OPA1652_15 Datasheet, PDF (15/29 Pages) Texas Instruments – Low Noise and Distortion, General-Purpose, FET-Input AUDIO OPERATIONAL AMPLIFIERS

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POWER DISSIPATION
The OPA1652 and OPA1654 series op amps are
capable of driving 2-kΩ loads with a power-supply
voltage up to ±18V and full operating temperature
range. Internal power dissipation increases when
operating at high supply voltages. Copper leadframe
construction used in the OPA165x series op amps
improves heat dissipation compared to conventional
materials. Circuit board layout can also help minimize
junction temperature rise. Wide copper traces help
dissipate the heat by acting as an additional heat
sink. Temperature rise can be further minimized by
soldering the devices to the circuit board rather than
using a socket.
ELECTRICAL OVERSTRESS
Designers often ask questions about the capability of
an operational amplifier to withstand electrical
overstress. These questions tend to focus on the
device inputs, but may involve the supply voltage pins
or even the output pin. Each of these different pin
functions have electrical stress limits determined by
the voltage breakdown characteristics of the
particular semiconductor fabrication process and
specific circuits connected to the pin. Additionally,
internal electrostatic discharge (ESD) protection is
built into these circuits to protect them from
accidental ESD events both before and during
product assembly.
These ESD protection diodes also provide in-circuit,
input overdrive protection, as long as the current is
limited to 10 mA as stated in the Absolute Maximum
Ratings. Figure 40 shows how a series input resistor
may be added to the driven input to limit the input
current. The added resistor contributes thermal noise
at the amplifier input and its value should be kept to a
minimum in noise-sensitive applications.
OPA1652
OPA1654
SBOS477 – DECEMBER 2011
I_OVERLOAD
10 mA max
V_IN
5 kW
V+
Device
V_OUT
Figure 40. Input Current Protection
An ESD event produces a short duration,
high-voltage pulse that is transformed into a short
duration, high-current pulse as it discharges through
a semiconductor device. The ESD protection circuits
are designed to provide a current path around the
operational amplifier core to prevent it from being
damaged. The energy absorbed by the protection
circuitry is then dissipated as heat.
When the operational amplifier connects into a circuit,
the ESD protection components are intended to
remain inactive and 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. Should this
condition occur, there is a risk that some of the
internal ESD protection circuits may be biased on,
and conduct current. Any such current flow occurs
through ESD cells and rarely involves the absorption
device.
If there is an uncertainty about the ability of the
supply to absorb this current, external zener diodes
may be added to the supply pins. The zener voltage
must be selected such that the diode does not turn
on during normal operation.
However, its zener voltage should be low enough so
that the zener diode conducts if the supply pin begins
to rise above the safe operating supply voltage level.
Copyright © 2011, Texas Instruments Incorporated
15
Product Folder Link(s): OPA1652 OPA1654