LTC3857-1_15 Datasheet, PDF (6/38 Pages) Linear Technology – Low IQ, Dual, 2-Phase Synchronous Step-Down Controller

LTC3857-1
TYPICAL PERFORMANCE CHARACTERISTICS
Total Input Supply Current
vs Input Voltage
500
450
V_OUT1 = 3.3V
RUN2 = 0V
400
FIGURE 13 CIRCUIT
350
300
250
500μA
200
300μA
150
100
NO LOAD
50
0
5 10 15 20 25 30 35 40
INPUT VOLTAGE (V)
38571 G10
Maximum Current Sense Voltage
vs I_TH Voltage
80
5% DUTY CYCLE
60
PULSE-SKIPPING MODE
40
Burst Mode
OPERATION
20
0
FORCED CONTINUOUS MODE
–20
–40
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
V_ITH (V)
38571 G13
EXTV_CC Switchover and INTV_CC
Voltages vs Temperature
6.0
5.8
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 80 105 130
TEMPERATURE (°C)
38571 G11
SENSE^– Pin Input Bias Current
0
–50
–100
–150
–200
–250
–300
–350
–400
–450
–500
–550
–600
0
5
10 15 20 25
V_SENSE COMMON MODE VOLTAGE (V)
38571 G14
Foldback Current Limit
90
80
70
60
50
40
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)
38571 G16
Quiescent Current vs Temperature
80
75
70
65
60
55
50
45
40
–45 –20
5 30 55 80
TEMPERATURE (°C)
105 130
38571 G17
6
INTV_CC Line Regulation
5.2
5.1
5.0
4.9
4.8
0
5 10 15 20 25 30 35 40
INPUT VOLTAGE (V)
38571 G12
Maximum Current Sense
Threshold vs Duty Cycle
80
60
40
20
0
0 10 20 30 40 50 60 70 80 90 100
DUTY CYCLE (%)
38571 G15
INTV_CC and EXTV_CC
vs Load Current
5.20
V_IN = 12V
5.15
5.10
EXTV_CC = 0V
5.05
EXTV_CC = 8.5V
5.00
4.95
0 20 40 60 80 100 120 140 160 180 200
LOAD CURRENT (mA)
38571 G18
38571fc