LTC3408EDD Linear Technology, LTC3408EDD Datasheet

IC REG BUCK W/BYPASS TXRX 8-DFN

LTC3408EDD

Manufacturer Part Number
LTC3408EDD
Description
IC REG BUCK W/BYPASS TXRX 8-DFN
Manufacturer
Linear Technology
Datasheet

Specifications of LTC3408EDD

Applications
Converter, WCDMA Power Amplifier Applications
Voltage - Input
2.5 ~ 5 V
Number Of Outputs
1
Voltage - Output
0.3 ~ 3.5 V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
8-DFN
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LTC3408EDD
Manufacturer:
LINEAR
Quantity:
50
FEATURES
TYPICAL APPLICATIO
APPLICATIO S
Dynamically Adjustable Output from 0.3V to 3.5V
600mA Output Current
Internal 0.08
Transistor
High Efficiency: Up to 96%
1.5MHz Constant Frequency Operation
No Schottky Diode Required
Low Dropout Operation: 100% Duty Cycle
2.5V to 5V Input Voltage Range
Shutdown Mode Draws < 1µA Supply Current
Current Mode Operation for Excellent Line and
Load Transient Response
Overtemperature Protected
Available in 8-Lead 3mm × 3mm DFN Package
WCDMA Cell Phone Power Amplifiers
Wireless Modems
PROGRAMMING
OUTPUT
DAC
TO 5V
2.7V
V
IN
WCDMA Transmitter Power Supply
P-Channel MOSFET Bypass
C
10µF
CER
U
IN
**
*
MURATA LQH32CN4R7M11
TAIYO YUDEN JMK212BJ475MG
TAIYO YUDEN JMK212BJ106MN
V
RUN
REF
IN
LTC3408
GND
V
U
OUT
SW
4.7µH*
Regulator with Bypass Transistor
C
4.7µF
CER
OUT
WCDMA
RF PA
**
V
3× V
600mA
3403 TA01
OUT
DESCRIPTIO
The LTC
nous buck regulator optimized for WCDMA power ampli-
fier applications. The output voltage can be dynamically
programmed from 0.3V to 3.5V. At V
0.08Ω bypass P-channel MOSFET connects V
to V
The input voltage range is 2.5V to 5V making the LTC3408
ideally suited for single Li-Ion battery-powered applica-
tions. 100% duty cycle provides low dropout operation,
extending battery life in portable systems.
Switching frequency is internally set at 1.5MHz, allowing
the use of small surface mount inductors and capacitors.
The internal synchronous switch increases efficiency and
eliminates the need for an external Schottky diode.
The LTC3408 is available in a low profile (0.75mm) 8-lead
3mm × 3mm DFN package.
U.S. Patent Numbers: 5481178, 6580258, 6304066, 6127815, 6498466, 6611131
REF
, LTC and LT are registered trademarks of Linear Technology Corporation.
IN
Synchronous Step-Down
, eliminating power loss through the inductor.
®
3408 is a high efficiency monolithic synchro-
0.01
0.01
0.1
Efficiency Power Lost vs Load Current
1
U
1
1.5MHz, 600mA
LOAD CURRENT (mA)
10
OUT
> 3.6V an internal
100
V
V
V
V
LTC3408
OUT
OUT
OUT
OUT
= 1.2V
= 1.5V
= 1.8V
= 2.5V
OUT
3408 F04
1000
directly
100
90
80
70
60
50
40
30
20
10
0
1
3408f

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LTC3408EDD Summary of contents

Page 1

... The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. The LTC3408 is available in a low profile (0.75mm) 8-lead 3mm × 3mm DFN package. , LTC and LT are registered trademarks of Linear Technology Corporation. U.S. Patent Numbers: 5481178, 6580258, 6304066, 6127815, 6498466, 6611131 4.7µH* V OUT 3× ...

Page 2

... Note calculated from the ambient temperature T J dissipation P according to the following formula: D LTC3408 ORDER PART NUMBER 8 V OUT LTC3408EDD REF 5 RUN DD PART MARKING LAEA = 43°C/ W, θ = 3° 25°C. A MIN TYP MAX ● ...

Page 3

ELECTRICAL CHARACTERISTICS Note 4: When V > 1.2V and V x3 > the P-channel FET will be on REF REF IN in parallel with the bypass PFET reducing the overall R Note 5: This IC includes overtemperature protection ...

Page 4

LTC3408 W U TYPICAL PERFOR A CE CHARACTERISTICS Frequency vs V OUT 1600 T = 25° 3.6V IN 1400 1200 1000 800 600 400 0 0.2 0.4 0.6 0.8 1.0 1.2 V (V) OUT 3408 G08 R ...

Page 5

W U TYPICAL PERFOR A CE CHARACTERISTICS Output Ripple Waveform V OUT 10mV/DIV I L 100mA/DIV V = 3.6V 200ns/DIV 0.6V REF LOAD REF Transient V REF 0.5V/DIV V OUT 1V/DIV V = 4.2V ...

Page 6

LTC3408 CTIO AL DIAGRA OSC FREQ ÷ 2 REF 6 V OUT FB 8 360k V OUT 1 180k – BCMP + 1.2V RUN 5 U OPERATIO (Refer to Functional Diagram) 4.7µ 2. ...

Page 7

U OPERATIO (Refer to Functional Diagram) off and on the bypass P-channel MOSFET with a frequency of approximately 50kHz to 100kHz at 1.6A peak current. This will continue until the short is removed. While the bypass P-channel MOSFET is pulsing ...

Page 8

LTC3408 U U APPLICATIO S I FOR ATIO At output voltages below 0.6V, the switching frequency decreases linearly to a minimum of approximately 700kHz. This places the maximum ripple current (in forced con- tinuous mode) at the highest input voltage ...

Page 9

U U APPLICATIO S I FOR ATIO forced continuous mode, the LTC3408 will actually pull current from the output until the command from V satisfied. On alternate half cyles, this current actually exits the V terminal, potentially causing a rise ...

Page 10

LTC3408 U U APPLICATIO S I FOR ATIO 1 0.1 0.01 V OUT V OUT V OUT V OUT 0. 100 LOAD CURRENT (mA) Figure 4. Power Lost vs Load Current where ...

Page 11

... BOLD LINES INDICATE HIGH CURRENT PATHS Figure 5. Layout Diagram Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights 70° ...

Page 12

... Dual (I Monolithic Step-Down Regulator LTC5505 ThinSOT RF Power Detector with Buffered Output and >40dB Dynamic Range Burst Mode is a registered trademark of Linear Technology Corporaton. ThinSOT is a trademark of Linear Technology Corporation. Linear Technology Corporation 12 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● ...

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