Datasheet LTC3499, LTC3499B (Analog Devices)

LTC3499/LTC3499B 750mA Synchronous Step-Up DC/DC Converters with Reverse-Battery Protection
FEATURES DESCRIPTION
n
Reverse-Battery Protection for DC/DC Converter
The LTC®3499/LTC3499B are synchronous, fixed frequency
and Load
step-up DC/DC power converters with integrated reverse n
High Efficiency: Up to 94%
battery protection that protect and disconnect the devices n
Generates 5V at 175mA from a 1.8V Input
and load when the battery polarity is reversed while n
Operates from 1.8V to 5.5V Input Supply
delivering high efficiency in a small (3mm × 3mm) DFN n
2V to 6V Adjustable Output Voltage
package. True output disconnect eliminates inrush current n
Inrush Current Controlled During Start-Up
and allows zero load current in shutdown. n
Output Disconnnect in Shutdown
The devices feature an input voltage range of 1.8V to 5.5V n Low Noise 1.2MHz PWM Operation enabling operation from two alkaline or NiMH batteries. The n Tiny External Components switching frequency is internally set at 1.2MHz allowing n Automatic Burst Mode® Operation (LTC3499) the use of tiny surface mount inductors and capacitors. n Continuous Switching at Light Loads (LTC3499B) A minimal number of external components are required n Overvoltage Protection to generate output voltages ranging from 2V to 6V. The n 8-Lead (3mm × 3mm × 0.75mm) DFN LTC3499 features automatic Burst Mode operation to and MSOP Packages increase efficiency at light loads, while the LTC3499B features continuous switching at light loads.
APPLICATIONS
The soft-start time is externally programmable through a n Medical Equipment small capacitor. Anti-ring circuitry reduces EMI emissions n Digital Cameras by damping the inductor in discontinuous mode. The de- n MP3 Players vices feature <1µA shutdown supply current, integrated n Handheld Instruments overvoltage protection and are available in both 8-pin L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. (3mm × 3mm) DFN and 8-pin MSOP packages. Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION Two AA Cells to 5V Synchronous Boost Converter Battery Current vs VIN
1.0 4.7µH V SHDN = 0V IN 1.8V TO 3.2V + VOUT = 0V 2.2µF VIN SW 0.5 LTC3499 VOUT VOUT 5V ON OFF SHDN 175mA 0 1M VC Y CURRENT (µA) FB 10µF 100k TTER SS GND BA 324k –0.5 330pF 0.01µF –1.0 3499 TA01 –6 –4 –2 0 2 4 6 VIN AND SW VOLTAGE (V) 3499 TA01b 3499fc 1