Datasheet

LTC3866
5
3866fb
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
RUN
= 5V unless otherwise specified.
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)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
On-Chip Driver
TG R
UP
TG Pull-Up R
DS(ON)
TG High 2.6 Ω
TG R
DOWN
TG Pull-Down R
DS(ON)
TG Low 1.5 Ω
BG R
UP
BG Pull-Up R
DS(ON)
BG High 2.4 Ω
BG R
DOWN
BG Pull-Down R
DS(ON)
BG Low 1.1 Ω
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
Efficiency vs Load Current
and Mode
Efficiency vs Load Current
and Mode
Efficiency and Power Loss
vs Load Current
T
A
= 25°C, unless otherwise noted.
LOAD CURRENT (A)
30
EFFICIENCY (%)
90
100
20
10
80
50
70
60
40
0.01 1 10 100
3866 G01
0
0.1
CCM
PULSE SKIPPING
Burst Mode
OPERATION
V
IN
= 4.5V
V
OUT
= 1.5V
L = 0.33µH
(DCR = 0.32mΩ TYP)
FRONT PAGE CIRCUIT
LOAD CURRENT (A)
30
EFFICIENCY (%)
90
100
20
10
80
50
70
60
40
0.01 1 10 100
3866 G02
0
0.1
CCM
PULSE SKIPPING
Burst Mode
OPERATION
V
IN
= 12V
V
OUT
= 1.5V
L = 0.33µH
(DCR = 0.32mΩ TYP)
FRONT PAGE CIRCUIT
LOAD CURRENT (A)
0
EFFICIENCY (%)
POWER LOSS (W)
89
92
95
94
93
90
91
87
88
84
85
81
82
15 25 3530
3866 G03
86
83
80
15
10
5
0
5 10
20
EFFICIENCY
POWER LOSS
V
IN
= 20V
V
OUT
= 1.5V
FRONT PAGE CIRCUIT