Datasheet
PLL
External
Loop
Filter
LPF
(Pin64)
DAC5682ZPLL
C2 C1
R1
( )
( )
VCO
K K tan Φ + sec Φ
1
d d d
1 = tan Φ + sec Φ 2 = 3 =
d d
2
tan Φ + sec Φ
d
d d d
d
t t t
w
w
w
DAC5682Z
www.ti.com
SLLS853E –AUGUST 2007–REVISED AUGUST 2012
where,
(2)
charge pump current: iqp = 1 mA
vco gain: K
VCO
= 2π × G
VCO
rad/V
PFD Frequency: ω
d
≤160 MHz
phase detector gain: K
d
= iqp ÷ (2 × π × M) A/rad
An Excel spreadsheet is available from Texas Instruments for automatically calculating the values for C1, R1 and
C2 in the Tools & Software section of the DAC5682Z webpage;
http://focus.ti.com/docs/prod/folders/print/dac5682z.html#toolssoftware .
Figure 48. Recommended External Loop Filter Topology
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Product Folder Links: DAC5682Z