Document
FEATURES
n Delivers 3.3V at 200mA from a Single Alkaline/ NiMH Cell or 3.3V at 400mA from Two Cells
n VIN Start-Up Voltage: 700mV n 0.50V to 5.5V Input Range n 1.6V to 5.25V VOUT Range n Up to 94% Efficiency n Output Disconnect n 2MHz Fixed Frequency Operation n VIN > VOUT Operation n Integrated Soft-Start n Current Mode Control with Internal Compensation n Burst Mode® Operation with 12µA Quiescent Current n Internal Synchronous Rectifier n Logic Controlled Shutdown: <1µA n Anti-Ringing Control n Low Profile (2mm × 3mm × 0.75mm) DFN Package
APPLICATIONS
n Medical Instruments n Noise Canceling Headphones n Wireless Mice n Bluetooth Headsets
LTC3528-2 1A, 2MHz Synchronous Step-Up DC/DC Converter
in 2mm × 3mm DFN DESCRIPTION
The LTC®3528-2 is a synchronous, fixed frequency step-up DC/DC converter with output disconnect. High efficiency synchronous rectification, in addition to a 700mV startup voltage and operation down to 500mV once started, provides longer run-time for single or multiple cell batterypowered products. A switching frequency of 2MHz minimizes solution footprint by allowing the use of tiny, low profile inductors and ceramic capacitors. The current mode PWM is internally compensated, simplifying the design process. The LTC3528-2 enters Burst Mode operation at light loads. Anti-ringing circuitry reduces EMI by damping the inductor in discontinuous mode. Additional features include a low shutdown current, open-drain power good output, short-circuit protection and thermal overload protection. The LTC3528-2 is offered in an 8-lead 2mm × 3mm × 0.75mm DFN package.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
2.2µH
VIN 1.8V TO 3.2V
4.7µF OFF ON
SW VIN VOUT
LTC3528-2
PGOOD SHDN
GND
FB
499k 287k
68pF
VOUT 3.3V 400mA 10µF
35282 TA01a
EFFICIENCY (%)
Efficiency and Power Loss
100
90
VOUT = 3.3V VIN = 2.4V
80 EFFICIENCY
70
1000 100
60 10
50
40 1 POWER LOSS
30
20 0.1
10
0 0.01 0.01 0.1 1 10 100 1000
LOAD CURRENT (mA)
35282 TA01b
POWER LOSS (mW)
35282fb
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LTC3528-2
ABSOLUTE MAXIMUM RATINGS
(Note 1)
VIN Voltage.................................................... –0.3V to 6V SW Voltage DC............................................................. –0.3V to 6V Pulsed < 100ns......................................... –0.3V to 7V SHDN, FB Voltage......................................... –0.3V to 6V VOUT.............................................................. –0.3V to 6V PGOOD.......................................................... –0.3V to 6V Operating Junction Temperature Range (Notes 2, 5)............................................. –40°C to 125°C Junction Temperature............................................ 125°C Storage Temperature Range................... –65°C to 125°C
PIN CONFIGURATION
TOP VIEW
SHDN 1
8 VIN
FB 2 PGOOD 3
9
7 SGND 6 PGND
VOUT 4
5 SW
DDB PACKAGE 8-LEAD (3mm × 2mm) PLASTIC DFN TJMAX = 125°C, θJA = 76°C/W (NOTE 6) EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LTC3528EDDB-2#PBF
LTC3528EDDB-2#TRPBF LDNZ
8-Lead (3mm × 2mm) Plastic DFN
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 125°C
E LECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 1.2V, VOUT = 3.3V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
VIN Range
Operating, Excluding Start-Up
l 0.5
5.5 V
Minimum Start-Up Voltage Output Voltage Adjust Range
Feedback Voltage
ILOAD = 1mA
TA = 0°C to 85°C (Note 7)
l
l 1.7 1.6
l 1.170
0.70 1.200
0.88 5.25 5.25 1.230
V V V V
Feedback Input Current Quiescent Current—Shutdown Quiescent Current—Active Quiescent Current—Burst N-Channel MOSFET Switch Leakage Current P-Channel MOSFET Switch Leakage Current N-Channel MOSFET Switch On Resistance
VFB = 1.3V VSHDN = 0V, Not Including Switch Leakage, VOUT = 0V Measured on VOUT, Nonswitching (Note 4) Measured on VOUT , FB > 1.230V VSW = 5V VSW = 5V, VOUT = 0V
1 0.01 300 12 0.1 0.1 0.175
50 1 500 20 10 10
nA µA µA µA µA µA Ω
P-Channel MOSFET Switch On Resistance
0.250
Ω
N-Channel MOSFET Current Limit
l 1.0
1.5
A
Current Limit Delay Time to Output
(Note 3)
60 ns
Maximum Duty Cycle
VFB = 1.15V
l 87
92
%
35282fb
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LTC3528-2
E LECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the .