11

FN9151.4

July 18, 2005

VMSET/MODE - This pin is a dual function pin. Tie this pin to

VCC5 to disable voltage margining. When not tied to VCC5,

this pin serves as VMSET. Connect a resistor from this pin to

ground to set the delta for voltage margining. If voltage

margining and external reference tracking mode are not

needed, this pin can be tied directly to ground.

GPIO2 - This is general purpose IO pin for voltage

margining. Refer to Table 2.

TABLE 2. VOLTAGE MARGINING CONTROLLED BY

GPIO1/REFIN AND GPIO2

GPIO1/REFIN

GPIO2

VOUT

L

L

No Change

LH

+ Delta VOUT

H

L

- Delta VOUT

H

H

Ignored

TABLE 3. VOLTAGE MARGINING/DDR OR TRACKING SUPPLY PIN CONFIGURATION

FUNCTION/MODES

PIN CONFIGURATIONS

COMMENTS

VMSET/MODE

REFOUT

GPIO1/REFIN

GPIO2

Enable Voltage

Margining

Pin Connected to GND

with resistor. It is used

as VMSET.

Connect a 1µF

capacitor for bypass of

external reference.

Serves as a general

purpose I/O. Refer to

Table 2

Serves as a general

purpose I/O. Refer to

Table 2

REFIN or REFOUT

functions will not be

available in this mode.

The internal 0.6V

reference is used.

No Voltage Margining.

Normal operation using

internal reference.

REFOUT not used.

Pin Connected to GND

with resistor. It is used

as VMSET

Connect a 1µF

capacitor for bypass of

external reference.

LL

No Voltage Margining.

Normal operation with

internal reference.

0.6V.

H

Connect a 2.2µF

capacitor to GND.

H (Note 2)

L

No Voltage Margining.

External reference.

H

Connect a 2.2µF

capacitor to GND.

Connect to an external

reference voltage

source (0.6V to 1.25V)

L

NOTES:

1. The GPIO1/REFIN and GPIO2 pins cannot be left floating.

2. Ensure that GPIO1/REFIN is tied high prior to the logic change at VMSET/MODE.

ISL6420