|
|
PDF LD7750RGN Data sheet ( Hoja de datos )
| Número de pieza | LD7750RGN | |
| Descripción | High Voltage Green-Mode PWM Controller | |
| Fabricantes | Leadtrend | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LD7750RGN (archivo pdf) en la parte inferior de esta página. Total 19 Páginas | ||
|
No Preview Available !
LD7750R
05/12/2010
High Voltage Green-Mode PWM Controller with
Over Temperature Protection
Rev. 00
General Description
The LD7750R integrates several functions of protections,
and EMI-improved solution in a SOP-7, SOP-8 or DIP-8
package to minimize the component counts and the circuit
space.
The device provides functions of low startup current,
green-mode power-saving operation, leading-edge
blanking of the current sensing and internal slope
compensation. Also, the LD7750R features more
protections like OLP (Over Load Protection), OVP (Over
Voltage Protection), and OTP (Over Temperature
Protection) to prevent the circuit being damaged under the
abnormal conditions. The LD7750R features built-in
auto-recovery function for OVP on Vcc pin and OLP.
Features
z High-Voltage (500V) Startup Circuit
z Current Mode Control
z Green Mode Control
z UVLO (Under Voltage Lockout)
z LEB (Leading-Edge Blanking) on CS Pin
z Internal Frequency Swapping
z Internal Slope Compensation
z Internal Over Current Protection
z OVP (Over Voltage Protection) on Vcc
z OLP (Over Load Protection)
z External OTP through a NTC
z 500mA Driving Capability
Applications
z Switching AC/DC Adaptor and Battery Charger
z Open Frame Switching Power Supply
z LCD Monitor/TV Power
Typical Application
Leadtrend Technology Corporation
LD7750R-DS-00 May 2010
1
www.leadtrend.com.tw
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
Supply Voltage (Vcc Pin)
Startup Current
VCC< UVLO(on), HV=500V
VCC> UVLO(off), 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
Green Mode Threshold VCOMP
Zero Duty
Current Sensing (CS Pin)
Maximum Input Voltage, Vcs_off
Leading Edge Blanking Time
Input impedance
Delay to Output
LD7750R
MIN TYP MAX UNITS
0.5 1.0 1.5 mA
35 μA
200 320 400
1.2
2.3
0.61
0.70
9.0 10.0 11.0
15.0 16.0 17.0
25.0 26.0 27.0
μA
mA
mA
mA
mA
V
V
V
0.20 0.26 0.32
5.5 6.0
2.75
1.8
mA
V
V
V
0.80 0.85 0.90
V
250 ns
1 MΩ
100 ns
Leadtrend Technology Corporation
LD7750R-DS-00 May 2010
5
www.leadtrend.com.tw
5 Page 
LD7750R
Oscillator and Switching Frequency
The LD7750R is implemented with Frequency Swapping
function which helps the power supply designers to both
optimize EMI performance and minimize the system
cost. The switching frequency substantially centers at
65KHz, and swaps between a range of ±4KHz.
Output Stage and Maximum Duty-Cycle
An output stage of a CMOS buffer with driving capability
of 500mA typically is incorporated to drive a power
MOSFET directly. And the maximum duty-cycle of
LD7750R is limited to 75% to avoid the transformer
saturation.
Voltage Feedback Loop
The voltage feedback signal is provided from the TL431 in
the secondary side through the photo-coupler to the
COMP pin of LD7750R. The input stage of LD7750R,
like the UC384X, is incorporated with 2 diodes voltage
offset circuit and a voltage divider with 1/3 ratio.
Therefore,
V+ (PWM COMPARATOR
)
=
1
3
× (VCOMP
−
2VF )
A pulled-high resistor is embedded internally and thus no
external one is required.
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
LD7750R, the internal slope compensation circuit has
been implemented to simplify the external circuit design.
On/Off Control
The LD7750R can be turned off by pulling COMP pin to
below 1.8V. The gate output pin of LD7750R will be
disabled immediately under such condition. The off-mode
can be released when the pull-low signal is removed.
Green-Mode Operation
By using the green-mode control, the switching frequency
can be reduced under the light load condition. This feature
helps to improve the efficiency in light load conditions.
The green-mode control is Leadtrend Technology’s own
IP.
Over Load Protection (OLP) - Auto
Recovery
To protect the circuit from damage due to overload
condition or output short condition, a smart OLP function
is implemented in the LD7750R for it. The OLP function is
an auto-recovery type protection. Fig. 17 shows the
waveforms of the OLP operation. Under such fault
condition, the feedback system will force the voltage loop
toward saturation and thus pull up the voltage of COMP
pin (VCOMP). If the VCOMP trips the OLP threshold of
5.0V and stays for over 63mS, the protection will be
activated to turn off the gate output and to shutdown the
switching of power circuit. The 30mS delay time is to
prevent the false-trigger during the power-on and turn-off
transient.
A divided-by-2 counter is implemented to reduce the
average power consumption under OLP behavior.
Whenever OLP is activated, the output is latched off and
the divided-by-2 counter starts to count the number of
UVLO(off). The latch will be released if the 2nd UVLO(off)
point is counted, and then the output recovers switching
again.
By using such protection mechanism, the average input
power can be reduced to a very low level so that the
Leadtrend Technology Corporation
LD7750R-DS-00 May 2010
11
www.leadtrend.com.tw
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet LD7750RGN.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LD7750RGN | High Voltage Green-Mode PWM Controller | Leadtrend |
| LD7750RGR | High Voltage Green-Mode PWM Controller | Leadtrend |
| LD7750RGS | High Voltage Green-Mode PWM Controller | Leadtrend |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |