LD7550
Block Diagram
VCC
40V
16.0V/
11.4V
UVLO
internal bias
& Vref
RT
OSC
EN
Vref OK
EN
OUT
Green-Mode
Oscillator
S
COMP
2R
R
PWM
Comparator
+
+
R
Q
CS
Leading
Edge
Blanking
∑
Ramp from
Oscillator
GND
Absolute Maximum Ratings
Supply Voltage VCC
COMP, RT, CS
Operating Junction Temperature
Storage Temperature Range
Package thermal resistance (DIP-8)
Package thermal resistance (SOT-26)
Lead temperature (DIP-8, Soldering, 10sec)
Lead temperature (SOT-26, Soldering, 10sec)
36V
-0.3 ~7V
150°C
-65°C to 150°C
100°C/W
250°C/W
260°C
260°C
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
limited.
3
Leadtrend Technology Corporation
LD7550-DS-00 August 2004
LD7550
Electrical Characteristics
(T
A
= +25 C unless otherwise stated, V
CC
=15.0V)
PARAMETER
Supply Voltage (Vcc Pin)
Startup Current
V
COMP
=0V
Operating Current
UVLO (off)
UVLO (on)
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
VCC=15V, Io=20mA
VCC=15V, Io=20mA
Load Capacitance=1000pF
Load Capacitance=1000pF
8
50
30
200
125
1
V
V
nS
nS
RT=100KΩ
Fs=66.5KHz
(-30°C ~85°C)
(VCC=12V-30V)
61.5
66.5
20
5
2
71.5
KHz
KHz
%
%
0.80
0.85
250
50
300
0.90
V
nS
KΩ
nS
V
COMP
=0V
COMP pin open
2.2
5.0
2.35
3.0
mA
V
V
V
COMP
=3V
V
COMP
=open
10.4
14.8
5
3
2
0.7
11.4
16.0
12.4
17.5
25
4
µA
mA
mA
mA
V
V
CONDITIONS
MIN
TYP
MAX
UNITS
o
4
Leadtrend Technology Corporation
LD7550-DS-00 August 2004
LD7550
Typical Performance Characteristics
12.2
17.0
16.8
12.0
16.4
UVLO (On) (V)
UVLO (Off) (V)
11.8
16.0
15.6
15.2
14.8
11.6
11.4
11.2
14.4
14.0
-40
11.0
-40
-20
0
20
40
60
80
100
120
-20
0
20
40
60
80
100
120
Temperature (°C)
Fig. 1
72.0
UVLO (Off) vs. Temperature
18.2
Fig. 2
Temperature (°C)
UVLO (On) vs. Temperature
71.0
18.0
Frequency (KHz)
Frequency (KHz)
70.0
17.8
69.0
17.6
68.0
17.4
67.0
17.2
66.0
-40
-20
0
20
40
60
80
100
120
17.0
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
Fig. 3
Frequency vs. Temperature
Fig. 4
Temperature (°C)
Green-Mode Frequency vs. Temperature
75.9
75.6
Max. Duty-Cycle (%)
75.3
75.0
74.7
74.4
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
Fig. 5
Duty-Cycle (max.) vs. Temperature
5
Leadtrend Technology Corporation
LD7550-DS-00 August 2004
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