LTC3230
5-LED Main/Sub Display
Driver with Dual LDO
FEATURES
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DESCRIPTION
The LTC
®
3230 is a low noise charge pump DC/DC converter
designed to drive 4 Main LEDs and 1 Sub LED, plus two
200mA linear regulators to provide additional system
power. The LTC3230 charge pump requires only four small
ceramic capacitors and one current set resistor 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.
Main and Sub full-scale current settings are programmed
by a single external resistor.
Charge pump efficiency is optimized based on the voltage
across the LED current sources. The part powers up in 1x
mode and automatically switches to the next higher mode,
1.5x and subsequently 2x, whenever any LED current
source approaches dropout.
Two 200mA linear regulators have independent enable
and output voltage select pins. Each regulator can be set
to one of three pre-selected output voltages with tri-level
input pins. The regulators may be enabled independently
of the charge pump.
The LTC3230 is available in a low profile (0.75mm) 3mm
×
3mm 20-lead QFN package.
Low Noise Charge Pump Provides High Efficiency
with Automatic Mode Switching
Multimode Operation: 1x, 1.5x, 2x
Full-Scale Current Set Resistor
Up to 125mA Total LED Current
Single Wire Enable/Brightness Control for Main and
Sub Display LEDs
32:1 Linear LED Brightness Control
Dual 200mA Linear Regulators
Four 25mA Low Dropout Main LED Current Sources
One 25mA Low Dropout Sub LED Current Source
Low Noise Constant Frequency Operation
Low Shutdown Current: 3μA
Internal Soft-Start Limits Inrush Current During
Start-Up and Mode Switching
Open/Short LED Protection
No Inductors
20-Lead 3mm
×
3mm QFN Package
APPLICATIONS
■
Multi-LED Driver and Dual LDO Supplies for Cell
Phone, PDA, Digital Camera and PND Applications
, 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
C1
1
m
F
C2
1
m
F
Efficiency vs V
IN
Voltage
100
90
MAIN
C6
1
m
F D1
D2
D3
D4
SUB
C3
2.2
m
F
ENM
ENS
EFFICIENCY (P
LED
/P
IN
) (%)
V
IN
= 2.7V
TO 5.5V
C1P C1M C2P C2M 125mA
CPO
V
IN
LTC3230
ENM
ENS
ENLDO1
ENLDO2
V1
V2
R
SET
MLED1
MLED2
MLED3
MLED4
SLED
LDO1
LDO2
80
70
60
50
40
30
20
10
0
3
3.2
3.4
3.6 3.8
V
IN
(V)
4
4.2
4.4
4 LEDs AT 9mA/LED
V
F
= 3V
T
A
= 25°C
D5
C4
1
m
F
C5
1
m
F
1.5V
200mA
2.8V
200mA
3230 TA01a
R
SET
17.4k
1%
ENM OR ENS
GND
SET BRIGHTNESS LEVEL
ON
OFF
3230 TA01b
3230fa
1
LTC3230
ABSOLUTE MAXIMUM RATINGS
(Notes 1-5)
PIN CONFIGURATION
TOP VIEW
C1M
MLED3
C2M
15 LDO1
14 LDO2
21
13 V1
12 V2
11 ENM
6
SLED
7
MLED1
8
MLED2
9 10
MLED4
C1P
CPO 1
ENLDO1 2
ENLDO2 3
R
SET
4
ENS 5
C2P
V
IN
20 19 18 17 16
V
IN
, CPO....................................................... –0.3V to 6V
ENM, ENS, ENLDO1, ENLDO2,
V1, V2, LDO1, LDO2 ......................–0.3V to (V
IN
+ 0.3V)
I
CPO
(Note 2) ........................................................200mA
LD01, LD02 (Note 3)............................................200mA
MLED1-4, SLED, R
SET
.................................. –0.3V to 6V
Operating Ambient Temperature Range
(Note 4).................................................... –40°C to 85°C
Junction Temperature ........................................... 125°C
Storage Temperature Range................... –65°C to 150°C
UD PACKAGE
20-LEAD (3mm
×
3mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 68°C/W
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3230EUD#PBF
TAPE AND REEL
LTC3230EUD#TRPBF
PART MARKING
LCYB
PACKAGE DESCRIPTION
20-Lead (3mm
×
3mm) Plastic QFN
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
CONDITIONS
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, C1 = C2 = C4 = C5 = C6 = 1μF, R
SET
= 17.4k, ENM = ENS =
high, ENLDO1 = ENLDO2 = low, unless otherwise noted.
MIN
●
TYP
0.48
1.2
1.6
MAX
5.5
UNITS
V
mA
mA
mA
2.7
I
CPO
= 0, 1x Mode
I
CPO
= 0, 1.5x Mode
I
CPO
= 0, 2x Mode
ENM = ENS = ENLD02 = ENLD01 = Low
●
V
IN
Shutdown Current
LED Current Ratio (I
LED
/I
RSET
)
LED Dropout Voltage
LED Current Matching
MLED/SLED Current, 5-Bit Linear DAC
Unused LED Detection
Threshold Voltage
Test Current
3
555
9
μA
A/A
mV
%
mA
mA
MLED1, MLED2, MLED3, MLED4 and SLED Currents
Mode Switch Threshold, I
MLED
= 15mA
Any Two MLED Outputs, I
MLED
= Full Scale
1 ENM/ENS Strobe (FS)
31 ENM/ENS Strobes (FS/31)
V
CPO
– MLED
LED Tied to CPO
●
●
100
0.5
25.5
0.860
200
39
780
178
mV
μA
3230fa
2
LTC3230
ELECTRICAL CHARACTERISTICS
PARAMETER
CPO Short Circuit Detection
Threshold Voltage
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
Mode Switching Delay
t
EN
LDO1, LDO2
Bias per 1 LDO
Additional DC Bias per LDO
Output Voltage Accuracy
Current Limit
Line Regulation
Load Regulation
Dropout Voltage
V1, V2
V
IL
V
IH
Shutdown Input Current
Active Input Current
ENM, ENS, ENLDO1, ENLDO2
V
IL
V
IH
I
IH
I
IL
ENM, ENS Timing
t
PWH
t
PWL
t
SD
R
SET
V
RSET
I
RSET
●
●
●
●
●
●
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, C1 = C2 = C4 = C5 = C6 = 1μF, R
SET
= 17.4k, ENM = ENS =
high, ENLDO1 = ENLDO2 = low, unless otherwise noted.
CONDITIONS
MIN
0.4
V
IN
4.5
5.0
1.6
V
IN
= 3.4V, V
CPO
= 4.6V (Note 6)
V
IN
= 3.4V, V
CPO
= 5.1V (Note 6)
7.9
9.2
0.9
0.5
Current Source Enable Time (ENM, ENS = High)
(Note 7)
ENM = ENS = Low
I
OUT
= 100μA
V
LDO
= 1.8V, I
OUT
= 50mA
V
IN
= 3.6V, 100μA < I
LDO
< 200mA
LDO2, V
LDO
= 3.3V, V
IN
– V
LDO
at V
LDO
3% Down
from V
LDO
Measureed at V
IN
= 4.3V
●
●
●
TYP
MAX
1.3
UNITS
V
V
V
V
Ω
Ω
Ω
MHz
ms
I
CPO
= 0mA
I
CPO
= 0mA
I
CPO
= 0mA
250
μs
125
60
–3
280
475
0.1
0.65
250
3
750
μA
μA
%
mA
%/V
%
mV
0.2
V
IN
– 0.2
–1
–3
1
3
0.4
1.4
3
–1
0.2
0.2
20
250
768
800
832
70
1
V
V
μA
μA
V
V
μA
μA
μs
μs
μs
mV
μA
3230fa
ENLDO1 = ENLDO2 = Low
ENLDO1 = ENLDO2 = High
V
IH
= 3.6V
V
IL
= 0V
High Pulse Width
Low Pulse Width
Low Time to Shutdown (ENM, ENS = Low)
●
●
●
3
LTC3230
ELECTRICAL CHARACTERISTICS
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. Maximum current for continuous
operation is 125mA.
Note 3:
Based on long-term current density limitations. LD01 and LD02
have short circuit protection which limits current to no more than 750mA.
Assumes an operating short circuit duty cycle less than 3% for durations
less than 10 seconds.
Note 4:
The LTC3230 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.
Note 5:
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 result in device degradation or failure.
Note 6:
1.5x mode output impedance is defined as (1.5V
IN
– V
CPO
)/I
OUT
. 2x
mode output impedance is defined as (2V
IN
– V
CPO
)/I
OUT
.
Note 7:
If the part has been shut down then the initial enable time is about
100μs longer due to the bandgap start-up and charge pump soft-start
times.
TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Time from Enable
1.5x
CPO
2V/DIV
1x
2x
CPO
2V/DIV
1x
T
A
= 25°C unless otherwise noted.
1.5x CPO Ripple
Dropout Time when Enabled
1.5x
2x
MODE RESET
ENM
2V/DIV
ENM
2V/DIV
V
CPO
20mV/DIV
AC COUPLED
ENS = LOW
400μs/DIV
3230 G01
ENS = HIGH
400μs/DIV
3230 G02
V
IN
= 3V
400ns/DIV
I
CPO
= 80mA
C1 = C2 = C6 = 1μF
3230 G03
2x CPO Ripple
2.0
1x Mode Switch Resistance vs
Temperature
11
10
RESISTANCE (Ω)
9
8
7
6
I
CPO
= 100mA
1.9 V
IN
= 3.6V
1.8
RESISTANCE (Ω)
1.5x Mode Charge Pump Open-
Loop Output Resistance vs
Temperature (1.5V
IN
– V
CPO
)/I
CPO
V
IN
= 3V
V
CPO
= 4.2V
C1 = C2 = C6 = 1μF
V
CPO
20mV/DIV
AC COUPLED
1.7
1.6
1.5
1.4
1.3
V
IN
= 3.6V
400ns/DIV
I
CPO
= 80mA
C1 = C2 = C6 = 1μF
3230 G04
1.2
1.1
1.0
–40
–15
35
10
TEMPERATURE (°C)
60
85
3230 G05
5
–40
–15
10
35
TEMPERATURE (°C)
60
85
3230 G06
3230fa
4
LTC3230
TYPICAL PERFORMANCE CHARACTERISTICS
1.5x Mode CPO Voltage
vs Load Current
4.8
4.6
CPO VOLTAGE (V)
4.4
4.2
4.0
3.8
3.6
0
50
100
150
LOAD CURRENT (mA)
200
3230 G07
2x Mode Charge Pump Open-Loop
Output Resistance vs Temperature
(2V
IN
– V
CPO
)/I
CPO
12
11
RESISTANCE (Ω)
10
9
8
7
4.3
6
–40
–15
10
35
TEMPERATURE (°C)
60
85
3230 G08
2x Mode CPO Voltage
vs Load Current
5.1
5.0
4.9
CPO VOLTAGE (V)
4.8
4.7
4.6
4.5
4.4
V
IN
= 3.5V
V
IN
= 3.4V
V
IN
= 3.3V
V
IN
= 3.2V
V
IN
= 3.1V
V
IN
= 3V
V
IN
= 3.6V
C1 = C2 = C6 = 1μF
C1 = C2 = C6 = 1μF
V
IN
= 3.3V
V
IN
= 3.4V
V
IN
= 3.5V
V
IN
= 3.6V
V
IN
= 3V
V
CPO
= 4.8V
C1 = C2 = C6 = 1μF
V
IN
= 3.2V
V
IN
= 3.1V
V
IN
= 3V
4.2
0
100
50
150
LOAD CURRENT (mA)
200
3230 G09
MLED/SLED Pin Dropout Voltage
vs MLED/SLED Pin Current
160
MLED/SLED DROPOUT VOLTAGE (mV)
140
120
FREQUENCY (kHz)
100
80
60
40
20
0
0
20
15
MLED/SLED PIN CURRENT (mA)
5
10
25
3230 G10
Oscillator Frequency
vs V
IN
Voltage
1000
980
960
V
IN
CURRENT (μA)
940
920
900
880
860
840
820
800
2.7
3.2
3.7
4.2
V
IN
(V)
4.7
5.2
3230 G11
V
IN
Shutdown Current
vs V
IN
Voltage
5.0
4.5
4.0
T
A
= 25°C
T
A
= –40°C
T
A
= 85°C
V
IN
= 3.6V
T
A
= 85°C
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
2.7
3.7
T
A
= 25°C
T
A
= –40°C
4.7
V
IN
(V)
3230 G12
1x Mode No-Load V
IN
Current vs
V
IN
Voltage
580
560
SUPPLY CURRENT (mA)
540
V
IN
CURRENT (μA)
520
500
480
460
440
420
400
2.8
3.2
3.6
4
V
IN
(V)
3230 G13
1.5x Mode Supply Current vs I
CPO
(I
VIN
– 1.5I
CPO
)
7
6
4
5
4
3
2
1
0
0
SUPPLY CURRENT (mA)
V
IN
= 3.6V
5
2x Mode Supply Current vs I
CPO
(I
VIN
– 2I
CPO
)
V
IN
= 3.6V
R
SET
= 17.4k
3
2
1
4.4
4.8
5.2
0
100
50
LOAD CURRENT (mA)
150
3230 G14
0
100
50
LOAD CURRENT (mA)
150
3230 G15
3230fa
5
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