Safety Limiting (1) intends to minimize potential damage to the isolation barrier upon failure of input or output circuitry. A failure of the I/O can allow low resistance to ground or the supply and, without current limiting, dissipate sufficient power to over-heat the die and damage the isolation barrier potentially leading to secondary system failures.
| PARAMETER |
TEST CONDITIONS |
MAX |
UNIT |
| IS |
Safety input, output or supply current |
RθJA = 61.1°C/W, VVINP = 5.5V, TJ = 150°C, TA = 25°C, POUT = 2.4W |
808 |
mA |
| RθJA = 61.1°C/W, VVINP = 4.5V, TJ = 150°C, TA = 25°C, POUT = 1.65W |
821 |
mA |
| PS |
Safety power dissipation (input power - output power) |
RθJA = 61.1 °C/W, TJ = 150 °C, TA = 25 °C |
2.05 |
W |
| TS |
Safety temperature |
|
150 |
°C |
(1) The maximum safety temperature, T
S, has the same value as the maximum junction temperature, T
J, specified for the device. The I
S and P
S parameters represent the safety current and safety power respectively. The maximum limits of I
S and PS should not be exceeded. These limits vary with the ambient temperature, T
A.
The junction-to-air thermal resistance, R
θJA, in the
Thermal Information table is that of a device installed on a high-K test board for leaded surface-mount packages. Use these equations to calculate the value for each parameter:
T
J = T
A + R
qJA × P, where P is the power dissipated in the device.
T
J(max) = T
S = T
A + R
θJA × P
S, where T
J(max) is the maximum allowed junction temperature.
P
S = I
S × V
VINP, where V
VINP is the maximum input voltage.