Micrel, Inc.
SY89218U
August 2007
4
M9999-082407-C
hbwhelp@micrel.com or (408) 955-1690
Pin Description
Pin Number
Pin Name
Pin Function
1, 2
3, 4
15, 16
17, 18
FSELA1, FSELA0
FSELB1, FSELB0
FSELC1, FSELC0
FSELD1, FSELD0
Single-Ended Inputs: These TTL/CMOS inputs select the divide ratio for each of the
four banks of outputs. Note that each of these inputs is internally connected to a 25k
pull-up resistor and will default to a logic HIGH state if left open. The input-switching
threshold is VCC/2.
5, 8,
11, 14
IN0, /IN0
IN1, /IN1
Differential Inputs: These input pairs are the differential signal inputs to the device.
These inputs accept AC- or DC-coupled signals as small as 100mV. The input pairs
internally terminate to a VT pin through 50
. Note that these inputs will default to an
indeterminate state if left open. Please refer to the “Input Interface Applications”
section for more details.
6, 12
VT0, VT1
Input Termination Center-Tap: Each side of a differential input pair terminates to a VT
pin. The VT pin provides a center-tap to a termination network for maximum interface
flexibility. See “ Input Interface Applications” section for more details.
7,
13
VREF-AC0,
VREF-AC1
Reference Voltage: These outputs bias to VCC–1.2V. They are used for AC-coupling
inputs IN and /IN. Connect VREF-AC directly to the corresponding VT pin. Bypass with
0.01F low ESR capacitor to VCC. Due to limited drive capability, the VREF-AC pin is
only intended to drive its respective VT pin. Maximum sink/source current is ±1.5mA.
Please refer to the “Input Interface Applications” section for more details.
9
/MR
Single-Ended Input: This TTL/CMOS-compatible master reset function asynchronously
sets the true outputs LOW, complimentary outputs HIGH, and holds them in that state
as long as /MR remains LOW. This input is internally connected to a 25k
pull-up
resistor and will default to logic HIGH state if left open. The input-switching threshold is
VCC/2.
10
CLK_SEL
Single-Ended Input: This single-ended TTL/CMOS-compatible input selects the inputs
to the multiplexer. Note that this input is internally connected to a 25k
pull-up resistor
and will default to logic HIGH state if left open. The input-switching threshold is VCC/2.
20, 25, 30, 33,
40
41, 48, 50, 55,
62
VCC
Positive Power Supply. Bypass with a 0.1F||0.01F low ESR capacitor as close to
VCC pin as possible.
21, 22
23, 24
26, 27
28, 29
/QC0, QC0
/QC1, QC1
/QC2, QC2
/QC3, QC3
Bank C LVDS differential output pairs controlled by FSELC1 and FSELC0. Refer to
“Function Table” for details. Unused output pairs should be terminated with 100
across the differential pair
31
NC
No connect.
34, 35,
36, 37
38, 39,
42, 43
44, 45,
46, 47
/QD0, QD0
/QD1, QD1
/QD2, QD2
/QD3, QD3
/QD4, QD4
/QD5, QD5
Bank D LVDS differential output pairs controlled by FSELD1 and FSELD0. Refer to
“Function Table” for details. Unused output pairs should be terminated with 100
across the differential pair
51, 52
53, 54
/QA0, QA0
/QA1, QA1
Bank A LVDS differential output pairs controlled by FSELA1 and FSELA0. Refer to
“Function Table” for details. Unused output pairs should be terminated with 100
across the differential pair
56, 57
58, 59
60, 61
/QB0, QB0
/QB1, QB1
/QB2, QB2
Bank B LVDS differential output pairs controlled by FSELB1 and FSELB0. Refer to
“Function Table” for details. Unused output pairs should be terminated with 100
across the differential pair