1
DEMO MANUAL DC275
DC/DC CONVERTER
LTC1702
Dual 550kHz Synchronous
2-Phase 15A DC/DC Converter
Demonstration circuit DC275 is a dual, high efficiency
regulator using the LTC
®
1702 switching regulator con-
troller. The LTC1702 is optimized for high efficiency with
low input voltages. Typical applications are power for a
digital signal processor (DSP), microprocessor and/or
an application specific integrated circuit (ASIC). The
input voltage of the LTC1702 can range from 3V to 7V.
One of the output voltages (V
OUT2
) is fixed at 3.3V and the
other (V
OUT1
) is programmable from 1.6V to 2.5V by
means of a jumper. The LTC1702 includes two complete,
on-chip, independent switching regulator controllers,
each designed to drive a pair of external N-channel
MOSFET devices in a voltage mode control, synchronous
, LTC and LT are registered trademarks of Linear Technology Corporation.
buck configuration. The LTC1702 also provides open-
drain logic outputs (PGOOD1 and PGOOD2) that indicate
whether either output has risen to within 5% of the final
output voltage. An optional latching fault mode protects
the load if the output rises 15% above the intended
voltage. The LTC1702 uses a constant 550kHz switching
frequency, minimizing external component size and maxi-
mizing load transient performance. Operating efficien-
cies exceeding 90% are obtained for load current currents
from 1A to 14A. Additionally, the supply current in
shutdown is less than 100
µ
A. Gerber files for this circuit
board are available. Call the LTC factory.
DESCRIPTIO
U
TYPICAL PERFOR A CE CHARACTERISTICS A D BOARD PHOTO
U
U
W
LTC1702 Efficiency
PARAMETER
CONDITIONS
VALUE
V
IN
Input Voltage Range
4.75V to 7V
V
OUT2
Fixed Output Voltage
3.3V
I
OUT2
Maximum Output Load Current
15A
Typical Output Ripple
I
OUT
= 15A
18mV
V
OUT1
Jumper Selectable Output Voltage
1.6V, 1.8V, 2V or 2.5V
I
OUT1
Maximum Output Load Current
15A
Typical Output Ripple
I
OUT
= 15A
17mV
I
Q
Supply Current in Shutdown
100
µ
A
PERFOR A CE SU ARY
U
W
WW
LOAD CURRENT (A)
0
70
EFFICIENCY (%)
80
90
100
5
10
1702 G01
15
V
IN
= 5V
V
OUT
= 3.3V
V
OUT
= 2.5V
V
OUT
= 1.6V
