LTC7813 datasheet(5/38 Pages) LINER

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LTC3895

3895fa

For more information www.linear.com/LTC3895

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

INTVCC LDO Regulator

VINTVCC

INTVCC Voltage

ICC = 0mA to 2mA

4.7

5.0

5.2

Oscillator and Phase-Locked Loop

Programmable Frequency

RFREQ = 25k, PLLIN = DC Voltage

105

kHz

Programmable Frequency

RFREQ = 65k, PLLIN = DC Voltage

375

440

505

kHz

Programmable Frequency

RFREQ =105k, PLLIN = DC Voltage

835

kHz

Low Fixed Frequency

VFREQ = 0V, PLLIN = DC Voltage

320

350

380

kHz

High Fixed Frequency

VFREQ = INTVCC, PLLIN = DC Voltage

485

535

585

kHz

fSYNC

Synchronizable Frequency

PLLIN = External Clock

850

kHz

PLLIN Input High Level

PLLIN Input Low Level

PLLIN = External Clock

2.8

0.5

PGOOD Output

VPGL

PGOOD Voltage Low

IPGOOD = 2mA

0.02

0.04

IPGOOD

PGOOD Leakage Current

VPGOOD = 3.3V

µA

PGOOD Trip Level

VFB with Respect to Set Regulated Voltage

VFB Ramping Negative

Hysteresis

–13

–10

2.5

–7

VFB with Respect to Set Regulated Voltage

VFB Ramping Positive

Hysteresis

2.5

Delay for Reporting a Fault

µs

elecTrical characTerisTics The

denotes the specifications which apply over the specified operating

junction temperature range, otherwise specifications are at TA = 25°C (Note 2), VIN = 12V, VRUN = 5V, VEXTVCC = 0V, VDRVSET = 0V,

VPRG = FLOAT unless otherwise noted.

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Ratings for extended periods may affect device reliability and

lifetime.

Note 2: The LTC3895 is tested under pulsed load conditions such that TJ ≈

TA. The LTC3895E is guaranteed to meet performance specifications from

0°C to 85°C. Specifications over the –40°C to 125°C operating junction

temperature range are assured by design, characterization and correlation

with statistical process controls. The LTC3895I is guaranteed over the

–40°C to 125°C operating junction temperature range and the LTC3895H

is guaranteed over the –40°C to 150°C operating junction temperature

range. Note that the maximum ambient temperature consistent with

these specifications is determined by specific operating conditions in

conjunction with board layout, the rated package thermal impedance

and other environmental factors. High temperatures degrade operating

lifetimes; operating lifetime is derated for junction temperatures greater

than 125ºC. The junction temperature (TJ, in °C) is calculated from the

ambient temperature (TA, in °C) and power dissipation (PD, in Watts)

according to the formula:

TJ = TA + (PD • θJA)

where θJA = 28°C/W for the TSSOP package.

Note 3: 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 specified absolute maximum operating

junction temperature may impair device reliability or permanently damage

the device.

Note 4: The LTC3895 is tested in a feedback loop that servos VITH to a

specified voltage and measures the resultant VFB. The specification at 85°C

is not tested in production and is assured by design, characterization and

correlation to production testing at other temperatures (125°C for the

LTC3895E and LTC3895I, 150°C for the LTC3895H). For the LTC3895I

and LTC3895H, the specification at 0°C is not tested in production and is

assured by design, characterization and correlation to production testing

at –40°C.

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).

Note 8: Do not apply a voltage or current source to these pins. They must

be connected to capacitive loads only, otherwise permanent damage may

occur.

Note 9: Do not apply a voltage or current source to the NDRV pin, other

than tying NDRV to DRVCC when not used. If used it must be connected

to capacitive loads only (see DRVCC Regulators in the Applications

Information section), otherwise permanent damage may occur.

Note 10: The minimum input supply operating range is dependent on the

DRVCC UVLO thresholds as determined by the DRVUV pin setting.

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