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LTC1149

LTC1149-3.3/LTC1149-5

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

V9 – V8

Current Sense Threshold Voltage

LTC1149

V8 = 5V, V10 = 1.32V (Forced)

V8 = VOUT – 100mV

130

150

170

LTC1149-3.3

V8 = 3.5V (Forced)

V8 = VOUT – 100mV

130

150

170

LTC1149-5

V8 = 5.3V (Forced)

V8 = VOUT – 100mV

130

150

170

V10

Shutdown 1 Threshold

LTC1149-3.3, LTC1149-5

0.5

0.8

V15

Shutdown 2 Threshold

0.8

1.4

I15

Shutdown 2 Input Current

V15 = 5V

µA

CT Pin Discharge Current

VOUT In Regulation, VSENSE– = VOUT

µA

VOUT = 0V

µA

tOFF

Off-Time (Note 4)

CT = 390pF, ILOAD = 700mA

µs

tr, tf

Driver Output Transition Times

CL = 3000pF (Pins 4, 13), VIN = 6V

100

200

ELECTRICAL C

HARA TERISTICS T

A = 25°C, VIN = 12V, V10 = 0V (Note 2), unless otherwise noted.

–40

°C ≤ TA ≤ 85°C (Note 5), unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

V10

Feedback Voltage LTC1149 Only

1.2

1.25

1.3

VOUT

Regulated Output Voltage

VIN = 9V

LTC1149-3.3

ILOAD = 700mA

3.17

3.33

3.43

LTC1149-5

ILOAD = 700mA

4.85

5.05

5.2

Input DC Supply Current (Note 3)

Normal Mode

VIN = 12V

2.0

3.2

VIN = 48V

2.2

3.5

Burst Mode

VIN = 12V

0.6

1.05

VIN = 48V

0.8

1.30

Shutdown

VIN = 12V, V15 = 2V

135

230

µA

VIN = 48V, V15 = 2V

300

520

µA

VCC

Internal Regulator Voltage

VIN = 12V to 48V

9.75

10.25

(Sets MOSFET Gate Drive Levels)

I3 = 20mA

V9 – V8

Current Sense Threshold Voltage

Low Threshold (Forced)

High Threshold (Forced)

125

150

175

V15

Shutdown 2 Threshold

0.8

1.4

tOFF

Off-Time (Note 4)

CT = 390pF, ILOAD = 700mA, VIN = 10V

3.8

µs

The q denotes specifications which apply over the full operating

temperature range.

Note 1: TJ is calculated from the ambient temperature TA and power

dissipation PD according to the following formulas:

LTC1149CN, LTC1149CN-3.3, LTC1149CN-5: TJ = TA + (PD )(70°C/W)

LTC1149CS, LTC1149CS-3.3, LTC1149CS-5: TJ = TA + (PD)(110°C/W)

Note 2: Pin 10 is a shutdown pin on the LTC1149-3.3 and LTC1149-5

fixed output voltage versions and must be at ground potential for testing.

Note 3: Dynamic supply current is higher due to the gate charge being

delivered at the switching frequency. The allowable operating frequency

may be limited by power dissipation at high input voltages. See Typical

Performance Characteristics and Applications Information.

Note 4: In applications where RSENSE is placed at ground potential, the off-

time increases approximately 40%.

Note 5: The LTC1149, LTC1149-3.3, and LTC1149-5 are not tested and

not quality assurance sampled at – 40

°C and 85°C. These specifications

are guaranteed by design and/or correlation.

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