OPA2140AIDR datasheet(18/48 Pages) TI

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7.3.7 Thermal Protection

The OPAx140 series of op amps are capable of driving 2-kΩ loads with power-supply voltages of up to ±18

V over the specified temperature range. In a single-supply configuration, where the load is connected to the

negative supply voltage, the minimum load resistance is 2.8 kΩ at a supply voltage of 36 V. For lower supply

voltages (either single-supply or symmetrical supplies), a lower load resistance may be used, as long as the

output current does not exceed 13 mA; otherwise, the device short circuit current protection circuit may activate.

Internal power dissipation increases when operating at high supply voltages. Copper leadframe construction

used in the OPA140, OPA2140, and OPA4140 series devices improves heat dissipation compared to

conventional materials. Printed-circuit-board (PCB) layout can also help reduce a possible increase in junction

temperature. Wide copper traces help dissipate the heat by acting as an additional heatsink. Temperature rise

can be further minimized by soldering the devices directly to the PCB rather than using a socket.

Although the output current is limited by internal protection circuitry, accidental shorting of one or more output

channels of a device can result in excessive heating. For instance, when an output is shorted to mid-supply, the

typical short-circuit current of 36 mA leads to an internal power dissipation of over 600 mW at a supply of ±18 V.

In the case of a dual OPA2140 in an 8-pin VSSOP package (thermal resistance θJA = 180°C/W), such power

dissipation would lead the die temperature to be 220°C above ambient temperature, when both channels are

shorted. This temperature increase significantly decreases the operating life of the device.

To prevent excessive heating, the OPAx140 series has an internal thermal shutdown circuit that shuts down

the device if the die temperature exceeds approximately 180°C. When this thermal shutdown circuit activates,

a built-in hysteresis of 15°C makes sure that the die temperature must drop to approximately 165°C before the

device switches on again.

Additional consideration should be given to the combination of maximum operating voltage, maximum operating

temperature, load, and package type. Figure 7-3 and Figure 7-4 show several practical considerations when

evaluating the OPA2140 (dual version) and the OPA4140 (quad version).

As an example, the OPA4140 has a maximum total quiescent current of 10.8 mA (2.7 mA/channel) over

temperature. The 14-pin TSSOP package has a typical thermal resistance of 135°C/W. This parameter means

that because the junction temperature should not exceed 150°C to provide reliable operation, either the supply

voltage must be reduced, or the ambient temperature should remain low enough so that the junction temperature

does not exceed 150°C. This condition is illustrated in Figure 7-3 for various package types. Moreover, resistive

loading of the output causes additional power dissipation and thus self-heating, which also must be considered

when establishing the maximum supply voltage or operating temperature. To this end, Figure 7-4 shows the

maximum supply voltage versus temperature for a worst-case dc load resistance of 2 kΩ.

100

110

120

130

140

150

160

Ambient Temperature (°C)

TSSOP Quad

SOIC Quad

MSOP Dual

SOIC Dual

Figure 7-3. Maximum Supply Voltage vs

Temperature (OPA2140 and OPA4140), Quiescent

Condition

100

110

120

130

140

150

160

Ambient Temperature ( C)

TSSOP Quad

SOIC Quad

MSOP Dual

SOIC Dual

Figure 7-4. Maximum Supply Voltage vs

Temperature (OPA2140 and OPA4140), Maximum

DC Load

OPA140, OPA2140, OPA4140

SBOS498E – JULY 2010 – REVISED JULY 2021

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