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LTC3855

3855f

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 LTC3855E is guaranteed to meet performance specifications

from 0°C to 85°C. Specifications over the –40°C to 85°C operating

junction temperature range are assured by design, characterization and

correlation with statistical process controls. The LTC3855I is guaranteed

to meet performance specifications over the full –40°C to 125°C operating

junction temperature range.

Note 3: TJ is calculated from the ambient temperature TA and power

dissipation PD according to the following formulas:

LTC3855UJ: TJ = TA + (PD • 33°C/W)

LTC3855FE: TJ = TA + (PD • 25°C/W)

elecTrical characTerisTics The

denotes the specifications which apply over the full operating

junction temperature range (E-Grade), otherwise specifications are at TA = 25°C. VIN = 15V, VRUN/SS = 5V unless otherwise noted.

Note 4: The LTC3855 is tested in a feedback loop that servos VITH1,2 to a

specified voltage and measures the resultant VFB1,2.

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.

Note 7: The minimum on-time condition is specified for an inductor

peak-to-peak ripple current ≥40% of IMAX (see Minimum On-Time

Considerations in the Applications Information section).

Note 8: Guaranteed by design.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX UNITS

On Chip Driver

TG RUP

TG Pull-Up RDS(ON)

TG High

2.6

TG RDOWN

TG Pull-Down RDS(ON)

TG Low

1.5

BG RUP

BG Pull-Up RDS(ON)

BG High

2.4

BG RDOWN

BG Pull-Down RDS(ON)

BG Low

1.1

Typical perForMance characTerisTics

Efficiency vs Output Current

and Mode

Efficiency vs Output Current

and Mode

LOAD CURRENT (A)

0.01

100

3855 G23

100

0.1

VIN = 12V

VOUT = 1.8V

Burst Mode

OPERATION

DCM

CCM

CIRCUIT OF FIGURE 19

LOAD CURRENT (A)

0.01

100

3855 G24

100

0.1

VIN = 12V

VOUT = 1.2V

Burst Mode

OPERATION

DCM

CCM

CIRCUIT OF FIGURE 19

Full Load Efficiency and Power

Loss vs Input Voltage

INPUT VOLTAGE (V)

3855 G24

1.8V

1.2V

EFFICIENCY

POWER LOSS

CIRCUIT OF FIGURE 19

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