LTC3868 Datasheet, PDF (6/38 Pages) Linear Technology – Low IQ, Dual 2-Phase Synchronous Step-Down Controller

LTC3868
Typical Performance Characteristics
Total Input Supply Current
vs Input Voltage
400
FIGURE 12 CIRCUIT
350
V_OUT = 3.3V
ONE CHANNEL ON
300
300µA LOAD
250
200
150
NO LOAD
100
50
0
5
10
15
20
25 28
INPUT VOLTAGE (V)
3868 G10
Maximum Current Sense Voltage
vs I_TH Voltage
80
PULSE-SKIPPING
FORCED CONTINUOUS
60
Burst Mode OPERATION
(FALLING)
40
Burst Mode OPERATION
(RISING)
20
0
–20
–40
0
I_LIM = GND
I_LIM = FLOAT
I_LIM = INTV_CC
5% DUTY CYCLE
0.2 0.4 0.6 0.8 1.0 1.2 1.4
I_TH PIN VOLTAGE
3868 G13
Foldback Current Limit
90
80
I_LIM = INTV_CC
70
60
I_LIM = FLOAT
50
40
I_LIM = GND
30
20
10
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
FEEDBACK VOLTAGE (V)
3868 G16
EXTV_CC Switchover and INTV_CC
Voltages vs Temperature
5.6
5.4
5.2
INTV_CC
5.0
EXTV_CC RISING
4.8
4.6
EXTV_CC FALLING
4.4
4.2
4.0
–45 –20
5 30 55 80
TEMPERATURE (°C)
105 130
3868 G11
SENSE^– Pin Input Bias Current
0
–50
–100
–150
–200
–250
–300
–350
–400
–450
–500
–550
–600
0
5
10
15
V_SENSE COMMON MODE VOLTAGE (V)
3868 G14
Quiescent Current vs Temperature
240
230 ^{PLLIN/MODE = 0}
220
V_IN = 12V
V_OUT = 3.3V
210 _{ONE CHANNEL ON}
200
190
180
170
160
150
140
130
120
110
–45 –20
5 30 55 80 105 130
TEMPERATURE (°C)
3868 G17
INTV_CC Line Regulation
5.2
5.2
5.1
5.1
5.0
0
5
10 15 20
INPUT VOLTAGE (V)
25 28
3868 G12
Maximum Current Sense
Threshold vs Duty Cycle
80
I_LIM = INTV_CC
60
I_LIM = FLOAT
40
I_LIM = GND
20
0
0 10 20 30 40 50 60 70 80 90 100
DUTY CYCLE (%)
3868 G15
Shutdown Current vs Temperature
10
9
8
7
6
5
4
–45 –20
5 30 55 80
TEMPERATURE (°C)
105 130
3868 G18
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