|
Leadtrend |
LD7577
1/15/2009
High Voltage Green-Mode PWM Controller with
Brown-Out Protection
Rev. 01
General Description
The LD7577 integrates several functions of protections, and
EMI-improved solution in SOP-8 package. It minimizes 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, it features more protections like OLP (Over Load
Protection), OVP (Over Voltage Protection), and brownout
protection to prevent the circuit from being damaged under
abnormal conditions.
Features
z High-Voltage (500V) Startup Circuit
z Current Mode Control
z Non-Audible-Noise Green Mode Control
z UVLO (Under Voltage Lockout)
z LEB (Leading-Edge Blanking) on CS Pin
z Internal Slope Compensation
z OVP (Over Voltage Protection) on Vcc Pin
z AC Input OVP (Over Voltage Protection)
z OLP (Over Load Protection)
z Precision Brownout Protection
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
AC EMI
input Filter
*
HV VCC OUT
BNO
LD7577
CS
GND COMP
*
*See Application Information
Leadtrend Technology Corporation
LD7577-DS-01 January 2009
1
www.leadtrend.com.tw
photocoupler
TL431
Pin Configuration
SOP-8 & DIP-8 (TOP VIEW)
8765
TOP MARK
YYWWPP
1 234
YY:
WW:
PP:
Year code
Week code
Production code
LD7577
Ordering Information
Part number
Package
LD7577 GS
SOP-8
Green package
LD7577 GN
DIP-8
Green package
The LD7577 is ROHS compliant.
Top Mark
LD7577GS
LD7577GN
Shipping
2500 /tape & reel
3600 /tube /Carton
Pin Descriptions
PIN NAME
1 BNO
2 COMP
3 CS
4 GND
5 OUT
6 VCC
7 NC
8 HV
FUNCTION
Brownout Protection Pin. Connect a resistor divider between this pin and bulk
capacitor voltage to set the brownout level. If the voltage is less than threshold
voltage, the PWM output will be disabled. As soon as the voltage is over 4.0V, the
OVP will be tripped and the gate drive will be turned off.
Voltage feedback pin. By connecting a photo-coupler to close the control loop, it can
achieve the regulation.
Current sense pin. Connect it to sense the MOSFET current.
Ground.
Gate drive output to drive the external MOSFET.
Supply voltage pin.
Unconnected Pin.
Connect this pin to positive terminal of bulk capacitor to provide the startup current
for the controller. When VCC voltage trips UVLO(on), this HV loop will be turned off
to save the power loss of the startup circuit.
Leadtrend Technology Corporation
LD7577-DS-01 January 2009
2
www.leadtrend.com.tw
|