4

DS691DB1

CDB4350

6. POWER SUPPLY CIRCUITRY

Power is supplied to the evaluation board by three binding posts (GND, +12V, and -12V), as shown in Figure 7. The

‘+12V’ and ‘-12V’ terminals supply the active output filters. The +3.3 V and +5.0 V circuitry is powered by regulators

fed by the ‘+12V’ terminal. Headers J3, J4, and J7 allow the user to either select +3.3 V or +5.0 V supplies for the

various CS4350 voltage supply pins. Alternatively, the user can remove the shunts on J3, J4, and J7, and provide

an external power supply.

WARNING: Refer to the CS4350 datasheet for maximum allowable voltage levels. Operation outside of this range

can cause permanent damage to the device.

7. GROUNDING AND POWER SUPPLY DECOUPLING

As with any high-performance converter, the CS4350 requires careful attention to power supply and grounding ar-

rangements in order to optimize performance. Figure 2 details the connections to the CS4350 while Figures 8, 9,

and 10 show the component placement and top and bottom layout. The decoupling capacitors are located as close

to the CS4350 as possible. Extensive use of ground plane fill in the evaluation board yields large reductions in ra-

diated noise.

8. ANALOG OUTPUT FILTERING

The analog output on the CDB4350 has been designed according to the CS4350 datasheet. This output circuit in-

cludes an active 2-pole, 50 kHz filter which utilizes the multiple-feedback topology and a passive output filter.