LTC3870_15 Datasheet, PDF (4/22 Pages) Linear Technology – PolyPhase Step-Down Slave Controller for LTC3880/LTC3883 with Digital Power System Management

LTC3870
Electrical Characteristics The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T_A = 25°C. (Note 2) V_IN = 15V, V_RUN0,V_RUN1 = 3.3V, f_SYNC = 350kHz
(externally driven) unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
Digital Inputs RUN0/RUN1, MODE0/MODE1, FAULT0/FAULT1
V_IH
Input High Threshold Voltage
V_IL
Input Low Threshold Voltage
MIN TYP MAX UNITS
l
l 1.4
2.0
V
V
Note 1: Stresses beyond those listed in under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3870 is tested under pulsed load conditions such that
T_J ≈ T_A. The LTC3870E is guaranteed to meet specifications from
0°C to 85°C junction temperature. Specifications over the –40°Ç to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3870I is guaranteed over the full –40°C to 125°C operating junction
temperature range. Note that the maximum ambient temperature
consistent with these specifications is determined by specific operating
conditions in conjunction with board layout, the related package thermal
impedance and other environmental factors. The junction temperature T_J
is calculated from the ambient temperature T_A and power dissipation P_D
according to the following formula:
T_J = T_A + (P_D • 43°C/W)
Note 3: When V_IN >15V, EXTV_CC is recommended to reduce IC
Temperature.
Note 4: Output voltage is set and controlled by the LTC3880/LTC3883 in
multiphase operations.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Application Information.
Note 6: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 7: The minimum on-time condition corresponds to an inductor
peak-to-peak ripple current ≥40% of I_MAX (see Minimum On-Time
Considerations in the Applications Information section.
Note 8: EXTV_CC is enabled only if V_IN is higher than 6.5V.
Note 9: Guaranteed by design.
Typical Performance Characteristics
Efficiency vs Load Current
100
DCM
90
CCM
80
70
60
50
40
30
20
10
0
0.1
V_IN = 12V
V_OUT = 1.8V
f_SW = 400kHz
L = 0.56µH
DCR = 1.8mΩ
1
10
100
LOAD CURRENT (A)
3870 G01
Efficiency vs Load Current
100
DCM
90
CCM
80
70
60
50
40
30
20
10
0
0.1
V_IN = 12V
V_OUT = 3.3V
f_SW = 400kHz
L = 0.56µH
DCR = 1.8mΩ
1
10
100
LOAD CURRENT (A)
3870 G02
Full Load Efficiency and Power
Loss vs Input Voltage
94
POWER LOSS ³
EFFICIENCY
93
2.5
92
2
91
1.5
90
1
89
88 _{VIN = 12V}
V_OUT = 1.8V
87
579
11 13 15 17
INPUT VOLTAGE (V)
0.5
0
19
3870 G03
3870fa
4
For more information www.linear.com/LTC3870