DESCRIPTION
Demonstration circuit 2383A-A features the LTC®3644: the
wide input and output voltage range, high efficiency and
power density, quad 1.25A outputs DC/DC synchronous
step-down monolithic regulator. The input voltage range
of DC2383A-A is 2.7V to 17V. The default demo board
setting of VOUT1, VOUT2, VOUT3, VOUT4 is 1.2V, 3.3V, 2.5V
and 1.8V at 1.25A maximum DC output current per channel.
There are two assembly versions. The DC2383A-A
features LTC3644 which operates at an internally fixed
frequency of 1MHz (Typ), while the DC2383A-B features
LTC3644-2 which operates at an internally fixed frequency
of 2.25MHz (Typ). Peak current limit is internally fixed at
2.2A typical per channel. Each channel comes with independent
run pin control and power good indicators. Phase
shift selection of either 0 degree or 180 degrees between
switch rising edge of channels 1, 2 and channels 3, 4 is
also available.
DC2383A-A provides optional onboard 0Ω jumpers to
configure the LTC3644 as 4-phase dual 2.5A/2.5A outputs
or 4-phase triple 2.5A/1.25A/1.25A outputs. Optional 0Ω
jumpers connecting VIN1 to VIN2, VIN3, VIN4 are available
for users to operate selected channels of LTC3644 at different
input voltages than VIN1.
A user-selectable MODE/SYNC input is provided to allow
users to trade off ripple noise for light load efficiency:
pulse-skipping mode (PS) or Burst Mode® operation delivers
higher efficiency at light load while forced continuous
conduction mode (FCM) is preferred for noise sensitive
applications. The MODE/SYNC pin can also be used to
synchronize the switching frequency to an external clock
or set the phase shift between channels 1, 2 and channels
3, 4. Constant frequency, peak current mode control
architecture and integrated internal control loop compensation
network, allows very fast transient response to line
and load changes while maintaining loop stability.
The LTC3644 is available in a thermally enhanced, low
profile 36-lead 5mm × 5mm BGA package.
It is recommended to read the data sheet and demo manual
of LTC3644 prior to using or making any changes to
DC2383A-A.