ADA4800

Rev. A | Page 12 of 16

POWER SUPPLY BYPASSING

Attention must be paid to bypassing the power supply pin of

the ADA4800. Use high quality capacitors with low equivalent

series resistance (ESR), such as multilayer ceramic capacitors

(MLCCs), to minimize supply voltage ripple and power dissipa-

tion. A large, usually tantalum, 2.2 μF to 47 μF capacitor located

in close proximity to the ADA4800 is required to provide good

decoupling for lower frequency signals. The actual value is

determined by the circuit transient and frequency requirements. In

addition, 0.1 μF MLCC decoupling capacitors should be located

as close to the power supply pin as is physically possible, no more

than ⅛ inch away. The ground returns should terminate imme-

diately into the ground plane. Locating the bypass capacitor

return close to the load return minimizes ground loops and

improves performance.

POWER SEQUENCING

All I/O pins are ESD protected with internal back-to-back

diodes connected to VCC and GND as shown in Figure 24.

an I/O pin can turn on the protection diodes and cause permanent

damage or destroy the IC. To prevent this condition during

power-on, no voltages should be applied to any I/O pins until

VCC is fully on and settled. During power-off, I/O pin voltages

should be removed or reduced to 0 V before VCC is turned off.

ADA4800

VCC

EXTERNAL

PIN

Figure 24. Simplified Input/Output Circuitry

current should be limited to 5 mA or less by the source or by

adding a series resistor.