LTC3210EUD-1#TRPBF [Linear]
暂无描述;
| 型号： | LTC3210EUD-1#TRPBF |
| 厂家： | 
Linear |
| 描述： | 暂无描述 控制器 |
| 文件： | 总16页 (文件大小：193K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC3210-1
MAIN/CAM LED Controller
with 64-Step Brightness Control
in 3mm × 3mm QFN
FEATURES
DESCRIPTION
The LTC®3210-1 is a low noise charge pump DC/DC con-
verter designed to drive four MAIN LEDs and one high
current CAM LED for camera lighting. The LTC3210-1
requires only four small ceramic capacitors and two cur-
rent set resistors to form a complete 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.
■
64:1 Linear Brightness Control Range for
MAIN Display
■
■
■
■
■
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 Packages with
0.55mm and 0.75mm Profiles
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 6-bit
linear DAC (64 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 LTC3210-1 is available in a 3mm × 3mm
16-lead QFN package. Standard (0.75mm) and ultra-thin
(0.55mm) package profiles are available.
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
4-LED MAIN Display
Efficiency vs VBAT Voltage
C2
C3
100
2.2μF
2.2μF
90
80
C1P C1M
BAT
C2P
C2M
MAIN
CAM
70
CPO
V
BAT
V
60
50
40
30
C1
2.2μF
C4
2.2μF
LTC3210-1
MLED1
MLED2
MLED3
MLED4
CLED
20
4 LEDs AT 9mA/LED
ENM
ENC
ENM
ENC
(TYP V AT 9mA = 3V, NICHIA NSCW100)
F
10
0
32101 TA01
T
= 25°C
A
RM
RC
GND
3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4
(V)
V
BAT
30.1k
1%
24.3k
1%
32101 TA01b
32101fc
1
LTC3210-1
W W
U W
ABSOLUTE AXI U RATI GS
(Note 1)
I
(Note 2) ......................................................500mA
CLED
V
, CPO to GND ........................................–0.3V to 6V
BAT
CPO Short-Circuit Duration.............................. Indefinite
Operating Temperature Range (Note 3)....–40°C to 85°C
Storage Temperature Range...................–65°C to 125°C
ENM, ENC ................................... –0.3V to (V + 0.3V)
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
CP0
1
2
3
4
12 GND
11 CLED
C1P
CPO
1
2
3
4
12 GND
11 CLED
17
17
ENM
ENC
RC
10
9
ENM
ENC
RC
10
9
MLED1
MLED1
5
6
7
8
5
6
7
8
UD PACKAGE
16-LEAD (3mm s 3mm) PLASTIC QFN
PD PACKAGE
16-LEAD (3mm s 3mm) PLASTIC UTQFN
T
= 125°C, θ = 68°C/W
JA
T
= 150°C, θ = 68°C/W
JA
JMAX
JMAX
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO A 4-LAYER PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3210EUD-1#PBF
LTC3210EPD-1#PBF
TAPE AND REEL
PART MARKING
LCBT
PACKAGE DESCRIPTION
TEMPERATURE RANGE
–40°C to 85°C
LTC3210EUD-1#TRPBF
LTC3210EPD-1#TRPBF
16-Lead (3mm × 3mm) Plastic QFN
LCXT
16-Lead (3mm × 3mm) Plastic UTQFN –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/
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
●
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, MLED4 Current
LED Current Ratio (I /I
)
I
= Full Scale
481
535
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
%
32101fc
2
LTC3210-1
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
MLED Current, 6-Bit Linear DAC
1 ENM Strobe (FS)
63 ENM Strobes (FS/63)
20
0.318
mA
mA
Unused MLED Detection
Test Current
●
●
MLED Tied to CPO
4
16
μA
V
Threshold Voltage
CLED Current
V
– V
0.5
1.5
CPO
MLED
●
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
CPO
CPO
Ω
BAT
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
PW
t
SD
t
EN
Minimum Pulse Width
200
50
ns
μs
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 LTC3210-1 is 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 4: 1.5x mode output impedance is defined as (1.5V – V )/I
.
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.
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.
32101fc
3
LTC3210-1
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C unless otherwise stated.
1.5x CPO Ripple
Dropout Time from Shutdown
Dropout Time When Enabled
V
CPO
C
= 3.6V
= 200mA
= 2.2μF
BAT
I
5.1V
2X
5.1V
2X
CPO
1V/DIV
CPO
1V/DIV
CPO
1.5X
1.5X
1X
1X
V
CPO
50mV/DIV
AC
COUPLED
EN
2V/DIV
ENC
2V/DIV
MODE
RESET
MODE
RESET
ENM = HIGH
250μs/DIV
500μs/DIV
500ns/DIV
32101 G01
32101 G02
32101 G03
1.5x Mode Charge Pump Open-Loop
Output Resistance vs Temperature
(1.5VBAT – VCPO)/ICPO
1x Mode Switch Resistance
vs Temperature
2x CPO Ripple
0.70
0.65
3.8
3.6
I
= 200mA
V
V
= 3V
= 4.2V
CPO
BAT
CPO
V
= 3.6V
= 200mA
= 2.2μF
BAT
I
CPO
CPO
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
500ns/DIV
32101 G04
–40
–15
35
60
85
–15
10
35
85
–40
60
TEMPERATURE (°C)
TEMPERATURE (˚C)
32101 G05
32101 G06
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
5.2
5.1
5.0
4.9
4.8
4.7
4.6
4.5
4.4
4.3
4.2
4.8
4.6
4.6
4.4
C2 = C3 = C4 = 2.2μF
V
V
= 3V
C2 = C3 = C4 = 2.2μF
BAT
CPO
= 4.8V
C2 = C3 = C4 = 2.2μF
V
= 3.3V
V
BAT
V
BAT
= 3.6V
= 3.4V
BAT
BAT
V
= 3.5V
= 3.6V
4.2
4.0
3.8
3.6
3.4
3.2
4.4
4.2
V
= 3.5V
BAT
V
BAT
V
= 3.4V
BAT
V
= 3.3V
BAT
4.0
3.8
3.6
V
= 3.2V
= 3.1V
BAT
V
= 3.2V
BAT
V
= 3.1V
BAT
V
BAT
V
= 3V
200
V
BAT
= 3V
400
BAT
0
100
200
300
500
–15
10
35
85
0
100
300
400
500
–40
60
LOAD CURRENT (mA)
LOAD CURRENT (mA)
TEMPERATURE (˚C)
32101 G09
32101 G07
32101 G08
32101fc
4
LTC3210-1
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
850
840
830
820
810
800
790
780
770
120
100
80
60
40
20
0
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
V
3.6
VOLTAGE (V)
4.5
3.9
4.2
MLED PIN CURRENT (mA)
BAT
32101 G10
32101 G11
32101 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
2.7
3.0
3.6
3.9
4.2
4.5
3.9
3.6
VOLTAGE (V)
4.5
3.3
V
2.7
3.0
3.3
V
4.2
VOLTAGE (V)
LOAD CURRENT (mA)
BAT
BAT
32101 G15
32101 G14
32101 G13
2x Mode Supply Current
CLED Pin Current
vs CLED Pin Voltage
vs ICPO (IVBAT – 2ICPO
)
20
400
V
= 3.6V
V
= 3.6V
BAT
BAT
360
320
280
240
200
160
120
80
15
10
5
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)
32101 G16
32101 G17
32101fc
5
LTC3210-1
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
V
= 3.6V
BAT
BAT
RC = 24.3k
6
4
2
0
0.00
0
0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20
MLED PIN VOLTAGE (V)
0.02
0
6
5
4
3
2
1
7
NUMBER OF ENC STROBE PULSES
32101 G18
32101 G19
MLED Current
vs ENM Strobe Pulses
Efficiency vs VBAT Voltage
20
18
16
14
12
10
8
90
80
70
60
50
40
30
20
10
0
V
= 3.6V
BAT
RM = 33.2k
6
4
300mA LED CURRENT
(TYP V AT 300mA = 3.1V, AOT-2015HPW
2
F
T
A
= 25°C
0
0
50 43 36 29 22 15
8
1
57
2.9 3.05 3.2 3.35 3.5 3.65
4.4
3.8 3.95 4.1 4.25
NUMBER OF ENM STROBE PULSES
V
(V)
BAT
32101 G20
32101 G21
32101fc
6
LTC3210-1
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.
and MLED1-4 (cathodes). The current to each LED output
is set via the ENM input, and the programming resistor
connected between RM and GND. Each of the four LED
outputs can be disabled by connecting the output directly
to CPO. A 10μA current will flow through each directly
connected LED output.
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.
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 12k or less will cause the LTC3210-1 to enter
overcurrent shutdown.
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 63
times to decrement the 6-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.HoldingtheENMorENCpinlowwillclearthecounter
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.
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.
V
(Pin15):Supplyvoltage.Thispinshouldbebypassed
BAT
with a 2.2μF, or greater low ESR ceramic capacitor.
MLED1, MLED2, MLED3, MLED4 (Pins 4, 5, 6, 7):
Outputs. MLED1 to MLED4 are the MAIN current source
outputs. The LEDs are connected between CPO (anodes)
Exposed Pad (Pin 17): This pad should be connected
directly to a low impedance ground plane for optimal
thermal and electrical performance.
32101fc
7
LTC3210-1
BLOCK DIAGRAM
C1P
1
C1M
14
C2P
16
C2M
13
800kHz
OSCILLATOR
12 GND
15
V
2
CPO
BAT
CHARGE PUMP
–
+
ENABLE CP
+
–
1.215V
4
5
6
7
MLED1
MLED2
MLED3
MLED4
TIMER
ENABLE MAIN
500Ω
8
3
RM
6-BIT
DOWN
COUNTER
6-BIT
LINEAR
DAC
MLED
CURRENT
SOURCES
4
ENM
50ns FILTER
250k
+
–
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
32101 BD
32101fc
8
LTC3210-1
OPERATION
Power Management
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 LTC3210-1 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
BAT
is connected directly to CPO. This mode provides maxi-
mum efficiency and minimum noise. The LTC3210-1 will
remain in 1x mode until an LED 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 LTC3210-1 will switch into 1.5x
mode. The CPO voltage will then start to increase and will
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.
attempt to reach 1.5x V
up to 4.6V. Any subsequent
BAT
dropout will cause the part to enter the 2x mode. The CPO
voltage will attempt to reach 2x V up to 5.1V. The part
BAT
will be 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)) • 535
CLED full-scale output current
= (1.215V/(RC + 500)) • 7700
phase.Thissequenceofcharginganddischargingtheflying
capacitors continues at a constant frequency of 800kHz.
LED Current Control
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.
The MLED currents are delivered by the four program-
mable current sources. 64 linear current settings (0mA
to 20mA, RM = 30.1k) are available by strobing the ENM
pin. Each positive strobe edge decrements a 6-bit down
counter which controls a 6-bit linear DAC. When the
ENC resets the mode to 1x on a falling edge.
t
≥
t
t
SD 150μs (TYP)
PW 200ns
EN 150μs (TYP)
ENM
OR ENC
PROGRAMMED
CURRENT
LED
CURRENT
ENM = ENC = LOW
SHUTDOWN
32101 F01
Figure 1. Current Programming Timing Diagram
32101fc
9
LTC3210-1
OPERATION
Soft-Start
When the LTC3210-1 operates 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 effective
Initially, when the part is in shutdown, a weak switch
connects V to CPO. This allows V to slowly charge
BAT
BAT
the CPO output capacitor to prevent large charging
currents.
open-loop output resistance, R (Figure 2).
OL
The LTC3210-1 also employs a soft-start feature on its
charge pump to prevent excessive inrush current and
supplydroopwhenswitchingintothestep-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
–
–
32101 F02
Figure 2. Charge Pump Thevenin
Equivalent Open-Loop Circuit
Charge Pump Strength and Regulation
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
1.5V
– CPO for 1.5x mode and 2V
– CPO for 2x
BAT
BAT
Table 1. Charge Pump Output Regulation Voltages
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
32101fc
10
LTC3210-1
OPERATION
From Figure 2, for 1.5x mode the available current is
given by:
Thermal Protection
The LTC3210-1 has 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
The LTC3210-1 will automatically switch from 1x mode
to 1.5x mode and subsequently to 2x mode whenever a
dropoutconditionisdetectedatanLEDpin.Dropoutoccurs
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 typically 0.4ms.
Notice that the advantage voltage in this case is 3.1V • 2
– 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.
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
Shutdown Current
In shutdown mode all the circuitry is turned off and the
LTC3210-1 draws a very low current from the V
sup-
BAT
BAT
connect V and CPO in 1x mode until the voltage at the
BAT
ply. Furthermore, CPO is weakly connected to V . The
CPO pin has decayed to less than or equal to the voltage
LTC3210-1 enters 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 define the
shutdown state when the drivers are in a high imped-
ance state.
at the V pin.
BAT
3.8
4.6
V
V
= 3V
V
= 3V
BAT
CPO
BAT
CPO
= 4.2V
V
= 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)
32101 F03
32101 F04
Figure 3. Typical 1.5x ROL vs Temperature
Figure 4. Typical 2x ROL vs Temperature
32101fc
11
LTC3210-1
APPLICATIONS INFORMATION
V , CPO Capacitor Selection
BAT
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
The style and value of the capacitors used with the
LTC3210-1determineseveralimportantparameterssuch
as regulator control loop stability, output ripple, charge
pump strength and minimum start-up time.
good stability. As the value of C
controls the amount of
controls the amount of
CPO
output ripple, the value of CV
BAT
To reduce noise and ripple, it is recommended that low
equivalentseriesresistance(ESR)ceramiccapacitorsare
ripplepresentattheinputpin(V ).TheLTC3210-1’sinput
BAT
currentwillberelativelyconstantwhilethechargepumpis
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 LTC3210-1 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.
used for both CV
and C . Tantalum and aluminum
BAT
CPO
capacitors are not recommended due to high ESR.
The value of C directly controls the amount of output
CPO
ripple for a given load current. Increasing the size of C
CPO
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
(3fOSC •CCPO
VRIPPLE(P−P)
=
(3)
)
Where f
is the LTC3210-1 oscillator frequency or typi-
OSC
cally 800kHz and C
is the output storage capacitor.
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.
Both style and value of the output capacitor can signifi-
cantly affect the stability of the LTC3210-1. As shown in
the Block Diagram, the LTC3210-1 uses a control loop
to adjust the strength of the charge pump to match the
required output current. The error signal of the loop is
storeddirectlyontheoutputcapacitor.Theoutputcapacitor
also serves as the dominant pole for the control loop. To
prevent ringing or instability, it is important for the output
capacitor to maintain at least 1.3μF of capacitance over
all conditions.
V
BAT
LTC3210-1
GND
32101 F05
Figure 5. 10nH Inductor Used for Input Noise
Reduction (Approximately 1cm of Board Trace)
32101fc
12
LTC3210-1
APPLICATIONS INFORMATION
Flying Capacitor Selection
Layout Considerations and Noise
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
LTC3210-1. Ceramic capacitors should always be used
for the flying capacitors.
Due to the high switching frequency and the transient cur-
rents produced by the LTC3210-1, careful board layout is
necessary. A true ground plane and short connections to
allcapacitorswillimproveperformanceandensureproper
regulation under all conditions.
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 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 LTC3210-1 (i.e., the loop area is large).
To decouple capacitive energy transfer, a Faraday shield
may be used. This is a grounded PCB trace between the
sensitive node and the LTC3210-1 pins. For a high quality
AC ground, it should be returned to a solid ground plane
that extends all the way to the LTC3210-1.
The following guidelines should be followed when design-
ing a PCB layout for the LTC3210-1:
• The exposed pad should be soldered to a large copper
planethatisconnectedtoasolid,lowimpedanceground
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
and handle high currents.
Table 2. Recommended Capacitor Vendors
• LED pads must be large and connected to other layers
of metal to ensure proper heat sinking.
AVX
www.avxcorp.com
www.kemet.com
www.murata.com
www.t-yuden.com
www.vishay.com
Kemet
• RM and RC pins are sensitive to noise and capacitance.
The resistors should be placed near the part with mini-
mum line width.
Murata
Taiyo Yuden
Vishay
32101fc
13
LTC3210-1
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
)
VLED
ηIDEAL
=
=
=
PLED
η=
PIN (VBAT •(1.5)•ILED) (1.5• VBAT
)
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:
TheefficiencyoftheLTC3210-1dependsuponthemodein
which it is operating. Recall that the LTC3210-1 operates
as a pass switch, connecting V
to CPO, until dropout
BAT
is detected at the LED pin. This feature provides the op-
timum efficiency available for a given input voltage and
LED forward voltage. When it is operating as a switch, the
efficiency is approximated by:
PLED
(VLED •ILED
(VBAT •(2)•ILED) (2• VBAT
)
VLED
ηIDEAL
=
=
=
P
)
IN
Thermal Management
PLED
(VLED •ILED) VLED
= =
For higher input voltages and maximum output cur-
rent, there can be substantial power dissipation in the
LTC3210-1. 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 recom-
mended. 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=
P
(VBAT •IBAT) VBAT
IN
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 LTC3210-1 is negligible and the expression above
is valid.
Once dropout is detected at any LED pin, the LTC3210-1
enables the charge pump in 1.5x mode.
32101fc
14
LTC3210-1
PACKAGE DESCRIPTION
UD Package
16-Lead Plastic QFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1691)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
BOTTOM VIEW—EXPOSED PAD
PIN 1 NOTCH R = 0.20 TYP
OR 0.25 s 45o CHAMFER
R = 0.115
TYP
0.75 p 0.05
3.00 p 0.10
(4 SIDES)
15 16
0.70 p 0.05
PIN 1
TOP MARK
(NOTE 6)
0.40 p 0.10
1
2
1.45 p 0.10
(4-SIDES)
3.50 p 0.05
2.10 p 0.05
1.45 p 0.05
(4 SIDES)
PACKAGE
OUTLINE
(UD16) QFN 0904
0.25 p 0.05
0.50 BSC
0.200 REF
0.25 p 0.05
0.50 BSC
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
PD Package
16-Lead Plastic UTQFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1738 Rev Ø)
PIN 1 NOTCH R = 0.20 TYP
OR 0.25 s 45o CHAMFER
R = 0.115
TYP
0.55 p 0.05
3.00 p 0.10
15 16
R = 0.05
TYP
PIN 1
0.40 p 0.10
0.70 p 0.05
TOP MARK
(NOTE 6)
1
1.45 p0.10
1.45 p0.10
2
3.50 p 0.05
1.45 p 0.05
1.45 p 0.05
1.50 REF
3.00 p 0.10
(4 SIDES)
1.50 REF
2.10 p 0.05
PACKAGE
OUTLINE
(PD16) UTQFN 1106 REV
Ø
0.125 REF
0.25 p 0.05
0.50 BSC
BOTTOM VIEW—EXPOSED PAD
0.25 p 0.05
0.50 BSC
0.00 – 0.05
NOTE:
1. DRAWING CONFORMS TO JEDEC PACKAGE VARIATION (TBI)
2. DRAWING NOT TO SCALE
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
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
32101fc
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
LTC3210-1
TYPICAL APPLICATION
3-LED MAIN, One LED Camera
C2
2.2μF
C3
2.2μF
MAIN
CAM
C1P C1M
V
BAT
C2P
C2M
CPO
V
BAT
C4
2.2μF
C1
2.2μF
LTC3210-1
MLED1
MLED2
MLED3
MLED4
CLED
MLED4 DISABLED
ENM
ENC
ENM
ENC
32101 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 and Ultra-Thin 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
32101fc
LT 0708 REV C • 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：
LTC3210EUD-2#PBF
LTC3210-2/LTC3210-3 - MAIN/CAM LED Controllers with 32-Step Brightness Control in 3mm x 3mm QFN; Package: QFN; Pins: 16; Temperature Range: -40°C to 85°C
Linear
LTC3210EUD-3#PBF
LTC3210-2/LTC3210-3 - MAIN/CAM LED Controllers with 32-Step Brightness Control in 3mm x 3mm QFN; Package: QFN; Pins: 16; Temperature Range: -40°C to 85°C
Linear
LTC3212EDDB#PBF
LTC3212 - RGB LED Driver and Charge Pump; Package: DFN; Pins: 12; Temperature Range: -40°C to 85°C
Linear
©2020 ICPDF网 联系我们和版权申明