LTC3854_15 Datasheet, PDF (4/28 Pages) Linear Technology – Small Footprint, Wide VIN Range Synchronous Step-Down DC/DC Controller

LTC3854
ELECTRICAL CHARACTERISTICS
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 LTC3854E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTC3854I is guaranteed to meet
performance specifications over the full –40°C to 85°C operating
temperature range.
Note 3: T_J is calculated from the ambient temperature T_A and power
dissipation PD according to the following formulas:
LTC3854DDB: T_J = T_A + (P_D • 76°C/W)
LTC3854MSE: T_J = T_A + (P_D • 40°C/W)
Note 4: The LTC3854 is tested in a feedback loop that servos V_ITH to a
specified voltage and measures the resultant V_FB.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 6: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels. Not 100% tested in production.
Note 7: The minimum on-time condition is specified for an inductor peak-
to-peak ripple current 40% of I_MAX (see Minimum On-Time Considerations
in the Applications Information section).
Note 8: The LTC3854 maximum LDO current specification assumes there
is no external DC load current being pulled from INTV_CC pin.
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Output Current
100
V_IN = 6V
98 _{VIN = 12V}
V_OUT = 5V
96
V_IN = 24V
94
V_IN = 32V
92
90
88
(SEE FIGURE 9)
86
1 2 3 4 5 6 7 8 9 10
LOAD CURRENT (A)
3854 G01
Efficiency vs Input Voltage
99
V_OUT = 5V
98
97
I_OUT = 5A
96
95
I_OUT = 10A
94
(SEE FIGURE 9)
93
5 10 15 20 25 30 35 40
V_IN (V)
3854 G02
5A Load Step V_OUT = 5V, V_IN = 24V
Top Gate and Bottom Gate in
Forced Continuous Mode
Top Gate and Bottom Gate in
Dropout
5V_OUT
200mV/DIV
I_LOAD
10A/DIV
5A/DIV
LOAD STEP
BG
50µs/DIV
TG
3854 G03
4µs/DIV
BG
TG
3854 G04
4µs/DIV
3854 G05
3854fb
4