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DEMO MANUAL DC1740A
DESCRIPTION
LTC3880EUJ
PolyPhase Step-Down DC/DC Converter
with Digital Power System Management
Demonstration circuit 1740A is a PolyPhase
®
synchronous
buck converter featuring the LT C
®
3880EUJ, a dual-phase
current mode controller with PMBus interface and digital
power system management functions. There are two ver
-
sions of the boards available:
• DC1740A-A: 4-phase single-output configuration.
Default output setting V
OUT0
= 1.2V/80A
• DC1740A-B: 3+1-phase dual-output configuration. De-
fault output
setting
V
OUT0
= 1.5V/20A, V
OUT1
= 1.2V/60A
The DC1740A powers up to default settings and pro-
duces power
based on configuration resistors or with
non-volatile memory (NVM) settings without the need for
any serial bus communication. This allows easy evalua
-
tion of the DC/DC converter aspects of the LTC3880.
To fully explore the extensive digital power manage-
ment features
of the parts, download the GUI software
L, LT, LTC, LTM, Linear Technology, the Linear logo and PolyPhase are registered trademarks
and LTpowerPlay is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
LTpowerPlay™ onto your PC and use LT C ’s I
2
C/SMBus/
PMBus Dongle DC1613A to connect to the board.
LTpowerPlay allows
the user to reconfigure the part on the
fly and store the configuration in EEPROM, view telemetry
of voltage, current, temperature and fault status.
GUI Download
The software can be downloaded from:
http://www.linear.com/ltpowerplay
For more digital power system management information
and instructions of LTpowerPlay, please visit:
http://www.linear.com/dpsm
Design files for this circuit board are available at
http://www.linear.com/demo
PERFORMANCE SUMMARY
Specifications are at T
A
= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Input Supply Range 7 12 14 V
V
OUT0
Output Voltage Range (1740A-A version) I
OUT0
= 0A TO 80A, V
IN
= 7V to 14V 0.5 1.2 4.096 V
I
OUT0
Output Current Range (1740A-A version) 0 80 A
V
OUT0
Output Voltage Range (1740A-B version) I
OUT0
= 0A TO 20A, V
IN
= 7V to 14V 0.5 1.5 4.096 V
I
OUT0
Output Current Range (1740A-B version) 0 20 A
V
OUT1
Output Voltage Range (1740A-B version) I
OUT1
= 0A TO 60A, V
IN
= 7V to 14V 0.5 1.2 4.096 V
I
OUT1
Output Current Range (1740A-B version) 0 60 A
F
SW
Factory Default Switching 425 kHz
EFF Peak Efficiency (-A version) V
OUT0
= 1.2V, See Figure 4 88.6 %
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DEMO MANUAL DC1740A
QUICK START PROCEDURE
Demonstration circuit 1740A makes it easy to set up
to evaluate the performances of the LTC3880. Refer to
Figure2 for proper measurement equipment setup and
follow the procedure below:
Note: When measuring the input or output voltage ripple,
care must be taken to avoid a long ground lead on the
oscilloscope probe. Measure the output voltage ripple by
touching the probe tip directly across the C11 or C44. See
Figure 3 for proper scope probe technique.
1. Make sure jumpers are in the following positions:
DC1740A-A Version
JUMPER POSITION FUNCTION
JP2 C Tie RUN0 to RUN1
JP3 ON 3.3V for LED indicator
JP4 OFF External V
CC
for LTC3880-1
JP5 C Tie GPIO0B to GPIO1B
DC1740A-B Version
JUMPER POSITION FUNCTION
JP2 NC Tie RUN0 to RUN1
JP3 ON 3.3V for LED indicator
JP4 OFF External Vcc for LTC3880-1
JP5 NC Tie GPIO0B to GPIO1B
2. With power off, connect the input power supply to
V
IN
and GND. Connect active load to the output.
3. Make sure both RUN switches are OFF.
4. Turn on the power at the input.
Note: Make sure that the input voltage does not exceed
15V.
5. Turn on RUN switches as desired.
6. Check for the correct output voltage from TP15 to TP16
and from TP24 to TP26.
Note. If there is no output, temporarily disconnect the
load to make sure that the load is not set too high.
7. Once the proper output voltage is established, adjust
the loads within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
8. Connect the dongle and control the output voltages
from the GUI. See LTpowerPlay Quick Start section for
details.
Connecting a PC to DC1740A
You
can use a PC to reconfigure the power management
features
of the LTC3880 such as: nominal V
OUT
, margin
set points, OV/UV limits, temperature fault limits, sequenc-
ing parameters
,
the fault log, fault responses, GPIO and
other functionality. The DC1613A dongle may be plugged
in regardless of whether or not V
IN
is present. Dongle can
be hot plugged.