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PDF LD7932R Data sheet ( Hoja de datos )
| Número de pieza | LD7932R | |
| Descripción | Green Mode Off-line Power Switch | |
| Fabricantes | Leadtrend Technology | |
| Logotipo |  |
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LD7932R
06/19/2012
Green Mode Off-line Power Switch
with Brown-Out Protections
REV.00
General Description
The LD7932R integrates with a 700V power MOSFET and
a current mode PWM controller in a DIP-7 package. It
takes less components counts or circuit space, especially
ideal for those total solutions of low cost.
The implemented functions include low startup current,
green-mode power-saving operation, leading-edge
blanking of the current sensing and internal slope
compensation. It also features more protections like
OLP (Over Load Protection) and OVP (Over Voltage
Protection) to prevent circuit from being damaged under
abnormal conditions.
Furthermore, the Frequency Swapping function is to
reduce the noise level and thus helps the power circuit
designers to easily deal with the EMI filter design by
spending minimum amount of component cost and
developing time.
Features
Built-in 700V Power MOSFET
High-Voltage CMOS Process with Excellent ESD
Protection
Very Low Startup Current (<17A)
Current Mode Control
Green Mode Control
UVLO (Under Voltage Lockout)
LEB (Leading-Edge Blanking) on CS Pin
Internal Frequency Swapping
Internal Slope Compensation
OVP (Over Voltage Protection) on Vcc Pin
Brownout Protection
OLP (Over Load Protection)
Applications
Switching AC/DC Adaptor
Open Frame Switching Power Supply
Typical Application
AC
input
EMI
Filter
BNO
VCC
Drain
LD7932R
COMP
S
GND
DC
Output
photocoupler
Leadtrend Technology Corporation
LD7932R-DS-00 June 2012
1
www.leadtrend.com.tw
1 page  
Absolute Maximum Ratings
Supply Voltage VCC
COMP, BNO, S
OUT
Drain
Continuous drain current1, TC=25°C
Maximum Junction Temperature
Operating Ambient Temperature
Operating Junction Temperature
Storage Temperature Range
Package Thermal Resistance (DIP-7, JA)
Total Power Dissipation of DIP-7, Ta=25°C
Lead temperature (Soldering, 10sec)
ESD Voltage Protection, Human Body Model
ESD Voltage Protection, Machine Model
1. Repetitive rating: Pulse width limited by maximum junction temperature
2. w/o heat-sink, under natural convection
LD7932R
-0.3V ~29V
-0.3V ~6V
-0.3V ~Vcc+0.3V
-0.3V ~700V
2.0A
150°C
-20°C to 85°C
-40°C to 125°C
-65°C to 150°C
80°C/W
1.2W
260°C
2.5 KV
250 V
Caution:
Stresses beyond the ratings specified in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only
rating and operation of the device at these. Any other conditions above those indicated in the operational sections of this specification is
not implied.
Leadtrend Technology Corporation
LD7932R-DS-00 June 2012
5
www.leadtrend.com.tw
5 Page 
respectively. As a result, the current limit will be lowered
at high-line inputs. This compensation control mechanism
is developed with patents pending by Leadtrend
Technology.
The maximum voltage threshold of the current sensing pin
is set at 0.85V for low-line input. Thus the MOSFET peak
current can be calculated as:
IPEAK(MAX )
0.85V
RS
Vcs-off
0.85V
AC
Line
VCC
Drain
LD7932R
S
GND
LD7932R
LEB time
0.65V
20%
40%
Fig. 15
Duty %
A leading-edge blanking (LEB) time is included in the
input of CS pin to prevent the false-trigger from the current
spike. (As shown in Fig.16).
Maximum Duty-Cycle
The maximum duty-cycle of LD7932R is limited to 75% to
avoid the transformer saturation.
Voltage Feedback Loop
The voltage feedback signal is provided from TL431 at the
secondary side through the photo-coupler to the COMP
pin of the LD7932R. Similar to UC3842, the LD7932R
would carry a diode voltage offset at the stage to feed the
voltage divider at the ratio of RA and RB, that is,
V(PWMCOMPARATOR )
RB
RA RB
(VCOMP
VF )
A pull-high resistor is embedded internally and no external
resistor is required.
Fig. 16
Internal Slope Compensation
In the conventional applications, the problem of the
stability is a critical issue for current mode controlling,
when it operates over 50% duty-cycle. It injects a current
ramp to increase slope compensation to RT/CT pin
through a coupling capacitor. It therefore requires no extra
design for the LD7932R since it has this function built-in
already.
On/Off Control
The LD7932R can be turned off by pulling COMP pin
lower than 1.5V. The gate output pin of the LD7932R will
be disabled immediately under such condition. The
off-mode can be released when the pull-low signal is
removed.
Over Load Protection (OLP) - Auto
Recovery
To protect the circuit from damage due to over-load
condition, short or open-loop condition, the LD7932R is
implemented with smart OLP function for it. It also
Leadtrend Technology Corporation
LD7932R-DS-00 June 2012
11
www.leadtrend.com.tw
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LD7932R.PDF ] | |
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