LTC2159 datasheet(26/32 Pages) LINER

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LTC2159

2159f

GROUNDING AND BYPASSING

The LTC2159 requires a printed circuit board with a clean

unbroken ground plane in the first layer beneath the ADC.

A multilayer board with an internal ground plane is rec-

ommended. Layout for the printed circuit board should

ensure that digital and analog signal lines are separated as

much as possible. In particular, care should be taken not

to run any digital track alongside an analog signal track

or underneath the ADC.

High quality ceramic bypass capacitors should be used at

the VDD, OVDD, VCM, VREF, REFH and REFL pins. Bypass

capacitors must be located as close to the pins as pos-

sible.Size0402ceramiccapacitorsarerecommended.The

traces connecting the pins and bypass capacitors must

be kept short and should be made as wide as possible.

applicaTions inForMaTion

Of particular importance is the capacitor between REFH

and REFL. This capacitor should be on the same side of

the circuit board as the A/D, and as close to the device

as possible.

The analog inputs, encode signals, and digital outputs

should not be routed next to each other. Ground fill and

grounded vias should be used as barriers to isolate these

signals from each other.

HEAT TRANSFER

Most of the heat generated by the LTC2159 is transferred

from the die through the bottom-side exposed pad and

package leads onto the printed circuit board. For good

electrical and thermal performance, the exposed pad must

be soldered to a large grounded pad on the PC board. This

pad should be connected to the internal ground planes by

an array of vias.

LTC2159 Datasheet(PDF) 26 Page - Linear Technology