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LT1738

1738fa

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

temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, VC = 0.9V, VFB = VREF, RVSL, RCSL = 16.9k, RT = 16.9k and

other pins open unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

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

life of a device may be impaired.

Note 2: Supply current specification includes loads on each gate as in

Figure 1a. Actual supply currents vary with operating frequency, operating

voltages, V5 load, slew rates and type of external FET.

Note 3: The LT1738E is guaranteed to meet performance specifications

from 0

°C to 70°C. Specifications from –40°C to 125°C are assured by

Oscillator and Sync

fMAX

Max Switch Frequency

250

kHz

fSYNC

Synchronization Frequency Range

Oscillator Frequency = 250kHz

290

kHz

VSYNC

SYNC Pin Input Threshold

0.7

1.4

RSYNC

SYNC Pin Input Resistance

Ω

Gate Drive

DCMAX

Maximum Switch Duty Cycle

RVSL = RCSL = 3.9k,

93.5

Osc Frequency = 25kHz

VGON

Gate On Voltage

VIN = 12, GCL = 12

10.4

10.7

VIN = 12, GCL = 8

7.6

7.9

8.1

VGOFF

Gate Off Voltage

VIN = 12V

0.2

0.35

IGSO

Max Gate Source Current

VIN = 12V

0.3

IGSK

Max Gate Sink Current

VIN = 12V

0.3

VINUVLO

Gate Drive Undervoltage Lockout (Note 5)

VGCL = 6.5V

7.3

7.5

Current Sense

tIBL

Switch Current Limit Blanking Time

100

VSENSE

Sense Voltage Shutdown Voltage

VC Pulled Low

103

120

VSENSEF

Sense Voltage Fault Threshold

220

300

Slew Control for the Following Slew Tests See Test Circuit in Figure 1b

VSLEWR

Output Voltage Slew Rising Edge

RVSL = RCSL = 17k

µs

VSLEWF

Output Voltage Slew Falling Edge

RVSL = RCSL = 17k

µs

VISLEWR

Output Current Slew Rising Edge (CS pin V)

RVSL = RCSL = 17k

2.1

µs

VISLEWF

Output Current Slew Falling Edge (CS pin V)

RVSL = RCSL = 17k

2.1

µs

Supply and Protection

VINMIN

Minimum Input Voltage (Note 4)

VGCL = VIN

2.55

3.6

IVIN

Supply Current (Note 3)

RVSL = RCSL = 17k

VIN = 12

RVSL = RCSL = 17k

VIN = 20

VSHDN

Shutdown Turn-On Threshold

1.31

1.39

1.48

∆VSHDN

Shutdown Turn-On Voltage Hysteresis

110

180

ISHDN

Shutdown Input Current Hysteresis

µA

5V Reference Voltage

6.5V

≤ VIN ≤ 20V, IV5 = 5mA

4.85

5.20

6.5V

≤ VIN ≤ 20V, IV5 = –5mA

4.80

5.15

IV5SC

5V Reference Short-Circuit Current

VIN = 6.5V Source

VIN = 6.5V Sink

–10

design, characterization and correlation with statistical process

controls.The LT1738I is guaranteed and tested to meet performance

specifications from – 40

°C to 125°C.

Note 4: Output gate drive is enabled at this voltage. The GCL voltage will

also determine driver activity.

Note 5: Gate drive is ensured to be on when VIN is greater than max value.

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