CY28400-2

Rev 1.0, November 21, 2006

Page 9 of 15

Output Enable Clarification

OE functionality allows for enabling and disabling individual

outputs. OE_1 and OE_6 are Active HIGH or Active LOW

inputs depending on the strapped value of the OE_INV input.

Disabling the outputs may be implemented in two ways, via

writing a ‘0’ to SMBus register bit corresponding to output of

interest or by deasserting the OE input pin. In both methods,

if SMBus registered bit has been written low or the OE pin is

deasserted or both, the output of interest will be tri-stated. (The

assertion and deassertion of this signal is absolutely

asynchronous.)

DIFC (Stoppable)

DIFT (Stoppable)

DIFC(Free Running

DIFT(Free Running

PWRDWN

1 ms

SRC_STP

Figure 9. SRC_STP = Driven, PWRDWN = Driven, OE_INV = 1

DIFC (Stoppable)

DIFC(Free Running

DIFT(Free Running

PWRDWN

1 ms

SRC_STP

DIFT (Stoppable)

Figure 10. SRC_STP = Tri-state, PWRDWN = Driven, OE_INV = 1

DIFC(Free Running

DIFT(Free Running

DIFT (Stoppable)

DIFC (Stoppable)

PWRDWN

1 ms

SRC_STP

Figure 11. SRC_STP = Tri-state, PWRDWN = Tri-state, OE_INV = 1

Table 6. OE Functionality

OE_INV

OE (Pin)

OE (SMBus Bit)

DIF[T/C]

0

0

0

Tri-State

0

0

1

Tri-State

0

1

0

Tri-State

0

1

1

Enabled

1

0

0

Tri-State

1

0

1

Enabled

1

1

0

Tri-State

1

1

1

Tri-State