7

enabling the accompanying voltage converter. The DC-DC

converter then provides a well regulated output voltage to

the IM circuitry.

Available from Intersil is the ISL6160EVAL2. The

ISL6160EVAL2 is a complete InfiniBand Class I (non isolated)

power topology evaluation platform consisting of the ISL6160

and the HIP6006 single output PWM controller. See Figure 2

for a simplified block diagram of the ISL6160EVAL2 platform.

This evaluation platform allows the Infiniband Module (IM)

power supply designer to evaluate the concept of this design

and apply it to a specific IM power requirement. The evaluation

platform is configured for 5V Vout and 3A Iout capability and

exhibits a 92% total efficiency. See Figures 19 and 20 for

ISL6160EVAL2 turn-on and turn-off waveforms.

Additional information for the ISL6160EVAL2 can be found in

application note AN9959.

Using the ISL6160 beyond IM Applications

-48V, +5V Control Circuit

The ISL6160 can also be used for -48V and +5V telecom power

control. The VB portion of the ISL6160 configured as a low side

switch controller as shown in Figure 3. is capable of controlling

several hundreds of volts, positive or negative and at the same

time provide control and protection for the +5V supply with its

1A integrated current regulating function.

Biased by an external 12V reference in the low side switch

configuration the ISL6160 retains all of its features except for

the DC-DC_EN feature. This is nonfunctional in the low side

to indicate that voltage is good.

When controlling a negative voltage the VB_ON control can

be implemented through an optocoupler for on-off control or

left open for an always on hot pluggable adaptor card

application .

Application Considerations

The manufacturers’ MOSFET safe operating area (SOA) data

should be consulted, as during the soft start ramp and current

regulation times, the VGS of the external N-Channel MOSFETs

is reduced driving the N-Channel MOSFET switch into the

(linear region) high rDS(ON) state. Thus avoid extended soft

start and time out periods as the external N-Channel

MOSFETs may be damaged or destroyed due to excessive

internal power dissipation. Refer to the MOSFET

manufacturers’ data sheets for SOA information.

With the high levels of inrush current e.g., highly capacitive

loads and HDD motor start up currents, choosing the ramp up

rate and regulation level of the load current is crucial to provide

both protection and still allow for this inrush current without

latching off. Consider this in addition to the time out delay when

choosing MOSFETs for your design.

Correct physical layout of RSENSE resistor is critical to the

accuracy of sensing the VB current. Ideally trace routing

short as possible with zero current in the sense lines. (See

Figure 4.)

FIGURE 2. SIMPLIFIED ISL6160EVAL2 BLOCK DIAGRAM

LCL_POWER_EN

VBX_EN_L

ISL6160

HIP6006

VB CONTROL

VA CONTROL

VB_IN

VA_IN

VAout

Vout

VB_ON

DC-DC_ON

EN

HI GATE

LO_GATE

5

6

8

7

4

3

2

1

9

10

11

12

13

14

FIGURE 3. -48V/+5V APPLICATION CIRCUIT

0V +

-

LOAD

+5V

LOAD

+

-

+5V

12V

REG

-48V

-48V

ISL6160

CORRECT

TO ISEN AND

CURRENT

SENSE RESISTOR

INCORRECT

FIGURE 4. SENSE RESISTOR PCB LAYOUT

ISL6160