GS6150 Datasheet, PDF (18/64 Pages) Gennum Corporation – Automatic or Manual Rate Selection

1. The DDI_SEL0 and DDI_SEL1 pins can be used to select the input.
2. A GSPI accessible register can be used to select the input, with the state change
occurring as soon as the register value changes.
3. A GSPI accessible register can be used to select the input, with a rising edge on the
STROBE pin triggering a change to the next state.
Since these states are mutually exclusive, the DDI_SEL0 pin is shared with the STROBE
function.
In the case of using the DDI_SEL0/STROBE and DDI_SEL1 pins (#1 above) or the STROBE
pre-select method (#3 above), the input selector will switch within 1μs of the change of
state on the corresponding pin(s). This strict timing requirement is not maintained when
using GSPI register selection (#2 above).
Each of the device’s four inputs is selected as shown in Table 4-1.
Table 4-1: Pin and Register Settings for Input Selection
Register Settings
INPUT_SELECTION_CONTROL
7_h[9:8]
X0 (default)
X0 (default)
X0 (default)
X0 (default)
01
01
01
01
DDI_SELECT
7_h[11]
X
X
X
X
0
0
1
1
DDI_SELECT
7_h[10]
X
X
X
X
0
1
0
1
11
0
0
11
0
1
11
1
0
11
1
1
Note: ‘X’ indicates ‘Do Not Care’
Pin Settings
Differential
DDI_SEL1
DDI_SEL0/
STROBE
High-speed
Input Selected
LOW
LOW
HIGH
HIGH
X
X
X
X
X
X
X
X
LOW
DDI0, DDI0
HIGH
DDI1, DDI1
LOW
DDI2, DDI2
HIGH
DDI3, DDI3
X
DDI0, DDI0
X
DDI1, DDI1
X
DDI2, DDI2
X
DDI3, DDI3
on LOW-to-
HIGH transition
DDI0, DDI0
on LOW-to-
HIGH transition
DDI1, DDI1
on LOW-to-
HIGH transition
DDI2, DDI2
on LOW-to-
HIGH transition
DDI3, DDI3
The DDI_SEL0/STROBE and DDI_SEL1 pins include internal pull-downs, which pulls the
input voltage LOW if either pin is unconnected.
When using the STROBE pre-select method (#3 above), the pre-selected input buffer
and trace EQ is powered up in advance of the STROBE pulse.
GS6150
Final Data Sheet
PDS-060127
Rev.2
March 2015
www.semtech.com
18 of 64
Proprietary & Confidential