LD7575
6/5/2007
Green-Mode PWM Controller with High-Voltage
Start-Up Circuit
REV: 04a
General Description
The LD7575 is a current-mode PWM controller with
excellent power-saving operation.
It features a high-
voltage current source to directly supply the startup current
from bulk capacitor and further to provide a lossless startup
circuit.
The integrated functions such as the leading-edge
blanking of the current sensing, internal slope compensation,
and the small package provide the users a high efficiency,
minimum external component counts, and low cost solution
for AC/DC power applications.
Furthermore, the embedded over voltage protection, over
load protection and the special green-mode control provide
the solution for users to design a high performance power
circuit easily.
DIP-8 package.
The LD7575 is offered in both SOP-8 and
Features
High-Voltage (500V) Startup Circuit
Current Mode Control
Non-Audible-Noise Green Mode Control
UVLO (Under Voltage Lockout)
LEB (Leading-Edge Blanking) on CS Pin
Programmable Switching Frequency
Internal Slope Compensation
OVP (Over Voltage Protection) on Vcc
OLP (Over Load Protection)
500mA Driving Capability
Applications
Switching AC/DC Adapter and Battery Charger
Open Frame Switching Power Supply
LCD Monitor/TV Power
Typical Application
1
Leadtrend Technology Corporation
LD7575-DS-04a June 2007
LD7575
Pin Configuration
SOP-8 & DIP-8 (TOP VIEW)
VCC
6
8
7
OUT
5
NC
HV
TOP MARK
YYWWPP
1
2
3
4
YY:
WW:
PP:
Year code
Week code
Production code
RT
COMP
Ordering Information
Part number
LD7575 PS
LD7575 PN
Package
SOP-8
DIP-8
Top Mark
LD7575PS
LD7575PN
Shipping
2500 /tape & reel
3600 /tube /Carton
The LD7575 is ROHS compliant.
Pin Descriptions
PIN
1
NAME
RT
FUNCTION
This pin is to program the switching frequency. By connecting a resistor to ground
to set the switching frequency.
Voltage feedback pin (same as the COMP pin in UC384X), By connecting a
photo-coupler to close the control loop and achieve the regulation.
Current sense pin, connect 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
8
HV
for the controller. When Vcc voltage trips the UVLO(on), this HV loop will be off to
save the power loss on the startup circuit.
2
3
4
5
6
7
COMP
CS
GND
OUT
VCC
NC
GND
CS
2
Leadtrend Technology Corporation
LD7575-DS-04a June 2007
LD7575
Block Diagram
HV
1mA
8V
POR
32V
16.0V/
10.0V
UVLO
Comparator
OVP
Comparator
VCC
internal bias
& Vref
VCC OK
27.5V
RT
OSC
PG
Vref OK
S
Q
R
Green-Mode
Control
Vbias
OVP
PG
S
Q
OLP
COMP
PWM
Comparator
2R
R
R
∑
+
Slope
Compensation
POR
0.85V
OCP
Comparator
CS
Leading
Edge
Blanking
+
Driver
Stage
OUT
clear
30mS
Delay
OLP
Comparator
/2
Counter
S
Q
5.0V
PG
R
GND
3
Leadtrend Technology Corporation
LD7575-DS-04a June 2007
LD7575
Absolute Maximum Ratings
Supply Voltage VCC
High-Voltage Pin, HV
COMP, RT, CS
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
30V
-0.3V~500V
-0.3 ~7V
150°C
-40°C to 85°C
-65°C to 150°C
160°C/W
100°C/W
400mW
650mW
260°C
3KV
200V
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.
Recommended Operating Conditions
Item
Supply Voltage Vcc
Vcc Capacitor
Switching Frequency
Min.
11
10
50
Max.
25
47
130
Unit
V
µF
KHz
4
Leadtrend Technology Corporation
LD7575-DS-04a June 2007
LD7575
Electrical Characteristics
(T
A
= +25 C unless otherwise stated, V
CC
=15.0V)
PARAMETER
High-Voltage Supply (HV Pin)
High-Voltage Current Source
Off-State Leakage Current
Supply Voltage (Vcc Pin)
Startup Current
Operating Current
(with 1nF load on OUT pin)
UVLO (off)
UVLO (on)
OVP Level
Voltage Feedback (Comp Pin)
Short Circuit Current
Open Loop Voltage
Green Mode Threshold VCOMP
Current Sensing (CS Pin)
Maximum Input Voltage
Leading Edge Blanking Time
Input impedance
Delay to Output
Oscillator (RT pin)
Frequency
Green Mode Frequency
Temp. Stability
Voltage Stability
Gate Drive Output (OUT Pin)
Output Low Level
Output High Level
Rising Time
Falling Time
OLP (Over Load Protection)
OLP Trip Level
OLP Delay Time (note)
Fs=65KHz
5.0
30
V
mS
VCC=15V, Io=20mA
VCC=15V, Io=20mA
Load Capacitance=1000pF
Load Capacitance=1000pF
9
50
30
160
60
1
V
V
nS
nS
RT=100KΩ
Fs=65.0KHz
(-40°C ~105°C)
(VCC=11V-25V)
60.0
65.0
20
3
1
70.0
KHz
KHz
%
%
1
100
0.80
0.85
350
0.90
V
nS
MΩ
nS
V
COMP
=0V
COMP pin open
1.5
6.0
2.35
2.2
mA
V
V
V
COMP
=0V
V
COMP
=3V
Protection tripped (OLP, OVP)
9.0
15.0
25.0
2.0
2.5
0.5
10.0
16.0
27.5
11.0
17.0
30.0
100
3.0
4.0
µA
mA
mA
mA
V
V
V
Vcc< UVLO(on), HV=500V
Vcc> UVLO(off), HV=500V
0.5
1.0
1.5
35
mA
µA
CONDITIONS
MIN
TYP
MAX
UNITS
o
Note: The OLP delay time is proportional to the period of switching cycle.
frequency and the shorter OLP delay time.
So that, the lower RT value will set the higher switching
5
Leadtrend Technology Corporation
LD7575-DS-04a June 2007
Embedded System
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