L6610

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Simply connecting the power supply outputs to the L6610 relevant pins ensures the protection against over/un-

dervoltage in the Main section; the protection against overcurrent can be achieved (for 12V and 5V or 3.3V)

adding a small sense resistor.

A crowbar on the auxiliary output is switched on through DFAULT in case of overvoltage.

The L6610 is supplied by the Auxiliary output; the signals sent to the primary side are:

– a "digital" ON/OFF signal through an optocoupler that drives the relevant pin of primary Main controller

to switch the Main converter ON and OFF;

– two analog signals that provide voltage feedback for both the Auxiliary and the Main section, driving the

primary controller pins responsible for the duty cycle modulation.

In server's SMPS applications, a current sharing system is usually required to allow paralleling of several mod-

ules: the L6615 (ST's Current sharing IC, [1]) does the job providing an interface for this purpose (fig. 25) and

guaranteeing an homogeneous current distribution between the paralleled power supplies.

The voltage drop across the sense resistors for overcurrent detection can be also used whenever current shar-

ing is required for 5V (or 3.3V) and/or 12V: the L6615 has a differential sense amplifier whose inputs can be

connected (through two resistors) at the two sense resistor leads. The share bus, referred to ground, links all

the paralleled power supplies.

REFERENCES

[1] "L6615 - Load share controller" (Datasheet)

Figure 24. Detailed Secondary Side

+5Vaux

+5V

+12V

COM

-5V

+3.3V

-12

3V3

DMON

12V

5V

GND

-5

Bout

Binv

M-FAULT

Ainv

Cout

PS-ON

12Visns

Cinv

VREF

Aout

3V3/5Visns

Vdd

ACsns

DFAULT

PW-OK

GND

FAN

+

-

L6610

PROG

-12V