IL610 Datasheet, PDF (7/14 Pages) List of Unclassifed Manufacturers – Passive Input Digital Isolators

IL610 IL611 IL612
IL613 IL614
Operation
The IL600 series are current mode devices. Changes in
current flow into the input coil result in logic state changes
at the output. One of the great advantages of the passive coil
input is that both single ended and differential inputs can be
handled without the need for reverse bias protection. The
internal GMR sensor switches the output to logic low if
current flows from (In-) to (In+). Only a single resistor is
required to limit the input coil to the recommended 10 mA.
This allows large input voltages to be used since there is no
semiconductor structure on the input.
The absolute maximum current through the coil of the IL600
series is 25 mA DC. However, it is important to limit input
current to levels well below this in all applications. The
worst case logic threshold current is 10 mA. While typical
threshold currents are substantially less than this, NVE
recommends designing a 10 mA logic threshold current in
each application. In all cases, the current must flow from In-
to In+ in the coil to switch the output low. This is true
regardless of true or inverted data configurations. Output
logic high is the zero input current state.
Figure 1 shows the response of the IL600 series. The GMR
bridge structure is designed such that the output of the
isolator is logic high when no field signal is present. The
output will switch to the low state with 10 mA of coil
current and the output will switch back to the high state
when the input current falls below 2 mA. This allows glitch-
free interface with low slew rate signals.
Figure 1. IL600 Series Transfer Function
To calculate the value of the protection resistor (R1)
required, use Ohm’s law as shown in the examples below. It
should be noted that we are concerned only with the
magnitude of the voltage across the coil. The absolute values
of V_in High and V_in Low are arbitrary.
Figure 2. Series Resistor Calculation Equivalent Circuit.
Example 1. In this case, T_nom = 25ºC, V_in High is 24 V, V_in
Low is 1.8 V, and I_coil minimum is specified as 10 mA. Total
loop resistance is
(R1 + Rcoil) = ^{(Vin High - Vin Low)} = ^22.2 Ω = 2220 Ω
Icoil
0.01
Therefore,
R1 = (2220 − 55) Ω = 2145 Ω
Example 2. At a maximum operating temperature of 85°C,
T_max = 85ºC, T_nom = 25ºC, V_in High = 5 V, V_in Low = 0 V,
and nominal R_coil = 55 Ω. At T_max = 85ºC
Rcoil = 55 + (Tmax − Tmin) × TCRcoil
= 55 + (85 - 25)× 0.165 = 55 + 9.9 = 65 Ω
Therefore, the recommended series resistor is
R1 = ^{(VinHigh - VinLow)} - Rcoil
Icoil
= ^{5 - 0} − 65 = 435 Ω
0.01
Allowance should also be made for the temperature
coefficient of the current limiting resistor to ensure that I_coil
is 10 mA at maximum operating temperature.
Power Supplies
It is recommended that 47 nF ceramic capacitors be used to
decouple the power supplies. The capacitors must be placed
as close as possible to V_DD for proper operation.
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