design ideas Compensate for Wire Drop to a Remote Load
Philip Karantzalis A common problem in power distribution systems is degradation of regulation due to the
wire voltage drop between the regulator and the load. Any increase in wire resistance,
cable length or load current increases the voltage drop over the distribution wire, increasing
the difference between voltage at the load and the voltage programmed by the regulator.
Remote sensing requires routing additional wires to the load. No extra wiring is required
with the LT6110 cable/wire drop compensator. This article shows how the LT6110 can
improve regulation by compensating for a wide range of regulator-to-load voltage drops.
THE LT6110 CABLE/WIRE
COMPENSATOR Figure 1 shows a 1-wire compensation
block diagram. If the remote load circuit
does not share the regulator’s ground,
two wires are required, one to the load
and one ground return wire. The LT6110
high side amplifier senses the load current by measuring the voltage, VSENSE ,
across the sense resistor, RSENSE , and sinks
a current, IIOUT, proportional to the load
current, ILOAD. IIOUT scale factor is programmable with the RIN resistor from
10Вµ A to 1m A. Wire voltage drop, VDROP,
compensation is accomplished by sinking
IIOUT through the RFA feedback resistor
to increase the regulator’s output by an
amount equal to VDROP. An LT6110 cable/ Figure 1. No extra wires are required to compensate …