LT1534/LT1534-1
Ultralow Noise
2A Switching Regulators
FEATURES
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: 12µA Typical
s Easier Layout than with Conventional Switchers
U
APPLICATIO S
s Precision Instrumentation Systems
s Isolated Supplies for Industrial Automation
s Medical Instruments
s Wireless Communications
s Single Board Data Acquisition Systems
DESCRIPTIO
The LT®1534/LT1534-1 are a new class of switching regula-
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
L1
3.3V 50µH
1N5817
A
L3
50µH B
+ CIN
15
33µF
6.3V
12
SHDN
VIN
2
COL
4
SYNC
3300pF
5 CT
16.9k 6 RT
PGND
LT1534-1
RVSL
3
14
13
RCSL
10Ω
L2
24k
24k
220pF
11
VC GND
6.8k 1,8,
15nF
9,16
FB
NFB
10
7
2.49k
+ C1
47µF
6.3V
×2
1nF
+
OPTIONAL
C2
47µF
7.5k
1534 TA01
CIN: MATSUSHITA ECGCOJB330
C1, C2: MATSUSHITA ECGCOJB47O
L1, L3: COILTRONICS CTX50-4
L2: COILCRAFT B08T (28nH) OR PC TRACE
5V
650mA
A
50mV/DIV
B
2mV/DIV
Figure 1. Low Noise 3.3V to 5V Boost Converter
5V Output Noise (BW = 100MHz)
10µs/DIV
1534 TA02
1
