LMH2190 Datasheet, PDF (25/32 Pages) National Semiconductor (TI) – Quad Channel 27 MHz Clock Tree Driver with I2C Interface

LMH2190
www.ti.com
Field
Reserved
SNAS473H – JUNE 2009 – REVISED MAY 2013
Table 7. Status Register⁽¹⁾ (continued)
Bits
Description
[7]
LAYOUT RECOMMENDATIONS
As with any other device, careful attention must be paid to the board layout. If the board isn't properly designed,
the performance of the device can be less than might be expected. Especially the input clock trace (SCLK_IN)
and output traces (CLK1/2/3/4) should be as short as possible to reduce the capacitive load observed by the
clock outputs. Also proper decoupling close to the device is necessary. Beside a capacitor in the µF range (See
Table 8), a capacitor of 100 nF on V_BAT and V_OUT is recommended close to device. The equivalent series
resistance (ESR) of the capacitors should be sufficiently low. A standard capacitor is usually adequate. Advised
values are given in Table 8. An evaluation board is available to ease evaluation and demonstrate a proper board
layout.
Table 8. Recommended Component Values
Symbol
C_BAT ⁽¹⁾
C_OUT ⁽¹⁾
ESR
C_{SCLK_IN}
Parameter
Capacitor on V_BAT
Capacitor on V_OUT
Equivalent Series Resistance
Input AC Coupling Capacitor
Min
Typ
Max
0.47
1
1
2.2
5
500
330
470
10000
(1) C_BAT, C_OUT: Low-ESR Surface-Mount Ceramic Capacitors (MLCC's) used in setting electrical characteristics.
Units
µF
mΩ
pF
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