L6615D Просмотр технического описания (PDF) - STMicroelectronics

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L6615D

HIGH/LOW SIDE LOAD SHARE CONTROLLER

STMicroelectronics 

L6615

DESCRIPTION (continued)

Load sharing is a technique used in all the systems in which the load requires low voltage, high current

and/or redundancy; for this reason a modular power system is necessary in which two or more power sup-

plies or DC-DC converters are paralleled.

The device is able to perform both high side and low side current sensing, that is the sense current resistor

can be placed either in series to the power supplies output or on the ground return.

The L6615 then drives the share bus to a voltage proportional to the output current of the master that is

to the highest amongst the output currents delivered by the paralleled power supplies.

The share bus dynamics is independent of the power supply output voltage and is clamped only by the

device supply voltage (VCC).

The output voltage of the other paralleled power supplies (slaves) is then trimmed by the ADJ pin so that

they can support their amount of load current. The slave power supplies work as current-controlled current

sources.

Sharing the output currents is useful for equalizing also the thermal stress of the different modules and

providing an advantage in term of reliability.

Moreover the paralleled supplies architecture allows achieving redundancy; the failure of one of the mod-

ules can be tolerated until the capability of the remaining power supplies is enough to provide the required

load current.

PIN DESCRIPTION

N°

Pin

Function

1

GND Ground.

2

CS- Input of current sense amplifier; it is connected to the negative side of the sense resistor through

a resistor (RG2).

3

CS+ Input of current sense amplifier. A resistor (RG1, of the same value as RG2) is placed between

this pin and the positive side of the sense resistor: its value defines the transconductance gain

between ICGA and VSENSE.

4

ADJ Output of Adjust amplifier; it is connected to both the load (through a resistor RADJ) and to the

positive remote sense pin of the power system. This pin is an open collector diverting (from the

feedback path) a current proportional to the difference between the current supplied to the load

by the relevant power supply and the current supplied by the master.

5

COMP Output of the current sharing (transconductance) error amplifier and input of ADJ amplifier.

Typically, a compensation network is placed between this pin and ground. The maximum voltage

is internally clamped to 1.5V (typ.)

6

SH Share bus pin. During the power supply slave operation, this pin acts as positive input from

share bus. During power supply master operation, it drives the share bus to a voltage

proportional to the load current.

The share bus connects the SH pins of all the paralleled modules. A capacitor between this pin

and GND could be useful to reduce the noise present on the share bus.

7

CGA Current Gain Adjust pin; current sense amplifier output. A resistor connected between this pin

and ground defines the maximum voltage on the share bus and sets the gain of the current

sharing system.

8

VCC Supply voltage of the IC.

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