LTC3210EUD-3#TRPBF [Linear]
暂无描述;
| 型号： | LTC3210EUD-3#TRPBF |
| 厂家： | 
Linear |
| 描述： | 暂无描述 控制器 |
| 文件： | 总16页 (文件大小：212K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC3210-2/LTC3210-3
MAIN/CAM LED Controllers
with 32-Step Brightness Control
in 3mm × 3mm QFN
FEATURES
DESCRIPTION
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.
TheLTC3210-2/LTC3210-3requireonlyfoursmallceramic
capacitorsandtwocurrentsetresistorstoformacomplete
LED power supply and current controller.
■
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
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.
■
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
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
wheneveranyenabledLEDcurrentsourcebeginstoenter
dropout. The LTC3210-2/LTC3210-3 are available in a
3mm × 3mm 16-lead 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.
TYPICAL APPLICATION
C2
C3
4-LED MAIN Display
Efficiency vs VBAT Voltage
2.2μF
2.2μF
100
90
C1P C1M
BAT
C2P
C2M
MAIN
CAM
80
70
60
50
40
30
CPO
V
V
BAT
C1
2.2μF
C4
2.2μF
LTC3210-2
MLED1
MLED2
MLED3
MLED4
CLED
ENM
ENC
ENM
ENC
20
4 LEDs AT 9mA/LED
(TYP V AT 9mA = 3V, NICHIA NSCW100)
F
10
321023 TA01
T
= 25°C
A
RM
RC
GND
0
3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4
(V)
30.1k
1%
24.3k
1%
V
BAT
321023 TA01b
321023fa
1
LTC3210-2/LTC3210-3
ABSOLUTE MAXIMUM RATINGS(Note 1)
V
, CPO to GND ........................................–0.3V to 6V
I
(Note 2) ......................................................500mA
BAT
CLED
ENM, ENC ................................... –0.3V to (V + 0.3V)
CPO Short-Circuit Duration.............................. Indefinite
Operating Temperature Range (Note 3) ...–40°C to 85°C
Storage Temperature Range...................–65°C to 125°C
BAT
I
I
(Note 2)........................................................600mA
CPO
MLED1-4
.................................................................35mA
PIN CONFIGURATION
TOP VIEW
TOP VIEW
16 15 14 13
16 15 14 13
C1P
CPO
1
2
3
4
12 GND
11 CLED
C1P
CPO
1
2
3
4
12 GND
11 CLED
17
17
ENM
ENC
RC
ENM
ENC
RC
10
9
10
9
MLED1
MLED1
5
6
7
8
5
6
7
8
UD PACKAGE
16-LEAD (3mm × 3mm) PLASTIC QFN
= 125°C, θ = 68°C/W
UD PACKAGE
16-LEAD (3mm × 3mm) PLASTIC QFN
= 125°C, θ = 68°C/W
T
T
JMAX
JMAX
JA
JA
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3210EUD-2#PBF
LTC3210EUD-3#PBF
TAPE AND REEL
PART MARKING
LCHX
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3210EUD-2#TRPBF
LTC3210EUD-3#TRPBF
16-Lead (3mm × 3mm) Plastic QFN
16-Lead (3mm × 3mm) Plastic QFN
–40°C to 85°C
–40°C to 85°C
LCHY
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 The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C.VBAT = 3.6V, C1 = C2 = C3 = C4 = 2.2μF, RM = 30.1k, RC = 24.3k,
ENM = high, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
●
V
Operating Voltage
Operating Current
2.9
4.5
V
BAT
I
I
I
I
= 0, 1x Mode, LSB Setting
= 0, 1.5x Mode
= 0, 2x Mode
0.4
2.5
4.5
mA
mA
mA
VBAT
CPO
CPO
CPO
●
●
V
Shutdown Current
ENM = ENC = Low
3
6
μA
BAT
MLED1, MLED2, MLED3 and MLED4 (LTC3210-2 Only) Current
LED Current Ratio (I /I
)
I
= Full Scale
481
525
75
589
A/A
mV
%
MLED RM
MLED
LED Dropout Voltage
LED Current Matching
Mode Switch Threshold, I
= Full Scale
MLED
Any Two Outputs
0.5
321023fa
2
LTC3210-2/LTC3210-3
The ● denotes the specifications which apply over the full operating
ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at TA = 25°C.VBAT = 3.6V, C1 = C2 = C3 = C4 = 2.2μF, RM = 30.1k, RC = 24.3k,
ENM = high, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
MLED Current, 5-Bit Linear DAC
1 ENM Strobe (FS)
31 ENM Strobes (FS/31)
20
0.640
mA
mA
CLED Current
●
LED Current Ratio (I
/I
)
I
= Full Scale
6930
7700
500
8470
A/A
mV
CLED RC
CLED
LED Dropout Voltage
Mode Switch Threshold, I
= Full Scale
CLED
CLED Current, 3-Bit Linear DAC
1 ENC Strobe (FS)
7 ENC Strobes (FS/7)
380
54
mA
mA
Charge Pump (CPO)
1x Mode Output Voltage
1.5x Mode Output Voltage
2x Mode Output Voltage
1x Mode Output Impedance
1.5x Mode Output Impedance
2x Mode Output Impedance
CLOCK Frequency
I
I
I
= 0mA
= 0mA
= 0mA
V
V
V
CPO
CPO
CPO
BAT
4.55
5.05
0.55
3.15
3.95
0.8
V
Ω
Ω
V
V
= 3.4V, V
= 3.2V, V
= 4.6V (Note 4)
= 5.1V (Note 4)
BAT
BAT
CPO
Ω
CPO
MHz
ms
Mode Switching Delay
CPO Short Circuit Detection
Threshold Voltage
0.4
●
●
0.4
10
1.3
30
V
Test Current
CPO = 0V, ENM = ENC = Low
mA
ENC, ENM
●
●
●
●
V
V
0.4
V
V
IL
1.4
10
–1
IH
I
IH
I
IL
ENM = ENC = 3.6V
ENM = ENC = 0V
15
20
1
μA
μA
ENC, ENM Timing
●
●
t
t
t
Minimum Pulse Width
200
50
ns
μs
PW
SD
EN
Low Time to Shutdown (ENC, ENM = Low)
150
150
250
250
Current Source Enable Time
(ENC, ENM = High) (Note 5)
●
50
μs
RM, RC
, V
●
●
V
1.16
1.20
1.24
80
V
RM RC
I
, I
RM RC
μA
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 3: The LTC3210-2/LTC3210-3 are guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the –40°C to
85°C ambient operating temperature range are assured by design,
characterization and correlation with statistical process controls.
Note 2: Based on long-term current density limitations. Assumes an
operating duty cycle of ≤10% under absolute maximum conditions
for durations less than 10 seconds. Maximum current for continuous
operation is 300mA.
Note 4: 1.5x mode output impedance is defined as (1.5V – V )/I
.
BAT
CPO OUT
2x mode output impedance is defined as (2V – V )/I
.
BAT
CPO OUT
Note 5: If the part has been shut down then the initial enable time is about
100μs longer due to the bandgap enable time.
321023fa
3
LTC3210-2/LTC3210-3
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C unless otherwise stated.
Dropout Time from Shutdown
Dropout Time When Enabled
1.5x CPO Ripple
V
= 3.6V
= 200mA
= 2.2μF
BAT
CPO
CPO
I
5.1V
2X
5.1V
2X
CPO
1V/DIV
CPO
1V/DIV
C
1.5X
1.5X
1X
1X
V
CPO
50mV/DIV
AC
COUPLED
EN
2V/DIV
ENC
2V/DIV
MODE
RESET
MODE
RESET
ENM = HIGH
321023 G01
321023 G02
321023 G03
250μs/DIV
500μs/DIV
500ns/DIV
1.5x Mode Charge Pump Open-Loop
Output Resistance vs Temperature
(1.5VBAT – VCPO)/ICPO
1x Mode Switch Resistance
vs Temperature
2x CPO Ripple
3.8
3.6
0.70
I
= 200mA
V
V
= 3V
= 4.2V
V
= 3.6V
= 200mA
= 2.2μF
CPO
BAT
CPO
BAT
CPO
CPO
I
0.65
C
C2 = C3 = C4 = 2.2μF
3.4
3.2
3.0
2.8
2.6
2.4
V
CPO
0.60
0.55
20mV/DIV
AC
V
= 3.3V
BAT
COUPLED
V
= 3.6V
BAT
0.50
0.45
0.40
V
= 3.9V
10
BAT
321023 G04
500ns/DIV
–15
10
35
85
–40
60
–40
–15
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
321023 G06
321023 G05
2x Mode Charge Pump Open-Loop
Output Resistance vs Temperature
(2VBAT – VCPO)/ICPO
2x Mode CPO Voltage
vs Load Current
1.5x Mode CPO Voltage
vs Load Current
4.8
4.6
5.2
5.1
5.0
4.9
4.8
4.7
4.6
4.5
4.4
4.3
4.2
4.6
4.4
C2 = C3 = C4 = 2.2μF
C2 = C3 = C4 = 2.2μF
V
V
= 3V
BAT
CPO
= 4.8V
C2 = C3 = C4 = 2.2μF
V
= 3.3V
BAT
V
= 3.6V
V
= 3.4V
BAT
BAT
4.2
4.0
3.8
3.6
3.4
3.2
V
= 3.5V
4.4
4.2
BAT
V
= 3.5V
V
= 3.6V
BAT
BAT
V
= 3.4V
BAT
V
= 3.3V
BAT
4.0
3.8
3.6
V
V
= 3.2V
BAT
V
= 3.2V
BAT
= 3.1V
V
V
= 3.1V
BAT
BAT
= 3V
200
V
= 3V
400
BAT
BAT
0
100
300
400
500
–40
–15
10
35
60
85
0
100
300
LOAD CURRENT (mA)
200
500
LOAD CURRENT (mA)
TEMPERATURE (°C)
321023 G07
321023 G09
321023 G08
321023fa
4
LTC3210-2/LTC3210-3
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C unless otherwise stated.
CLED Pin Dropout Voltage
vs CLED Pin Current
MLED Pin Dropout Voltage
vs MLED Pin Current
Oscillator Frequency
vs VBAT Voltage
500
400
300
200
100
0
120
100
80
60
40
20
0
850
840
830
820
810
800
790
780
770
V
= 3.6V
BAT
V
= 3.6V
BAT
T
= 25°C
A
T
= 85°C
A
T
= –40°C
A
760
50 100 150 200 250 300 350 400
CLED PIN CURRENT (mA)
0
2
4
6
8
10 12 14 16 18 20
2.7
3.0
3.3
3.6
4.5
3.9
4.2
MLED PIN CURRENT (mA)
V
VOLTAGE (V)
BAT
321023 G10
321023 G11
321023 G12
VBAT Shutdown Current
vs VBAT Voltage
1x Mode No Load VBAT Current
vs VBAT Voltage
1.5x Mode Supply Current
vs ICPO (IVBAT – 1.5ICPO
)
20
15
10
5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
800
780
760
740
720
700
680
660
640
620
600
V
= 3.6V
BAT
RM = 33.2k
RC = 24.3k
T
= 25°C
A
T
= –40°C
A
T
= 85°C
A
0
0
100
200
300
400
500
3.9
3.6
VOLTAGE (V)
4.5
2.7
3.0
3.3
4.2
2.7
3.0
3.6
3.9
4.2
4.5
3.3
LOAD CURRENT (mA)
V
V
VOLTAGE (V)
BAT
BAT
321023 G15
321023 G13
321023 G14
2x Mode Supply Current
CLED Pin Current
vs CLED Pin Voltage
vs ICPO (IVBAT – 2ICPO
)
20
15
10
5
400
360
320
280
240
200
160
120
80
V
= 3.6V
V
= 3.6V
BAT
BAT
40
0
0
0
100
200
300
400
500
0
0.2
0.4
0.6
0.8
1
LOAD CURRENT (mA)
CLED PIN VOLTAGE (V)
321023 G16
321023 G17
321023fa
5
LTC3210-2/LTC3210-3
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C unless otherwise stated.
MLED Pin Current
vs MLED Pin Voltage
CLED Current
vs ENC Strobe Pulses
22
20
18
16
14
12
10
8
400
350
300
250
200
150
100
50
V
= 3.6V
BAT
V
= 3.6V
BAT
RC = 24.3k
6
4
2
0
0.00
0
0
6
5
4
3
2
1
0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20
MLED PIN VOLTAGE (V)
7
0.02
NUMBER OF ENC STROBE PULSES
321023 G19
321023 G18
MLED Current
vs ENM Strobe Pulses
Efficiency vs VBAT Voltage
21
18
90
80
70
60
50
40
30
20
10
0
V
= 3.6V
BAT
RM = 30.1k
15
12
9
6
3
300mA LED CURRENT
(TYP V AT 300mA = 3.1V, AOT-2015HPW
F
0
28 24 20 16 12
NUMBER OF ENM STROBE PULSES
0
8
4
1
2.9 3.05 3.2 3.35 3.5 3.65
4.4
3.8 3.95 4.1 4.25
V
(V)
BAT
321023 G20
321023 G21
321023fa
6
LTC3210-2/LTC3210-3
PIN FUNCTIONS
C1P, C2P, C1M, C2M (Pins 1, 16, 14, 13): Charge Pump
Flying Capacitor Pins. A 2.2μF X7R or X5R ceramic ca-
pacitor should be connected from C1P to C1M and C2P
to C2M.
MLED4 (Pin 7, LTC3210-2 Only): Output. MLED4 is the
fourth main current source output available only on the
LTC3210-2 product. The LED is connected between CPO
(anode) and MLED4 (cathode). The current to MLED4
is set via the ENM input and the programming resistor
connected between RM and GND. MLED4 tracks the LED
currents of MLED1-3.
CPO (Pin 2): Output of the Charge Pump Used to Power
All LEDs. This pin is enabled or disabled using the ENM
and ENC inputs. A 2.2μF X5R or X7R ceramic capacitor
should be connected to ground.
NC (Pin 7, LTC3210-3 Only): This pin is not connected
and can be left floating or connected to ground.
ENM, ENC (Pins 3, 10): Inputs. The ENM and ENC pins
are used to program the LED output currents. The ENC
pin is strobed up to 7 times to decrement the internal 3-bit
DAC’s from full-scale to 1LSB. The ENM pin is strobed 31
times to decrement the 5-bit DAC from full-scale to 1LSB.
The counters will stop at 1LSB if the strobing continues.
The pin must be held high after the final desired positive
strobe edge and the data is transferred after a 150μs (typ)
delay. Holding the ENM or ENC pin low will clear the coun-
ter for the selected display and reset the LED current to
0. If both inputs are held low for longer than 150μs (typ)
the part will go into shutdown. The charge pump mode
is reset to 1x whenever ENC goes low or when the part
is shut down.
RM, RC (Pins 8,9): LED Current Programming Resistor
Pins. The RM and RC pins will servo to 1.22V. Resistors
connected between each of these pins and GND are used
to set the high and low LED current levels. Connecting a
resistor 15k or less will cause the LTC3210-2/LTC3210-3
to enter overcurrent shutdown.
CLED (Pin 11): Output. CLED is the CAM current source
output. The LED is connected between CPO (anode) and
CLED (cathode). The current to the LED output is set via
the ENC input, and the programming resistor connected
between RC and GND.
GND (Pin 12): Ground. This pin should be connected to
a low impedance ground plane.
MLED1, MLED2, MLED3 (Pins 4, 5, 6): Outputs. MLED1
to MLED3 are the MAIN current source outputs. The LEDs
areconnectedbetweenCPO(anodes)andMLED1-3(cath-
odes). The current to each LED output is set via the ENM
input, and the programming resistor connected between
RM and GND.
V
(Pin15):Supplyvoltage.Thispinshouldbebypassed
BAT
with a 2.2μF, or greater low ESR ceramic capacitor.
Exposed Pad (Pin 17): This pad should be connected
directly to a low impedance ground plane for optimal
thermal and electrical performance.
321023fa
7
LTC3210-2/LTC3210-3
BLOCK DIAGRAM
C1P
1
C1M
14
C2P
16
C2M
13
800kHz
OSCILLATOR
12 GND
15
V
BAT
2
CPO
CHARGE PUMP
–
+
ENABLE CP
+
–
1.215V
4
5
6
7
MLED1
MLED2
MLED3
TIMER
ENABLE MAIN
500Ω
8
3
RM
5-BIT
DOWN
COUNTER
5-BIT
LINEAR
DAC
MLED
CURRENT
SOURCES
4
ENM
50ns FILTER
250k
MLED4
(LTC3210-2 ONLY)
+
–
1.215V
TIMER
TIMER
SHUTDOWN
ENABLE CAM
3-BIT
500Ω
RC
9
3-BIT
DOWN
COUNTER
CLED
CURRENT
SOURCE
10
11 CLED
50ns FILTER
LINEAR
DAC
ENC
250k
321023 BD
321023fa
8
LTC3210-2/LTC3210-3
OPERATION
Power Management
counter which controls a 5-bit linear DAC. When the
desired current is achieved ENM is stopped high. The
output current then changes to the programmed value
after 150μs (typ). The counter will stop when the LSB
is reached. The output current is set to 0 when ENM is
toggled low after the output has been enabled. If strobing
is started within 150μs (typ), after ENM has been set low,
the counter will continue to count down. After 150μs (typ)
the counter is reset.
The LTC3210-2/LTC3210-3 uses a switched capacitor
charge pump to boost CPO to as much as 2 times the
input voltage up to 5.1V. The part starts up in 1x mode. In
this mode, V is connected directly to CPO. This mode
BAT
provides maximum efficiency and minimum noise. The
LTC3210-2/LTC3210-3willremainin1xmodeuntilanLED
current source drops out. Dropout occurs when a current
source voltage becomes too low for the programmed
current to be supplied. When dropout is detected, the
LTC3210-2/LTC3210-3 will switch into 1.5x mode. The
CPO voltage will then start to increase and will attempt
The CLED current is delivered by a programmable current
source. Eight linear current settings (0mA to 380mA, RC
= 24.3k) are available by strobing the ENC pin. Each posi-
tive strobe edge decrements a 3-bit down counter which
controls a 3-bit linear DAC. When the desired current is
reached, ENC is stopped high. The output current then
changes to the programmed value after 150μs (typ). The
counter will stop when the LSB is reached. The output
currentissetto0whenENCistoggledlowaftertheoutput
has been enabled. If strobing is started within 150μs (typ)
after ENC has been set low, the counter will continue to
count down. After 150μs (typ) the counter is reset.
to reach 1.5x V
up to 4.6V. Any subsequent dropout
BAT
will cause the part to enter the 2x mode. The CPO voltage
will attempt to reach 2x V up to 5.1V. The part will be
BAT
reset to 1x mode whenever the part is shut down or when
ENC goes low.
A two phase nonoverlapping clock activates the charge
pump switches. In the 2x mode the flying capacitors are
charged on alternate clock phases from V to minimize
inputcurrentrippleandCPOvoltageripple.In1.5xmodethe
flyingcapacitorsarechargedinseriesduringthefirstclock
phase and stacked in parallel on V
BAT
The full-scale output current is calculated as follows:
during the second
BAT
MLED full-scale output current
= (1.215V/(RM + 500)) • 525
phase.Thissequenceofcharginganddischargingtheflying
capacitors continues at a constant frequency of 800kHz.
CLED full-scale output current
= (1.215V/(RC + 500)) • 7700
LED Current Control
The MLED currents are delivered by the four program-
mable current sources. 32 linear current settings (0mA
to 20mA, RM = 30.1k) are available by strobing the ENM
pin. Each positive strobe edge decrements a 5-bit down
When both ENM and ENC are held low for more than
150μs (typ) the part will go into shutdown. See Figure 1
for timing information.
ENC resets the mode to 1x on a falling edge.
t
t
t
SD 150 s (TYP)
PW 200ns
EN 150 s (TYP)
ENM
OR ENC
PROGRAMMED
CURRENT
LED
CURRENT
ENM = ENC = LOW
SHUTDOWN
321023 F01
Figure 1. Current Programming Timing Diagram
321023fa
9
LTC3210-2/LTC3210-3
OPERATION
Soft-Start
When the LTC3210-2/LTC3210-3 operate in either 1.5x
mode or 2x mode, the charge pump can be modeled as
a Thevenin-equivalent circuit to determine the amount of
current available from the effective input voltage and ef-
Initially, when the part is in shutdown, a weak switch con-
nects V to CPO. This allows V to slowly charge the
BAT
BAT
CPO output capacitor to prevent large charging currents.
fective open-loop output resistance, R (Figure 2).
OL
TheLTC3210-2/LTC3210-3alsoemployasoft-startfeature
on its charge pump to prevent excessive inrush current
andsupplydroopwhenswitchingintothestep-upmodes.
The current available to the CPO pin is increased linearly
over a typical period of 150μs. Soft-start occurs at the
start of both 1.5x and 2x mode changes.
R
OL
+
+
CPO
1.5V
OR 2V
BAT
BAT
–
–
321023 F02
Charge Pump Strength and Regulation
Figure 2. Charge Pump Thevenin Equivalent Open-Loop Circuit
Regulation is achieved by sensing the voltage at the CPO
pin and modulating the charge pump strength based
on the error signal. The CPO regulation voltages are set
internally, and are dependent on the charge pump modes
as shown in Table 1.
R
is dependent on a number of factors including the
OL
switching term, 1/(2f
• C ), internal switch resis-
OSC
FLY
tances and the nonoverlap period of the switching circuit.
However, for a given R , the amount of current available
OL
will be directly proportional to the advantage voltage of
Table 1. Charge Pump Output Regulation Voltages
1.5V
– CPO for 1.5x mode and 2V
– CPO for 2x
BAT
BAT
mode. Consider the example of driving white LEDs from
a 3.1V supply. If the LED forward voltage is 3.8V and the
current sources require 100mV, the advantage voltage for
1.5x mode is 3.1V • 1.5 – 3.8V – 0.1V or 750mV. Notice
that if the input voltage is raised to 3.2V, the advantage
voltage jumps to 900mV—a 20% improvement in avail-
able strength.
Charge Pump Mode
Regulated V
4.55V
CPO
1.5x
2x
5.05V
321023fa
10
LTC3210-2/LTC3210-3
OPERATION
From Figure 2, for 1.5x mode the available current is
given by:
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.
(1.5VBAT – VCPO
ROL
)
IOUT
=
For 2x mode, the available current is given by:
(2VBAT – VCPO
ROL
)
IOUT
=
Mode Switching
Notice that the advantage voltage in this case is 3.1V • 2
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.
– 3.8V – 0.1V = 2.3V. R is higher in 2x mode but a sig-
OL
nificant overall increase in available current is achieved.
Typical values of R as a function of temperature are
OL
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
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
V
supply.Furthermore,CPOisweaklyconnectedtoV
.
BAT
BAT
The LTC3210-2/LTC3210-3 enter shutdown mode when
boththeENMandENCpinsarebroughtlowat150μs(typ).
ENMandENChave250kinternalpulldownresistorstode-
finetheshutdownstatewhenthedriversareinahighimped-
ance state.
connect V and CPO in 1x mode until the voltage at the
BAT
CPO pin has decayed to less than or equal to the voltage
at the V pin.
BAT
3.8
4.6
V
V
= 3V
BAT
CPO
V
V
= 3V
BAT
CPO
= 4.2V
= 4.8V
3.6
4.4
C2 = C3 = C4 = 2.2μF
C2 = C3 = C4 = 2.2μF
3.4
3.2
3.0
2.8
2.6
2.4
4.2
4.0
3.8
3.6
3.4
3.2
–15
10
35
85
–40
60
–15
10
35
85
–40
60
TEMPERATURE (°C)
TEMPERATURE (°C)
321023 F03
321023 F04
Figure 3. Typical 1.5x ROL vs Temperature
Figure 4. Typical 2x ROL vs Temperature
321023fa
11
LTC3210-2/LTC3210-3
APPLICATIONS INFORMATION
V , CPO Capacitor Selection
BAT
loop is stored directly on the output capacitor. The output
capacitor also serves as the dominant pole for the control
loop.Topreventringingorinstability,itisimportantforthe
output capacitor to maintain at least 1.3μF of capacitance
over all conditions.
The style and value of the capacitors used with the
LTC3210-2/LTC3210-3 determine several important pa-
rameters such as regulator control loop stability, output
ripple, charge pump strength and minimum start-up
time.
In addition, excessive output capacitor ESR >100mΩ will
tend to degrade the loop stability. Multilayer ceramic chip
capacitorstypicallyhaveexceptionalESRperformanceand
when combined with a tight board layout will result in very
To reduce noise and ripple, it is recommended that low
equivalentseriesresistance(ESR)ceramiccapacitorsare
used for both CV
and C . Tantalum and aluminum
BAT
CPO
good stability. As the value of C
of output ripple, the value of CV
controls the amount
controls the amount
CPO
capacitors are not recommended due to high ESR.
BAT
The value of C directly controls the amount of output
CPO
of ripple present at the input pin(V ). The LTC3210-2/
BAT
ripple for a given load current. Increasing the size of C
CPO
LTC3210-3’s input current will be relatively constant while
the charge pump is either in the input charging phase or
the output charging phase but will drop to zero during
the clock nonoverlap times. Since the nonoverlap time
is small (~35ns), these missing “notches” will result in
only a small perturbation on the input power supply line.
Note that a higher ESR capacitor such as tantalum will
have higher input noise due to the higher ESR. Therefore,
ceramic capacitors are recommended for low ESR. Input
noise can be further reduced by powering the LTC3210-2/
LTC3210-3 through a very small series inductor as shown
in Figure 5. A 10nH inductor will reject the fast current
notches, thereby presenting a nearly constant current
load to the input power supply. For economy, the 10nH
inductor can be fabricated on the PC board with about
1cm (0.4") of PC board trace.
will reduce output ripple at the expense of higher start-up
current. The peak-to-peak output ripple of the 1.5x mode
is approximately given by the expression:
IOUT
(3f•C
VRIPPLE(P−P)
=
(3)
)
where f
is the LTC3210-2/LTC3210-3 oscillator fre-
OSC
quencyortypically800kHzandC
capacitor.
istheoutputstorage
CPO
The output ripple in 2x mode is very small due to the fact
that load current is supplied on both cycles of the clock.
Bothstyleandvalueoftheoutputcapacitorcansignificantly
affectthestabilityoftheLTC3210-2/LTC3210-3.Asshown
in the Block Diagram, the LTC3210-2/LTC3210-3 use a
control loop to adjust the strength of the charge pump to
match the required output current. The error signal of the
V
BAT
LTC3210-2
LTC3210-3
GND
321023 F05
Figure 5. 10nH Inductor Used for Input Noise
Reduction (Approximately 1cm of Board Trace)
321023fa
12
LTC3210-2/LTC3210-3
APPLICATIONS INFORMATION
Flying Capacitor Selection
Layout Considerations and Noise
Due to the high switching frequency and the transient
currents produced by the LTC3210-2/LTC3210-3, careful
board layout is necessary. A true ground plane and short
connections to all capacitors will improve performance
and ensure proper regulation under all conditions.
Warning: Polarized capacitors such as tantalum or
aluminum should never be used for the flying capaci-
tors since their voltage can reverse upon start-up of
the LTC3210-2/LTC3210-3. Ceramic capacitors should
always be used for the flying capacitors.
The flying capacitor pins C1P, C2P, C1M and C2M will
have high edge rate waveforms. The large dv/dt on these
pins can couple energy capacitively to adjacent PCB runs.
Magneticfieldscanalsobegeneratediftheflyingcapacitors
are not close to the LTC3210-2/LTC3210-3 (i.e., the loop
area is large). To decouple capacitive energy transfer, a
Faraday shield may be used. This is a grounded PCB trace
betweenthesensitivenodeandtheLTC3210-2/LTC3210-3
pins. For a high quality AC ground, it should be returned
to a solid ground plane that extends all the way to the
LTC3210-2/LTC3210-3.
The flying capacitors control the strength of the charge
pump. In order to achieve the rated output current it is
necessary to have at least 1.6μF of capacitance for each
of the flying capacitors. Capacitors of different materials
losetheircapacitancewithhighertemperatureandvoltage
at different rates. For example, a ceramic capacitor made
of X7R material will retain most of its capacitance from
–40°C to 85°C whereas a Z5U or Y5V style capacitor will
lose considerable capacitance over that range. Capacitors
mayalsohaveaverypoorvoltagecoefficientcausingthem
to lose 60% or more of their capacitance when the rated
voltage is applied. Therefore, when comparing different
capacitors, it is often more appropriate to compare the
amount of achievable capacitance for a given case size
ratherthancomparingthespecifiedcapacitancevalue.For
example, over rated voltage and temperature conditions,
a 1μF, 10V, Y5V ceramic capacitor in a 0603 case may not
provide any more capacitance than a 0.22μF, 10V, X7R
available in the same case. The capacitor manufacturer’s
data sheet should be consulted to determine what value
of capacitor is needed to ensure minimum capacitances
at all temperatures and voltages.
The following guidelines should be followed when design-
ing a PCB layout for the LTC3210-2/LTC3210-3:
• The Exposed Pad should be soldered to a large cop-
per plane that is connected to a solid, low impedance
ground plane using plated through-hole vias for proper
heat sinking and noise protection.
• Input and output capacitors must be placed close to the
part.
• The flying capacitors must be placed close to the part.
The traces from the pins to the capacitor pad should
be as wide as possible.
Table 2 shows a list of ceramic capacitor manufacturers
and how to contact them:
• V , CPO traces must be wide to minimize inductance
BAT
Table 2. Recommended Capacitor Vendors
and handle high currents.
AVX
www.avxcorp.com
www.kemet.com
www.murata.com
www.t-yuden.com
www.vishay.com
• LED pads must be large and connected to other layers
of metal to ensure proper heat sinking.
Kemet
Murata
Taiyo Yuden
Vishay
• RM and RC pins are sensitive to noise and capacitance.
The resistors should be placed near the part with mini-
mum line width.
321023fa
13
LTC3210-2/LTC3210-3
APPLICATIONS INFORMATION
Power Efficiency
In 1.5x boost mode, the efficiency is similar to that of a
linear regulator with an effective input voltage of 1.5 times
the actual input voltage. This is because the input current
for a 1.5x charge pump is approximately 1.5 times the
load current. In an ideal 1.5x charge pump, the power
efficiency would be given by:
To calculate the power efficiency (η) of a white LED
driver chip, the LED power should be compared to the
input power. The difference between these two numbers
represents lost power whether it is in the charge pump
or the current sources. Stated mathematically, the power
efficiency is given by:
PLED
(VLED •ILED
(VBAT •(1.5)•ILED
)
VLED
(1.5•VBAT )
η
IDEAL
=
=
=
PIN
)
PLED
η =
PIN
Similarly, in 2x boost mode, the efficiency is similar to
that of a linear regulator with an effective input voltage
of 2 times the actual input voltage. In an ideal 2x charge
pump, the power efficiency would be given by:
TheefficiencyoftheLTC3210-2/LTC3210-3dependsupon
themodeinwhichitisoperating.RecallthattheLTC3210-2/
LTC3210-3 operates as a pass switch, connecting V to
BAT
CPO, until dropout is detected at the LED pin. This feature
providestheoptimumefficiencyavailableforagiveninput
voltage and LED forward voltage. When it is operating as
a switch, the efficiency is approximated by:
PLED
(VLED •ILED
PIN (VBAT •(2)•ILED
Thermal Management
)
VLED
(2•VBAT )
η
=
=
=
IDEAL
)
PLED
PIN
(VLED •ILED
(VBAT •IBAT
)
)
VLED
VBAT
For higher input voltages and maximum output cur-
rent, there can be substantial power dissipation in the
LTC3210-2/LTC3210-3. If the junction temperature
increases above approximately 150°C the thermal shut
down circuitry will automatically deactivate the output
current sources and charge pump. To reduce maximum
junction temperature, a good thermal connection to the
PC board is recommended. Connecting the Exposed Pad
to a ground plane and maintaining a solid ground plane
under the device will reduce the thermal resistance of the
package and PC board considerably.
η =
=
=
since the input current will be very close to the sum of
the LED currents.
At moderate to high output power, the quiescent current
of the LTC3210-2/LTC3210-3 is negligible and the expres-
sion above is valid.
Once dropout is detected at any LED pin, the LTC3210-2/
LTC3210-3 enable the charge pump in 1.5x mode.
321023fa
14
LTC3210-2/LTC3210-3
PACKAGE DESCRIPTION
UD Package
16-Lead Plastic QFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1691)
0.70 0.05
3.50 0.05
2.10 0.05
1.45 0.05
(4 SIDES)
PACKAGE OUTLINE
0.25 0.05
0.50 BSC
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
BOTTOM VIEW—EXPOSED PAD
PIN 1 NOTCH R = 0.20 TYP
OR 0.25 × 45° CHAMFER
R = 0.115
TYP
0.75 0.05
3.00 0.10
(4 SIDES)
15 16
PIN 1
TOP MARK
(NOTE 6)
0.40 0.10
1
2
1.45 0.10
(4-SIDES)
(UD16) QFN 0904
0.25 0.05
0.50 BSC
0.200 REF
0.00 – 0.05
NOTE:
1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WEED-2)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
321023fa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LTC3210-2/LTC3210-3
TYPICAL APPLICATION
3-LED MAIN, One LED Camera
C2
2.2μF
C3
2.2μF
MAIN
CAM
C1P C1M
C2P
C2M
CPO
V
V
BAT
BAT
C4
2.2μF
C1
2.2μF
LTC3210-3
MLED1
MLED2
MLED3
CLED
ENM
ENC
ENM
ENC
321023 TA02
RM
RC
GND
30.1k
1%
24.3k
1%
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1618
Constant Current, 1.4MHz, 1.5A Boost Converter VIN: 1.6V to 18V, VOUT(MAX) = 36V, IQ = 1.8mA, ISD <1μA, MS Package
LTC3205
250mA, 1MHz, Multi-Display LED Controller
400mA, 800kHz, Multi-Display LED Controller
VIN: 2.8V to 4.5V, VOUT(MAX) = 5.5V, IQ = 50μA, ISD <1μA, QFN Package
VIN: 2.8V to 4.5V, VOUT(MAX) = 5.5V, IQ = 50μA, ISD <1μA, QFN Package
LTC3206
LTC3208
High Current Software Configurable Multi-Display VIN: 2.9V to 4.5V, VOUT(MAX) = 5.5V, IQ = 250μA, ISD <3μA, 17 Current Sources
LED Controller
(MAIN, SUB, RGB, CAM, AUX), 5mm × 5mm QFN Package
LTC3209-1/
LTC3209-2
600mA MAIN/Camera/AUX LED Controller
VIN: 2.9V to 4.5V, IQ = 400mA, Up to 94% Efficiency, 4mm × 4mm
QFN-20 Package
LTC3210
MAIN/CAM LED Controller in 3mm × 3mm QFN
VIN: 2.9V to 4.5V, IQ = 400μA, 3-Bit DAC Brightness Control for MAIN and
CAM LEDs, 3mm × 3mm QFN Package
LTC3210-1
MAIN/CAM LED Controller with 64-Step
Brightness Control
6-Bit DAC Brightness Control for MAIN and 3-Bit Brightness Control for CAM,
3mm × 3mm QFN Package
LTC3214
LTC3215
500mA Camera LED Charge Pump
VIN: 2.9V to 4.5V, Single Output, 3mm × 3mm DFN Package
700mA Low Noise High Current LED
Charge Pump
VIN: 2.9V to 4.4V, VOUT(MAX) = 5.5V, IQ = 300μA, ISD <2.5μA, DFN Package
LTC3216
1A Low Noise High Current LED Charge Pump
with Independent Flash/Torch Current Control
VIN: 2.9V to 4.4V, VOUT(MAX) = 5.5V, IQ = 300μA, ISD <2.5μA, DFN Package
LTC3217
600mA Low Noise Multi-LED Camera Light
VIN: 2.9V to 4.4V, I = 400μA, Four 100mA Outputs, QFN Package
Q
LTC3440/LTC3441
600mA/1.2A IOUT, 2MHz/1MHz, Synchronous
Buck-Boost DC/DC Converter
VIN: 2.4V to 5.5V, VOUT(MAX) = 5.25V, IQ = 25μA/50μA, ISD <1μA,
MS/DFN Packages
LTC3443
600mA/1.2A IOUT, 600kHz, Synchronous
Buck-Boost DC/DC Converter
VIN: 2.4V to 5.5V, VOUT(MAX) = 5.25V, IQ = 28μA, ISD <1μA, DFN Package
LTC3453
1MHz, 800mA Synchronous Buck-Boost High
Power LED Driver
VIN(MIN): 2.7V to 5.5V, VIN(MAX): 2.7V to 4.5V, IQ = 2.5mA, ISD <6μA,
QFN Package
LT3467/LT3467A
LT3479
1.1A (ISW), 1.3/2.1MHz, High Efficiency Step-Up
DC/DC Converters with Integrated Soft-Start
VIN: 2.4V to 16V, VOUT(MAX) = 40V, IQ = 1.2mA, ISD <1μA, ThinSOT Package
3A, 42V, 3.5MHz Boost Converter
VIN: 2.5V to 24V, VOUT(MAX) = 40V, IQ = 2μA, ISD <1μA DFN, TSSOP Packages
321023fa
LT 1207 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
© LINEAR TECHNOLOGY CORPORATION 2006
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
相关型号：
LTC3212EDDB#PBF
LTC3212 - RGB LED Driver and Charge Pump; Package: DFN; Pins: 12; Temperature Range: -40°C to 85°C
Linear
LTC3212EDDB#TR
IC LED DISPLAY DRIVER, PDSO12, 3 X 2 MM, LEAD FREE, PLASTIC, DFN-12, Display Driver
Linear
LTC3212EDDB#TRM
IC LED DISPLAY DRIVER, PDSO12, 3 X 2 MM, LEAD FREE, PLASTIC, DFN-12, Display Driver
Linear
LTC3212EDDB#TRMPBF
LTC3212 - RGB LED Driver and Charge Pump; Package: DFN; Pins: 12; Temperature Range: -40°C to 85°C
Linear
LTC3214EDD#PBF
LTC3214 - 500mA Camera LED Charge Pump; Package: DFN; Pins: 10; Temperature Range: -40°C to 85°C
Linear
©2020 ICPDF网 联系我们和版权申明