8

LT1585A/LT1585A-3.3

1585afa

load regulation is obtained when the top of resistor divider

R1 connects directly to the regulator output and not to the

load. Figure 5 illustrates this point. If R1 connects to the

load, the effective resistance between the regulator and

the load is:

per foot with 16-gauge wire. This translates to 4mV per

foot at 1A load current. At higher load currents, this drop

represents a significant percentage of the overall regula-

tion. It is important to keep the positive lead between the

regulator and the load as short as possible and to use large

wire or PC board traces.

Load Regulation

It is not possible to provide true remote load sensing

because the LT1585A/LT1585A-3.3 are 3-terminal de-

vices. Load regulation is limited by the resistance of the

wire connecting the regulators to the load. Load regula-

tion per the data sheet specification is measured at the

bottom of the package.

For fixed voltage devices, negative side sensing is a true

Kelvin connection with the ground pin of the device

returned to the negative side of the load. This is illustrated

in Figure 4.

For adjustable voltage devices, negative side sensing is a

true Kelvin connection with the bottom of the output

divider returned to the negative side of the load. The best

LT1585A-3.3

PARASITIC

LINE RESISTANCE

GND

IN

OUT

LT1585A • F04

Figure 4. Connection for Best Load Regulation

LT1585A

OUT

IN

ADJ

PARASITIC

LINE RESISTANCE

R1*

*CONNECT R1 TO CASE

CONNECT R2 TO LOAD

LT1585A • F05

R2*

Figure 5. Connection for Best Load Regulation