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dc1948af

DEMO MANUAL DC1948A

positive or negative current monitor configuration

cable Drop compensation configuration

Figure 5. Temperature Rise at 2.1W Dissipation

There are both positive and negative current monitors on

the LT3090. The configurations for these two monitors are

different. When the positive current monitor is in use, JP1

needs to be configured on IMP position and JP3 needs to

be configured on +3V position. Meantime a +3V external

powersupplyneedstobeconnectedto+3Vturret.Figure3

shows this configuration.

When the negative current monitor is in use, JP1 needs

to be configured on VIN position and JP3 needs to be

configured on IMN position. There is no external power

supply needed. Figure 4 shows this configuration.

thermal image

Figure 3. Positive Current Monitor Configuration

Figure 4. Negative Current Monitor Configuration

Demo Circuit 1948A can be configured to evaluate the

cable drop compensation on the LT3090. Note that cable

drop compensation is only using negative current monitor

configuration. JP1, JP3 and R12 shall be configured. JP1

needs to be configured on VIN position. JP3 needs to be

configured on CDC position. R12 needs be replaced by a

calculated value which has the following relationship with

An example thermal image shows the temperature distri-

bution on board. The test is complete in still air at room

temperature with 2.1W power dissipation in the LT3090.

This gives the IC case-to-ambient thermal resistance of

about