8

NXP Semiconductors

34845

Boost (continued)

VOVP_EXT

OVP Programming Range

• (set through an external resistor divider)

15

-

60

V

(10)

VREF_OVP

OVP Reference Voltage

6.3

6.9

7.5

V

ISINK_OVP

OVP Sink Current

-

0.2

-

μA

fS

Switching Frequency

• 34845C

• 34845D

540

270

600

300

660

330

kHz

tSS

Soft Start Time (fs = 600 kHz, 100% PWM duty)

-

3.0

-

ms

SS_VOUT

Soft Start VOUT Overshoot (fs = 600 kHz, 100% PWM duty)

-

-

OVP

V

BOOST_tR

Boost Switch Rise Time

-

8.0

-

ns

BOOST_tF

Boost Switch Fall Time

-

6.0

-

ns

ACSA

Current sense Amplifier Gain

-

9.0

-

GM

OTA Transconductance

-

200

-

μS

ISS

Transconductance Sink and Source Current Capability

-

100

-

μA

VSLOPE

Slope Compensation

• 34845C

• 34845D

-

-

0.52

0.22

-

-

V/

μs

LED driver

ILED

LED Driver Sink Current

• RISET = 51 kΩ 0.1%, PWM = 3.3 V

• RISET = 5.1 kΩ 0.1%, PWM = 3.3 V

2.88

29.4

3.0

30

3.12

30.6

mA

VISET

ISET Pin Voltage

• RISET = 5.1 kΩ 0.1%

2.011

2.043

2.074

V

VMIN

Regulated Minimum Voltage Across LED Drivers

• Pulse Width > 400 ns

0.675

0.75

0.825

V

ITOLERANCE

LED Current Channel to Channel Tolerance

• 10 mA

≤ ILED ≤ 30 mA

• 3.0 mA

≤ ILED < 10 mA

-2.0

-4.0

-

-

2.0

4.0

%

ICH_LEAK

Off State leakage Current, All Channels

• VCH = 45 V

-

-

1.0

μA

tR/tF

LED Channels Rise and Fall Time

-

50

75

ns

OFDV

LED Open Protection, Channel Disabled if VCH ≤ OFDV

-

-

0.55

V

SFDV

LED Short Protection Voltage, Channel Disabled if VCH ≥ SFDV

(channel on time

≥ 10 μs)

6.5

7.0

7.5

V

Fail pin

IFAIL_LEAK

Off State Leakage Current

• VFAIL = 5.5 V

-

-

5.0

μA

VOL

On State Voltage Drop

• ISINK = 4.0 mA

-

-

0.4

V

Overtemperature shutdown

OTTSHUTDOWN

Over-temperature Threshold (shutdown mode)

• Rising

• Hysteresis

150

-

165

25

-

-

°C

Notes

10.

The OVP level must be set 5.0 V above the worst-case LED string voltage.

Table 4. Static and dynamic electrical characteristics (continued)

Characteristics noted under conditions VIN = 12 V, VOUT = 35 V, ILED = 30 mA, fS = 600 kHz, fPWM = 600 Hz - 40 °C ≤ TA ≤ 85 °C, unless

otherwise noted. Typical values noted reflect the approximate parameter means at TA = 25 °C under nominal conditions, unless otherwise

noted.

Symbol

Characteristic

Min.

Typ.

Max.

Unit

Notes