LINEAR AN108-1 Data Handbook

Application Note 108

July 2007

LTC3207/LTC3207-1 User’s Guide by Marty Merchant

INTRODUCTION The LTC3207/LTC3207-1 is a slave I2C device that only can receive data.

The LTC®3207/LTC3207-1 is a 600m A LED/Camera driver which illuminates 12 Universal LEDs (ULEDs) and one

camera fl ash LED. The ULEDs are considered universal DATA BYTES

because they may be individually turned on or off, set

REG0 (Tables 3 and 4) is used to fl ash the CAM LED with

in general purpose output (GPO) mode, set to blink at a

the CAMHL bit and set the charge pump to Auto, force 1x,

selected on-time and period, or gradate on and off at a

force 1.5x, or force 2x modes. It is also used to prepare for

selected gradation rate. This device also has an external

a Quick write, or set the gradation UP bit. REG1 through

enable (ENU) pin that may be used to blink, gradate, or

REG12 set the intensity and mode for the twelve individual

turn on/off the LEDs without using the I2C bus. This may be

ULEDs (Table 5). REG13 is divided into two sub-registers

useful if the microprocessor is in sleep or standby mode. If

as illustrated in Table 6. The lower four bits, D3 to D0, are

used properly, these features may save valuable memory

the CAML register which sets the CAM LED in torch mode.

space, programming time, and reduce the I2C traffi c.

The upper four bits, D7 to D4, are the CAMH register, which sets the CAM LED when in fl ash mode. REG14 is used to

I2C Control

select ULED1 to ULED8 for ENU control, as shown in Table

The LTC3207/LTC3207-1 has 16 data registers, each 7. REG15 is separated into three portions as illustrated with its own sub-address as shown in Table 2. The data in Tables 8 and 9. D3 to D0 are used to select ULED9 to is loaded into the registers when the device receives a ULED12 for ENU control. D5 and D4 are used to control Stop bit. This device is written using the standard I2C the gradation time, while D7 and D6 are used to select the protocol. A 7-bit slave address and write bit is followed blinking on-time and period. by the 8-bit sub-address byte and an 8-bit data byte. The

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. only difference between the LTC3207 and LTC3207-1 is All other trademarks are the property of their respective owners.

the I2C address.

Table 1. Features of LTC3207/LTC3207-1 FEATURE BENEFITS 12 Separate 27.5m A Current Sources 12 Individually Controlled LEDs Camera LED High Current Torch Mode

High Current Flash

Blink Mode Blinks One of Four Blinking Patterns GPO Mode I2C Controlled Open Drain Drivers Gradation Gradually Turns On and Off LEDs External Enable (ENU) Controls LEDs with Single Input Auto Switching Charge Pump Automatically Switches to 1x, 1.5x, or 2x Modes for Better Effi ciency Forced Charge Pump Mode Can Be Programmed to Remain in 1x, 1.5x or 2x Mode

an108f

AN108-1