ADM2486BRW 查看數據表（PDF） - Analog Devices
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ADM2486BRW Datasheet PDF : 20 Pages
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ADM2486
CIRCUIT DESCRIPTION
ELECTRICAL ISOLATION
In the ADM2486, electrical isolation is implemented on the
logic side of the interface. Therefore, the part has two main
sections: a digital isolation section and a transceiver section
(see Figure 26). Driver input and request-to-send signals,
applied to the TxD and RTS pins, respectively, and referenced to
logic ground (GND1), are coupled across an isolation barrier to
appear at the transceiver section referenced to isolated ground
(GND2). Similarly, the receiver output, referenced to isolated
ground in the transceiver section, is coupled across the isolation
barrier to appear at the RxD pin referenced to logic ground.
iCoupler Technology
The digital signals are transmitted across the isolation barrier
using iCoupler technology. This technique uses chip-scale
transformer windings to couple the digital signals magnetically
from one side of the barrier to the other. Digital inputs are
encoded into waveforms that are capable of exciting the
primary transformer winding. At the secondary winding, the
induced waveforms are then decoded into the binary value that
was originally transmitted.
VDD1
ISOLATION
BARRIER
VDD2
A
TxD
ENCODE
DECODE
D
B
RTS
ENCODE
DECODE
DE
RxD
DECODE
ENCODE
R
RE
DIGITAL ISOLATION
TRANSCEIVER
GND1
GND2
Figure 26. ADM2486 Digital Isolation and Transceiver Sections
TRUTH TABLES
The truth tables in this section use these abbreviations:
Letter
H
I
L
X
Z
NC
Description
High level
Indeterminate
Low level
Irrelevant
High impedance (off)
Disconnected
Table 9. Transmitting
Supply Status
Inputs
Output
VDD1
VDD2
RTS TxD A B
DE
On
On
H
H
HL
H
On
On
H
L
L
H
H
On
On
L
X
ZZ
L
On
Off
X
X
ZZ
L
Off
On
X
X
ZZ
L
Off
Off
X
X
ZZ
L
Table 10. Receiving
Supply Status Inputs
VDD1
VDD2
A − B (V)
On
On
On
On
On
On
On
On
On
On
On
Off
Off
On
Off
Off
>0.2
<−0.2
−0.2 < A − B < 0.2
Inputs open
X
X
X
X
RE
L or NC
L or NC
L or NC
L or NC
H
L or NC
L or NC
L or NC
Output
RxD
H
L
I
H
Z
H
H
L
POWER-UP/POWER-DOWN THRESHOLDS
The power-up/power-down characteristics of the ADM2486 are
in accordance with the supply thresholds shown in Table 11.
Upon power-up, the ADM2486 output signals (A, B, RxD, and
DE) reach their correct state once both supplies have exceeded
their thresholds. Upon power-down, the ADM2486 output
signals retain their correct state until at least one of the supplies
drops below its power-down threshold. When the VDD1 power-
down threshold is crossed, the ADM2486 output signals reach
their unpowered states within 4 µs.
Table 11. Power-Up/Power-Down Thresholds
Supply
Transition
Threshold (V)
VDD1
Power-up
2.0
VDD1
Power-down
1.0
VDD2
Power-up
3.3
VDD2
Power-down
2.4
Rev. C | Page 14 of 20
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