OP462_15 Datasheet, PDF (13/20 Pages) Analog Devices – 15 MHz Rail-to-Rail Operational Amplifiers

Data Sheet
and VIN swings up to 5 V, the output current will not exceed
30 mA. For single 5 V supply applications, resistors less than
169 Ω are not recommended.
5V
V_IN
OPx62
169Ω
V_OUT
Figure 32. Output Short-Circuit Protection
INPUT OVERVOLTAGE PROTECTION
The input voltage should be limited to ±6 V, or damage to the
device can occur. Electrostatic protection diodes placed in the
input stage of the device help protect the amplifier from static
discharge. Diodes are connected between each input as well as
from each input to both supply pins as shown in the simplified
equivalent circuit in Figure 30. If an input voltage exceeds either
supply voltage by more than 0.6 V, or if the differential input
voltage is greater than 0.6 V, these diodes energize causing
overvoltage damage.
The input current should be limited to less than 5 mA to
prevent degradation or destruction of the device by placing an
external resistor in series with the input at risk of being overdriven.
The size of the resistor can be calculated by dividing the maxi-
mum input voltage by 5 mA. For example, if the differential
input voltage could reach 5 V, the external resistor should be
5 V/5 mA = 1 kΩ. In practice, this resistor should be placed in
series with both inputs to balance any offset voltages created by
the input bias current.
OUTPUT PHASE REVERSAL
The OP162/OP262/OP462 are immune to phase reversal as
long as the input voltage is limited to ±6 V. Figure 27 shows the
output of a device with the input voltage driven beyond the
supply voltages. Although the device’s output does not change
phase, large currents due to input overvoltage could result,
damaging the device. In applications where the possibility of an
input voltage exceeding the supply voltage exists, overvoltage
protection should be used, as described in the previous section.
POWER DISSIPATION
The maximum power that can be safely dissipated by the
OP162/OP262/OP462 is limited by the associated rise in
junction temperature. The maximum safe junction temperature
is 150°C; device performance suffers when this limit is
exceeded. If this maximum is only momentarily exceeded,
proper circuit operation will be restored as soon as the die
temperature is reduced. Leaving the device in an “overheated”
condition for an extended period can result in permanent
damage to the device.
OP162/OP262/OP462
To calculate the internal junction temperature of the OPx62, use
the formula
TJ = PDISS × θJA + TA
where:
TJ is the OPx62 junction temperature.
PDISS is the OPx62 power dissipation.
θJA is the OPx62 package thermal resistance, junction-to-
ambient temperature.
TA is the ambient temperature of the circuit.
The power dissipated by the device can be calculated as
PDISS = ILOAD × (VS – VOUT)
where:
ILOAD is the OPx62 output load current.
VS is the OPx62 supply voltage.
VOUT is the OPx62 output voltage.
Figure 33 and Figure 34 provide a convenient way to determine
if the device is being overheated. The maximum safe power
dissipation can be found graphically, based on the package type
and the ambient temperature around the package. By using the
previous equation, it is a simple matter to see if PDISS exceeds the
device’s power derating curve. To ensure proper operation, it is
important to observe the recommended derating curves shown
in Figure 33 and Figure 34.
0.9
0.8
0.7
8-LEAD SOIC
0.6
0.5
8-LEAD MSOP
0.4
8-LEAD TSSOP
0.3
0.2
0.1
0
20
40
60
80
100
120
AMBIENT TEMPERATURE (°C)
Figure 33. Maximum Power Dissipation vs. Temperature for
8-Lead Package Types
Rev. H | Page 13 of 20