LT3439 Datasheet, PDF (1/12 Pages) Linear Technology – Slew Rate Controlled Ultralow Noise1A Isolated DC/DC Transformer Driver

FEATURES
s _{Reduced Conducted and Radiated EMI}
s _{Single Resistor Control of Output Switch Voltage}
and Current Slew Rates
s _{Cross Conduction Prevention Circuitry}
s _{Two 1A Current Limited Power Switches}
s _{Low Minimum Supply Voltage: 2.8V}
s _{Low Shutdown Current: < 20µA}
s _{50% Duty Cycle}
s _{20kHz to 250kHz Oscillator Frequency}
s _{Synchronizable to 300kHz}
s _{Overcurrent and Overtemperature Protected}
U
APPLICATIO S
s _{Low Noise Isolated Supplies}
s _{Radio and Telecom Supplies}
s _{Distributed Supplies}
s _{Medical Instruments}
s _{Precision Instruments}
s _{Low Noise Filament Supplies}
LT3439
Slew Rate Controlled
Ultralow Noise1A Isolated
DC/DC Transformer Driver
DESCRIPTIO
The LT^®3439 is a push-pull DC/DC transformer driver that
reduces conducted and radiated electromagnetic interfer-
ence (EMI). Ultralow noise and EMI are achieved by
controlling the output switch voltage and current slew
rates. Slew rates are user adjustable to optimize output
noise versus efficiency. The LT3439 can reduce high
frequency harmonic content by as much as 40dB with only
a minor decrease in efficiency.
The LT3439 includes two 1A current limited power switches
to ensure start-up under heavy loads. It also includes an
oscillator that can be synchronized to an external clock for
more accurate placement of switcher harmonics. Protec-
tion features include current limiting, undervoltage lock-
out, thermal shutdown and cross conduction prevention
circuitry.
The LT3439 is available in a thermally enhanced 16-pin
TSSOP with an exposed backside.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Low Noise 5V to 5V Push-Pull DC/DC Transformer
OPTIONAL
V_IN
D1
T1
A
L1 33µH _B
V_OUT
5V
C_IN
22µF
13
••
10V
11
V_IN
3
SHDN
COL A
••
C1
47µF
6.3V
C2
47µF
6.3V
5V
500mA
B
200µV/DIV
LT3439
5
14
SYNC
COL B
6
680pF 7 ^CT
R_T
4
R_SL
16.9k _{GND PGND}
34k
D2
C_IN: MURATA GRM235Y5V226Z10
C1, C2: TDK C4532X5R0J476M
D1, D2: MBR0520
L1: TDK SLF6028T-330MR69
A
20mV/DIV
10
1, 16
T1: COILTRONICS 15835
3439 TA01
5V Output Noise
5µs/DIV
3439 TA01b
sn3439 3439fs
1