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PDF LD7580A Data sheet ( Hoja de datos )
| Número de pieza | LD7580A | |
| Descripción | PWM Current Mode Controller | |
| Fabricantes | Leadtrend Technology | |
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LD7580A
9/5/2012
PWM Current Mode Controller with
Quasi-Resonant Operation
REV：00
General Description
The LD7580A is a current mode PWM controller and
features quasi resonant operation. It operates in DCM at
light load to optimize the efficiency and operates in
boundary condition at high power level.
The LD7580A is integrated with high voltage startup
circuit, green-mode power-saving operation, and
leading-edge blanking of the current sensing. It also
incorporates with several protections like OLP (Over Load
Protection), OVP (Over Voltage Protection), OTP (Over
Temperature Protection) …etc. Highly integration and tiny
package make it an ideal choice in wide variety of
applications, and in addition to minimize the component
counts and the circuit space.
In capable of performing boundary operation, it can
reduce the switching loss and the reverses recovery loss
of rectify diode when the MOSFET turns on. It is designed
to meet the latest power saving regulations for wide input
voltage range of applications.
Features
High-Voltage (500V) Startup Circuit
Current Mode Control
Minimum Drain Voltage Switching
Green Mode Control at Light Load
UVLO (Under Voltage Lockout)
LEB (Leading-Edge Blanking) on CS Pin
Over Voltage Comparator on VCC and QRD Pin
OLP (Over Load Protection)
Internal Over Temperature Shutdown
+500/-700mA Driving Capability
Applications
Switching AC/DC Adaptor
Open Frame Switching Power Supply
LCD Monitor/TV Power Supply
Leadtrend Technology Corporation
LD7850A-DS-00 September 2012
1
www.leadtrend.com.tw
1 page  
LD7580A
Absolute Maximum Ratings
Supply Voltage VCC
High-Voltage Pin, HV
FB, CS, QRD
OUT
Maximum Junction Temperature
Operating Ambient Temperature Range
Operating Junction Temperature Range
Storage Temperature Range
Package Thermal Resistance (SOP-8)
Package Thermal Resistance (DIP-8)
Power Dissipation (SOP-8, at Ambient Temperature = 85C)
Power Dissipation (DIP-8, at Ambient Temperature = 85C)
Lead temperature (Soldering, 10sec)
ESD Voltage Protection, Human Body Model (Except HV Pin)
ESD Voltage Protection, Human Body Model (HV Pin)
ESD Voltage Protection, Machine Model (Including HV Pin)
Gate Output Current
-0.3V~30V
-0.3V~500V
-0.3V~7V
-0.3V~Vcc+0.3V
150C
-40C to 85C
-40C to 125C
-65C to 150C
160C/W
100C/W
250mW
400mW
260C
2.5KV
1.0KV
250V
+500/-700mA
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.
Recommended Operating Conditions
Item
Min.
Max.
Unit
Supply Voltage Vcc
12 26
V
COMP Capacitor Value
1 100 nF
Note:
1. It’s essential to connect a capacitor to COMP pin to filter out the undesired switching noise for
stable operation.
2. The small signal components should be placed around the IC pin as close as possible.
Leadtrend Technology Corporation
LD7850A-DS-00 September 2012
5
www.leadtrend.com.tw
5 Page 
V from Cbulk
VCC
HV
1 mA
16 /10
UVLO
comparator
Fig. 12.
Internal
Bias & Vref
Vcc
UVLO(on)
UVLO(off)
HV Current
t
LD7580A
pulse-by-pulse current limit. The maximum voltage
threshold of the current sensing pin is set as 0.85V. Thus
the MOSFET peak current can be calculated as:
IPEAK (MAX)
0.85V
RS
A 200nS leading-edge blanking (LEB) time is incorporated
in the input of CS pin to prevent the false-trigger being
caused by the current spike. In the low power application,
if the total pulse width of the turn-on spikes is less than
200nS and the negative spike on the CS pin is not over
-0.3V, the R-C filter (as shown in Fig. 14) is eliminable.
However, the total pulse width of the turn-on spike is
determined by the output power, circuit design and PCB
layout. It is strongly recommended to add a small R-C
filter (as shown in Fig. 15) for higher power application to
avoid the CS pin from damage by the negative turn-on
spike.
1mA
Vcc current
Startup Current
(<100uA)
~ 0mA (off)
t
Operating Current
(Supply from Auxiliary Winding)
Fig. 13.
Current Sensing, Leading-edge Blanking
and the Negative Spike on CS Pin
The typical current mode PWM controller feedbacks both
current signal and voltage signal to close the control loop
and achieve voltage regulation. The LD7580A detects the
primary MOSFET current from the CS pin, which is not
only for the peak current mode control but also for the
VCC
OUT
LD7580A
CS
GND
200ns
blanking
time
Removeable if the negative spike
is not over spec. (-0.3V).
Fig. 14.
11
Leadtrend Technology Corporation www.leadtrend.com.tw
LD7850A-DS-00 September 2012
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet LD7580A.PDF ] | |
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