MAX8647 Ver la hoja de datos (PDF) - Maxim Integrated
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MAX8647 Datasheet PDF : 15 Pages
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Ultra-Efficient Charge Pumps for
Six White/RGB LEDs in 3mm x 3mm Thin QFN
Table 2. I2C Control Data Byte—Device Address 0x9A
SDA CONTROL BYTE
FUNCTION
Not used
LED1 current
LED2 current
LED3 current
LED4 current
LED5 current
LED6 current
COMMAND
DATA
C2
C1
C0
D4
D3
D2
D1
D0
0
0
0
—
—
—
—
—
0
0
1
24.0mA to 0.1mA and off in 32 steps
0
1
0
24.0mA to 0.1mA and off in 32 steps
0
1
1
24.0mA to 0.1mA and off in 32 steps
1
0
0
24.0mA to 0.1mA and off in 32 steps
1
0
1
24.0mA to 0.1mA and off in 32 steps
1
1
0
24.0mA to 0.1mA and off in 32 steps
Not used
1
1
1
—
—
—
—
—
Note: C2 is MSB and D0 is LSB. The power-on default settings for D4 to D0 are all 0, which indicates that all LED_ are off.
Table 3. MAX8647 I2C Data vs. LED Currents
D4
D3
D2
D1
D0
mA
1
1
1
1
1
24
1
1
1
1
0
22.4
1
1
1
0
1
20.8
1
1
1
0
0
19.2
1
1
0
1
1
17.6
1
1
0
1
0
16
1
1
0
0
1
14.4
1
1
0
0
0
12.8
1
0
1
1
1
11.2
1
0
1
1
0
9.6
1
0
1
0
1
8
1
0
1
0
0
6.4
1
0
0
1
1
5.6
1
0
0
1
0
4.8
1
0
0
0
1
4
1
0
0
0
0
3.2
D4
D3
D2
D1
D0
mA
0
1
1
1
1
2.8
0
1
1
1
0
2.4
0
1
1
0
1
2
0
1
1
0
0
1.6
0
1
0
1
1
1.4
0
1
0
1
0
1.2
0
1
0
0
1
1
0
1
0
0
0
0.8
0
0
1
1
1
0.7
0
0
1
1
0
0.6
0
0
1
0
1
0.5
0
0
1
0
0
0.4
0
0
0
1
1
0.3
0
0
0
1
0
0.2
0
0
0
0
1
0.1
0
0
0
0
0
OFF
Temperature Derating Function
The MAX8647/MAX8648 contain a derating function that
automatically limits the LED current at high temperatures
to help protect the LEDs from damage. The derating
function enables the safe usage of higher LED current at
room temperature, thus reducing the number of LEDs
required to backlight the display. The derating circuit
lowers the LED current at approximately 2.5%/°C once
the IC is above +60°C. The typical derating function
characteristic is shown in the Typical Operating
Characteristics.
Power-Up LED Detection and
Fault Protection
The MAX8648 contains special circuitry to detect short-
circuit conditions at power-up and disable the corre-
sponding current regulator to avoid wasting battery
current. Connect any unused LED_ to IN to disable the
corresponding current regulator. If an LED fails short
circuit, the current regulator continues the current regu-
lated operation until power to the IC is cycled and the
short circuit is detected. An open-circuit LED failure dri-
ves the voltage on the corresponding LED_ output
10 ______________________________________________________________________________________
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