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PDF LTC3210-2 Data sheet ( Hoja de datos )
| Número de pieza | LTC3210-2 | |
| Descripción | MAIN/CAM LED Controllers | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTC3210-2w/wLwT.DCataS3he2et41U.c0om-3
MAIN/CAM LED Controllers
with 32-Step Brightness Control
in 3mm × 3mm QFN
FEATURES
DESCRIPTION
■ Low Noise Charge Pump Provides High Efficiency
with Automatic Mode Switching
■ Multimode Operation: 1x, 1.5x, 2x
■ Individual Full-Scale Current Set Resistors
■ Up to 500mA Total Output Current
■ Single Wire EN/Brightness Control for MAIN and
CAM LEDs
■ 32:1 Linear Brightness Control Range for
MAIN Display
■ Three or Four 25mA Low Dropout MAIN LED Outputs
■ One 400mA Low Dropout CAM LED Output
■ Low Noise Constant Frequency Operation*
■ Low Shutdown Current: 3μA
■ Internal Soft-Start Limits Inrush Current During
Startup and Mode Switching
■ Open/Short LED Protection
■ No Inductors
■ 3mm × 3mm 16-Lead Plastic QFN Package
APPLICATIONS
■ Multi-LED Light Supply for Cellphones/DSCs/PDAs
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*Protected by US Patents including 6411531.
The LTC®3210-2/LTC3210-3 are low noise charge pump
DC/DC converters designed to drive three or four MAIN
LEDs and one high current CAM LED for camera lighting.
The LTC3210-2/LTC3210-3 require only four small ceramic
capacitors and two current set resistors to form a complete
LED power supply and current controller.
Built-in soft-start circuitry prevents excessive inrush cur-
rent during start-up and mode changes. High switching
frequency enables the use of small external capacitors.
Independent MAIN and CAM full-scale current settings
are programmed by two external resistors.
Shutdown mode and current output levels are selected
via two logic inputs. ENM and ENC are toggled to adjust
the LED currents via internal counters and DACs. A 5-bit
linear DAC (32 steps) provides high resolution brightness
control for the MAIN display.
The charge pump optimizes efficiency based on the volt-
age across the LED current sources. The part powers up
in 1x mode and will automatically switch to boost mode
whenever any enabled LED current source begins to enter
dropout. The LTC3210-2/LTC3210-3 are available in a
3mm × 3mm 16-lead QFN package.
TYPICAL APPLICATION
C2
2.2μF
C3
2.2μF
VBAT
C1
2.2μF
ENM
ENC
C1P C1M C2P
VBAT
LTC3210-2
C2M
CPO
ENM
ENC
RM
MLED1
MLED2
MLED3
MLED4
CLED
RC GND
30.1k
1%
24.3k
1%
C4
2.2μF
MAIN
CAM
321023 TA01
4-LED MAIN Display
Efficiency vs VBAT Voltage
100
90
80
70
60
50
40
30
20 4 LEDs AT 9mA/LED
10 (TYP VF AT 9mA = 3V, NICHIA NSCW100)
TA = 25°C
0
3.0 3.2 3.4 3.6 3.8 4.0 4.2
4.4
VBAT (V)
321023 TA01b
321023fa
1
1 page  
LTC3210-2w/wLwT.DCataS3he2et41U.c0om-3
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C unless otherwise stated.
CLED Pin Dropout Voltage
vs CLED Pin Current
500
VBAT = 3.6V
400
300
200
100
0
50 100 150 200 250 300 350 400
CLED PIN CURRENT (mA)
321023 G10
VBAT Shutdown Current
vs VBAT Voltage
5.0
4.5
TA = 25°C
4.0
TA = –40°C
3.5
3.0
2.5
TA = 85°C
2.0
1.5
2.7 3.0
3.3 3.6 3.9
VBAT VOLTAGE (V)
4.2 4.5
321023 G13
MLED Pin Dropout Voltage
vs MLED Pin Current
120
VBAT = 3.6V
100
80
60
40
20
0
0 2 4 6 8 10 12 14 16 18 20
MLED PIN CURRENT (mA)
321023 G11
1x Mode No Load VBAT Current
vs VBAT Voltage
800
RM = 33.2k
780 RC = 24.3k
760
740
720
700
680
660
640
620
600
2.7 3.0 3.3 3.6 3.9 4.2 4.5
VBAT VOLTAGE (V)
321023 G14
Oscillator Frequency
vs VBAT Voltage
850
840
TA = 25°C
830
820
810 TA = 85°C
800
TA = –40°C
790
780
770
760
2.7 3.0 3.3 3.6 3.9
VBAT VOLTAGE (V)
4.2 4.5
321023 G12
1.5x Mode Supply Current
vs ICPO (IVBAT – 1.5ICPO)
20
VBAT = 3.6V
15
10
5
0
0 100 200 300 400 500
LOAD CURRENT (mA)
321023 G15
2x Mode Supply Current
vs ICPO (IVBAT – 2ICPO)
20
VBAT = 3.6V
15
10
5
0
0 100 200 300 400 500
LOAD CURRENT (mA)
321023 G16
CLED Pin Current
vs CLED Pin Voltage
400
VBAT = 3.6V
360
320
280
240
200
160
120
80
40
0
0 0.2 0.4 0.6 0.8 1
CLED PIN VOLTAGE (V)
321023 G17
321023fa
5
5 Page 
LTC3210-2w/wLwT.DCataS3he2et41U.c0om-3
OPERATION
From Figure 2, for 1.5x mode the available current is
given by:
IOUT
=
(1.5VBAT –
ROL
VCPO )
For 2x mode, the available current is given by:
IOUT
=
(2VBAT – VCPO)
ROL
Notice that the advantage voltage in this case is 3.1V • 2
– 3.8V – 0.1V = 2.3V. ROL is higher in 2x mode but a sig-
nificant overall increase in available current is achieved.
Typical values of ROL as a function of temperature are
shown in Figure 3 and Figure 4.
Shutdown Current
In shutdown mode all the circuitry is turned off and the
LTC3210-2/LTC3210-3 draw a very low current from the
VBAT supply. Furthermore, CPO is weakly connected to VBAT.
The LTC3210-2/LTC3210-3 enter shutdown mode when
both the ENM and ENC pins are brought low at 150μs (typ).
ENM and ENC have 250k internal pull down resistors to de-
fine the shutdown state when the drivers are in a high imped-
ance state.
Thermal Protection
The LTC3210-2/LTC3210-3 have built-in overtemperature
protection. At internal die temperatures of around 150°C
thermal shut down will occur. This will disable all of the
current sources and charge pump until the die has cooled
by about 15°C. This thermal cycling will continue until the
fault has been corrected.
Mode Switching
The LTC3210-2/LTC3210-3 will automatically switch from
1x mode to 1.5x mode and subsequently to 2x mode
whenever a dropout condition is detected at an LED pin.
Dropout occurs when a current source voltage becomes
too low for the programmed current to be supplied. The
time from drop-out detection to mode switching is typi-
cally 0.4ms.
The part is reset back to 1x mode when the part is shut
down (ENM = ENC = Low) or on the falling edge of ENC.
An internal comparator will not allow the main switches to
connect VBAT and CPO in 1x mode until the voltage at the
CPO pin has decayed to less than or equal to the voltage
at the VBAT pin.
3.8
VBAT = 3V
3.6
VCPO = 4.2V
C2 = C3 = C4 = 2.2μF
3.4
3.2
3.0
2.8
2.6
2.4
–40
–15 10
35
TEMPERATURE (°C)
60 85
321023 F03
Figure 3. Typical 1.5x ROL vs Temperature
4.6
VBAT = 3V
4.4
VCPO = 4.8V
C2 = C3 = C4 = 2.2μF
4.2
4.0
3.8
3.6
3.4
3.2
–40
–15 10 35 60
TEMPERATURE (°C)
85
321023 F04
Figure 4. Typical 2x ROL vs Temperature
321023fa
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LTC3210-2.PDF ] | |
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