DEMO BOARD QUICK START GUIDE DC398
1.2MHZ SINGLE CELL SYNCHRONOUS BOOST CON VERTER
1
LTC3400
DESCRIPTION
Demonstration Circuit DC398 is a micropower boost
converter that guarantees to start up at 1V. Once it starts
up, the chip is powered from the output; therefore the
input voltage can go lower. DC398 version A uses the
LTC3400ES6; version B uses the LTC3400BES6. The
LTC3400 shifts automatically to low power Burst Mode
TM
operation at light loads; whereas the LTC3400B operates
at a fixed frequency for all loads. Both LTC3400 and
LTC3400B switch at 1.2MHz to allow up to 95% effi-
ciency with a tiny PCB footprint, which will fit nicely in
many battery powered applications such as GPS receiv-
ers, PDAs, pagers and toys. The converter produces 3.3
volts with current guaranteed up to 90mA from a single
AA cell. When JP1 is closed, the IC is turned off, which
draws less than 1
ยต
A current.
On the bench test, an electrolytic capacitor is reco m-
mended at the input posts to dump the voltage over-
shoot when first powered up. The spike is caused by the
energy stored in the parasitic inductance of the connec-
tion wire. In real applications, since the connection to
the source is short and the battery internal impedance
also provides damping, the damping capacitor is usually
not needed. The Vin pin is rated for 6V.
QUICK START PROCEDURE
Refer to Figure 1 for proper equipment setup and follow
the procedure below.
1.
Apply a voltage source to the input of the circuit be-
tween the Vin and GND terminals. The circuit is guar-
anteed to start up at input voltages higher than 1V. Do
not apply more than 5 volts. The boost circuit will
only regulate the output voltage when the input volt-
age is less than the output.
2.
Attach a voltmeter or oscilloscope probe between the
Vout and GND terminals of the circuit to monitor the
output.
3.
To start the circuit, open the jumper, JP1.
4.
Attach a load to the output. The available output
power depends on the input voltage. Please refer to
the performance summary for maximum current at
different input voltages.
Figure 1. Proper Measurement Equipment Setup
DEMO BOARD QUICK STA
RT GUIDE
DC398
1.2MHZ SINGLE CELL SYNCHRONOUS BOOST CON VERTER
2
Table 1. Performance Summary
PARAMETER CONDITION VALUE
Maximum Load Current, Min V
OUT
= 3.3V, V
IN
= 1.0V 90mA
Maximum Load Current, Min V
OUT
= 3.3V, V
IN
= 2.0V 250mA
Switching Frequency, Typ 1.2MHz
Efficiency, Typ V
IN
= 2.4V, V
OUT
= 3.3V, I
OUT
= 100mA 92%
Output Ripple, Typ V
IN
= 1.2V, V
OUT
= 3.3V, I
OUT
= 90mA 20mV
