Intel ULV 353 LE80536VC900512 Data Sheet
Product codes
LE80536VC900512
Mobile Intel
®
Celeron
®
Processor (0.18µ) in BGA2 and Micro-PGA2 Packages
283654-003 Datasheet
79
Table 42. PLL Filter Capacitor Recommendations
Capacitor Part
Number
Value Tolerance
ESL ESR
C1 Kemet
T495D336M016AS
33
µ
F
20% 2.5
nH
0.225
Ω
C2 AVX
TPSD336M020S0200
33
µ
F
20% unknown
0.2
Ω
NOTE:
There may be other vendors who might provide parts of equivalent characteristics and the OEMs
should consider doing their own testing for selecting their own vendors.
should consider doing their own testing for selecting their own vendors.
Table 43. PLL Filter Resistor Recommendations
Resistor Part
Number
Value Tolerance
Power
R1 various
1
Ω
10% 1/16W
To satisfy damping requirements, total series resistance in the filter (from V
CCT
to the top plate of
the capacitor) must be at least 0.35
Ω
. This resistor can be in the form of a discrete component, or
routing, or both. For example, if the picked inductor has minimum DCR of 0.25
Ω
, then a routing
resistance of at least 0.10
Ω
is required. Be careful not to exceed the maximum resistance rule
(2
Ω
). For example, if using discrete R1, the maximum DCR of the L should be less than 2.0 - 1.1
= 0.9
Ω
, which precludes using L2 and possibly L1.
Other routing requirements:
•
The capacitor should be close to the PLL1 and PLL2 pins, with less than 0.1
Ω
per route (These
routes do not count towards the minimum damping resistance requirement).
•
The PLL2 route should be parallel and next to the PLL1 route (minimize loop area).
•
The inductor should be close to the capacitor; any routing resistance should be inserted
between VCCT and the inductor.
between VCCT and the inductor.
•
Any discrete resistor should be inserted between VCCT and the inductor.
A.4 Comments
•
A magnetically shielded inductor protects the circuit from picking up external flux noise. This
should provide better timing margins than with an unshielded inductor.
should provide better timing margins than with an unshielded inductor.
•
A discrete or routed resistor is required because the LC filter by nature has an under-damped
response, which can cause resonance at the LC pole. Noise amplification at this band, although
not in the PLL-sensitive spectrum, could cause a fatal headroom reduction for analog circuitry.
The resistor serves to dampen the response. Systems with tight space constraints should
consider a discrete resistor to provide the required damping resistance. Too large of a damping
resistance can cause a large IR drop, which means less analog headroom and lower frequency.
response, which can cause resonance at the LC pole. Noise amplification at this band, although
not in the PLL-sensitive spectrum, could cause a fatal headroom reduction for analog circuitry.
The resistor serves to dampen the response. Systems with tight space constraints should
consider a discrete resistor to provide the required damping resistance. Too large of a damping
resistance can cause a large IR drop, which means less analog headroom and lower frequency.
•
Ceramic capacitors have very high self-resonance frequencies, but they are not available in
large capacitance values. A high self-resonant frequency coupled with low ESL/ESR is crucial
for sufficient rejection in the PLL and high frequency band. The recommended tantalum
capacitors have acceptably low ESR and ESL.
large capacitance values. A high self-resonant frequency coupled with low ESL/ESR is crucial
for sufficient rejection in the PLL and high frequency band. The recommended tantalum
capacitors have acceptably low ESR and ESL.
•
The capacitor must be close to the PLL1 and PLL2 pins, otherwise the value of the low ESR
tantalum capacitor is wasted. Note the distance constraint should be translated from the 0.1-
tantalum capacitor is wasted. Note the distance constraint should be translated from the 0.1-
Ω
requirement.