Rev. 1.00

4

April 13, 2012

HT7945

Note:Thesearestressratingsonly.Stressesexceedingtherangespecifiedunder“AbsoluteMaximumRatings”

maycausesubstantialdamagetothedevice.Functionaloperationofthisdeviceatotherconditionsbeyond

thoselistedinthespecificationisnotimpliedandprolongedexposuretoextremeconditionsmayaffect

devicereliability.

Electrical Characteristics

Parameter

Test Conditions

Min.

Typ.

Max.

Unit

Supply Selection

IN Input Voltage

4.5

—

6.0

V

6.0

—

26.0

IN Quiescent Current

—

3.3

—

mA

EN=GND

—

—

10

μA

VCC5 Output Voltage

(Only for internal circuit used)

4.9

5.2

5.6

V

VCC5 UVLO Threshold

Rising edge,

typical hysteresis=85mV

3.6

3.8

4.0

V

Boost Selection

Switching Frequency

OSC=AGND

335

500

665

kHz

0.67

1.00

1.33

MHz

LX_Internal MOSFET Current Limit

—

—

2.2

—

A

—

—

0.35

1.50

Ω

Maximum Duty Cycle

—

—

94

—

%

Control Selection

Enable High Level Threshold Voltage

—

2

—

—

V

Enable Low Level Threshold Voltage

—

—

—

0.8

Dimming PWM Frequency

—

—

2

—

kHz

Dimming PWM High Level Threshold

—

2

—

—

V

Dimming PWM Low Level Threshold

—

—

—

0.8

LED_Selection

LED_Current

19.2

20.0

20.8

mA

LED_Current Regulation Between Strings

—

±1.5

±2.5

%

LED_Open Detector Threshold

LED_=Open

300

400

500

mV

LED_Short Detector Threshold

5.2

5.6

6.0

V

OVP Threshold Voltage

—

1.21

1.28

1.35

V

Thermal Selection

Thermal Shutdown Temperature

—

—

140

—

°C

Thermal Shutdown Hysteresis

—

—

50

—

Note:Specificationsoverthe-40°Cto85°Coperatingtemperaturerangeareassuredbydesign.

Absolute Maximum Ratings

IN,EN....................................................................28V

LED1~LED8,LX1,LX2.......................................44V

AVDD,OVP.............................................................6V

DIM........................................................................30V

OperatingTemperatureRange............... -40°C~+85°C

MaximumJunctionTemperature.....................+165°C