LTC1872 datasheet(4/36 Pages) LINER

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LTC1871

1871fe

ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at TA = 25°C. VIN = VINTVCC = 5V, VRUN = 1.5V, RFREQ = 80k, VMODE/SYNC = 0V, unless

otherwise speciﬁed.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

DMAX

Maximum Duty Cycle

I-Grade or H-Grade (Note 2)

●

fSYNC/fOSC

Recommended Maximum Synchronized

Frequency Ratio

fOSC = 300kHz (Note 6)

1.25

1.30

fOSC = 300kHz (Note 6), I-Grade or H-Grade (Note 2) ●

1.25

1.30

tSYNC(MIN)

MODE/SYNC Minimum Input Pulse Width

VSYNC = 0V to 5V

tSYNC(MAX)

MODE/SYNC Maximum Input Pulse Width VSYNC = 0V to 5V

0.8/fOSC

VIL(MODE)

Low Level MODE/SYNC Input Voltage

0.3

I-Grade or H-Grade (Note 2)

●

0.3

VIH(MODE)

High Level MODE/SYNC Input Voltage

1.2

I-Grade or H-Grade (Note 2)

●

1.2

RMODE/SYNC

MODE/SYNC Input Pull-Down Resistance

kΩ

VFREQ

Nominal FREQ Pin Voltage

0.62

Low Dropout Regulator

VINTVCC

INTVCC Regulator Output Voltage

VIN = 7.5V

5.0

5.2

5.4

VIN = 7.5V, I-Grade (Note 2)

●

5.0

5.2

5.4

VIN = 7.5V, H-Grade (Note 2)

●

4.95

5.2

5.45

ΔVINTVCC

ΔVIN1

INTVCC Regulator Line Regulation

7.5V ≤ VIN ≤ 15V

ΔVINTVCC

ΔVIN2

INTVCC Regulator Line Regulation

15V ≤ VIN ≤ 30V

200

VLDO(LOAD)

INTVCC Load Regulation

0 ≤ IINTVCC ≤ 20mA, VIN = 7.5V

– 2

–0.2

VDROPOUT

INTVCC Regulator Dropout Voltage

VIN = 5V, INTVCC Load = 20mA

280

IINTVCC

Bootstrap Mode INTVCC Supply

Current in Shutdown

RUN = 0V, SENSE = 5V

μA

I-Grade (Note 2)

●

μA

H-Grade (Note 2)

●

μA

GATE Driver

GATE Driver Output Rise Time

CL = 3300pF (Note 7)

100

GATE Driver Output Fall Time

CL = 3300pF (Note 7)

100

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 LTC1871E is guaranteed to meet performance speciﬁcations

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

85°C operating temperature range are assured by design, characterization

and correlation with statistical process controls. The LTC1871I is

guaranteed over the full –40°C to 125°C operating temperature range

and the LTC1871H is guaranteed over the full –40°C to 150°C operating

temperature range.

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

dissipation PD according to the following formula:

TJ = TA + (PD • 110°C/W)

Note 4: The dynamic input supply current is higher due to power MOSFET

gate charging (QG • fOSC). See Applications Information.

Note 5: The LTC1871 is tested in a feedback loop which servos VFB to

the reference voltage with the ITH pin forced to the midpoint of its voltage

range (0.3V ≤ VITH ≤ 1.2V, midpoint = 0.75V).

Note 6: In a synchronized application, the internal slope compensation

gain is increased by 25%. Synchronizing to a signiﬁcantly higher ratio will

reduce the effective amount of slope compensation, which could result in

subharmonic oscillation for duty cycles greater than 50%.

Note 7: Rise and fall times are measured at 10% and 90% levels.

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