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LT1947

1947f

VIN Voltage ................................................................ 8V

CT Voltage.................................................................. 6V

SW1, SW2 Voltage .................................................. 36V

VON, VO2 Voltage ..................................................... 30V

FB1, FB2 .................................................................... 3V

SHDN ......................................................................... 8V

Operating Temperature Range (Note 2) .. – 40

°C to 85°C

Lead Temperature (Soldering, 10 sec).................. 300

°C

ORDER PART

NUMBER

MS PART MARKING

TJMAX = 125°C, θJA = 120°C/W

LTUE

LT1947EMS

(Note 1)

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

of a device may be impaired.

Note 2: The LT1947 is guaranteed to meet performance specifications

from 0

°C to 70°C. Specifications over the –40°C to 85°C operating

The q denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. VIN = 3.3V, VSHDN = 3.3V unless otherwise specified.

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Input Voltage Range

2.7

Supply Current

SHDN = 2.4V

9.5

12.5

SHDN = 0V

µA

FB1 Voltage

1.240

1.26

1.280

1.225

1.295

FB2 Voltage

1.225

1.26

1.295

1.210

1.310

Reference Line Regulation

VIN = 2.7V to 8V

0.01

0.05

%/V

Error Amplifier Voltage Gain

EA1 and EA2

100

V/V

CT Current Source

VFB1 = 1.3V

5.5

6.5

µA

CT Threshold to Turn On Q3

1.25

1.28

1.30

FB1 Voltage to Begin CT Charge

1.17

1.2

1.23

SW1 Current Limit

(Note 3)

1.1

1.4

SW2 Current Limit

(Note 3)

0.35

0.6

SW1 Saturation Voltage

ISW1 = 800mA

0.230

0.280

SW2 Saturation Voltage

ISW2 = 300mA

0.3

0.36

SW1 Maximum Duty Cycle

SW2 Maximum Duty Cycle

Oscillator Frequency

2.3

3.5

MHz

VON Switch Drop

IQ3 = 7mA

160

200

SW1 Leakage Current

Switch Off, SW1 = 3.3V

0.01

µA

SW2 Leakage Current

Switch Off, SW2 = 3.3V

0.01

µA

SHDN Pin Bias Current

VSHDN = 2.4V

µA

SHDN Pin High

Active Mode

2.4

SHDN Pin Low

Shutdown Mode

0.4

ABSOLUTE

AXI U

RATI GS

PACKAGE/ORDER I FOR ATIO

FB1

FB2

SW1

GND

VON

VO2

SHDN

SW2

VIN

TOP VIEW

MS PACKAGE

10-LEAD PLASTIC MSOP

ELECTRICAL CHARACTERISTICS

temperature range are assured by design, characterization and correlation

with statistical process controls.

Note 3: Switch current limit guaranteed by design and/or correlation to

static tests.

Consult LTC Marketing for parts specified with wider operating temperature ranges.

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