LT8705 datasheet(3/44 Pages) LINER

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LTC7812

7812fc

For more information www.linear.com/LTC7812

ELECTRICAL CHARACTERISTICS

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

VBIAS

Bias Input Supply Operating Voltage

Range

4.5

VOUT1

Buck Regulated Output Voltage Set Point

(SENSE1 Pins Common Mode Range)

0.8

VOUT2

Boost Regulated Output Voltage Set Point

SENSE2 Pins Common Mode Range

(BOOST Converter Input Supply Voltage)

2.5

VFB1

Buck Regulated Feedback Voltage

(Note 4); ITH1 Voltage = 1.2V

0°C to 85°C, All Grades

LTC7812E, LTC7812I

LTC7812H

0.792

0.788

0.786

0.800

0.808

0.812

VFB2

Boost Regulated Feedback Voltage

(Note 4); ITH2 Voltage = 1.2V

0°C to 85°C, All Grades

LTC7812E, LTC7812I

LTC7812H

1.183

1.181

1.176

1.200

1.214

1.218

IFB1,2

Feedback Current

(Note 4)

–2

±50

Reference Voltage Line Regulation

(Note 4); VIN = 4.5V to 38V

0.002

0.02

%/V

Output Voltage Load Regulation (Note 4) Measured in Servo Loop;

DITH Voltage = 1.2V to 0.7V

0.01

0.1

Measured in Servo Loop;

DITH Voltage = 1.2V to 2V

–0.01

–0.1

gm1,2

Transconductance Amplifier gm

(Note 4); ITH1,2 = 1.2V;

Sink/Source 5µA

mmho

Input DC Supply Current

(Note 5)

Pulse-Skipping or

Forced Continuous Mode

(One Channel On)

RUN1 = 5V and RUN2 = 0V or

RUN2 = 5V and RUN1 = 0V

VFB1 ON = 0.83V (No Load)

VFB2 = 1.25V (No Load)

1.5

Pulse-Skipping or

Forced Continuous Mode

(Both Channels On)

RUN1,2 = 5V,

VFB1 = 0.83V (No Load)

VFB2 = 1.25V (No Load)

Sleep Mode

(One Channel On, Buck)

RUN1 = 5V and RUN2 = 0V

VFB1 = 0.83V (No Load)

µA

Sleep Mode

(One Channel On, Boost)

RUN2 = 5V and RUN1 = 0V

VFB2 = 1.25V (No Load)

µA

Sleep Mode

(Both Channels On)

RUN1,2 = 5V

VFB1 = 0.83V (No Load)

VFB2 = 1.25V (No Load)

µA

Shutdown

RUN1,2 = 0V

µA

UVLO

Undervoltage Lockout

INTVCC Ramping Up

4.15

4.5

INTVCC Ramping Down

3.5

3.8

4.0

Buck Feedback Overvoltage Protection

Measured at VFB1 Relative to

Regulated VFB1

SENSE1+ Pin Current

±1

µA

SENSE2+ Pin Current

170

µA

SENSE1– Pin Current

VOUT1 < VINTVCC – 0.5V

VOUT1 > VINTVCC + 0.5V

700

±2

µA

SENSE2– Pin Current

VSENSE2+, VSENSE2– = 12V

±1

µA

The l denotes the specifications which apply over the specified operating

junction temperature range, otherwise specifications are at TA = 25°C. VBIAS = 12V, VRUN1,2 = 5V, EXTVCC = 0V unless otherwise

noted. (Note 2)

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