ISO7420E, ISO7420FE, ISO7421E, ISO7421FE

SLLSE45F – DECEMBER 2010 – REVISED JULY 2015

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Typical Application (continued)

9.2.1 Design Requirements

Unlike optocouplers, which require external components to improve performance, provide bias, or limit current,

the ISO742x only require two external bypass capacitors to operate.

9.2.2 Detailed Design Procedure

9.2.2.1 Maximum Supply Current Equations

(Calculated over recommended operating temperature range and Silicon process variation)

9.2.2.1.1

ISO7420

At VCC1 = VCC2 = 3.3V ± 10%

ICC1(max) = ICC1_Q (max) + 1.791 x 10

-2 x f

(1)

ICC2(max) = ICC2_Q (max) + 1.687 x 10

-2 x f + 3.570 x 10-3 x f x C

L

(2)

At VCC1 = VCC2 = 5V ± 10%

ICC1(max) = ICC1_Q (max) + 3.152 x 10

-2 x f

(3)

ICC2(max) = ICC2_Q (max) + 2.709 x 10

-2 x f + 5.365 x 10-3 x f x C

L

(4)

9.2.2.1.2

ISO7421

At VCC1 = VCC2 = 3.3V ± 10%

ICC1(max) = ICC1_Q (max) + 1.726 x 10

-2 x f + 1.785 x 10-3 x f x C

L

(5)

ICC2(max) = ICC2_Q (max) + 1.726 x 10

-2 x f + 1.785 x 10-3 x f x C

L

(6)

At VCC1 = VCC2 = 5V ± 10%

ICC1(max) = ICC1_Q (max) + 2.920 x 10

-2 x f + 2.682 x 10-3 x f x C

L

(7)

ICC2(max) = ICC2_Q (max) + 2.920 x 10

-2 x f + 2.682 x 10-3 x f x C

L

(8)

ICC1_Q (max) and ICC2_Q (max) are equivalent to the maximum supply currents measured in mA under DC input

conditions (provided in the specification tables of this data sheet); f is data rate in Mbps of both channels; CL is

the capacitive load in pF of both channels. ICC1(max) and ICC2(max) are measured in mA.

9.2.2.2 Typical Supply Current Equations:

(Calculated over recommended operating temperature range and Silicon process variation)

9.2.2.2.1

ISO7420

At VCC1 = VCC2 = 3.3V

ICC1(typ) = ICC1_Q (typ) + 1.528 x 10

-2 x f

(9)

ICC2(typ) = ICC2_Q (typ) + 1.637 x 10

-2 x f + 3.275 x 10-3 x f x C

L

(10)

At VCC1 = VCC2 = 5V

ICC1(typ) = ICC1_Q (typ) + 2.640 x 10

-2 x f

(11)

ICC2(typ) = ICC2_Q (typ) + 2.502 x 10

-2 x f + 4.919 x 10-3 x f x C

L

(12)

9.2.2.2.2

ISO7421

At VCC1 = VCC2 = 3.3V

ICC1(typ) = ICC1_Q (typ) + 1.567 x 10

-2 x f + 1.640 x 10-3 x f x C

L

(13)

ICC2(typ) = ICC2_Q (typ) + 1.567 x 10

-2 x f + 1.640 x 10-3 x f x C

L

(14)

At VCC1 = VCC2 = 5V

ICC1(typ) = ICC1_Q (typ) + 2.550 x 10

-2 x f + 2.416 x 10-3 x f x C

L

(15)

ICC2(typ) = ICC2_Q (typ) + 2.550 x 10

-2 x f + 2.461 x 10-3 x f x C

L

(16)

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