LT8355-1

4

Rev. A

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ELECTRICAL CHARACTERISTICS

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2: Do not apply a positive or negative voltage to the PWMTG1,

PWMTG2, RT, VREF, VC1, VC2, GATE1 or GATE2 pin, otherwise permanent

damage may occur. Use these pins only as directed in the Pin Functions

and Applications Information sections.

Note 3: LT8355I-1 is guaranteed to meet performance specifications from

–40°C to 125°C junction temperature. Operation lifetime is derated at

junction temperatures greater than 125°C.

Note 4: This IC include overtemperature protection that is intended to

protect the device during momentary overload conditions. The maximum

rated junction temperature will be exceeded when this protection is active.

Continuous operation above the specified absolute maximum operating

junction temperature may impair device reliability or permanently damage

the device.

Note 5: LED voltage and current sense amplifier parameters are measured

in a servo loop with VC.

Note 6: Tested in a non-switching setup and correlated by design.

Note 7: Tested at RT = 51.1kΩ, guaranteed for all RT by design.

Note 8: GATE1,2 rise and fall times as well as the step size for the PWM

ADC are guaranteed by design and not tested.

Note 9: ISP1 – ISN1 and ISP2 – ISN2 may exceed 10V transiently. Do not

exceed ISP1 – ISN1 = 10V or ISP2 – ISN2 = 10V for more than 1 ms.

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Minimum On-Time

CGATE1,2 = 3.3nF

CGATE1,2 = 10nF, RT = 51.1kΩ (Note 7)

100

180

ns

ns

Channel 1, Channel 2 External NMOS Power Switch Driver

Pull-Up Device On-Resistance

5

Ω

Pull-Down Device On-Resistance

3

Ω

GATE Rise Time (Note 8)

CGATE1,2 = 3.3nF, 10% to 90%

45

ns

GATE Fall Time (Note 8)

CGATE1,2 = 3.3nF, 90% to 10%

40

ns

Channel 1, Channel 2 External PMOS Driver

PWMTG ON Voltage (VISP – VPWMTG)

VISP1,2 = 100V

7.5

8.5

9.5

V

PWMTG OFF Voltage (VISP – VPWMTG)

VISP1,2 = 100V

0

0.3

V

PWMTG Turn-On Time

CL = 470pF, VISP1,2 = 100V

150

ns

PWMTG Turn-Off Time

CL = 470pF, VISP1,2 = 100V

180

ns

Channel 1, Channel 2 Fault Detection

FB LED Open Threshold

VISP1,2 = VISN 1,2, FB Rising

1.116

1.14

1.164

V

FB Overvoltage Threshold

FB1,2 Rising

1.235

1.26

1.285

V

FB Shorted LED Threshold

FB1,2 Falling

300

330

mV

LED Overcurrent Protection Threshold (VISP – VISN)

580

670

760

mV

FAULT Pin Pull Down Current

VFAULT1-2 = 0.3V, VFB1,2 = 1.3V

0.5

mA

FAULT Pin Leakage Current

VFAULT1-2 = 15V, VFB1,2 = 0.7V

100

nA

Channel 1, Channel 2 Internal PWM Generator

PWM Pin Voltage for Max Duty Ratio

1.5

V

PWM Pin Voltage for Min Duty Ratio

0.5

V

PWM Off Threshold (Falling)

0.4

V

PWM On Threshold (Rising)

1.6

V

Minimum Duty Ratio

VPWM1,2 = 0.5V, RT = 51.1kΩ

0.78

%

Maximum Duty Ratio

VPWM1,2 = 1.5V, RT = 51.1kΩ

100

%

PWM Voltage Step per Duty Ratio Setting

(Note 8)

7.8

mV

PWM Pin Current

VPWM1,2 = 1V

0

nA

PWM Clock Frequency

fSW/1000

Hz

Fraction of VREF for 10% Duty

RT = 51.1kΩ

0.511VREF

V

The l denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. (Note 2). Unless otherwise noted, VIN = EN/UVLO = 12V, ISP1,2 =

ISN1,2 = 60V, CTRL1,2 = IADJ2 = 2V, PWM1,2 = INTVCC, FB1,2 = 1V, SENSEN1,2 = 0V.