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IEC SAFETY LIMITING VALUES

0

75

50

25

100

125

150

175

200

0

50

100

150

200

Case Temperature

C

o

−

V

= 3.6 V,

CC1

V

= 3.6 V

CC2

V

= 5.5 V,

CC1

V

= 5.5 V

CC2

ISO721, ISO721M

ISO722, ISO722M

SLLS629B – JANUARY 2006 – REVISED MAY 2006

Safety limiting intends to prevent potential damage to the isolation barrier upon failure of input or output circuitry.

A failure of the IO can allow low resistance to ground or the supply, and without current limiting, dissipate

sufficient power to overheat the die and damage the isolation barrier, potentially leading to secondary system

failures.

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

θ

100

Safety input, output, or supply current

mA

θ

153

Maximum case temperature

150

°C

The safety-limiting constraint is the absolute maximum junction temperature specified in the absolute maximum

ratings table. The power dissipation and junction-to-air thermal impedance of the device installed in the

application hardware determines the junction temperature. The junction-to-air thermal resistance in the Thermal

Characteristics table is that of a device installed in the JESD51-3, Low Effective Thermal Conductivity Test

Board for Leaded Surface Mount Packages and is conservative. The power is the recommended maximum input

voltage times the current. The junction temperature is then the ambient temperature plus the power times the

junction-to-air thermal resistance.

THERMAL CHARACTERISTICS

(over recommended operating conditions unless otherwise noted)

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

263

°C/W

θ

JA

Junction-to-Air

125

°C/W

Junction-to-Board Thermal

θ

JB

44

°C/W

Resistance

Junction-to-Case Thermal

θ

JC

75

°C/W

Resistance

ISO72x

159

cycle square wave

Device Power Dissipation

mW

195

cycle square wave

(1)

Tested in accordance with the Low-K or High-K thermal metric definition of EIA/JESD51-3 for leaded surface mount packages.

Figure 7.

θ

12

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