LTC3452 Linear Technology, LTC3452 Datasheet

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LTC3452

Manufacturer Part Number
LTC3452
Description
Synchronous Buck-Boost MAIN/CAMERA White LED Driver
Manufacturer
Linear Technology
Datasheet

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Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LTC3452EUF
Manufacturer:
LT
Quantity:
10 000
Part Number:
LTC3452EUF
Manufacturer:
LINEAR/凌特
Quantity:
20 000
Part Number:
LTC3452EUF#PBF
Manufacturer:
LT
Quantity:
600
Part Number:
LTC3452EUF#PBF
Manufacturer:
LINEAR/凌特
Quantity:
20 000
FEATURES
TYPICAL APPLICATIO
All other trademarks are the property of their respective owners.
APPLICATIO S
2.7V TO 4.2V
Li-Ion CELL
, LTC and LT are registered trademarks of Linear Technology Corporation.
High Efficiency:
Range
Wide V
Independent MAIN/CAMERA Current Control
Up to 425mA Continuous Output Current
Internal Soft-Start
Open/Shorted LED Protection
PWM Brightness Control
LED Current Matching Typically <2.5%
Constant Frequency 1MHz Operation
Low Shutdown Current: 6.5µA
Overtemperature Protection
Small Thermally Enhanced 20-Lead
(4mm × 4mm) QFN Package
Cell Phones
Digital Cameras
PDAs
Portable Devices
SINGLE
V
0.1µF
IN
+
6.19k
10.2k
I
IN
I
SETH
SETL
EN
EN
V
5 × 20mA White LED Display + 200mA Camera Light Driver
H
C
L
Range: 2.7V to 5.5V
2.2µF
GND
V
IN
U
PV
85% Over Entire Li-Ion Battery
IN
BUCK/BOOST
GND
LTC3452
SW1
4.7µH
1MHz
L
SW2
PGND
V
OUT
U
EXPOSED PAD
CAM
LED
LED
LED
LED
LED
LED
LED
D1
H1
H2
L1
L2
L3
L4
L5
200mA
0mA TO
20mA
D2
MAIN/CAMERA White LED Driver
0mA TO
20mA
MAIN DISPLAY LED BACKLIGHT
D1: AOT 2015
D2 TO D6: NICHIA NSCW100
L: COILCRAFT DO3314-472
D3
0mA TO
20mA
D4
0mA TO
20mA
DESCRIPTIO
D5
The LTC
verter optimized for driving two banks of white LEDs from
a single Li-Ion battery input. Five parallel LEDs can be
driven at up to 25mA each in the low power LED bank,
while two LEDs can be driven at up to 150mA each (or a
single LED at 300mA) in the high power LED bank. The
regulator operates in either synchronous buck, synchro-
nous boost or buck-boost mode, depending on input
voltage and LED maximum forward voltage. Optimum
efficiency is achieved by sensing which LED requires the
largest forward voltage drop at its programmed current,
and regulating the common output rail for lowest dropout.
Efficiency of 85% can be achieved over the entire usable
range of a Li-Ion battery (2.7V to 4.2V).
Maximum LED current for each LED display is program-
mable with a single external resistor. Dual enable pins
allow for PWM brightness control in the low power bank
and independent on/off control for the high current bank
(optimal for LED camera flash). In shutdown, the supply
current is only 6.5µA.
A high constant operating frequency of 1MHz allows the
use of a small external inductor. The LTC3452 is offered
in a low profile (0.75mm) thermally enhanced 20-lead
(4mm × 4mm) QFN package.
0mA TO
20mA
D6
Synchronous Buck-Boost
®
3452 TA01a
3452 is a synchronous buck-boost DC/DC con-
4.7µF
U
Torch and Flash Mode Efficiency
95
93
91
89
87
85
83
81
79
77
75
2.7
EFFICIENCY = Σ
T
A
FLASH MODE AT 200mA
TORCH MODE AT 100mA
= 25°C
3.1
www.DataSheet4U.com
3.5
(V
3.9
V
OUT
IN
LTC3452
(V)
– V
V
4.3
IN
LEDx
• I
IN
4.7
) • I
LEDx
5.1
3452 TA01b
5.5
1
3452f

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LTC3452 Summary of contents

Page 1

... LED camera flash). In shutdown, the supply current is only 6.5µA. A high constant operating frequency of 1MHz allows the use of a small external inductor. The LTC3452 is offered in a low profile (0.75mm) thermally enhanced 20-lead (4mm × 4mm) QFN package. D1 ...

Page 2

... OUT + 0.3V OUT + 0.3V ORDER PART NUMBER LTC3452EUF Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: Consult LTC Marketing for parts specified with wider operating temperature ranges. CONDITIONS 2.7V ≤ ...

Page 3

... Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC3452E is guaranteed to meet specifications from 0°C to 70°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls ...

Page 4

... LTC3452 W U TYPICAL PERFOR A CE CHARACTERISTICS Shutdown Current vs Temperature –55 – 105 125 – TEMPERATURE (°C) 3452 G01 Enable Thresholds vs Temperature 1200 V = 3.6V IN 1100 1000 900 800 700 600 V IH ...

Page 5

... 4.2V 175 IN 150 125 –55 –35 – 105 125 TEMPERATURE (°C) 3452 G11 Start-Up Transient 300mA LEDH 3452 G13 LTC3452 www.DataSheet4U.com Oscillator Frequency vs Temperature 1050 OUT 1040 1030 V = 5.5V IN 1020 V = 4.2V 1010 IN 1000 V = 3.6V IN 990 980 V = 2.7V IN 970 ...

Page 6

... LTC3452 CTIO S (Pin 1): Signal Voltage Input Supply Pin (2.7V ≤ 5.5V). Recommended bypass capacitor to GND is 2.2µF ceramic or larger. Connect (Pin 2): Enable Input Pin and PWM Brightness Control L for Low Power LED Bank. Active high. For constant I operation, connect the EN ...

Page 7

... CLAMP I MAXL 256 8 LEVELS EXPONENTIAL BRIGHTNESS CONTROL SDL SHUTDOWN CIRCUIT SDH I MAXH 768 GND GND PGND EXPOSED PAD LTC3452 www.DataSheet4U.com 4 LED LED DETECT 5 LED LED DETECT 6 LED LED DETECT 200mA 7 LED LED DETECT 8 LED LED DETECT 1.23V V OUT ...

Page 8

... LTC3452 U OPERATIO Buck-Boost DC-DC Converter The LTC3452 employs an LTC proprietary buck-boost DC/DC converter to generate the output voltage required to drive the LEDs. This architecture permits high-effi- ciency, low noise operation at input voltages above, below or equal to the output voltage by properly phasing four internal power switches. The error amp output voltage on the V pin determines the duty cycle of the switches ...

Page 9

... Overtemperature Protection IN If the junction temperature of the LTC3452 exceeds 130°C for any reason, all four switches are shut off immediately. The overtemperature protection circuit has a typical hys- teresis of 11°C. Soft-Start The LTC3452 includes an internally fixed soft-start which is active when powering up or coming out of shutdown ...

Page 10

... PWMing of the EN input when EN L the LTC3452 is enabled immediately after a rising edge at the EN pin, but waits 200µs (typical) after a falling edge L to enter shutdown. Consequently, a minimum PWM fre- ...

Page 11

... U APPLICATIO S I FOR ATIO COMPONENT SELECTION Inductor Selection The high frequency operation of the LTC3452 allows the use of small surface mount inductors. The inductor cur- rent ripple is typically set to 20% to 40% of the maximum average inductor current. For a given ripple the inductance term in boost mode is: ...

Page 12

... Closing the Feedback Loop The LTC3452 incorporates voltage mode PWM control. The control to output gain varies with operation region (Buck, Boost, Buck/Boost), but is usually no greater than 15. The output filter exhibits a double pole response ...

Page 13

... U U APPLICATIO S I FOR ATIO Although the LTC3452 can safely provide this current continuously, the external LED(s) may not be rated for this high a level of continuous current. Higher current levels in a single LED are generally reserved for pulsed applica- tions, such as LED camera flash. This is accomplished by ...

Page 14

... APPLICATIO S I FOR ATIO Unused Outputs If fewer than 7 LED pins are to be used, unused LEDx pins should be connected The LTC3452 senses which OUT current source outputs are not being used and shuts off the corresponding output currents to save power. A small trickle current (10µ ...

Page 15

... U UF Package 20-Lead Plastic QFN (4mm × 4mm) (Reference LTC DWG # 05-08-1710) 0.70 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 0.75 ± 0.05 2.45 ± 0.10 (4-SIDES) 0.200 REF 0.00 – 0.05 LTC3452 www.DataSheet4U.com BOTTOM VIEW—EXPOSED PAD PIN 1 NOTCH R = 0.115 R = 0.30 TYP TYP 19 20 0.38 ± 0. (UF20) QFN 10-04 0.25 ± 0.05 ...

Page 16

... D1 D2 LED H1 LED H2 LED , 20mA L1 1MHz LED , 20mA L2 BUCK/BOOST LED , 20mA L3 LED , 20mA L4 LTC3452 LED , UNUSED L5 D1, D2: AOT 2015 D3-D6: NICHIA NSCW100 L: COILCRAFT D03314-472 GND PGND EXPOSED PAD 3452 TA02a COMMENTS V : 1.6V to 18V MS10 Package/EDD Package V : 2.6V to 16V ThinSOT Package ...

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