CY29973
Document #: 38-07291 Rev. *B
Page 2 of 8
Pin Description[2]
Pin
Name
PWR
I/O
Type
Description
11
PECL_CLK
I
PU
PECL Clock Input.
12
PECL_CLK#
I
PD
PECL Clock Input.
9TCLK0
I
PU
External Reference/Test Clock Input.
10
TCLK1
I
PU
External Reference/Test Clock Input.
44, 46, 48, 50 QA(3:0)
VDDC
O
Clock Outputs. See Table 2 on page 3 for frequency selections.
32, 34, 36, 38 QB(3:0)
VDDC
O
Clock Outputs. See Table 2 on page 3 for frequency selections.
16, 18, 21, 23 QC(3:0)
VDDC
O
Clock Outputs. See Table 2 on page 3 for frequency selections.
29
FB_OUT
VDDC
O
Feedback Clock Output. Connect to FB_IN for normal operation.
The divider ratio for this output is set by FB_SEL(0:2). See Table 1 on
page 1. A bypass delay capacitor at this output will control Input Ref-
erence/ Output Banks phase relationships.
25
SYNC
VDDC
O
Synchronous Pulse Output. This output is used for system synchro-
nization. The rising edge of the output pulse is in sync with both the
rising edges of QA (0:3) and QC(0:3) output clocks regardless of the
divider ratios selected.
42, 43
SELA(1,0)
I
PU
Frequency Select Inputs. These inputs select the divider ratio at
QA(0:3) outputs. See Table 2 on page 3.
40, 41
SELB(1,0)
I
PU
Frequency Select Inputs. These inputs select the divider ratio at
QB(0:3) outputs. See Table 2 on page 3.
19, 20
SELC(1,0)
I
PU
Frequency Select Inputs. These inputs select the divider ratio at
QC(0:3) outputs. See Table 2 on page 3.
5, 26, 27
FB_SEL(2:0)
I
PU
Feedback Select Inputs. These inputs select the divide ratio at
FB_OUT output. See Table 1 on page 1.
52
VCO_SEL
I
PU
VCO Divider Select Input. When set LOW, the VCO output is divided
by 2. When set HIGH, the divider is bypassed. See Table 1 on page 1.
31
FB_IN
I
PU
Feedback Clock Input. Connect to FB_OUT for accessing the PLL.
6
PLL_EN
I
PU
PLL Enable Input. When asserted HIGH, PLL is enabled. When
LOW, PLL is bypassed.
7
REF_SEL
I
PU
Reference Select Input. When HIGH, the PECL inputs are selected.
When LOW, TCLK[0:1] are selected.
8
TCLK_SEL
I
PU
TCLK Select Input. When LOW, TCLK0 is selected. When HIGH
TCLK1 is selected.
2MR#/OE
I
PU
Master Reset/Output Enable Input. When asserted LOW, resets all
of the internal flip-flops and also disables all of the outputs. When
pulled HIGH, releases the internal flip-flops from reset and enables all
of the outputs.
14
INV_CLK
I
PU
Inverted Clock Input. When set HIGH, QC(2,3) outputs are inverted.
When set LOW, the inverter is bypassed.
3SCLK
I
PU
Serial Clock Input. Clocks data at SDATA into the internal register.
4SDATA
I
PU
Serial Data Input. Input data is clocked to the internal register to
enable/disable individual outputs. This provides flexibility in power
management.
17, 22, 28,
33,37, 45, 49
VDDC
3.3V Power Supply for Output Clock Buffers.
13
VDD
3.3V Supply for PLL.
1, 15, 24, 30,
35, 39, 47, 51
VSS
Common Ground.
Note:
2. A bypass capacitor (0.1
µF) should be placed as close as possible to each positive power (<0.2”). If these bypass capacitors are not close to the pins their high
frequency filtering characteristics will be cancelled by the lead inductance of the traces.
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