Demonstration circuit 2860A is a quad step-down DC/DC switching converter featuring the LTM8051 silent switcher μModule® regulator. The demo board is designed to deliver quad 5V/1.2A, 3.3V/1.2A, 2.5V/1.2A and 1.8V/1.2A outputs from a 7V to 40V input. The Silent Switcher® architecture minimizes EMI while achieving high efficiency at frequencies up to 3MHz. The modes of operation (Burst Mode® operation or discontinuous mode/SYNC) are jumper selectable. Burst Mode operation improves efficiency at light loads.
The LTM8051 is a fixed frequency PWM regulator with current mode control scheme. The switching frequency of channel 1 and channel 4 is set by an appropriate resistor (R11) from the RT14 pin to ground. The switching frequency of channel 2 and channel 3 is set by another appropriate resistor (R23) from the RT23 pin to ground. The RUN14 pin (RUN14 terminal) can be used to set the LTM8051 channel 1 and channel 4 in micro power shut-down mode, while the RUN23 pin (RUN23 terminal) can be used to set the channel 2 and channel 3 in shutdown mode. Output tracking and soft start pins (TRSS1/TRSS2/TRSS3/TRSS4) allow user control of output voltage ramp rate during startup. The power good output of each channel (PG1/PG2/PG3/PG4) will be low when that channel’s output voltage is outside of the ±7.5% regulation window.
The LTM8051 data sheet gives a complete description of the operation and application information. The data sheet must be read in conjunction with the demo manual.