Rainbow-electronics MAX6948B Manual de usuario descargar pdf

_______________________________________________________________ Maxim Integrated Products 1

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

High-Efficiency PWM LED Driver with Boost

Converter and Five Constant-Current GPIO Ports

MAX6948B

General Description

The MAX6948B general-purpose input/output (GPIO)

peripheral drives a series string of white LEDs (WLEDs),

and contains up to five general-purpose input/output

(GPIO) ports to drive additional LEDs.

The integrated 2MHz boost converter minimizes the size

and cost of external components and supplies 30mA of

load current at up to 28V. The converter is stable under

all load conditions from 5V up to 28V and includes

open-circuit detection to prevent damage to the IC. An

C-programmable 10-bit pulse-width modulation (PWM)

signal enables 1024 levels of WLED intensity.

The five GPIO ports function as logic inputs, open-

drain logic outputs, or constant-current sinks in any

combination. Ports withstand 5.5V independent of the

MAX6948B’s supply voltage. Two of the ports drive addi-

tional LEDs up to 30mA/port, while the other three ports

drive LEDs at up to 10mA/port. The MAX6948B features

shutdown and standby modes for low-power dissipa-

tion. The constant-current drivers contain programmable

PWM outputs and allow staggering to reduce the input

peak-current requirements. The I/O ports also feature

ramp-up and ramp-down controls.

The MAX6948B features a single input to select from four

C slave addresses. Programming and functionality for

the five GPIO ports is identical to the MAX6946/MAX6947

I/O expanders.

The MAX6948B is available in a 25-bump (2.31mm x

2.31mm) WLP package for cell phones, PDAs, and

other portable consumer electronic applications. The

MAX6948B operates over the -40NC to +105NC tempera-

ture range.

Applications

LED Backlighting for LCDs

Cell Phones

PDAs

Handheld Games

Portable Consumer Electronics

Features

S 28V Step-Up DC-DC Converter with Integrated

nMOS Power Switch

S Built-In 10-Bit PWM Control for Improved Efficiency

S No Discharge Path During PWM Off Period for

Increased Battery Life

S Fixed 2MHz Switching for Smaller Components

Drives up to 6 Series WLEDs

S ±8kV Human Body Model (HBM) ESD Protection

for GPIOs and Boost-Converter Output

S Five Open-Drain GPIOs Capable of Constant-

Current LED Drive with Individual 8-Bit PWM

Intensity Control

S 2.7V to 5V Power-Supply Operation

S 400kbps, 5.5V Tolerant I

C Interface

S Four I

C Slave Address Choices

S RST Input Clears Serial Interface and Exits

Shutdown (Reset-Run Option)

S Small (2.31mm x 2.31mm) WLP Package

19-4935; Rev 0; 9/09

Ordering Information

+Denotes a lead(Pb)-free/RoHS-compliant package.

Typical Operating Circuit

EVALUATION KIT

AVAILABLE

NOTE: R

= 0.2V/I

LED

= 0.2V/0.03A = 6.7I.

2.7V TO 5.0V

1.7V TO V+

V+

SCL

SDA

RST

SCL

SDA

RST

COMP

AD0

GND

OUT

PGND

LEDSW

0.22FF

10µH

0.1FF

47nF

EXT

MAX6948B

2.2FF

PART TEMP RANGE PIN-PACKAGE

MAX6948BGWA+

-40NC to +105NC

25 WLP

1 2 3 4 5 6 ... 27 28

Indice de contenidos

Pagina 1 - MAX6948B

_______________________________________________________________ Maxim Integrated Products 1For pricing, delivery, and ordering information, pleas

Pagina 2

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports10MAX6948BRegister DescriptionThe MAX6948B contains 25 interna

Pagina 3

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports11MAX6948BConfiguration Register Format (0x10)Use the config

Pagina 4

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports12MAX6948B Boost ConverterBoost-Con

Pagina 5

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports13MAX6948BBoost-Converter Shutdown/Standby ModesThe boost co

Pagina 6

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports14MAX6948B I/O Ports (P0–P4)The MAX6

Pagina 7

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports15MAX6948BPorts Configured as OutputsThe global-current regi

Pagina 8

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports16MAX6948BPWM Intensity Control and PhasingThe MAX6948B uses

Pagina 9

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports17MAX6948BFigure 3. Staggered Port and Boost PWM WaveformPorts

Pagina 10 - Register Description

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports18MAX6948BShutdown ModeIn shutdown mode, all ports config

Pagina 11

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports19MAX6948BFigure 4. Ramp-Up BehaviorFigure 5. Hold-Off and Ram

Pagina 12 - Boost-Converter Output PWM

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports2MAX6948BV+ to GND ...

Pagina 13

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports20MAX6948BTable 11. Port Ramp-Down Register Format (0x11) (con

Pagina 14

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports21MAX6948B RST InputThe ac

Pagina 15 - Ports Configured as Outputs

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports22MAX6948BFigure 9. START and STOP ConditionsFigure 10. Bit Tr

Pagina 16

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports23MAX6948BFigure 11. AcknowledgeFigure 12. Slave AddressTable

Pagina 17 - Ports Configured as Inputs

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports24MAX6948BFigure 13. Command Byte ReceivedFigure 14. Command a

Pagina 18 - Shutdown Mode

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports25MAX6948BTable 14. Recommended InductorsOperation with Multip

Pagina 19

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports26MAX6948BFigure 16. LED BrownoutDriving LEDs into BrownoutThe

Pagina 20

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports27MAX6948BThe MAX6948B can use an I/O port to automatically ge

Pagina 21 - Reset-Run Option

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO PortsMaxim cannot assume responsibility for use of any circuitry ot

Pagina 22 - START and STOP Conditions

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports3MAX6948BELECTRICAL CHARACTERISTICS (continued)(Typical Applic

Pagina 23 - Slave Addresses

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports4MAX6948BELECTRICAL CHARACTERISTICS (continued)(Typical Applic

Pagina 24 - Message Format for Reading

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports5MAX6948BTIMING CHARACTERISTICS(Typical Application Circuit, V

Pagina 25

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports6MAX6948B

Pagina 26 - Output-Level Translation

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports7MAX6948B Typical O

Pagina 27 - PCB Layout Considerations

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports8MAX6948B

Pagina 28

High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports9MAX6948B Detailed DescriptionThe MAX6948

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Indice de contenidos

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