Document
Features
n Low Noise Charge Pump Provides High Efficiency with Automatic Mode Switching
n Multimode Operation: 1x, 1.5x, 2x n Individual Full-Scale Current Set Resistors n Up to 500mA Total Output Current n Single Wire EN/Brightness Control for MAIN and
CAM LEDs (8 Brightness Steps) n 64:1 Brightness Control Range for MAIN Display n Four 25mA Low Dropout MAIN LED Outputs n One 400mA Low Dropout CAM LED Output n Low Noise Constant Frequency Operation* n Low Shutdown Current: 3µA n Internal Soft-Start Limits Inrush Current During
Startup and Mode Switching n Open/Short LED Protection n No Inductors n 3mm × 3mm 16-Lead Plastic QFN Package
Applications
n Multi-LED Light Supply for Cellphones/DSCs/PDAs
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. Patents including 6411531.
LTC3210
MAIN/CAM LED Controller in 3mm × 3mm QFN
Description
The LTC®3210 is a low noise charge pump DC/DC converter designed to drive four MAIN LEDs and one high current CAM LED for camera lighting. The LTC3210 requires only four small ceramic capacitors and two current set resistors to form a complete LED power supply and current controller.
Built-in soft-start circuitry prevents excessive inrush current during start-up and mode changes. High switching frequency enables the use of small external capacitors. Independent MAIN and CAM full-scale current settings are programmed by two external resistors. Shutdown mode and current output levels are selected via two logic inputs.
The full-scale current through the LEDs is programmed via external resistors. ENM and ENC are toggled to adjust the LED currents via internal counters and DACs. The part is shut down when both ENM and ENC are low for 150µs (typ).
The charge pump optimizes efficiency based on the voltage 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 is available in a 3mm × 3mm 16-lead QFN package.
Typical Application
C2 2.2µF
C3 2.2µF
VBAT C1
2.2µF
ENM ENC
C1P C1M C2P C2M
VBAT
CPO
LTC3210
MLED1
MLED2
MLED3
ENM
MLED4
ENC
CLED
RM
RC
GND
30.1k 1%
24.3k 1%
C4 2.2µF
MAIN
CAM
3210 TA01
EFFICIENCY (PLED/PIN) (%)
4-LED MAIN Display Efficiency vs VBAT Voltage
100
90
80
70
60
50
40
30
20 4 LEDs AT 9mA/LED 10 (TYP VF AT 9mA = 3V, NICHIA NSCW100)
TA = 25°C 0 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4
VBAT (V)
3210 TA01b
3210fb
LTC3210
Absolute Maximum Ratings
(Note 1)
VBAT, CPO to GND......................................... –0.3V to 6V ENM, ENC....................................–0.3V to (VBAT + 0.3V) ICPO (Note 2). ...................................................... 600mA IMLED1- 4..................................................................30mA ICLED (Note 2)...................................................... 450mA CPO Short-Circuit Duration.............................. Indefinite
Operating Temperature Range (Note 3)....–40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
Pin Configuration
TOP VIEW
C2M
C1M
VBAT
C2P
16 15 14 13
C1P 1
12 GND
CPO 2 ENM 3
11 CLED 17
10 ENC
MLED1 4
9 RC
5678
RM
MLED4
MLED3
MLED2
UD PACKAGE 16-LEAD (3mm s 3mm) PLASTIC QFN
TJMAX = 125°C, θJA = 68°C/W EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LTC3210EUD#PBF
LTC3210EUD#TRPBF
LBXH
16-Lead (3mm × 3mm) Plastic QFN
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/
TEMPERATURE RANGE –40°C to 85°C
Electrical Characteristics The l 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 VBAT Operating Voltage IVBAT Operating Current
VBAT Shutdown Current MLED1, MLED2, MLED3, MLED4 Current LED Current Ratio (IMLED/IRM) LED Dropout Voltage LED Current Matching MLED Current, 3-Bit Exponential DAC
CONDITIONS
ICPO = 0, 1x Mode, MLED LSB Setting ICPO = 0, 1.5x Mode ICPO = 0, 2x Mode ENM = ENC = LOW
IMLED = Full Scale Mode Switch Threshold, IMLED = Full Scale Any Two Outputs, IMLED = Full Scale 1 ENM Strobe (FS) 2 ENM Strobes 3 ENM Strobes 4 ENM Strobes 5 ENM Strobes 6 ENM Strobes 7 ENM Strobes (FS/64)
MIN TYP MAX UNITS
l 2.9
4.5
V
0.375
mA
2.5
mA
4.5
mA
l
3
6
µA
l 463
515
567
A/A
100
mV
1
%
20
mA
10
mA
5
mA
2.5
mA
1.25
mA
0.625
mA
0.