OPA830 datasheet(37/56 Pages) TI

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8.4 Layout

8.4.1 Layout Guidelines

The OPA838 EVM can be used as a reference when designing the circuit board. TI recommends following the

EVM layout of the external components near to the amplifier, ground plane construction, and power routing as

closely as possible. General guidelines are listed below:

1. Signal routing must be direct and as short as possible into and out of the op amp.

2. The feedback path must be short and direct avoiding vias if possible.

3. Ground or power planes must be removed from directly under the negative input and output pins of the

amplifier.

4. TI recommends placing a series output resistor as close to the output pin as possible when driving capacitive

or matched loads.

5. A 2.2-µF power-supply decoupling capacitor must be placed within two inches of the device and can be

shared with other op amps. For split-supply operation, a capacitor is required for both supplies.

6. A 0.1-µF power-supply decoupling capacitor must be placed as close to the supply pins as possible,

preferably within 0.1 inch. For split-supply operation, a capacitor is required for both supplies.

7. The PD pin uses logic levels referenced off the negative supply. If the pin is not used, the pin must tie to the

positive supply to enable the amplifier. If the pin is used, the pin must be actively driven. A bypass capacitor

is not necessary, but is used for EMI rejection in noisy environments.

8.4.2 Layout Example

Place bypass capacitors

close to power pins

Place input resistor close to pin 4

to minimize stray capacitance

Place output resistors close

to output pins to minimize

parasitic capacitance

Ground and power plane removed

from inner layers

Ground and power plane exist on

inner layers

Place bypass capacitors

close to power pins

Remove GND and Power plane

under pins 1 and 4 to minimize

stray PCB capacitance

Place feedback resistor on the bottom

of PCB between pins 4 and 6

Power control (disable) pin

Must be driven

Non-inverting input

terminated in 50 Ÿ

Figure 8-9. EVM Layout Example

www.ti.com

OPA838

SBOS867D – AUGUST 2017 – REVISED SEPTEMBER 2024

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