LT3999_15 Datasheet, PDF (1/16 Pages) Linear Technology – Low Noise, 1A, 1MHz Push-Pull DC/DC Driver with Duty Cycle Control

LT3999
Low Noise, 1A, 1MHz
Push-Pull DC/DC Driver
with Duty Cycle Control
FEATURES
DESCRIPTION
n _{Wide Input Operating Range: 2.7V to 36V}
n _{Dual 1A Switches with Programmable Current Limit}
n _{Programmable Switching Frequency: 50kHz to 1MHz}
n _{Frequency Synchronization Up to 1MHz}
n _{∆VIN Compensation Using Duty Cycle Control}
n _{Low Noise Topology}
n _{Programmable Input Over and Undervoltage Lockout}
n _{Cross Conduction Prevention Circuitry}
n _{Programmable Soft-Start}
n _{Low Shutdown Current: <1µA}
n _{10-Lead MSOP and DFN Packages}
APPLICATIONS
n _{Low Noise Isolated Supplies}
n _{Medical Instrument and Safety}
n _{Distributed Power}
n _{Multiple Output Supplies}
n _{Positive-to-Negative Supplies}
n _{Noise Immunity in Data Acquisition, RS232}
and RS485
The LT^®3999 is a monolithic, high voltage, high frequency
DC/DC transformer driver providing isolated power in a
small solution footprint.
The LT3999 has two 1A current limited power switches
that switch out of phase. The duty cycle is programmable
to adjust the output voltage. The switching frequency is
programmed up to 1MHz and can be synchronized to an
external clock for more accurate placement of switcher
harmonics. The input operating range is programmed
with the precision undervoltage and overvoltage lockouts.
The supply current is reduced to less than 1µA during
shutdown. A user-defined RC time constant provides an
adjustable soft-start capability by limiting the inrush cur-
rent at start-up.
The LT3999 is available in a 10-lead MSOP and 3mm ×
3mm DFN package with exposed pad.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
12V to 12V, 10W Low Noise Isolated DC/DC Converter
V_IN
12V
10µF
16V
255k
V_IN
SYNC
UVLO
SWA _{• •}
OVLO/DC
10k
RDC
15.8k
LT3999
••
28k
500kHz
0.1µF
SWB
RT
ILIM/SS
RBIAS
GND
49.9k
15.3µH
10µF
16V
V_OUT
12V
0.8A
3999 TA01a
For more information www.linear.com/LT3999
LT3999 Line Regulation with
Duty Cycle Control
16
15
14
13
I_OUT = 200mA
I_OUT = 400mA
12
I_OUT = 800mA
11
10
9
8
10 11 12 13 14 15 16 17 18
INPUT VOLTAGE (V)
3999 TA01b
3999fa
1