LTC3851A_15 Datasheet, PDF (6/30 Pages) Linear Technology – Synchronous Step-Down Switching Regulator Controller

LTC3851A
Typical Performance Characteristics
Ratiometric Tracking with Master
Supply
V_MASTER
0.5V/DIV
V_OUT
2A LOAD
0.5V/DIV
10ms/DIV
3851A G11
Maximum Current Sense Threshold
vs Common Mode Voltage
90
80
I_LIM = INTV_CC
70
60
I_LIM = FLOAT
50
40
30
I_LIM = GND
20
10
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
V_SENSE COMMON MODE VOLTAGE (V)
3851A G14
Maximum Current Sense
Threshold vs Duty Cycle
90
80
I_LIM = INTV_CC
70
60
I_LIM = FLOAT
50
40
I_LIM = GND
30
20
10
0
0
20
40
60
80
100
DUTY CYCLE (%)
3851A G17
6
Input DC Supply Current
vs Input Voltage
3.0
2.5
2.0
1.5
1.0
0.5
0
4 8 12 16 20 24 28 32 36 40
INPUT VOLTAGE (V)
3851A G12
Maximum Peak Current Sense
Threshold vs I_TH Voltage
90
DUTY CYCLE RANGE: 0% TO 100%
80
70
I_LIM = INTV_CC
60
50
I_LIM = FLOAT
40
30
20
I_LIM = GND
10
0
–10
–20
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
V_ITH (V)
3851A G15
Maximum Current Sense
Threshold vs Feedback Voltage
(Current Foldback)
90
80
I_LIM = INTV_CC
70
60
I_LIM = FLOAT
50
40
30
I_LIM = GND
20
10
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
FEEDBACK VOLTAGE (V)
3851A G18
INTV_CC Line Regulation
5.3
5.1
I_LOAD = 0mA
4.9
I_LOAD = 25mA
4.7
4.5
4.3
4.1
3.9
3.7
3.5
4
8 12 16 20 24 28 32 36 40
INPUT VOLTAGE (V)
3851A G13
Burst Mode Peak Current Sense
Threshold vs I_TH Voltage
60
MAXIMUIM
50
40
30
20
MINIMUIM
10 _{ILIM = FLOAT}
BURST COMPARATOR FALLING THESHOLD:
0 ^{VITH = 0.4V}
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
V_ITH (V)
3851A G16
TK/SS Pull-Up Current
vs Temperature
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
–75 –50 –25 0 25 50 75 100 125 150
TEMPERATURE (°C)
3851A G19
3851afa