LTC1148_15 Datasheet, PDF (4/20 Pages) Linear Technology – High Efficiency Synchronous Step-Down Switching Regulators

LTC1148
LTC1148-3.3/LTC1148-5
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: T_J is calculated from the ambient temperature T_A and power
dissipation P_D according to the following formulas:
LTC1148CN, LTC1148CN-3.3, LTC1148CN-5: T_J = T_A + (P_D × 70°C/W)
LTC1148CS, LTC1148CS-3.3, LTC1148CS-5: T_J = T_A + (P_D × 110°C/W)
Note 3: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 4: The LTC1148 and LTC1148HV versions are tested with external
feedback resistors resulting in a nominal output voltage of 5V. The
LTC1148L version is tested with external feedback resistors resulting in a
nominal output voltage of 2.5V.
Note 5: In applications where R_SENSE is placed at ground potential, the off
time increases approximately 40%.
Note 6: The LTC1148, LTC1148HV and LTC1148L series are not tested
and not quality assurance sampled at –40°C and 85°C. These
specifications are guaranteed by design and/or correlation. The
LTC1148HVI-5 is guaranteed over the full –40°C to 85°C operating
temperature range.
Note 7: The LTC1148L and LTC1148L-3.3 allow operation to V_IN = 3.5V.
TYPICAL PERFOR A CE CHARACTERISTICS
Efficiency vs Input Voltage
100
FIGURE 1 CIRCUIT
98
96
I_LOAD = 1A
94
92
90
88
I_LOAD = 100mA
86
84
82
80
0
4
8
12
16
20
INPUT VOLTAGE (V)
LTC1148 • TPC01
DC Supply Current
2.1
NOT INCLUDING
GATE CHARGE CURRENT
1.8
1.5
ACTIVE MODE
1.2
0.9
0.6
0.3
SLEEP MODE
0
0 2 4 6 8 10 12 14 16 18 20
INPUT VOLTAGE
LTC1148 • TPC04
Line Regulation
40
FIGURE 1 CIRCUIT
30 ^ILOAD ^{= 1A}
20
10
0
–10
– 20
– 30
– 40
0
4
8
12
16
20
INPUT VOLTAGE (V)
LTC1148 • TPC02
Supply Current in Shutdown
20
18 ^{VSHUTDOWN = 2V}
16
14
12
10
8
6
4
2
0
0 2 4 6 8 10 12 14 16 18 20
INPUT VOLTAGE (V)
LTC1148 • TPC05
Load Regulation
20
0
FIGURE 1 CIRCUIT
R_SENSE = 0.05Ω
– 20
V_IN = 6V
– 40
– 60
V_IN = 12V
– 80
– 100
0
0.5
1
1.5
LOAD CURRENT (A)
2
2.5
LTC1148 • TPC03
Operating Frequency
vs (V_IN – V_OUT)
1.6
V_OUT = 5V
1.4
0°C
1.2
1.0
70°C
25°C
0.8
0.6
0.4
0.2
0
0
2
4
6
8 10 12
(V_IN – V_OUT) VOLTAGE (V)
LTC1148 • TPC06
114835fd
4