AWG G3 PAD FOR PS3 Specifikace stáhnout pdf (Strana 171)

High Current Power Supply (HCDPS) 6 Device PowerSupply

System Reference, January 2001

171

2. The multiphase stepdown converter

This converter steps down two raw +12V supplies to

the required output level.

It consists of an array of 2, 6 phase step-down

converters, each phase shifted 30 degrees to each

other. Because of this multiphase technology, ripple

and the size of the circuit is minimized and speed is

enhanced. Each pair of switches has its own 4-wire

series resistor to measure current. The single measure-

ments are summed up to the total output current

which can be used for current limiting and current

monitoring. This converter delivers its power via a

tristate switch directly to the output. Because such a

buck converter is not able to sink currents, pre-loads

are included. These pre-loads are 2.2 Ohm for output

voltages >3V and 0.7 Ohm for output voltages < 3V.

3. Safety circuits

The following safety precautions are included in the

HCDPS:

a. Isolation

The 100A-low impedance cable to the DUT Board

includes, among others, three signal pins: S_GND,

+5Vdut and safety_line. All three pins are isolated

from the HCDPS via optocouplers and are floating.

b. Shut Down

The +5Vdut line must have +5V (relative to S_GND)

applied to it for the HCDPS to operate. The

safety_line is connected to the +5Vdut line via an

internal pull-up resistor. The HCDPS monitors this

line: If high, the HCDPS operates correctly, if pulled

down, the HCDPS will be switched to tristate. This

line is bidirectional: When the HCDPS detects an

internal failure, it will pull down this line. This line

also allows you to synchronously shut down

different supplies in the event of a failure.

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AWG G3 PAD FOR PS3 Specifikace Strana 171