FEATURES
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LTC3216
1A Low Noise High Current
LED Charge Pump with
Independent Torch/Flash Current Control
DESCRIPTION
The LTC
®
3216 is a low noise, high current charge pump
DC/DC converter designed to power high current LEDs.
The part includes an accurate programmable current
source capable of driving loads up to 1A from a 2.9V to
4.4V input. Low external parts count (two flying capacitors,
two programming resistors and two bypass capacitors at
V
IN
and CPO) make the LTC3216 ideally suited for small,
battery-powered applications.
Built-in soft-start circuitry prevents excessive inrush cur-
rent during start-up. High switching frequency enables
the use of small external capacitors. Independent high
and low current settings are programmed by two external
resistors. Shutdown mode and current output levels are
selected via two logic inputs.
An ultralow dropout current source maintains accurate
LED current at very low I
LED
voltages. Automatic mode
switching optimizes efficiency by monitoring the voltage
across the LED current source and switching modes only
when I
LED
dropout is detected. The LTC3216 is available
in a small 3mm
×
4mm 12-Lead DFN package.
L,
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.
High Efficiency Operation: 1x, 1.5x or 2x Boost
Modes with Automatic Mode Switching
Ultralow Dropout I
LED
Current Control
Output Current up to 1A
Low Noise Constant Frequency Operation
Independent Low Current/High Current
Programming and Enable Pins
Wide V
IN
Range: 2.9V to 4.4V
Open/Shorted LED Protection
LED Disconnect in Shutdown
Low Shutdown Current: 2.5μA
4% LED Current Programming Accuracy
Automatic Soft-Start Limits Inrush Current
No Inductors
Tiny Application Circuit (All Components <1mm
Profile)
3mm
×
4mm 12-Lead DFN Package
APPLICATIONS
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LED Torch/Camera Light Supply for Cell Phones,
PDAs and Digital Cameras
Generic Lighting and/or Flash/Strobe Applications
TYPICAL APPLICATION
C1
2.2μF
C2
2.2μF
Torch Mode Efficiency vs V
IN
100
90
EFFICIENCY (P
LED
/PIN) (%)
I
LED
= 200mA
C1
2.9V TO 4.4V
C
IN
2.2μF
+
C1
–
C2
+
C2
–
CPO
C
CPO
4.7μF
LED1
80
70
60
50
40
30
20
10
0
2.8 3.0
3.2
3.4 3.6 3.8
V
IN
(V)
4.0
P
LED
/PIN
LUMILEDS LXCL-PWF1
V
F
= 3V TYP AT 200mA
4.2
4.4
V
IN
LTC3216
I
LED
EN1 (TORCH)
EN2 (FLASH)
EN1
EN2
I
SET1
20k
1%
I
SET2
6.65k
1%
EN1
0
1
0
1
EN2
0
0
1
1
I
LED
0 (SHUTDOWN)
200mA (TORCH)
600mA
800mA (FLASH)
3216 TA01a
LED1: LUMILEDS LXCL-PWF1 LUXEON FLASH
3216 TA01b
3216fc
1
LTC3216
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
C2
+
C1
+
CPO
I
SET1
I
LED
I
SET2
1
2
3
4
5
6
13
12 C1
–
11 GND
10 C2
–
9
8
7
VIN
EN2
EN1
V
IN
to GND ................................................ –0.3V to 5.5V
CPO to GND .............................................. –0.3V to 5.5V
EN2, EN1...........................................–0.3V to V
IN
+ 0.3V
I
CPO
, I
ILED
(Note 2) .............................................1500mA
CPO Short-Circuit Duration .............................. Indefinite
Operating Temperature Range (Note 3).... –40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
DE12 PACKAGE
12-LEAD (4mm
×
3mm) PLASTIC DFN
EXPOSED PAD IS GND (PIN 13)
MUST BE SOLDERED TO PCB
T
JMAX
= 125°C,
θ
JA
= 43°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC3216EDE#PBF
TAPE AND REEL
LTC3216EDE#TRPBF
PART MARKING
3216
PACKAGE DESCRIPTION
12-Lead (4mm
×
3mm) 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/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, C
IN
= C1 = C2 = 2.2μF C
CPO
= 4.7μF
,
.
PARAMETER
Input Power Supply
V
IN
Operating Voltage
I
VIN
Operating Current
I
CPO
= 0mA, 1x Mode
I
CPO
= 0mA, 1.5x
I
CPO
= 0mA, 2x Mode
EN2 = EN1 = LOW
I
LED
= 200mA to 800mA
Mode Switch Threshold, I
LED
= 200mA
EN1 = HIGH, EN2 = LOW
EN1 = LOW or HIGH, EN2 = HIGH
EN
to LED Current On
●
●
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
2.9
TYP
MAX
4.4
UNITS
V
μA
mA
mA
300
7
9.2
2.5
3120
3250
120
150
2
130
7
3380
I
VIN
Shutdown Current
LED Current
LED Current Ratio (I
LED
/I
SET1/2
)
I
LED
Dropout Voltage
Mode Switching Delay
(LED Warmup Time)
LED Current On Time
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
μA
mA/mA
mV
ms
ms
μs
I
CPO
= 0mA
I
CPO
= 0mA
I
CPO
= 0mA
V
IN
= 3.4V, V
CPO
< 4.6V, C1 = C2 = 2.2μF
V
IN
4.6
5.1
0.25
1.5
V
V
V
Ω
Ω
3216fc
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LTC3216
ELECTRICAL CHARACTERISTICS
PARAMETER
2x Mode Output Impedance
CLK Frequency
CPO Short-Circuit Detection
Threshold Voltage
Test Current
EN1, EN2
High Level Input Voltage (V
IH
)
Low Level Input Voltage (V
IL
)
Input Current (I
IH
)
Input Current (I
IL
)
I
SET1
, I
SET2
V
ISET1
, V
ISET2
I
ISET1
, I
ISET2
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. Assumes an
operating duty cycle of ≤ 10% under absolute maximum conditions for
durations less than 10 seconds. Max current for continuous operation is
500mA.
I
SETX
= 50μA
●
●
●
●
●
●
The
l
denotes the specifications which apply over the full operating
,
.
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, C
IN
= C1 = C2 = 2.2μF C
CPO
= 4.7μF
CONDITIONS
V
IN
= 3.2V, V
CPO
< 5.1V, C1 = C2 = 2.2μF
●
MIN
0.6
0.5
10
1.4
TYP
1.7
0.9
MAX
1.2
1.5
30
UNITS
Ω
MHz
V
mA
V
EN1/EN2 = High
EN1 = EN2 = Low, V
CPO
= 0V
●
●
0.4
–1
–1
1.195
1.22
1
1
1.245
321
V
μA
μA
V
μA
Note 3:
The LTC3216E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
TYPICAL PERFORMANCE CHARACTERISTICS
I
LED
Dropout Voltage
vs LED Current
0.8
0.7
I
LED
PIN CURRENT (mA)
DROPOUT VOLTAGE (V)
0.6
0.5
0.4
0.3
0.2
0.1
0
0
200
400
600
800
LED CURRENT (mA)
1000
3216 G01
(T
A
= 25°C unless otherwise specified)
I
LED
Pin Current
vs I
LED
Pin Voltage
600
500
400
300
200
100
0
I
LED
= 500mA
1000
400mA
300mA
200mA
100mA
I
LED
(mA)
800
600
400
200
0
1200
I
LED
vs R
SET
V
IN
= 3.6V
0
0.2
0.4
0.6
0.8
I
LED
PIN VOLTAGE (V)
1.0
3216 G02
0
5
10
15 20 25
R
SET
(kΩ)
30
35
40
1573 G03
3216fc
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LTC3216
TYPICAL PERFORMANCE CHARACTERISTICS
1x Mode Charge Pump Open-
Loop Output Resistance vs
Temperature
0.31
0.29
SWITCH RESISTANCE (Ω)
0.27
0.25
0.23
0.21
0.19
0.17
0.15
–40
–15
35
TEMPERATURE (°C)
10
60
85
3216 G04
(T
A
= 25°C unless otherwise specified)
2x Mode Charge Pump
Open-Loop Output Resistance
(2V
IN
– V
CPO
)/I
CPO
vs Temperature
2.0
1.8
OUTPUT RESISTANCE (Ω)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
V
IN
= 3V
V
CPO
= 4.8V
C
IN
= C1 = C2 = 2.2μF
C
CPO
= 4.7μF
–15
35
10
TEMPERATURE (°C)
60
85
3216 G06
1.5x Mode Charge Pump
Open-Loop Output Resistance
(1.5V
IN
– V
CPO
)/I
CPO
vs Temperature
1.8
1.6
I
CPO
= 200mA
V
IN
= 3.3V
V
IN
= 3.6V
V
IN
= 3.9V
OUTPUT RESISTANCE (Ω)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
V
IN
= 3V
V
CPO
= 4.2V
C
IN
= C1 = C2 = 2.2μF
C
CPO
= 4.7μF
–15
35
10
TEMPERATURE (°C)
60
85
3216 G05
0
–40
0
–40
Input Shutdown Current
vs Input Voltage
4.0
INPUT SHUTDOWN CURRENT (μA)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
2.9
3.1
3.5 3.7 3.9 4.1
INPUT VOLTAGE (V)
4.5
T
A
= 85°C
T
A
= –40°C
T
A
= 25°C
FREQUENCY (kHz)
930
920
Oscillator Frequency
vs Supply Voltage
100
90
T
A
= 25°C
T
A
= –40°C
T
A
= 85°C
EFFICIENCY (PLED/PIN) (%)
80
70
60
50
40
30
20
10
2.9
3.1
3.3 3.5 3.7 3.9 4.1
SUPPLY VOLTAGE (V)
4.3
4.5
0
Efficiency vs V
IN
910
900
890
880
870
860
850
840
200mA
400mA
600mA
I
LED
= 800mA
LED = LXCL-PWF1 LUMILEDS
2.8 3.0
3.2
3.4 3.6 3.8
V
IN
(V)
4.0
4.2
4.4
3.3
4.3
3216 G07
3216 G08
3216 G09
I
SET
/I
LED
Current Ratio vs I
LED
Current
3400
3350
CURRENT RATIO
3300
T
A
= –40°C
3250
T
A
= 85°C
3200
3150
3100
T
A
= 25°C
V
CPO
50mV/DIV
A/C COUPLED
1.5x Mode CPO Output Ripple
V
IN
= 3.6V
I
CPO
= 200mA
0 100 200 300 400 500 600 700 800 900
I
LED
CURRENT(mA)
3216 G10
500ns/DIV
3216 G11
3216fc
4
LTC3216
TYPICAL PERFORMANCE CHARACTERISTICS
2x Mode CPO Output Ripple
V
CPO
1V/DIV
V
CPO
20mV/DIV
A/C COUPLED
(T
A
= 25°C unless otherwise specified)
Charge Pump Mode Switching
and Input Current
I
VIN
500mA/DIV
EN2
5V/DIV
V
IN
= 3.6V
I
CPO
= 400mA
500ns/DIV
3216 G12
V
IN
= 3V
1ms/DIV
3216 G13
PIN FUNCTIONS
C2
+
, C1
+
, C2
–
, C1
–
(Pins 1, 2, 10, 12):
Charge Pump
Flying Capacitor Pins. A 2.2μF X5R or X7R ceramic ca-
pacitor should be connected from C1
+
to C1
–
and from
C2
+
to C2
–
.
CPO (Pin 3):
Output. CPO is the output of the charge
pump. This pin may be enabled or disabled using the EN1
and EN2 inputs. A 4.7μF X5R or X7R ceramic capacitor is
required from CPO to GND.
I
SET1
/I
SET2
(Pins 4, 6):
LED Current Programming Resistor
Pins. The I
SET1
and I
SET2
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 of 2k or less will cause the LTC3216 to enter
overcurrent shutdown mode.
I
LED
(Pin 5):
Output. I
LED
is the LED current source output.
The LED is connected between CPO (anode) and I
LED
(cathode). The current into the I
LED
pin is set via the EN1
and EN2 inputs, and the programming resistors connected
from I
SET2
and I
SET1
to GND.
EN1/EN2 (Pins 7, 8):
Inputs. The EN1 and EN2 pins are
used to select which current level is being supplied to the
LED, as well as to put the part into shutdown mode. The
truth table for these pins is as follows:
Truth Table
EN1
0
1
0
1
EN2
0
0
1
1
MODE
Shutdown
Low Current
High Current
Low + High Current
V
IN
(Pin 9):
Power. Supply voltage for the LTC3216. V
IN
should be bypassed with a 2.2μF or greater low impedance
ceramic capacitor to GND.
GND (Pin 11):
Charge Pump Ground. This pin should be
connected directly to a low impedance ground plane.
Exposed Pad (Pin 13):
Control Signal Ground. This pad
must be soldered to a low impedance ground plane for
optimum thermal and electrical performance.
3216fc
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