
www.leadtrend.com.tw
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet LD7752.PDF ] | |
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