ADP151 datasheet(32/47 Pages) AD

32 / 47 page

Data Sheet

LT3046

analog.com

Rev 0

32 of 47

If OUTS is externally held more than SET, the current sink turns on in an attempt to restore OUTS to its

programmed voltage. The current sink remains on until the external circuitry releases OUTS.

Direct Paralleling for Higher Current

Higher output current is obtained by paralleling multiple LT3046 devices. Connect all SET pins together and all IN

pins together. Connect the OUT pins together using small pieces of PCB trace (used as a ballast resistor) to equalize

currents in the LT3046 devices. PCB trace resistance in milliohms per inch is shown in Table 6.

Table 6. PCB Trace Resistance (Measured in mΩ per Inch)

WEIGHT (oz)

10mil WIDTH

20mil WIDTH

54.3

27.1

13.6

The small worst-case offset of 2mV for each paralleled LT3046 minimizes the required ballast resistor value. Figure

73 illustrates that two LT3046 devices, each using a 50mΩ PCB trace ballast resistor, providing better than 20%

accurate output current sharing at full load. The two 50mΩ external resistors only add 10mV of output regulation

drop with a 400mA maximum current. With a 3.3V output, this voltage drop only adds 0.3% to the regulation

accuracy. As mentioned previously, connect the OUTS pin directly to the output capacitor.

Figure 73. Parallel Devices

4.7µF

0.47µF

16.5kΩ

100µA

EN/UV

PGFB

SET

GND

ILIM

OUTS

OUT

LT3046

VOUT

3.3V

IOUT(MAX)

400mA

10µF

4.7µF

100µA

EN/UV

PGFB

VIN

5V ±5%

SET

GND

ILIM

OUTS

OUT

LT3046

50mΩ

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