LTC3212
RGB LED Driver and
Charge Pump
FeaTures
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■
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DescripTion
The LTC
®
3212 is a low noise charge pump RGB LED
driver capable of driving three LEDs up to 25mA each
from a 2.7V to 5.5V input. Low external part count (one
flying capacitor, two bypass capacitors and one to three
programming resistors) makes the LTC3212 ideally suited
for small, battery-powered applications.
Built-in soft-start circuitry prevents excessive inrush cur-
rent during start-up and mode switching. High switching
frequency enables the use of small external capacitors.
The charge pump shuts down to a high impedance mode
to prevent LED leakage while the LTC3212 is off.
Each LED may be individually turned on or off via a single
pin interface. The current through the LEDs may be indi-
vidually programmed with resistors or may share a single
programming resistor. White mode adjusts the red, green
and blue LED current ratios for a white light when all three
LEDs are programmed to be on.
LED currents are regulated using internal low dropout
current sources. Automatic mode switching optimizes
efficiency by monitoring the LED current drivers and
switches mode only when dropout is detected. The part
is available in a 3mm
×
2mm 12-lead DFN package.
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Power and Current Control for Driving RGB LEDs
Individually Programmable Current Sources
1x or 2x Mode, Low Noise, Constant Frequency
Charge Pump
Single Wire Enable Control for All LEDs
White Mode Adjusts R, G, B Currents for White Light
25mA Maximum LED Current
V
IN
Range: 2.7V to 5.5V
Automatic Soft-Start, Mode Switching and Output
Disconnect in Shutdown Mode
Available in 12-Lead (3mm
×
2mm) DFN Package
applicaTions
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Cellular Phones
Media Players
RGB Back Lights
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 6411531.
Typical applicaTion
RGB Power Supply and Current Control
1µF
V
IN
2.7V TO 5.5V
CM
V
IN
1µF
LEDEN
I
SETB
I
SETR
I
SETG
11.8k
CP
CPO
R
G
B
1µF
LTC3212
LEDR
LEDG
LEDB
INDIVIDUAL WHITE
SETTINGS MODE
LEDR
LEDG
LEDB
15mA
15mA
15mA
13.5mA
15mA
11.2mA
3212 TA01a
3212fb
LTC3212
absoluTe MaxiMuM raTinGs
(Note 1)
pin conFiGuraTion
TOP VIEW
CP 1
CPO 2
LEDEN 3
I
SETB
4
I
SETR
5
I
SETG
6
13
12 VIN
11 CM
10 GND
9 LEDB
8 LEDR
7 LEDG
V
IN
to GND ................................................... –0.3V to 6V
CPO to GND ................................................. –0.3V to 6V
LEDEN ............................................. –0.3V to V
IN
+ 0.3V
I
CPO
(Note 2) ..........................................................75mA
I
LED(R,G,B)
(Note 2) .................................................30mA
CPO Short-Circuit Duration .............................. Indefinite
Operating Temperature Range
(Notes 3, 4).......................................... –40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
DDB PACKAGE
12-LEAD (3mm
×
2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 76°C/W
EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LTC3212EDDB#PBF
TAPE AND REEL
LTC3212EDDB#TR
PART MARKING
LCWM
PACKAGE DESCRIPTION
12-Lead (3mm × 2mm) Plastic DFN
TEMPERATURE RANGE
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
elecTrical characTerisTics
PARAMETER
V
IN
Operating Voltage
I
VIN
Operating Current
V
IN
Shutdown Current
LED Current
Current Ratio (I
LEDG
/I
SETG
)
Current Ratio (I
LEDB
/I
SETB
)
Current Ratio (I
LEDB
/I
SETG
)
Current Ratio (I
LEDR
/I
SETR
)
Current Ratio (I
LEDR
/I
SETG
)
I
LED
Dropout Voltage (V
ILED
)
t
EN
Mode Switching Delay
Charge Pump (CPO)
Charge Pump Output Voltage Clamp
1x Mode Output Impedance
(Notes 6, 7)
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V.
CONDITIONS
●
MIN
2.7
TYP
0.4
2.0
3
MAX
5.5
UNITS
V
mA
mA
I
CPO
= 0mA, 1x Mode
I
CPO
= 0mA, 2x Mode
LEDEN = Low
I
SETG
= 78µA
I
SETB
= 78µA
White Mode, I
SETG
= 78µA
I
SETR
= 78µA
White Mode, I
SETG
= 78µA
Mode Switching Theshold, I
LED
= 15mA
Current Source Enable Time (LEDEN = High) (Note 5)
●
8
210
210
160
210
186
400
µA
A/A
A/A
A/A
A/A
A/A
mV
µs
µs
V
Ω
173
173
128
173
154
192
192
144
192
171
150
50
120
5.1
5
250
3212fb
LTC3212
elecTrical characTerisTics
PARAMETER
2x Mode Output Impedance
CLK Frequency
LEDEN
High Level Input Voltage (V
IH
)
Low Level Input Voltage (V
IL
)
Input Current (I
IH
)
Input Current (I
IL
)
t
PWH
t
PWL
t
SD
I
SET(R,G,B)
V
ISET
I
ISET
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
Based on long-term current density limitations.
Note 3:
The LTC3212E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C ambient
operating temperature range are assured by design, characterization and
correlation with statistical process controls
864
925
985
140
mV
µA
High Pulse Width
Low Pulse Width
Low Time to Shutdown (LEDEN = Low)
●
●
●
●
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V.
CONDITIONS
(Notes 6, 7)
650
1.4
0.4
3
–1
0.08
0.08
350
20
10
1
MIN
TYP
25
900
1275
MAX
UNITS
Ω
kHz
V
V
µA
µA
µs
µs
µs
LEDEN = 3.6V
Note 4:
This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 5:
If the LTC3212 has been shut down, then the initial enable time
is longer due to the bandgap settling time and the CPO output capacitor
soft-start time.
Note 6:
1x mode output impedance is defined as (V
IN
– V
CPO
)/I
OUT
.
2x mode output impedance is defined as (2V
IN
– V
CPO
)/I
OUT
.
Note 7:
Guaranteed by design.
Typical perForMance characTerisTics
Dropout Time
CPO
1V/DIV
3.6V
1V
LED
500mV/DIV
1x MODE
DROPOUT
DELAY
DROPOUT
50µs/DIV
0V
3212 G01
2x Mode CPO Ripple
250
2x MODE 5.1V
LED DROPOUT VOLTAGE (mV)
200
LED Pin Dropout Voltage
vs LED Pin Current
V
CPO
20mV/DIV
AC COUPLED
150
100
V
IN
= 3.6V
I
CPO
= 75mA
C
CPO
= 1µF
500ns/DIV
3212 G02
50
0
0
5
10
LED CURRENT (mA)
15
20
3212 G03
3212fb
LTC3212
Typical perForMance characTerisTics
1x Mode Charge Pump
Resistance vs Temperature
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
–40
V
IN
= 4.2V
V
IN
= 3V
V
IN
= 3.6V
OPEN-LOOP OUTPUT RESISTANCE (Ω)
I
CPO
= 50mA
35
33
31
29
27
25
23
21
19
17 C1, C2, C3 = 1µF
V
CPO
= 4.8V
15
2.7
3.0
85°C
CPO VOLTAGE (V)
4.8
3.4V
4.6
3.1V
4.4
4.2
4.0
C1, C2, C3 = 1µF
0 10 20 25 30 35 40 45 50 55 60 65 70
CPO CURRENT (mA)
3212 G06
2x Mode CPO Open-Loop Output
Resistance
5.2
5.0
2x Mode CPO Voltage
vs CPO Current
3.6V
RESISTANCE (Ω)
3.5V
3.3V
3.2V
25°C
–40°C
V
IN
= 3.0V
–20
40
20
0
TEMPERATURE (°C)
60
80
3212 G04
3.3
V
IN
(V)
3.6
4.0
3212 G05
Oscillator Frequency
vs V
IN
Voltage
892
890
FREQUENCY (kHz)
888
I
VIN
(µA)
886
884
882
880
2.7
6
5
V
IN
Shutdown Current
vs V
IN
Voltage
1x Mode No-Load V
IN
Current
vs V
IN
Voltage
350
340
V
IN
CURRENT (µA)
330
320
310
300
290
4
3
2
1
0
3.1
3.5
3.9 4.3
V
IN
(V)
4.7
5.1
5.5
2.7
3.1
3.5
3.9 4.3
V
IN
(V)
4.7
5.1
5.5
2.7
3.1
3.5
3.9 4.3
V
IN
(V)
4.7
5.1
5.5
3212 G07
3212 G08
3212 G09
4.0
3.5
3.0
V
IN
CURRENT (mA)
2.5
2.0
1.5
1.0
0.5
2x Mode V
IN
Current
vs V
IN
Voltage
Start-Up and Mode Switch
SOFT-START
CPO
1V/DIV
0V
LEDEN
2V/DIV 0V
V
IN
= 3.6V
200µs/DIV
5V 2x
3.6V MODE
DROPOUT
1x
DELAY
MODE
3.6V
3212 G11
0
2.7
3.1
3.5
3.9 4.3
V
IN
(V)
4.7
5.1
5.5
3212 G10
3212fb
LTC3212
pin FuncTions
CP, CM (Pins 1, 11):
Charge Pump Flying Capacitor Pins.
A 1µF X5R or X7R ceramic capacitor should be connected
from CP to CM.
CPO (Pin 2):
CPO is the output of the charge pump. A 1µF
X5R or X7R ceramic capacitor is required from CPO to
GND. While operating, this pin will supply current to the
LEDs and while in shutdown mode this pin will be high
impedance.
LEDEN (Pin 3):
The LEDEN pin is used to program, enable
and shut down the part. A 3µA internal current source
pulls this pin to ground.
I
SETB
, I
SETR
, I
SETG
(Pins 4, 5, 6):
LED current program-
ming resistor pins. A resistor connected between a pin
and GND is used to set the LED current. A resistor from
I
SETG
to GND is required. Resistors on I
SETR
and I
SETB
are optional. If I
SETR
and/or I
SETB
is not connected to a
resistor I
SETR
’s and/or I
SETB
’s respective output(s) will be
automatically programmed by the resistor connected to
I
SETG
. If I
SETR
or I
SETB
is unused the pin should be con-
nected to V
IN
.
LEDG, LEDR, LEDB (Pins 7, 8, 9):
These pins are
the LED current output pins. The LEDs are connected
from either the charge pump or V
IN
(anode) to LED
(R, G, B) (cathode).
GND (Pin 10):
This pin should be connected directly to a
low impedance ground plane.
V
IN
(Pin 12):
Supply voltage for the LTC3212. V
IN
should
be bypassed with a low impedance ceramic capacitor to
GND of at least 1µF of capacitance.
Exposed Pad (Pin 13):
GND. The Exposed Pad must be
soldered to a low impedance ground plane for optimum
performance.
3212fb
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