FEMTOCLOCKS™ CRYSTAL-TO-HCSL
CLOCK GENERATOR
841654 DATA SHEET
2 REVISION A 4/20/15
TABLE 1. PIN DESCRIPTIONS
TABLE 2. PIN CHARACTERISTICS
Number Name Type Description
1, 18 V
DD
Power Core supply pins.
2 REF_OUT Output
Single-ended reference frequency clock output.
LVCMOS/LVTTL interface levels.
3, 7, 15, 22 GND Power Power supply ground.
4, 5,
8, 9
QA0, nQA0,
QA1, nQA1
Ouput Differential Bank A output pairs. HCSL interface levels.
6V
DDOA
Power Output supply pin for Bank A outputs.
10 nREF_OE Input Pullup
Active low REF_OUT enable/disable. See Table 3E.
LVCMOS/LVTTL interface levels.
11 BYPASS Input Pulldown
Selects PLL operation/PLL bypass operation.
See Table 3C. LVCMOS/LVTTL interface levels.
12 REF_IN Input Pulldown
Single-ended PLL reference clock input.
LVCMOS/LVTTL interface levels.
13 REF_SEL Input Pulldown
Reference select. Selects the input reference source.
See Table 3B. LVCMOS/LVTTL interface levels.
14 V
DDA
Power Analog supply pin.
16, 17
XTAL_OUT,
XTAL_IN
Input
Parallel resonant crystal interface. XTAL_OUT is the output,
XTAL_IN is the input. (PLL reference.)
19 MR/nOE Input Pulldown
Active HIGH master reset. Active LOW output enable. When logic HIGH, the
internal dividers are reset and the differential outputs are in high impedance
(HiZ). When logic LOW, the internal dividers and the differential outputs are
enabled. See Table 3D. LVCMOS/LVTTL interface levels.
20, 21
24, 25
nQB1, QB1
nQB0, QB0
Output Differential Bank B output pairs. HCSL interface levels.
23 V
DDOB
Power Output supply pin for Bank B outputs.
26, 27
FSEL1,
FSEL0
Input Pulldown Output frequency select pins. LVCMOS/LVTTL interface levels.
28 IREF Output
HCSL current reference external resistor output. A fi xed precision resistor
(RREF = 475Ω) from this pin to ground provides a reference current used
for differential current-mode QA[0:1]/nQA[0:1] and QB[0:1]/nQB[0:1] clock
outputs.
NOTE: Pullup and Pulldown refer to internal input resistors. See Table 2, Pin Characteristics, for typical values.
Symbol Parameter Test Conditions Minimum Typical Maximum Units
C
IN
Input Capacitance 4 pF
R
PULLUP
Input PullupResistor 51
kΩ
R
PULLDOWN
Input Pulldown Resistor 51
kΩ
