LT1248CS datasheet(3/12 Pages) LINER

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LT1248

IAC (VAOUT – 2)

Note 2: Multiplier Gain Constant: K =

ELECTRICAL C

HARA TERISTICS The q denotes specifications which apply over the full operating tempera-

ture range, otherwise specifications are at TA = 25°C. Maximum operating voltage (VMAX) = 25V, VCC = 18V, RSET = 15k to GND,

CSET = 1nF to GND, IAC = 100µA, ISENSE = 0V, CAOUT = 3.5V, VAOUT = 5V, OVP = 7.5V, no load on any outputs, unless otherwise noted.

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Current Amplifier

Current Amp Short-Circuit Current

CAOUT = 0V

514

Input Range, ISENSE, MOUT (Linear Operation)

– 0.3

Reference

Reference Output Voltage

IREF = 0mA, TA = 25°C

7.39

7.50

7.60

VREF Load Regulation

– 5mA < IREF < 0mA

VREF Line Regulation

11.5V < VCC < VMAX

–20

VREF Short-Circuit Current

VREF = 0V

VREF Worst Case

Load, Line, Temperature

7.32

7.5

7.68

Current Limit

PKLIM Offset Voltage

–15

PKLIM Input Current

PKLIM = – 0.1V

– 50

– 100

µA

PKLIM to GTDR Propagation Delay

PKLIM Falling from 50mV to – 50mV

400

Multiplier

Multiplier Output Current

IAC = 100µA, RSET = 15k

µA

Multiplier Output Current Offset

RAC = 1M from IAC to GND

– 0.05

– 0.5

µA

Multiplier Maximum Output Current

IAC = 450µA, RSET = 15k, VAOUT = 7V, MOUT = 0V

– 286

– 260

– 235

µA

Multiplier Gain Constant (Note 2)

0.035

V–2

IAC Input Resistance

IAC from 50µA to 1mA

Ω

Oscillator

Oscillator Frequency

RSET = 15k, CSET = 1000pF

100

115

kHz

RSET = 15k, CSET = 1500pF

kHz

CSET Ramp Peak-to-Peak Amplitude

4.35

4.7

5.0

CSET Ramp Valley Voltage

1.25

1.4

1.55

Synchronization Pulse Threshold on EN/SYNC Pin

Pulse Low = 3.5V, High = 7V, Width > 200ns

4.5

5.6

6.5

Synchronization Frequency Range

RSET = 15k, CSET = 1000pF

1.2

1.6

f NOM

Overvoltage Comparator

Comparator Trip Voltage Ratio (VTRIP/VREF)

1.04

1.05

1.06

Hysteresis

0.35

OVP Bias Current

OVP = 7.5V

– 50

– 250

OVP Propagation Delay

100

Gate Driver

Max GTDR Output Voltage

0mA Load, 18V < VCC

17.5

GTDR Output High

– 200mA Load, 11.5V

≤ VCC ≤ 15V

VCC – 3.0

GTDR Output Low (Device Unpowered)

VCC = 0V, 50mA Load (Sinking)

0.9

1.5

GTDR Output Low (Device Active)

200mA Load (Sinking)

0.5

10mA Load

0.2

0.4

Peak GTDR Current

10nF from GTDR to GND

GTDR Rise and Fall Time

1nF from GTDR to GND

GTDR Max Duty Cycle

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