1

LT1534/LT1534-1

DESCRIPTIO

FEATURES

APPLICATIO S

Ultralow Noise

2A Switching Regulators

The LT

tor designed to reduce conducted and radiated electromag-

netic interference (EMI). Ultralow noise and EMI are achieved

by providing user control of the output switch slew rates.

Voltage and current slew rates can be independently pro-

grammed to optimize switcher harmonic content versus

efficiency. The LT1534/LT1534-1 can reduce high frequency

harmonic power by as much as 40dB with only minor losses

in efficiency.

The LT1534/LT1534-1 utilize a current mode architecture

optimized for low noise boost topologies. The ICs include a

2A power switch along with all necessary oscillator, control

and protection circuitry. Unique error amp circuitry can

regulate both positive and negative voltages. The internal

oscillator may be synchronized to an external clock for more

accurate placement of switching harmonics. Protection fea-

tures include cycle-by-cycle current limit protection, under-

voltage lockout and thermal shutdown.

Low minimum supply voltage and low supply current during

shutdown make the LT1534/LT1534-1 well suited for por-

table applications. The LT1534/LT1534-1 are available in the

16-pin narrow SO package.

s

Greatly Reduced Conducted and Radiated EMI

s

Low Switching Harmonic Content

s

Independent Control of Switch Voltage and

Current Slew Rates

s

2A Current Limited Power Switch

s

Regulates Positive and Negative Voltages

s

20kHz to 250kHz Oscillator Frequency

s

Easily Synchronized to External Clock

s

Wide Input Voltage Range: 2.7V to 23V

s

Low Shutdown Current: 12

µA Typical

s

Easier Layout than with Conventional Switchers

, LTC and LT are registered trademarks of Linear Technology Corporation.

s

Precision Instrumentation Systems

s

Isolated Supplies for Industrial Automation

s

Medical Instruments

s

Wireless Communications

s

Single Board Data Acquisition Systems

B

2mV/DIV

A

50mV/DIV

10

µs/DIV

1534 TA02

5V Output Noise (BW = 100MHz)

SHDN

SYNC

COL

NFB

LT1534-1

GND

3.3V

15

2

PGND

3

L2

14

13

7

12

4

5

6

11

3300pF

16.9k

220pF

1nF

24k

33

µF

6.3V

10

Ω

24k

+

1N5817

A

OPTIONAL

L1

50

µH

2.49k

6.8k

10

1,8,

9,16

7.5k

C1

47

µF

6.3V

×2

+

C1, C2: MATSUSHITA ECGCOJB47O

L1, L3: COILTRONICS CTX50-4

L2: COILCRAFT B08T (28nH) OR PC TRACE

1534 TA01

FB

L3

50

µH

C2

47

µF

5V

650mA

+

15nF

B

Figure 1. Low Noise 3.3V to 5V Boost Converter