MAX16806 データシートの表示（PDF） - Maxim Integrated

部品番号

コンポーネント説明

メーカー

MAX16806

EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback

Maxim Integrated 

MAX16805/MAX16806

EEPROM-Programmable, High-Voltage,

350mA LED Drivers with LED Current Foldback

SDA

tBUF

tLOW

tR

tF

tHD:STA

tSP

SCL

STOP

START

tHD:STA

tHD:DAT

tHIGH

tSU:DAT

tSU:STA

REPEATED

START

tSU:STO

P

Figure 1. I2C Serial Interface Timing Diagram

Detailed Description

The MAX16805/MAX16806 are constant-current regula-

tors that provide up to 350mA of current to one or more

strings of high-brightness LEDs, and have a wide 5.5V to

40V operating input voltage range. The devices feature

the I2C interface that allows communication with the inter-

nal dynamic registers and EEPROM.

Dynamic registers control the MAX16805/MAX16806

functions and can be updated in real time through the I2C

interface. See Table 2 for register addresses. Turning off

the input voltage clears the dynamic register contents.

To save settings, store them into the EEPROM. The

MAX16805/MAX16806 load the stored settings into the

dynamic registers at power-up. In addition, during normal

operation a write command to the EEPROM Content

Transfer register loads the stored settings into the

dynamic register. Information stored can be transferred

into dynamic registers after issuing a “write” command to

the EEPROM Content Transfer register.

The MAX16805/MAX16806’s 5V regulator (V5) provides

up to 2mA of current to external circuitry. However, the

MAX16806’s 5V regulator can deliver 2mA of output cur-

rent only when the momentary switch is not used. When

the momentary switch is active, the MAX16806 achieves

up to 0.5mA of current. In addition, the MAX16805/

MAX16806 feature thermal and output shortcircuit protec-

tion. The wide operating voltage range helps protect the

device against large transients up to 45V such as those

found in load dump situations.

The MAX16805/MAX16806 use a feedback loop to con-

trol the output current. The differential voltage across the

sense resistor is compared to a fixed reference voltage

and the error is amplified to serve as the drive to the

internal pass device, see the Functional Diagram. The

MAX16805/MAX16806 offer a programmable LED cur-

rent reference using the Binning Adjustment register.

These devices are current controllers internally optimized

for driving the impedance range expected from 1 to 10 (or

more) high-brightness LEDs.

Dimming Input (DIM)

The MAX16805/MAX16806’s dimming input operates

with either an analog or PWM control signal. If the pulse

detector detects three edges of a PWM signal with a

frequency range between 80Hz to 2kHz, the MAX16805/

MAX16806 synchronize to external PWM input signal and

pulse-width-modulate the LED current. If an analog con-

trol signal is applied to DIM, the MAX16805/MAX16806

compare the DC input to an internally generated 200Hz

ramp to pulse-width-modulate the LED current. The maxi-

mum peak value of the 200Hz ramp can be programmed

using the Ramp Peak register. This allows the LED cur-

rent to be adjusted through the I2C interface from 50%

(typ) to 100% in real time when VDIM is 1.54V.

The output current duty cycle is adjustable from 0% to

100% (0.21V < VDIM < 3.1V).

Use the following formula to calculate the output current

duty cycle:

Duty cycle = (VDIM - 0.21V) / VRAMP

www.maximintegrated.com

Maxim Integrated │  10

Share Link: