M1020/21
Integrated
Circuit
Systems, Inc.
VCSO BASED
CLOCK PLL
P r o d u c t D a t a S h e e t
PIN DESCRIPTIONS
Number
1, 2, 3, 10, 14, 26
Name
GND
I/O
Ground
Configuration
Description
Power supply ground connections.
4
9
OP_IN
nOP_IN
Input
External loop filter connections.
See Figure 5, External Loop Filter, on pg. 6.
5
8
nOP_OUT
OP_OUT
Output
6
7
nVC
VC
Input
11, 19, 33
VCC
Power
Power supply connection, connect to +3.3V.
FOUT1
nFOUT1
12
13
Output No internal terminator
Output No internal terminator
Internal pull-down resistor
Clock output 1. Differential LVPECL (CML, LVDS available).
FOUT0
nFOUT0
15
16
Clock output 0. Differential LVPECL (CML, LVDS available).
17
18
P_SEL1
P_SEL0
Post-PLL , P divider selection. LVCMOS/LVTTL. See Table 5,
P Divider Look-Up Table (LUT), on pg. 4.
1
2
20
21
nDIF_REF1
DIF_REF1
Biased to Vcc/2
Reference clock input pair 1. Differential LVPECL or LVDS.
Resistor bias on inverting terminal supports TTL or LVCMOS.
Input
1
1
Internal pull-down resistor
Reference clock input selection. LVCMOS/LVTTL:
Logic 1 selects DIF_REF1, nDIF_REF1.
Logic 0 selects DIF_REF0, nDIF_REF0.
22
REF_SEL
Input
Input
Internal pull-down resistor
2
23
24
nDIF_REF0
DIF_REF0
Biased to Vcc/2
Reference clock input pair 0. Differential LVPECL or LVDS.
Resistor bias on inverting terminal supports TTL or LVCMOS.
1
Internal pull-down resistor
25
27
28
29
30
NC
No internal connection.
MR_SEL3
MR_SEL2
MR_SEL0
MR_SEL1
M and R divider value selection. LVCMOS/ LVTTL.
Internal pull-down resistor See Tables 3 and 4, M and R Divider Look-Up Tables (LUT)
on pg. 3.
1
Input
Loss of Lock indicator output. Asserted when internal PLL is
3
not tracking the input reference for frequency and phase.
Logic 1 indicates loss of lock.
31
LOL
Output
Input
Logic 0 indicates locked condition.
Narrow Bandwidth enable. LVCMOS/LVTTL:
Logic 1 - Narrow loop bandwidth, RIN = 2100kΩ.
1
32
NBW
DNC
Internal pull-UP resistor
Logic 0 - Wide bandwidth, RIN = 100kΩ.
Internal nodes. Connection to these pins can cause erratic
34, 35, 36
Do Not Connect.
device operation.
Table 2: Pin Descriptions
Note 1: For typical values of internal pull-down and pull-UP resistors, see DC Characteristics on pg. 8.
Note 2: Biased toVcc/2, with 50kΩ to Vcc and 50kΩ to ground. See Differential Inputs Biased to VCC/2 on pg. 8.
Note 3: See LVCMOS Output in DC Characteristics on pg. 8.
M1020/21 Datasheet Rev 1.0
2 of 10
Revised 28Jul2004
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