LTC3866 Datasheet, PDF (5/36 Pages) Linear Technology – Current Mode Synchronous Controller for Sub Milliohm DCR Sensing

LTC3866
Electrical Characteristics The l denotes the specifications which apply over the specified operating
temperature range, otherwise specifications are at T_A = 25°C (Note 2). V_IN = 15V, V_RUN = 5V unless otherwise specified.
SYMBOL PARAMETER
On-Chip Driver
TG R_UP
TG R_DOWN
BG R_UP
BG R_DOWN
TG Pull-Up R_DS(ON)
TG Pull-Down R_DS(ON)
BG Pull-Up R_DS(ON)
BG Pull-Down R_DS(ON)
CONDITIONS
TG High
TG Low
BG High
BG Low
MIN
TYP
MAX UNITS
2.6
Ω
1.5
Ω
2.4
Ω
1.1
Ω
Note 1: Stresses beyond those listed 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 LTC3866 is tested under pulsed load conditions such that
T_J ≈ T_A. The LTC3866E is guaranteed to meet performance specifications
from 0°C to 85°C operating junction temperature. Specifications over
the –40°C to 125°C operating junction temperature range are assured by
design, characterization and correlation with statistical process controls.
The LTC3866I is guaranteed to meet performance specifications over the
full –40°C to 125°C operating junction temperature range. The maximum
ambient temperature consistent with these specifications is determined
by specific operating conditions in conjunction with board layout, the
package thermal impedance and other environmental factors.
Note 3: The junction temperature, T_J, is calculated from the ambient
temperature, T_A, and power dissipation, P_D, according to the following
formula:
LTC3866FE: T_J = T_A + (P_D • 33°C/W)
LTC3866UF: T_J = T_A + (P_D • 47°C/W)
Note 4: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. The maximum
rated junction temperature will be exceeded when this protection is active.
Continuous operation above the absolute maximum operating junction
temperature may impair device reliability or permanently damage the
device.
Note 5: The LTC3866 is tested in a feedback loop that servos V_ITH to a
specified voltage and measures the resultant V_FB.
Note 6: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 7: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 8: The minimum on-time condition corresponds to the on inductor
peak-to-peak ripple current ≥40% of I_MAX (see Minimum On-Time
Considerations in the Applications Information section).
Note 9: Guaranteed by design.
Typical Performance Characteristics T_A = 25°C, unless otherwise noted.
Efficiency vs Load Current
and Mode
100
90
80
70
60
50
40
30
20
10
0
0.01
V_IN = 4.5V
V_OUT = 1.5V
L = 0.33µH
(DCR = 0.32mΩ TYP)
FRONT PAGE CIRCUIT
CCM
PULSE SKIPPING
Burst Mode
OPERATION
0.1
1
10
100
LOAD CURRENT (A)
3866 G01
Efficiency vs Load Current
and Mode
100
90
80
70
60
50
40
30
20
10
0
0.01
V_IN = 12V
V_OUT = 1.5V
L = 0.33µH
(DCR = 0.32mΩ TYP)
FRONT PAGE CIRCUIT
CCM
PULSE SKIPPING
Burst Mode
OPERATION
0.1
1
10
100
LOAD CURRENT (A)
3866 G02
Efficiency and Power Loss
vs Load Current
95
94 ^VIN ^{= 20V}
93 ^{VOUT = 1.5V}
92 ^{FRONT PAGE CIRCUIT}
91
90
89
EFFICIENCY
88
87
86
85
84
POWER LOSS
83
82
81
80
0 5 10 15 20 25
LOAD CURRENT (A)
15
10
5
0
30 35
3866 G03
3866fa
5