1
DEMO CIRCUIT 383B
QUICK START GUIDE
LT1930ES5/LT1931ES5
1.2MHz, SOT-23 DC/DC CONVERTER
DESCRIPTION
Demonstration Circuit 383B is multipurpose demon-
stration board featuring the LT1930 and LT1931. The
demo board offers three separate DC/DC converters.
The Boost circuit is designed to convert 5V input to
12V output at 300mA maximum load. The SEPIC cir-
cuit generates constant 12V/300mA output with
10V~16V variable input. The Inverter circuit is de-
signed for applications requiring negative 12V/350mA
from a positive 12V input. All three circuits are de-
signed to demonstrate the advantages of the 1.2MHz
switching frequency, the internal 36V/1A switch, wide
input voltage range and small circuit size. These cir-
cuits are intended for space-conscious applications
such as digital cameras, cellular phones, palmtop
computers and LCD displays. The 1.2MHz switching
frequency, 1A integrated switch, small circuit size,
and low component count makes the LT1930 and
LT1931 suitable for use in many other applications,
such as PC cards, miniature disk drives, xDSL power
supplies, flash memory products and local 5V or 12V
supplies. The LT1930/LT1931 datasheets give complete
descriptions of the parts, their operation and application
information. The datasheets must be read in conjunction
with this quick start guide for working on or modifying
any circuit on the demo circuit 383B.
Design files for this circuit board are available. Call
the LTC factory.
LT is a trademark of Linear Technology Corporation
Table 1.
Performance Summary
SPECIFICATIONS ARE AT TA = 25°C
SYMBOL PARAMETER FOR BOOST CONVERTER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Input Supply Range
5
V
V
OUT
Output Voltage Accuracy
V
IN
= 5V, I
LOAD
= 300mA
11.76
12
12.24
V
Ripple
V
IN
= 5V, I
LOAD
= 300mA
50
mV
Fs
Switching Frequency
1.2
MHz
SYMBOL PARAMETER FOR SEPIC CONVERTER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Input Supply Range
10
16
V
V
OUT
Output Voltage Accuracy
V
IN
= 10V, I
LOAD
= 300mA
11.76
12
12.24
V
Ripple
V
IN
=105V, I
LOAD
= 300mA
50
mV
Fs
Switching Frequency
1.2
MHz
SYMBOL PARAMETER FOR INVERTING CONVERTER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Input Supply Range
12
V
V
OUT
Output Voltage Accuracy
V
IN
= 12V, I
LOAD
= 350mA
-11.76
-12
-12.24
V
Ripple
V
IN
= 12V, I
LOAD
= 350mA
40
mV
Fs
Switching Frequency
1.2
MHz
