LTC3853_15 datasheet(4/36 Pages) LINER

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LTC3853

3853fc

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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 junction temperature, TJ, is calculated from the ambient

temperature TA and power dissipation PD according to the following

formulas:

LTC3853UJ: TJ = TA + (PD • 33°C/W)

Note 3: The LTC3853 is tested under pulsed load conditions such that

TJ ≈ TA. The LTC3853E is guaranteed to meet performance specifications

from 0°C to 85°C 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

LTC3853I is guaranteed over the –40°C to 125°C operating junction

temperature range. The LTC3853H is guaranteed over the –40°C to 150°C

operating junction temperature range and the LTC3853MP is tested and

The l denotes the specifications which apply over the full operating

junction temperature range, otherwise specifications are at TA = 25°C (Note 3), VIN = 15V, VRUN1,2,3 = 5V, unless otherwise noted.

guaranteed over the –55°C to 150°C operating junction temperature range.

High junction temperatures degrade operating lifetimes; operating lifetime

is derated for junction temperatures greater than 125°C. The maximum

ambient temperature consistent with these specifications is determined by

specific operating conditions in conjunction with board layout, the rated

package thermal resistance and other environmental factors.

Note 4: The LTC3853 is tested in a feedback loop that servos VITH1,2,3 to a

specified voltage and measures the resultant VFB1,2,3.

Note 5: Dynamic supply current is higher due to the gate charge being

delivered at the switching frequency. See the Applications Information

section.

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).

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Bottom Gate Off to Top Gate On Delay

Top Switch-On Delay Time

(Note 6)

CLOAD = 3300pF Each Driver

tON(MIN)

Minimum On-Time

(Note 7)

INTVCC Linear Regulator

VINTVCC

Internal VCC Voltage

7V < VIN < 24V

4.8

5.2

INTVCC Load Regulation

ICC = 0mA to 50mA

0.5

VEXTVCC

EXTVCC Switchover Voltage

EXTVCC Ramping Positive

4.5

4.7

EXTVCC Voltage Drop

ICC = 20mA, VEXTVCC = 5V

EXTVCC Hysteresis

200

Oscillator and Phase-Locked Loop

Nominal Frequency

VFREQ = 1.2V

450

500

550

kHz

Lowest Frequency

VFREQ = 0V

210

250

290

kHz

Highest Frequency

VFREQ ≥ 2.4V

670

750

830

kHz

Channel 2-Channel 1 Phase

Channel 3-Channel 2 Phase

Channel 1-Channel 3 Phase

120

Deg

Channel 2-Channel 1 Phase

Channel 3-Channel 2 Phase

Channel 1-Channel 3 Phase

VFB2 Tied to VIN Through 200kΩ

180

120

Deg

MODE/PLLIN Input Resistance

250

kΩ

IFREQ

Phase Detector Output Current

Sinking Capability

Sourcing Capability

fMODE < fOSC

fMODE > fOSC

–13

µA

PGOOD Outputs

PGOOD Voltage Low

IPGOOD = 2mA

0.1

0.3

IPGOOD

PGOOD Leakage Current

VPGOOD = 5V

±2

µA

PGOOD Trip Level

VFB with Respect to Set Regulated Voltage

VFB Ramping Negative

VFB Ramping Positive

–5

–7.5

7.5

–10

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