OPA1677DBVT datasheet(15/52 Pages) TI

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Additionally, internal electrostatic discharge (ESD) protection is built into these circuits to protect them from

accidental ESD events both before and during product assembly.

A good understanding of this basic ESD circuitry and the relevance to an electrical overstress event is helpful.

Figure 7-2 illustrates the ESD circuits contained in the OPA167x (indicated by the dashed line area). The ESD

protection circuitry involves several current-steering diodes connected from the input and output pins and routed

back to the internal power-supply lines, where the diodes meet at an absorption device internal to the operational

amplifier. This protection circuitry is intended to remain inactive during normal circuit operation.

Power-Supply

ESD Cell

250 Ÿ

IN±

IN+

TVS

VIN

±VS

TVS

+VS

Figure 7-2. Equivalent Internal ESD Circuitry Relative to a Typical Circuit Application

An ESD event produces a short-duration, high-voltage pulse that is transformed into a short-duration, high-

current pulse when discharging through a semiconductor device. The ESD protection circuits are designed to

provide a current path around the operational amplifier core to prevent damage. The energy absorbed by the

protection circuitry is then dissipated as heat.

When an ESD voltage develops across two or more amplifier device pins, current flows through one or

more steering diodes. Depending on the path that the current takes, the absorption device can activate. The

absorption device has a trigger, or threshold voltage, that is greater than the normal operating voltage of the

OPA167x but less than the device breakdown voltage level. When this threshold is exceeded, the absorption

device quickly activates and clamps the voltage across the supply rails to a safe level.

When the operational amplifier connects into a circuit (see Figure 7-2), the ESD protection components

are intended to remain inactive and do not become involved in the application circuit operation. However,

circumstances may arise where an applied voltage exceeds the operating voltage range of a given pin. If this

condition occurs, there is a risk that some internal ESD protection circuits can turn on and conduct current. Any

such current flow occurs through steering-diode paths and rarely involves the absorption device.

Figure 7-2 shows a specific example where the input voltage (VIN) exceeds the positive supply voltage (V+)

by 500 mV or more. Much of what happens in the circuit depends on the supply characteristics. If V+ can

sink the current, one of the upper input steering diodes conducts and directs current to V+. Excessively high

current levels can flow with increasingly higher VIN. As a result, the data sheet specifications recommend that

applications limit the input current to 10 mA.

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OPA1677, OPA1678, OPA1679

SBOS855D – JANUARY 2017 – REVISED DECEMBER 2021

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