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DESCRIPTION
WARNING!
Do not look directly at operating LED.
This circuit produces light that can damage eyes.
Demonstration circuit 1187 is an RGB LED Driver
and Charge Pump featuring the LTC3212.
The LTC3212 is a low noise charge pump capable
of driving three LEDs up to 25mA each. This de-
vice requires only one flying capacitor, two by-pass
capacitors, and one to three programming resis-
tors. Each LED may be turned on individually, in
combination with each other, or in white mode us-
PERFORMANCE SUMMARY
PARAMETER
Input Supply Range
I
Shutdown Current
VIN
I
Operating Current
VIN
I
LED
I
(WHITE MODE)
LEDG
I
(WHITE MODE)
LEDB
I
(WHITE MODE)
LEDR
I
Dropout Voltage (V
)
LED
ILED
Charge Pump Output Clamp Voltage
I
CPO
ing a single wire interface. White mode optimizes
the red, green, and blue current settings to provide
the best white color.
LED currents are regulated using internal low
dropout current sources. Automatic mode switch-
ing optimizes efficiency by switching modes only
when a dropout is detected. Refer to the LTC3212
datasheet for more information on this device.
Design files for this circuit board are available.
Call the LTC factory.
, LTC, LTM, and LT are registered trademarks of Linear Technology Corporation.
L
Other product names may be trademarks of the companies that manufacture the
products.
Specifications are at T
CONDITIONS
LEDEN = LOW
= 0mA, 1X Mode
I CPO
= 0mA, 2X Mode
I CPO
R
= 33.87KΩ (Not in White Mode)
ISET
R
= 58.87KΩ (Not in White Mode)
ISET
R
= 8.87KΩ (Not in White Mode)
ISET
R
= 33.87KΩ
ISETG
R
= 58.87KΩ
ISETG
R
= 8.87KΩ
ISETG
R
= 33.87KΩ
ISETG
R
= 58.87KΩ
ISETG
R
= 8.87KΩ
ISETG
R
= 33.87KΩ
ISETG
R
= 58.87KΩ
ISETG
R
= 8.87KΩ
ISETG
Mode Switching Threshold, I
LED
DEMO CIRCUIT 1187
QUICK START GUIDE
RGB LED Driver and
Charge Pump
= 25° C
A
MIN
2.7
= 15mA
0
LTC3212
LTC3212
TYP
MAX
UNITS
5.5
V
3
8
µA
0.4
mA
2.0
mA
5.24
mA
3.0
mA
20.0
mA
5.24
mA
3.0
mA
20.0
mA
3.93
mA
2.62
mA
15.0
mA
4.72
mA
2.71
mA
18.0
mA
150
mV
5.1
V
75
mA
1
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