Document
LD7578J
03/03/2009
High Voltage Green-Mode PWM Controller with
Over Temperature Protection
Rev. 00
General Description
The LD7578J integrates several functions of protections, and EMI-improved solution in a 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 LD7578J 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 LD7578J features built-in auto-recovery function for OVP on Vcc pin and OLP.
Furthermore, the LD7578J features frequency trembling to depress radiation noise and is an excellent solution for EMI filter design.
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 Frequency Trembling 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 LD7578J-DS-00 March 2009
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Pin Configuration
SOP-8 & DIP-8 (TOP VIEW)
HV NC VCC OUT
8765
TOP MARK YYWWPP
1 234
YY:
WW: PP:
Year code
Week code Production code
LD7578J
(-) LATCH COMP CS GND
Ordering Information
Part number LD7578J GS
Switching Freq. 65KHz
Protection Mode
Auto recovery
LD7578J GN
65KHz Auto recovery
The LD7578J is green packaged.
Package
SOP-8 DIP-8
Green package Green package
Top Mark
LD7578J GS LD7578J GN
Shipping
2500 /tape & reel 3600 /tube /Carton
Pin Descriptions
PIN NAME
1 (-) LATCH
2 COMP 3 CS 4 GND 5 OUT 6 VCC 7 NC
8 HV
FUNCTION Pull this pin lower than 0.95V to shutdown the controller into latch mode until the AC power-on recycles. By connecting a NTC with this pin to ground, it can achieve the OTP protection function. Keep this pin float to disable the latch protection. Voltage feedback pin. By connecting a photo-coupler to close the control loop, it can achieve the regulation.
Current sense pin, for sensing the MOSFET current.
Ground.
Gate drive output to drive the external MOSFET.
Supply voltage pin.
Unconnected Pin. Connect this pin to a positive terminal of bulk capacitor to provide the startup current for the controller. When Vcc voltage trips the UVLO(on), this HV loop will be turned off to save the power loss on the startup circuit.
Leadtrend Technology Corporation LD7578J-DS-00 March 2009
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Block Diagram
LD7578J
Leadtrend Technology Corporation LD7578J-DS-00 March 2009
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Absolute Maximum Ratings
Supply Voltage VCC High-Voltage Pin, HV COMP, (-)LATCH, CS OUT Junction Temperature Operating Ambient Temperature Storage Temperature Range Package Thermal Resistance (SOP-8) Package Thermal Resistance (DIP-8) Power Dissipation (SOP-8, at Ambient Temperature = 85°C) Power Dissipation (DIP-8, at Ambient Temperature = 85°C) Lead temperature (Soldering, 10sec) ESD Voltage Protection, Human Body Model (except HV Pin) ESD Voltage Protection, Machine Model Gate Output Current
LD7578J
30V -0.3V~500V -0.3 ~7V -0.3 ~Vcc+0.3 150°C -20°C to 85°C -65°C to 150°C 160°C/W 100°C/W 400mW 650mW 260°C 2.5KV 250V 500mA
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 or any other conditions above those indicated in the operational sections of this specification is not implied.
Leadtrend Technology Corporation LD7578J-DS-00 March 2009
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Electrical Characteristics
(TA = +25oC 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, LD7578J VCOMP=3V, LD7578J OLP tripped, LD7578J OVP tripped, LD7578J
(-)Latch Pin Tripped LD7578J
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
Current Sensing (CS Pin) Maximum Input Voltage,Vcs_off
Leading Edge Blanking Time Input impedance
VCOMP > 1.9 VCOMP <1.9
Delay to Output
LD7578J
MIN
TYP
MAX UNITS
0.5 1.0 1.5 mA 35 μA
320 3.3 3.6 0.78 0.88
μA mA mA mA mA
0.68
mA
9.0
10.0
11.0
V
15.0
16.0
17.0
V
26.5
28.0
29.5
V
1.45 5.6 2.35
2.0 mA V V
0.80
0.85
0.90
V
250 nS
1700
nS
1 MΩ
100 nS
Leadtrend Technology Corporation LD7578.