DESCRIPTION
Demonstration circuit 1480A is a dual output synchronous
buck DC/DC converter featuring the LTC
input voltage range is from 4.5V to 14V. The outputs are
3.3V/5A and 1.8V/5A. Each output voltage can be precisely
programmed to a preset value within 1% error with the
VID pins. The demo board uses a high density, two sided
drop-in layout. The package of LTC3865EUH-1 is a small,
low thermal impedance 5mm × 5mm 32-Lead QFN.
The light load operation mode of the converter is de-
termined with the MODE/PLLIN pin. Use JP1 jumper to
select Burst Mode
operation, pulse-skipping mode or
®
PERFORMANCE SUMMARY
PARAMETER
Input Voltage Range
Output Voltage, V
OUT1
Output Voltage, V
OUT2
Maximum Output Current, I
OUT1
Maximum Output Current, I
OUT2
Typical Full Load Efficiency, Channel 1
Typical Full Load Efficiency, Channel 2
Typical Switching Frequency
DEMO MANUAL DC1480A
Dual 5A Synchronous Buck
Converter with Pin Selectable Outputs
forced continuous mode operation. Switching frequency
3865EUH-1. The
is preset at about 500kHz. This frequency can be modi-
®
fied by changing R5 value at the FREQ pin. The converter
can also be externally synchronized from 250kHz to
770kHz through MODE/PLLIN pin (SYNC terminal on the
board). To shut down a channel, force its RUN pin below
1.2V (Jumper: OFF). The power good output (PGOOD1
or PGOOG2 terminal) is low when that channel output
exceeds ±10% regulation window.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
(T
= 25°C)
A
CONDITION
V
= 4.5V to 14V, I
= 0A to 5A
IN
OUT1
V
= 4.5V to 14V, I
= 0A to 5A
IN
OUT2
V
= 4.5V to 14V, V
= 3.3V
IN
OUT1
V
= 4.5V to 14V, V
= 1.8V
IN
OUT2
V
= 12V, V
= 3.3V, I
IN
OUT1
OUT1
V
= 12V, V
= 1.8V, I
IN
OUT2
OUT2
LTC3865EUH-1
VALUE
4.5V to 14V
3.3V ±1%
1.8V ±1%
5A
5A
= 5A
91.6%
= 5A
86.6%
500kHz
dc1480af
1
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