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dc1807af

DEMO MANUAL DC1807A

DESCRIPTION

LTC3869EUFD

Dual, 2-Phase Synchronous

Step-Down DC/DC Controllers

Demonstration circuit 1807A is a dual output, dual phase

synchronous buck converter featuring the LTC3869EUFD.

The demo board uses a high density, two sided drop-in

layout. The power components, excluding the bulk out-

put and input capacitors, fit within a 1.35”

× 0.75” area

on the top layer. The control circuit resides in a 0.60”

×

0.75” area on the bottom layer. The package style for the

LTC3869EUFD is a 4mm

× 5mm 28-lead QFN with an

exposed ground pad.

The main features of the board include an internal 5V linear

pin and a PGOOD signal. The board can be configured

for either CCM (original setting), Burst Mode operation,

or pulse-skipping operation with the mode jumper. The

board also has optional resistors for single output/dual

phase operation, rail tracking and synchronization to an

external clock.

L, LT, LTC, LTM, μModule, Burst Mode, Linear Technology and the Linear logo are registered

trademarks of Linear Technology Corporation. All other trademarks are the property of their

respective owners.

PERFORMANCE SUMMARY

Two versions of the board are available. DC1807A-A has

an on-board sense resistor for current feedback, while

the DC1807A-B is configured with a DCR sense circuit

that allows the converter to use the inductors DCR as the

sense element instead of the on-board sense resistors to

save cost and board space and improves efficiency.

The input voltage range is 4.5V to 14V, output voltages

and currents are 1.5V/15A and 1.2V/15A. The LTC3869

datasheet gives a complete description of the part, opera-

tion and application information. The datasheet must be

read in conjunction with this demo manual for DC1807A.

Design files for this circuit board are available at

http://www.linear.com/demo

PARAMETER

CONDITIONS

VALUE

Minimum Input Voltage

4.5V

Maximum Input Voltage

14V

1.5V±2%

1.2V±2%

Nominal Switching Frequency

400kHz

Efficiency

DC1807A-A

DC1807A-B

88.7%** Typical

86.7%** Typical

89.1%** Typical

87.4%** Typical

*Measured at bulk output capacitor

**See Figures 3 and 4 for efficiency curves