LT1765/LT1765-1.8/LT1765-2.5/
LT1765-3.3/LT1765-5
ELECTRICAL CHARACTERISTICS
The
l
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= 15V, V
C
= 0.8V, Boost = V
IN
+ 5V,
SHDN,
SYNC and switch open unless otherwise noted.
PARAMETER
Maximum Switch Current Limit
Oscillator Frequency
Switch On Voltage Drop
V
IN
Undervoltage Lockout
V
IN
Supply Current
Shutdown Supply Current
Feedback Voltage
V
SHDN
= 0V, V
IN
= 25V, V
SW
= 0V
3V < V
IN
< 25V, 0.4V < V
C
< 0.9V
(Note 3)
LT1765 (Adj)
LT1765-1.8
LT1765-2.5
LT1765-3.3
LT1765-5
FB Input Current
FB Input Resistance
LT1765 (Adj)
LT1765-1.8
LT1765-2.5
LT1765-3.3
LT1765-5
0.4V < V
C
< 0.9V
ΔI
VC
=
±10μA
V
FB
= V
NOM
– 17%
V
FB
= V
NOM
+ 17%
Duty Cycle = 0%
V
C
= 1.2V, I
SW
= 800mA, V
IN
= 6V
I
SW
= 3A
I
SW
= 1A (Note 4)
I
SW
= 3A (Note 4)
85
80
l
l
l
CONDITIONS
3.3V < V
IN
< 25V
I = 3A
(Note 3)
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
MIN
3
1.1
2.47
TYP
4
1.25
270
2.6
1
15
MAX
6
1.6
430
2.73
1.3
35
55
1.218
1.224
1.836
2.55
3.366
5.1
–0.5
21
30
39
60
1300
160
180
UNITS
A
MHz
mV
V
mA
μA
μA
V
V
V
V
V
V
μA
kΩ
kΩ
kΩ
kΩ
μMho
μA
μA
A/V
V
V
%
%
1.182
1.176
1.764
2.45
3.234
4.9
10.5
14.7
19
29
150
500
80
70
1.2
1.8
2.5
3.3
5
–0.25
15
21
27.5
42
350
850
120
110
5
0.4
0.9
90
1.8
20
70
FB Error Amp Voltage Gain
FB Error Amp Transconductance
V
C
Pin Source Current
V
C
Pin Sink Current
V
C
Pin to Switch Current Transconductance
V
C
Pin Minimum Switching Threshold
V
C
Pin 3A ISW Threshold
Maximum Switch Duty Cycle
Minimum Boost Voltage Above Switch
Boost Current
SHDN
Threshold Voltage
SHDN
Threshold Current Hysteresis
SHDN
Input Current (Shutting Down)
SYNC Threshold Voltage
SYNC Input Frequency
SYNC Pin Resistance
l
l
l
l
l
l
2.7
30
140
1.40
10
–13
2.2
2
V
mA
mA
V
μA
μA
V
MHz
kΩ
1.27
4
–7
1.6
1.33
7
–10
1.5
SHDN
= 60mV Above Threshold
l
I
SYNC
= 1mA
20
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 LT1765E is guaranteed to meet performance specifications
from 0°C to 125°C. Specifications over the –40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 3:
Minimum input voltage is defined as the voltage where the internal
regulator enters lockout. Actual minimum input voltage to maintain a
regulated output will depend on output voltage and load current. See
Applications Information.
Note 4:
Current flows into the BOOST pin only during the on period of the
switch cycle.
1765fd
3
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