Cypress CY7B992, CY7B991 manual Test Mode, Typical Outputs with FB Connected to a Zero-Skew Output

CY7B991

CY7B992

Figure 1 shows the typical outputs with FB connected to a zero skew output.[4]

Figure 1. Typical Outputs with FB Connected to a Zero-Skew Output

U

U

U

U

U

U

U

U

U

U

U

U

– 6t

– 5t

– 4t

– 3t

– 2t

– 1t

+1t

+2t

+3t

+4t

+5t

+6t

0

0

0

0

0

0

0

0

0

0

0

0

0

t

t

t

t

t

t

t

t

t

t

t

t

t

FBInput

REFInput

1Fx

3Fx

2Fx

4Fx

(N/A)

LM

– 6t U

LL

LH

– 4t U

LM

(N/A)

– 3t U

LH

ML

– 2t U

ML

(N/A)

– 1t U

MM

MM

0tU

MH

(N/A)

+1t U

HL

MH

+2t U

HM

(N/A)

+3t U

HH

HL

+4t U

(N/A)

HM

+6t U

(N/A)

LL/HH

DIVIDED

(N/A)

HH

INVERT

Test Mode

The TEST input is a three level input. In normal system operation, this pin is connected to ground, enabling the CY7B991 or CY7B992 to operate as explained in “Skew Select Matrix” on page 3. For testing purposes, any of the three level inputs can have a removable jumper to ground, or be tied LOW through a 100Ω resistor. This enables an external tester to change the state of these pins.

If the TEST input is forced to its MID or HIGH state, the device operates with its internal phase locked loop disconnected, and input levels supplied to REF directly controls all outputs. Relative output to output functions are the same as in normal mode.

In contrast with normal operation (TEST tied LOW), all outputs function based only on the connection of their own function selects inputs (xF0 and xF1) and the waveform characteristics of the REF input.

Note

4. FB connected to an output selected for “zero” skew (i.e., xF1 = xF0 = MID).

Document Number: 38-07138 Rev. *B Page 4 of 19

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