LT3579E (Notes 2, 4) ......................... –40°C to 125°C
LT3579I (Notes 2, 4) .......................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
PIN CONFIGURATION
TOP VIEW
FB
V
C
GATE
FAULT
V
IN
SW1
SW1
SW1
SW1
1
2
3
4
5
6
7
8
9
21
GND
20 SYNC
19 SS
18 R
T
17
SHDN
16 CLKOUT
15 SW2
14 SW2
13 SW2
12 SW2
11 SW2
GATE 1
FAULT
2
V
IN
3
SW1 4
SW1 5
SW1 6
7
SW1
8
GND
9 10
GND
SW2
21
GND
TOP VIEW
SYNC
16 R
T
15
SHDN
14 CLKOUT
13 SW2
12 SW2
11 SW2
SS
V
C
FB
20 19 18 17
SW1 10
FE PACKAGE
20-LEAD PLASTIC TSSOP
T
JMAX
= 125°C,
θ
JA
= 38°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
UFD PACKAGE
20-LEAD (4mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 34°C/W,
θ
JC
= 2.7°C/W
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LT3579EFE#PBF
LT3579IFE#PBF
LT3579EUFD#PBF
LT3579IUFD#PBF
LT3579EFE-1#PBF
LT3579IFE-1#PBF
LT3579EUFD-1#PBF
LT3579IUFD-1#PBF
TAPE AND REEL
LT3579EFE#TRPBF
LT3579IFE#TRPBF
LT3579EUFD#TRPBF
LT3579IUFD#TRPBF
LT3579EFE-1#TRPBF
LT3579IFE-1#TRPBF
LT3579EUFD-1#TRPBF
LT3579IUFD-1#TRPBF
PART MARKING*
LT3579FE
LT3579FE
3579
3579
LT3579FE-1
LT3579FE-1
35791
35791
PACKAGE DESCRIPTION
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
20-Lead (4mm
×
5mm) Plastic QFN
20-Lead (4mm
×
5mm) Plastic QFN
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
20-Lead (4mm
×
5mm) Plastic QFN
20-Lead (4mm
×
5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications.
Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
2
Rev. B
For more information
www.analog.com
LT3579/LT3579-1
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 5V, V
SHDN
= V
IN,
V
FAULT
=
V
IN
unless otherwise noted. (Note 2).
PARAMETER
Minimum Input Voltage
V
IN
Overvoltage Lockout
Positive Feedback Voltage
Negative Feedback Voltage
Positive FB Pin Bias Current
Negative FB Pin Bias Current
Error Amp Transconductance
Error Amp Voltage Gain
Quiescent Current
Quiescent Current in Shutdown
Reference Line Regulation
Switching Frequency, f
OSC
Switching Frequency in Foldback
Switching Frequency Range
SYNC High Level for Sync
SYNC Low Level for Sync
SYNC Clock Pulse Duty Cycle
Recommended Minimum SYNC Ratio
f
SYNC
/f
OSC
Minimum Off-Time
Minimum On-Time
SW1 Current Limit
SW Current Sharing, I
SW2
/I
SW1
SW1 + SW2 Current Limit
Switch V
CESAT
SW1 Leakage Current
SW2 Leakage Current
At All Duty Cycles (Note 3)
SW1 and SW2 Tied Together
I
SW2
/I
SW1
= 0.78, At All Duty Cycles (Note 3)
SW1 and SW2 Tied Together, I
SW1
+ I
SW2
= 5.5A (Note 5)
V
SW1
= 5V
V
SW2
= 5V
l
l
l
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
l
TYP
2.3
18.7
1.215
9
83.3
83.3
250
70
1.9
0
0.01
MAX
2.5
21.2
1.230
16
85
85.5
UNITS
V
V
V
mV
µA
µA
µmhos
V/V
16.2
1.195
3
80.5
81
V
FB
=Positive Feedback Voltage, Current into Pin
V
FB
=Negative Feedback Voltage, Current out of Pin
ΔI=10μA
Not Switching
V
SHDN
= 0V
2.5V ≤ V
IN
≤ 15V
R
T
= 34kΩ
R
T
= 432kΩ
Compared to Normal f
OSC
Free-Running or Synchronizing
l
l
2.4
1
0.05
2.8
225
2500
0.4
mA
µA
%/V
MHz
kHz
ratio
kHz
V
V
%
l
l
2.2
175
200
1.3
20
2.5
200
1/6
l
l
l
V
SYNC
= 0V to 2V
80
3/4
45
55
nS
nS
5.1
9.4
350
1
1
A
A/A
A
mV
µA
µA
3.4
6
4.2
0.78
7.5
250
0.01
0.01
For more information
www.analog.com
3
Rev. B
LT3579/LT3579-1
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 5V, V
SHDN
= V
IN
, V
FAULT
=
V
IN
unless otherwise noted. (Note 2).
PARAMETER
Soft-Start Charge Current
Soft-Start Discharge Current
CONDITIONS
V
SS
= 30mV, Current Flows Out of SS pin
Part in FAULT
V
SS
= 2.1V,
Current Flows into SS Pin
Part in FAULT
Part Exiting FAULT
Active Mode,
SHDN
Rising
Active Mode,
SHDN
Falling
Shutdown Mode
V
SHDN
= 3V
V
SHDN
= 1.3V
V
SHDN
= 0V
C
CLKOUT
= 50pF
C
CLKOUT
= 50pF
LT3579, T
J
= 25°C
LT3579-1, All T
J
CLKOUT Rise Time
CLKOUT Fall Time
GATE Pull Down Current
GATE Leakage Current
FAULT
Output Voltage Low
FAULT
Leakage Current
FAULT
Input Voltage Low Threshold
FAULT
Input Voltage High Threshold
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LT3579E is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT3579I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
C
CLKOUT
= 50pF
C
CLKOUT
= 50pF
V
GATE
= 3V
V
GATE
= 80V
V
GATE
= 50V, GATE Off
50μA into
FAULT
Pin
V
FAULT
= 40V,
FAULT
Off
l
l
l
l
l
l
l
l
l
l
l
l
ELECTRICAL CHARACTERISTICS
MIN
5.7
5.7
1.65
30
1.27
1.24
TYP
8.7
8.7
1.8
50
1.33
1.3
40
11.4
0
2.1
100
42
50
12
8
MAX
11.3
11.3
1.95
85
1.41
1.38
.3
60
13.4
0.1
2.3
200
UNITS
µA
µA
V
mV
V
V
V
µA
µA
µA
V
mV
%
%
ns
ns
Soft-Start High Detection Voltage
Soft-Start Low Detection Voltage
SHDN
Minimum Input Voltage High
SHDN
Input Voltage Low
SHDN
Pin Bias Current
9.5
1.9
CLKOUT Output Voltage High
CLKOUT Output Voltage Low
CLKOUT Duty Cycle
800
800
933
933
0.01
100
0.01
1100
1100
1
300
1
800
1050
µA
µA
µA
mV
µA
mV
mV
700
950
750
1000
Note 3:
Current limit guaranteed by design and/or correlation to static test.
Note 4:
This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation over the specified maximum operating junction
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