LM3445M datasheet(4/39 Pages) TI

4 / 39 page

LM3445

SNVS570L – JANUARY 2009 – REVISED MAY 2013

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ELECTRICAL CHARACTERISTICS (continued)

Limits in standard type face are for TJ = 25°C and those with boldface type apply over the full Operating Temperature

Range ( TJ = −40°C to +125°C). Minimum and Maximum limits are specified through test, design, or statistical correlation.

Typical values represent the most likely parametric norm at TJ = +25ºC, and are provided for reference purposes only.

Symbol

Parameter

Conditions

Min

Typ

Max

Units

INTERNAL PWM RAMP

fRAMP

Frequency

5.85

kHz

VRAMP

Valley voltage

0.96

1.00

1.04

Peak voltage

2.85

3.00

3.08

DRAMP

Maximum duty cycle

96.5

98.0

DIM DECODER

tANG_DET

Angle detect rising threshold

Observed on BLDR pin

6.79

7.21

7.81

VASNS

ASNS filter delay

µs

ASNS VMAX

3.85

4.00

4.15

IASNS

ASNS drive capability sink

VASNS = 2V

7.6

ASNS drive capability source

VASNS = 2V

-4.3

DIM low sink current

VDIM = 1V

1.65

2.80

DIM High source current

VDIM = 4V

-4.00

-3.00

VDIM

DIM low voltage

PWM input voltage

0.9

1.33

threshold

DIM high voltage

2.33

3.15

VTSTH

Tri-state threshold voltage

Apply to FLTR1 pin

4.87

5.25

RDIM

DIM comparator tri-state impedance

Ω

CURRENT SENSE COMPARATOR

VFLTR2

FLTR2 open circuit voltage

720

750

780

RFLTR2

FLTR2 impedance

420

Ω

VOS

Current sense comparator offset voltage

-4.0

0.1

4.0

GATE DRIVE OUTPUT

VDRVH

GATE high saturation

IGATE = 50 mA

0.24

0.50

VDRVL

GATE low saturation

IGATE = 100 mA

0.22

0.50

IDRV

Peak souce current

GATE = VCC/2

-0.77

Peak sink current

GATE = VCC/2

0.88

tDV

Rise time

Cload = 1 nF

Fall time

Cload = 1 nF

THERMAL SHUTDOWN

TSD

Thermal shutdown temperature

See (1)

165

°C

Thermal shutdown hysteresis

THERMAL SHUTDOWN

RθJA

VSSOP-10 junction to ambient

121

°C/W

(1)

Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power

dissipation exists, special care must be paid to thermal dissipation issues in board design. In applications where high power dissipation

and/or poor package thermal resistance is present, the maximum ambient temperature may have to be derated. Maximum ambient

temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = 125°C), the maximum power dissipation

of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (RθJA), as

given by the following equation: TA-MAX = TJ-MAX-OP – (RθJA × PD-MAX).

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