THS4531
SLOS358B –SEPTEMBER 2011–REVISED MARCH 2012
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EVM AND LAYOUT RECOMMENDATIONS
The THS4531 EVM (SLOU334) should be used as a reference when designing the circuit board. It is
recommended to follow the EVM layout of the external components near to the amplifier, ground plane
construction, and power routing as closely as possible. General guidelines are:
1. Signal routing should be direct and as short as possible into and out of the op amp.
2. The feedback path should be short and direct avoiding vias if possible.
3. Ground or power planes should be removed from directly under the amplifier’s input and output pins.
4. A series output resistor is recommended to be placed as near to the output pin as possible. See Figure 78
“Recommended Series Output Resistor vs. Capacitive Load” for recommended values given expected
capacitive load of design.
5. A 2.2µF power supply decoupling capacitor should be placed within 2 inches of the device and can be
shared with other op amps. For split supply, a capacitor is required for both supplies.
6. A 0.1µF power supply decoupling capacitor should be placed as near to the power supply pins as possible.
Preferably within 0.1 inch. For split supply, a capacitor is required for both supplies.
7. The PD pin uses TTL logic levels referenced to the negative supply voltage (VS-). When not used it should
tied to the positive supply to enable the amplifier. When used, it must be actively driven high or low and
should not be left in an indeterminate logic state. A bypass capacitor is not required, but can be used for
robustness in noisy environments.
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