Linear DC1997A-A Demo Manual

DESCRIPTION
Demonstration circuits
dual output synchronous buck converters featuring the
LTC 3838EUHF-1/LTC3838EUHF-2. Both assemblies
®
provide two outputs of 1.5V/20A and 1.2V/20A over an
input voltage range of 4.5V to 14V at a switching frequency
of 300kHz.
Applications requiring the output to be adjusted with an
external reference can be implemented with the DC1997A-B
assembly. Such applications include adaptive voltage scal-
ing optimization (AVSO) where the processor voltage is
adjusted to achieve optimal efficiency, wide output voltage
applications controlled by a DAC, or margining. The 2nd
channel of the DC1997A-B assembly is regulated to an
onboard 1.2V reference in the default setup. The same
reference can be set from 0.8V to 1.5V with a potentiometer
or the 2nd channel can regulate to a source external to the
board. The 1st channel on the DC1997A-B assembly and
both channels on the DC1997A-A version are regulated
to the internal reference.
PERFORMANCE SUMMARY
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
Output Voltage V
OUT1
Output Voltage V
OUT2
V Maximum Output Current, I
OUT1
V Maximum Output Current, I
OUT2
Nominal Switching Frequency
Efficiency (Measured on DC1997A-B Assembly)
See Figure 2
DC1997A-A/DC1997A-B
Specifications are at T
CONDITION
I = 0A to 20A, V
OUT1
I = 0A to 20A, V
OUT2
V = 4.5V to 14V, V
OUT1 IN
V = 4.5V to 14V, V
OUT2 IN
V = 1.5V, I
OUT1
V = 1.2V, I
OUT2
DC1997A-A/DC1997A-B
High Current, Dual Output
Synchronous Buck Converter
are The entire converter, excluding the bulk input and output
capacitors, fits within a 1.5in
density is a result of the compact, 2-sided drop-in layout
and the use of dual channel FETs.
Additional features of this demo board include:
• Remote sensing for each output.
• PLLIN and CLKOUT pins.
• PGOOD, RUN and TRK/SS pins for each output.
• Optional resistors to tie the two outputs together.
• Optional footprint for discrete single channel FETs for
higher output current.
• Optional footprints to implement DTR (detect transient)
to reduce overshoot following a load release.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
= 25°C, No Airflow
A
= 4.5V to 14V
IN
= 4.5V to 14V
IN
= 1.5V
OUT1
= 1.2V
OUT2
= 20A, V = 12V
OUT1 IN
= 20A, V = 12V
OUT2 IN
DEMO MANUAL
LTC3838EUHF-1/
LTC3838EUHF-2
2
area on the board. The high
VALUE
4.5V
14V
1.5V ± 2%
1.2V ± 2%
20A
20A
300kHz
90.4% Typical
88.8% Typical
dc1997a-af
1