LP8543 datasheet(6/40 Pages) TI

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LP8543

SNVS604D – AUGUST 2009 – REVISED MARCH 2013

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Electrical Characteristics

(1) (2)

Limits in standard typeface are for TA = 25°C. Limits in boldface type apply over the full operating ambient temperature range

(

−40°C < TA < +85°C). Unless otherwise specified: VIN = 12.0V, VDDIO = 2.8V, CVLDO = 470 nF, L1 = 15 μH, CIN = 10 μF, COUT

= 4.7

μF.

(3)

Symbol

Parameter

Condition

Min

Typ

Max

Units

Standby supply current

Internal LDO disabled

μA

EN=L and PWM=L

IIN

Normal mode supply current

LDO enabled, boost enabled, no current

3.5

going through LED outputs

fOSC

Internal Oscillator Frequency

-4

Accuracy

-7

VLDO

Internal LDO Voltage

4.5

5.0

5.5

ILDO

Internal LDO External Loading

5.0

(1)

All voltages are with respect to the potential at the GND pins.

(2)

Min and Max limits are ensured by design, test, or statistical analysis. Typical numbers are not ensured, but do represent the most likely

norm.

(3)

Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics.

Boost Converter Electrical Characteristics

Symbol

Parameter

Condition

Min

Typ

Max

Units

RDS-ON

Switch ON resistance

ISW = 0.5A

0.12

Ω

VMAX

Boost maximum output voltage

Maximum Continuous Load

VIN ≥ 12V, VOUT = 38V

400

ILOAD

Current

VIN = 5.5V, VOUT = 38V

180

fSW

Switching Frequency

BOOST_FREQ_SEL = 0

625

kHz

BOOST_FREQ_SEL = 1

1250

VBOOST = 38V

VBOOST + 1.6V

VOV

Over-voltage protection voltage

VBOOST < 38V

VBOOST + 4V

tPULSE

Switch pulse minimum width

no load

Startup delay

EN_STANDALONE = 1, PWM input

tDELAY

active, EN is set from low to high

tSTARTUP

Startup time

(1)

IMAX_SEL[1:0] = 00

0.9

IMAX_SEL[1:0] = 01

1.4

IMAX

SW pin current limit

IMAX_SEL[1:0] = 10

2.0

IMAX_SEL[1:0] = 11

2.5

(1)

Start-up time is measured from the moment boost is activated until the VOUT crosses 90% of its target value.

LED Driver Electrical Characteristics

Symbol

Parameter

Condition

Min

Typ

Max

Units

Outputs OUT1 to OUT7 (Voltage on pins

ILEAKAGE

Leakage current

-1

µA

40V)

IMAX

Maximum Source Current

Outputs OUT1 to OUT7

Output current accuracy

-3

IOUT

Output current set to 20 mA

(1)

-4

IMATCH

Matching OUT1-7 (1)

Output current set to 20 mA

0.8

1.5

IMATCH

Matching OUT1-6 (1)

Output current set to 20 mA

0.5

1.35

fPWM_OUT ≤ 4883 Hz

PWMRES

PWM output resolution

fPWM_OUT = 9766Hz

bit

fPWM_OUT = 19531Hz

(1)

Output Current Accuracy is the difference between the actual value of the output current and programmed value of this current.

Matching is the maximum difference from the average. For the constant current sinks on the part (OUT1 to OUT7), the following are

determined: the maximum output current (MAX), the minimum output current (MIN), and the average output current of all outputs (AVG).

Two matching numbers are calculated: (MAX-AVG)/AVG and (AVG-MIN/AVG). The largest number of the two (worst case) is

considered the matching figure. The typical specification provided is the most likely norm of the matching figure for all parts. Note that

some manufacturers have different definitions in use.

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