LTC3870_15 Datasheet, PDF (5/22 Pages) Linear Technology – PolyPhase Step-Down Slave Controller for LTC3880/LTC3883 with Digital Power System Management

LTC3870
Typical Performance Characteristics
Load Step (Discontinuous
Conduction Mode) 4-Phase
Operation LTC3880 and LTC3870
Load Step (Forced Continuous
Mode) 4-Phase Operation
LTC3880 and LTC3870
Inductor Current at Light Load
I_LOAD
20A/DIV
0A TO 20A TO 0A
I_{L_3880(CH0)}
10A/DIV
I_{L_3870(CH0)}
10A/DIV
V_OUT
100mV/DIV
AC-COUPLED
I_LOAD
20A/DIV
0A TO 20A TO 0A
I_{L_3880(CH0)}
10A/DIV
I_{L_3870(CH0)}
10A/DIV
V_OUT
100mV/DIV
AC-COUPLED
I_{L_3870(CH0)}
FORCED CONTINUOUS
MODE
5A/DIV
I_{L_3870(CH0)}
DISCONTINUOUS
CONDUCTION MODE
5A/DIV
V_IN = 12V
V_OUT = 1.8V
50µs/DIV
3870 G04
V_IN = 12V
V_OUT = 1.8V
50µs/DIV
3870 G05
V_IN = 12V
V_OUT = 1.8V
I_LOAD = 1A
1µs/DIV
3870 G06
Start-Up Into a Pre-Biased
Output 4-Phase Operation
LTC3880 and LTC3870
RUN
ALL RUN PINS
TIED TOGETHER
2V/DIV
V_OUT
LTC3870 IN DCM
500mV/DIV
V_IN = 12V
V_OUT = 1.8V
2ms/DIV
3870 G07
Current Sense Threshold
vs I_TH Voltage
80
RANGE HIGH
RANGE LOW
60
40
20
0
–20
–40
0
0.5
1
1.5
2
2.5
V_ITH (V)
3870 G08
DC Output Current Matching
Between LTC3880 and LTC3870
25
Dynamic Current Sharing During
a Load Transient in a 4-Phase
Operation LTC3880 and LTC3870
20
15
10
5
LTC3880 CH0
LTC3880 CH1
LTC3870 CH0
LTC3870 CH1
0
0 10 20 30 40 50 60 70 80 90
TOTAL OUTPUT CURRENT (A)
3870 G10
I_{L_3880(CH0)}
I_{L_3880(CH1)}
I_{L_3870(CH0)}
I_{L_3870(CH1)}
5A/DIV
50µs/DIV
I_LOAD 0A TO 32A TO 0A
3870 G11
For more information www.linear.com/LTC3870
INTV_CC Line Regulation
6
5
4
3
2
1
0
0 10 20 30 40 50 60
INPUT VOLTAGE (V)
3870 G09
Quiescent Current vs Input
Voltage Without EXTV_CC
3.5
3
2.5
2
1.5
1
0.5
0
0 10 20 30 40 50 60
INPUT VOLTAGE (V)
3870 G12
3870fa
5