ltc3210-1 Linear Technology Corporation, ltc3210-1 Datasheet

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ltc3210-1

Manufacturer Part Number
ltc3210-1
Description
Main/cam Led Controller With 64-step Brightness Control In 3mm X 3mm Qfn
Manufacturer
Linear Technology Corporation
Datasheet
FEATURES
APPLICATIO S
All other trademarks are the property of their respective owners.
*Protected by US Patents including 6411531.
TYPICAL APPLICATIO
V
BAT
Multi-LED Light Supply for Cellphones/DSCs/PDAs
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
2.2μF
Low Noise Charge Pump Provides High Effi ciency
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
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 Profi les
C1
ENM
ENC
V
ENM
ENC
BAT
C1P
RM
2.2μF
30.1k
1%
C2
C1M
LTC3210-1
RC
U
24.3k
1%
C2P
2.2μF
C3
MLED1
MLED2
MLED3
MLED4
CLED
C2M
CPO
GND
C4
2.2μF
U
MAIN
with 64-Step Brightness Control
32101 TA01
DESCRIPTIO
The LTC
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.
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.
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 effi ciency 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 profi les are available.
CAM
MAIN/CAM LED Controller
®
3210-1 is a low noise charge pump DC/DC con-
in 3mm × 3mm QFN
100
90
80
70
60
50
40
30
20
10
0
3.0
U
4 LEDs AT 9mA/LED
(TYP V
T
A
Effi ciency vs V
= 25°C
3.2
4-LED MAIN Display
F
AT 9mA = 3V, NICHIA NSCW100)
3.4
3.6
V
BAT
BAT
(V)
3.8
LTC3210-1
Voltage
4.0
4.2
32101 TA01b
4.4
32101fb
1

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ltc3210-1 Summary of contents

Page 1

... LED current sources. The part powers 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 profi les are available. ...

Page 2

... LTC3210 ABSOLUTE AXI U RATI GS (Note CPO to GND ........................................ –0. BAT ENM, ENC ................................... –0. (Note 2) ........................................................600mA CPO I .................................................................35mA MLED1-4 PIN CONFIGURATION TOP VIEW C1P 1 CPO 2 17 ENM 3 MLED1 PACKAGE 16-LEAD (3mm × 3mm) PLASTIC QFN T = 125° ...

Page 3

... Low Time to Shutdown (ENC, ENM = Low) Current Source Enable Time (ENC, ENM = High) (Note 5) Note 3: The LTC3210-1 is guaranteed to meet performance specifi cations from 0°C to 70°C. Specifi cations 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 defi ...

Page 4

... LTC3210 TYPICAL PERFOR A CE CHARACTERISTICS Dropout Time from Shutdown 5.1V 2X CPO 1.5X 1V/DIV 1X EN 2V/DIV MODE RESET 500μs/DIV 32101 G01 2x CPO Ripple V = 3.6V BAT I = 200mA CPO C = 2.2μF CPO V CPO 20mV/DIV AC COUPLED 500ns/DIV 32101 G04 1.5x Mode CPO Voltage vs Load Current 4 2.2μF 4 ...

Page 5

... CLED Pin Current ) vs CLED Pin Voltage CPO 400 V 360 320 280 240 200 160 120 300 400 500 0 32101 G16 LTC3210 25°C unless otherwise stated. A Oscillator Frequency vs V Voltage BAT 850 840 T = 25°C A 830 820 T = 85°C A 810 800 T = – ...

Page 6

... LTC3210 TYPICAL PERFOR A CE CHARACTERISTICS MLED Pin Current vs MLED Pin Voltage 3.6V BAT 0.00 0.04 0.06 0.08 0.10 0.02 MLED PIN VOLTAGE (V) MLED Current vs ENM Strobe Pulses 3.6V BAT 33. NUMBER OF ENM STROBE PULSES ...

Page 7

... 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. CLED (Pin 11): Output. CLED is the CAM current source output ...

Page 8

... LTC3210-1 W BLOCK DIAGRA 800kHz OSCILLATOR 15 V BAT – – 500Ω ENM 50ns FILTER 250k + – 500Ω 50ns FILTER ENC 250k 8 C1P C1M C2P CHARGE PUMP 1.215V TIMER ENABLE MAIN 6- BIT 6- BIT DOWN LINEAR COUNTER DAC 1.215V ...

Page 9

... 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 attempt to reach 1. ...

Page 10

... Table 1. Charge Pump Output Regulation Voltages Charge Pump Mode 1. 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 to slowly charge BAT available from the effective input voltage and effective ...

Page 11

... Figure 3 and Figure 4. Shutdown Current In shutdown mode all the circuitry is turned off and the LTC3210-1 draws a very low current from the V ply. Furthermore, CPO is weakly connected to V 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 defi ...

Page 12

... 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 ...

Page 13

... PCB runs. Magnetic fi elds can also be generated if the fl ying capacitors 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 ...

Page 14

... P LED η The effi ciency of the LTC3210-1 depends upon the mode in which it is operating. Recall that the LTC3210-1 operates as a pass switch, connecting V BAT is detected at the LED pin. This feature provides the op- timum effi ciency available for a given input voltage and LED forward voltage. When it is operating as a switch, the effi ...

Page 15

... 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 LTC3210-1 BOTTOM VIEW—EXPOSED PAD PIN 1 NOTCH R = 0.20 TYP R = 0.115 OR 0.25 × 45° CHAMFER ...

Page 16

... Boost Converter Linear Technology Corporation 16 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● 3-LED MAIN, One LED Camera C3 2.2μF C1M C2P C2M MAIN CPO C4 2.2μF LTC3210-1 MLED1 MLED2 MLED3 MLED4 DISABLED MLED4 CLED RC GND 24.3k 1% COMMENTS V : 1.6V to 18V OUT(MAX ...

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