OPA1652_16 Datasheet, PDF (16/42 Pages) Texas Instruments – Audio Operational Amplifiers

OPA1652, OPA1654
SBOS477A – DECEMBER 2011 – REVISED AUGUST 2016
Feature Description (continued)
RF
R1
IN±
RS
IN+
ID
+
VIN
±
250 Ÿ
250 Ÿ
TVS
+VS
www.ti.com
+
Power-Supply
ESD Cell
RL
±VS
TVS
Copyright © 2016, Texas Instruments Incorporated
Figure 37. 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 above the normal operating voltage of the OPA165x but below
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 (refer to Figure 37), 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 37 shows a specific example where the input voltage (V_IN) 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 V_IN. As a result, the data sheet specifications recommend that
applications limit the input current to 10 mA.
If the supply is not capable of sinking the current, V_IN can begin sourcing current to the operational amplifier and
then take over as the source of positive supply voltage. The danger in this case is that the voltage can rise to
levels that exceed the operational amplifier absolute maximum ratings.
16
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