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PDF LD7932M Data sheet ( Hoja de datos )
| Número de pieza | LD7932M | |
| Descripción | Green Mode Off-line Power Switch | |
| Fabricantes | Leadtrend Technology | |
| Logotipo |  |
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LD7932M
04/10/2013
Green Mode Off-line Power Switch
REV. 00
with Brown-Out Protections
General Description
The LD7932M is integrated with a 600V 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 600V 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
LD7932M
COMP
S
GND
DC
Output
photocoupler
Leadtrend Technology Corporation
LD7932M-DS-00 April 2013
1
www.leadtrend.com.tw
1 page  
LD7932M
Absolute Maximum Ratings
Supply Voltage VCC
COMP, BNO, S
OUT
Drain
Drain current (Note), 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 (Drain pin excluded)
ESD Voltage Protection, Human Body Model (Drain pin)
ESD Voltage Protection, Machine Model
Note:
1. Repetitive rating: pulse width limited by maximum junction temperature
2. In condition of no heat-sink on natural convection
-0.3V ~29V
-0.3V ~6V
-0.3V ~Vcc+0.3V
-0.3V ~600V
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
1 KV
250 V
Caution:
Stress exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stress above Recommended Operating Conditions may affect
device reliability.
Leadtrend Technology Corporation
LD7932M-DS-00 April 2013
5
www.leadtrend.com.tw
5 Page 
LD7932M
high or low if duty ratio is over or below threshold values,
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
A pull-high resistor is embedded internally and no external
resistor is required.
AC
Line
VCC
Drain
LD7932M
S
GND
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 LD7932M 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 LD7932M. Similar to UC3842, the LD7932M
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 )
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 LD7932M since it has this function built-in
already.
On/Off Control
The LD7932M can be turned off by pulling COMP pin
below 1.5V. The gate output pin of the LD7932M 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 LD7932M is
implemented with smart OLP function for it. It also
features auto recovery function; see Fig. 17 for the
Leadtrend Technology Corporation
LD7932M-DS-00 April 2013
11
www.leadtrend.com.tw
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LD7932M.PDF ] | |
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