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LT1681

1681f

Supply Voltages

Power Supply (VCC)............................. – 0.3V to 20V

Topside Supply (VBST)................... VBSTREF – 0.3V to

VBSTREF + 20V (VBST(MAX) = 90V)

Topside Reference Pin (VBSTREF).......... – 0.6V to 75V

Input Voltages

SHDN Pin .................................. – 0.3V to VCC + 0.3V

All Other Inputs ..................... – 0.3V to 5VREF + 0.3V

Maximum Currents

5VREF Pin ........................................ – 85mA to 10mA

FSET Pin ............................................. – 2mA to 5mA

All Other Inputs .................................. – 2mA to 2mA

Operating Ambient Temperature Range

LT1681E (Note 4) .............................. – 40

°C to 85°C

LT1681I ............................................. – 40

°C to 85°C

Storage Temperature Range ................ – 65

°C to 150°C

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

°C

(Note 1)

ORDER PART

NUMBER

LT1681ESW

LT1681ISW

TJMAX = 125°C, θJA = 85°C/ W

The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C.

VCC = VBST = 12V, VBSTREF = 0V, VVC = 2V, VFB = VREF = 1.25V, CTG = CBG = CSG = 1000pF.

ABSOLUTE MAXIMUM RATINGS

PACKAGE/ORDER INFORMATION

ELECTRICAL CHARACTERISTICS

TOP VIEW

SW PACKAGE

20-LEAD PLASTIC SO

SHDN

OVLO

THERM

SGND

5VREF

FSET

SYNC

VFB

VBST

BSTREF

BLKSENS

PWRGND

VCC

IMAX

SENSE

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Supply and Protection

VCC

Operating Supply Voltage Range

912

ICC

DC Active Supply Current

(Note 2)

DC Active UVL Supply Current

VSHDN > 1.35V, VCC = 8V

800

1200

µA

DC Standby Supply Current

VSHDN < 0.3V

0.5

µA

IBST

DC Active Supply Current

TG Logic High (Note 2)

8.5

DC Standby Supply Current

VSHDN < 0.3V

0.1

µA

VSHDN

Shutdown Rising Threshold

1.15

1.25

1.35

Shutdown Threshold Hysteresis

100

150

200

ISS

Soft-Start Charge Current

VSS = 2V

–14

– 10

– 6

µA

VSS

Soft-Start Reset Threshold

225

VCCUVLO

Undervoltage Lockout Threshold

Falling Edge

8.0

8.40

8.60

Rising Edge

8.3

8.75

8.95

Undervoltage Lockout Hysteresis

0.25

0.35

VBSTUVLO Boost Undervoltage Lockout

Falling Edge

5.7

6.4

7.1

(VBST-BSTREF)

Rising Edge

6.5

7.0

7.5

Boost UVLO Hysteresis

0.3

0.6

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

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