IL3285-3E NVE, IL3285-3E Datasheet - Page 7

• Manufacturer Part Number: IL3285-3E
• Description: TXRX ISO BUS 5MBPS RS485 16SOIC
• Manufacturer: NVE
• Series: IsoLoop®r

Specifications of IL3285-3E

• Inputs - Side 1/side 2: RS-485
• Number Of Channels: 1
• Isolation Rating: 2500Vrms
• Voltage - Supply: 4.25V, 5V
• Data Rate: 5Mbps
• Propagation Delay: 100ns
• Output Type: Logic
• Package / Case: 16-SOIC (3.9mm Width)
• Operating Temperature: -40°C ~ 85°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 390-1126-5

Power Supply Decoupling
Both V
proper operation. Additionally, V
Operation
Coil Current
Figure 1. IL3000 Series Input Transfer Function
Typical Resistor Values
Boost Capacitor
The correct boost capacitor gives a great deal of design headroom and can usually eliminate design concerns related to temperature
and power supply fluctuations.
Logic State
V
3.3 V
5 V
Figure 2. C
NVE Corporation
Rise/Fall Time (ns)
Rise/Fall Time (ns)
COIL
High
Low
mA
3.5
1.5
DD1
Signal
Signal
5
and V
1000
boost
1000
500
0.125W, 5% Resistor
510 Ω
820 Ω
20
50
11409 Valley View Road, Eden Prairie, MN 55344-3617
3
3
DD2
Selector
must be bypassed with 47 nF ceramic capacitors. These should be placed as close as possible to V
16
16
C
C
Boost
Boost
( pF )
( pF )
100
2500
DD2
should be bypassed with a 10 µF tantalum capacitor.
210
5000
5000
The table shows typical values for the external resistor in 5 V and 3 V logic systems.
As always, these values as approximate and should be adjusted for temperature or
other application specifics If the expected temperature range is large, 1% tolerance
resistors may provide additional design margin.
t
t
The boost capacitor in parallel with the current-limiting resistor boosts
the instantaneous coil current at the signal transition. The boost current
pushes the GMR bridge output through the comparator threshold voltage
in a bipolar fashion providing important magnetic centering and very
reliable switching. Select the value of the boost capacitor based on the
rise and fall times of the signal driving the inputs.
Use the chart as a guide to boost capacitor selection. The capacitor value
is generally not critical, and can often vary ±50% with little noticeable
difference in device performance provided the center value is correct. If
in doubt, choose a value higher than indicated, up to a maximum of
470 nF. Note however that power dissipation in the input coil increases in
proportion to the capacitor value.
The IL3222 and IL3285 are current-mode devices. Changes in input coil
current switch internal spintronic GMR sensors, which then change the
logic state of the outputs. The GMR bridge is designed so the output of
the isolator is logic high when no field signal is present.
A single resistor is required to limit the input coil current to the
recommended 5 mA. The absolute maximum current through any coil is
25 mA DC. Although logic threshold currents are typically less than the
worst-case 5 mA, NVE recommends designing for 5 mA logic threshold
current in all applications.
Figure 1 shows the input response of the IL3222 and IL3285.
logic high is the zero input current state.
with approximately 3.5 mA of coil current, and back to the high state
when the input current falls below approximately 1.5 mA. This allows
glitch-free interface with low slew-rate signals.
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7
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www.IsoLoop.com
The output switches to the low state
IL3285/IL3222
©2008 NVE Corporation
DD
Output
pins for