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OPA623

INPUT PROTECTION

The need for protection from static damage has long been

recognized for MOSFET devices, but all semiconductor

devices deserve protection form this potentially damaging

source. The OPA623 incorporates on-chip ESD protection

diodes as shown in Figure 1. These diodes eliminate the

need for external protection diodes, which can add capaci-

tance and degrade AC performance.

As shown, all input pins of the OPA623 are internally

protected from ESD by a pair of back-to-back reverse-biased

diodes to either power supply. These diodes begin to con-

duct when the input voltage exceeds either power supply by

about 0.7V. This situation can occur when the amplifier

loses its power supplies while a signal source is still present.

The diodes can typically withstand a continuous current of

30mA without destruction. To ensure long-term reliability,

however, the diode current should be limited externally to

approximately 10mA whenever possible.

FIGURE 1. Internal ESD Protection.

+V

CC

–V

CC

ESD Protection diodes internally

connected to all pins.

Internal

Circuitry

External

Pin

The internal protection diodes are designed to withstand

2.5kV (using the Human Body Model) and will provide

adequate ESD protection for most normal handling proce-

dures. However, static damage can cause subtle changes in

the amplifier input characteristics without necessarily de-

stroying the device. In precision amplifiers, such changes

may degrade offset and drift noticeably. For this reason,

static protection is strongly recommended when handling

the OPA623.