Demonstration circuit 2891A features the LTM4670EY, a high efficiency, quad 10A step-down power μModule® regulator. The input voltage range is from 2.25V to 5.5V. The output voltage range is 0.5V to VIN. Derating is necessary for certain VIN, VOUT, frequency and thermal conditions. The DC2891A offers the SSTT pin allowing the user to program output tracking, soft-start period and die temperature monitoring.
The MODE/SYNC pin either synchronizes the switching frequency to an external clock, is a clock output, or sets the PWM mode. The PWM modes of operation are forced continues mode for low noise or pulse-skipping mode for high efficiency at light load. The LTM4670 defaults to forced continues mode in regulation and during synchronization. The LTM4670 operates in pulse-skipping mode when both the FREQ and MODE/SYNC pins are connected to VIN.
DC2891A has optional jumper resistors to parallel multiple LTM4670 channels. For paralleled channels, one channel can be set as master, and the rest can be set as slaves. The phase shift of a slave channel relative to the master channel can be programmed with a resistor divider on the FREQ pin.
For DC2891A, four channels of LTM4670 are working separately and all set as master. A multiphase oscillator LTC6902 is used to set 90-degree phase shift between adjacent phases and reduce the amount of ripple current in both the input and output capacitors.
The LTM4670 data sheet must be read in conjunction with the demo manual prior to working on or modifying demo circuit DC2891A.
