3
LTC1149
LTC1149-3.3/LTC1149-5
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
9
– V
8
Current Sense Threshold Voltage
LTC1149 V
8
= 5V, V
10
= 1.32V (Forced) 25 mV
V
8
= V
OUT
– 100mV ● 130 150 170 mV
LTC1149-3.3 V
8
= 3.5V (Forced) 25 mV
V
8
= V
OUT
– 100mV ● 130 150 170 mV
LTC1149-5 V
8
= 5.3V (Forced) 25 mV
V
8
= V
OUT
– 100mV ● 130 150 170 mV
V
10
Shutdown 1 Threshold
LTC1149-3.3, LTC1149-5 0.5 0.8 2 V
V
15
Shutdown 2 Threshold 0.8 1.4 2 V
I
15
Shutdown 2 Input Current V
15
= 5V 18 25 µA
I
6
C
T
Pin Discharge Current V
OUT
In Regulation, V
SENSE
–
= V
OUT
50 70 90 µA
V
OUT
= 0V 2 10 µA
t
OFF
Off-Time (Note 4) C
T
= 390pF, I
LOAD
= 700mA 4 5 6 µs
t
r
, t
f
Driver Output Transition Times C
L
= 3000pF (Pins 4, 13), V
IN
= 6V 100 200 ns
E
LECTR
IC
AL C CHARA TERIST
ICS
T
A
= 25°C, V
IN
= 12V, V
10
= 0V (Note 2), unless otherwise noted.
–40°C ≤ T
A
≤ 85°C (Note 5), unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
10
Feedback Voltage LTC1149 Only 1.2 1.25 1.3 V
V
OUT
Regulated Output Voltage V
IN
= 9V
LTC1149-3.3 I
LOAD
= 700mA 3.17 3.33 3.43 V
LTC1149-5 I
LOAD
= 700mA 4.85 5.05 5.2 V
I
2
Input DC Supply Current (Note 3)
Normal Mode V
IN
= 12V 2.0 3.2 mA
V
IN
= 48V 2.2 3.5 mA
Burst Mode V
IN
= 12V 0.6 1.05 mA
V
IN
= 48V 0.8 1.30 mA
Shutdown V
IN
= 12V, V
15
= 2V 135 230 µA
V
IN
= 48V, V
15
= 2V 300 520 µA
V
CC
Internal Regulator Voltage V
IN
= 12V to 48V 9.75 10.25 11 V
(Sets MOSFET Gate Drive Levels) I
3
= 20mA
V
9
– V
8
Current Sense Threshold Voltage Low Threshold (Forced) 25 mV
High Threshold (Forced) 125 150 175 mV
V
15
Shutdown 2 Threshold 0.8 1.4 2 V
t
OFF
Off-Time (Note 4) C
T
= 390pF, I
LOAD
= 700mA, V
IN
= 10V 3.8 5 6 µs
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC1149CN, LTC1149CN-3.3, LTC1149CN-5: T
J
= T
A
+ (P
D
)(70°C/W)
LTC1149CS, LTC1149CS-3.3, LTC1149CS-5: T
J
= T
A
+ (P
D
)(110°C/W)
Note 2: Pin 10 is a shutdown pin on the LTC1149-3.3 and LTC1149-5
fixed output voltage versions and must be at ground potential for testing.
Note 3: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. The allowable operating frequency
may be limited by power dissipation at high input voltages. See Typical
Performance Characteristics and Applications Information.
Note 4: In applications where R
SENSE
is placed at ground potential, the off-
time increases approximately 40%.
Note 5: The LTC1149, LTC1149-3.3, and LTC1149-5 are not tested and
not quality assurance sampled at –40°C and 85°C. These specifications
are guaranteed by design and/or correlation.
