2

dc2447af

DEMO MANUAL DC2447A

Quick start proceDure

Demonstration circuit 2447A is easy to set up to evaluate

theperformanceoftheLTC3896.Forpropermeasurement

equipment configuration, set up the circuit according to

the diagram in Figure 1. Before proceeding to test, insert

shunt into JP1 (RUN) into OFF position, which connects

the RUN pin to ground (GND) and shuts down the output.

Set jumper JP2 (MODE) into the FCM (Forced Continuous

Conduction Mode) position.

NOTE: When measuring the input or output voltage ripple,

care must be taken to avoid a long ground lead on the

oscilloscope probe. Measure the input or output voltage

VOUT– and GND terminals. See Figure 2 for proper scope

probe technique.

1. With the DC2447A set up according to the proper

measurement and equipment in Figure 1, apply 16V

one can measure the shutdown supply current at this

point. The supply current will be approximately 12µA,

or less, in shutdown.

2. Turn on VOUT– of the circuit by inserting the shunt

in header JP1 (RUN) into the ON position. The output

voltage should be regulating. Measure VOUT– and it

should measure –12.0V ± 2% (Do not apply more than

the maximum voltage of 72V to the board or the part

may be damaged). Vary the VOUT– load, which should

not exceed 5A. Vary the input voltage from 7V to 72V,

the VOUT–, it should measure –12.0V ± 2%.

3. SetoutputcurrenttozeroandmovejumperJP2(MODE)

into Burst Default position and measure VOUT–. It

should be –12.0V ± 2%. Vary the VOUT– load, which

should not exceed 5A. Vary the input voltage from 7V

to 72V, the VOUT–, it should measure –12.0V ± 2%.

4. SetoutputcurrenttozeroandmovejumperJP2(MODE)

into Pulse Skip position and measure VOUT–. It should

be –12.0V ± 2%. Vary the VOUT– load, which should

not exceed 5A. Vary the input voltage from 7V to 72V,

the VOUT–, it should measure –12.0V ± 2%.

DC2447A supports synchronization to external clock

referenced to input GND; use PLLIN terminal for

synchronization. PGOOD signal also referenced to

input GND. To activate PGOOD functionality, connect

external voltage source to terminals V_PGOOD and

Figure 1. Proper Measurement Equipment Setup

DC2447 F01

LOAD

80V DC/DC

POWER SUPPLY

+

–

+

–