AD8275ARMZ-R7 datasheet(5/17 Pages) AD

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AD8275

Rev. A | Page 4 of 16

ABSOLUTE MAXIMUM RATINGS

Table 3.

Parameter

Rating

Supply Voltage

18 V

Output Short-Circuit Current

See derating curve

(Figure 3)

Voltage at +IN, −IN Pins

−VS + 40 V, +VS − 40 V

Voltage at REFx, +VS, − VS, SENSE,

and OUT Pins

−VS − 0.5 V, +VS + 0.5 V

Current into REFx, +IN, −IN, SENSE,

and OUT Pins

3 mA

Storage Temperature Range

−65°C to +130°C

Specified Temperature Range

−40°C to +85°C

Thermal Resistance (θJA)

135°C/W

Package Glass Transition Temperature

(TG)

140°C

ESD Human Body Model

2 kV

Stresses above those listed under Absolute Maximum Ratings

may cause permanent damage to the device. This is a stress

rating only; functional operation of the device at these or any

other conditions above those indicated in the operational

section of this specification is not implied. Exposure to absolute

maximum rating conditions for extended periods may affect

device reliability.

MAXIMUM POWER DISSIPATION

The maximum safe power dissipation in the AD8275 package is

limited by the associated rise in junction temperature (TJ) on

the die. The plastic encapsulating the die locally reaches the

junction temperature. At approximately 140°C, which is the

glass transition temperature, the plastic changes its properties.

Even temporarily exceeding this temperature limit can change

the stresses that the package exerts on the die, permanently

shifting the parametric performance of the AD8275. Exceeding

a junction temperature of 140°C for an extended period can

result in changes in silicon devices, potentially causing failure.

The still air thermal properties of the package and PCB (θJA),

the ambient temperature (TA), and the total power dissipated in

the package (PD) determine the junction temperature of the die.

The junction temperature is calculated as follows:

TJ = TA + (PD × θJA)

The power dissipated in the package (PD) is the sum of the

quiescent power dissipation and the power dissipated in the

package due to the load drive for all outputs. The quiescent

power is the voltage between the supply pins (VS) times the

quiescent current (IS). Assuming the load (RL) is referenced to

midsupply, the total drive power is VS/2 × IOUT, some of which is

dissipated in the package and some of which is dissipated in the

load (VOUT × IOUT).

The difference between the total drive power and the load

power is the drive power dissipated in the package.

PD = Quiescent Power + (Total Drive Power − Load Power)

(

)

OUT

–













In single-supply operation with RL referenced to –VS, the worst

case is VOUT = VS/2.

Airflow increases heat dissipation, effectively reducing θJA. In

addition, more metal directly in contact with the package leads

from metal traces, through holes, ground, and power planes

reduces θJA.

Figure 3 shows the maximum safe power dissipation in the

package vs. the ambient temperature on a 4-layer JEDEC

standard board.

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

–40

–20

100

120

AMBIENT TEMPERATURE (°C)

Figure 3. Maximum Power Dissipation vs. Ambient Temperature

ESD CAUTION

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