MAX14934 Datasheet, PDF (19/24 Pages) Maxim Integrated Products – Four-Channel, 5kVRMS Digital Isolators

MAX14934–MAX14936
Four-Channel, 5kV_RMS Digital Isolators
Detailed Description
The MAX14934–MAX14936 are a family of four-channel
digital isolators. The MAX14934–MAX14936 family trans-
fers digital signals between circuits with different power
domains. The devices are rated for 5kV_RMS isolation volt-
age for 60 seconds. This family of digital isolators offers
low-power operation, high electromagnetic interference
(EMI) immunity, and stable temperature performance
through Maxim’s proprietary process technology. The
devices isolate different ground domains and block high-
voltage/high-current transients from sensitive or human
interface circuitry.
The MAX14934–MAX14936 family offers three unidirec-
tional channel configurations for design convenience. The
MAX14934 features four channels transferring digital sig-
nals in one direction for applications such as isolated digi-
tal I/O. The MAX14935 has three channels transmitting
data in one direction and one channel transmitting in the
opposite direction, making it ideal for applications such as
isolated SPI and RS-485 communication. The MAX14936
provides further design flexibility with two channels in
each direction for isolated RS-232 or other applications.
Devices are available with data rates from DC up to 1Mbps
(A/D versions), 25Mbps (B/E versions), or 150Mbps (C/F
versions). Each device can also be ordered with default-
high or default-low outputs. This is the state an output
will go to when the input side of the device is unpowered.
The devices have two supply inputs, V_DDA and V_DDB,
that independently set the logic levels on either side of
the device. V_DDA and V_DDB are referenced to GNDA and
GNDB, respectively. The MAX14934–MAX14936 family
also features a refresh circuit to ensure output accuracy
when an input remains in the same state indefinitely.
Digital Isolation
The MAX14934–MAX14936 family provides galvanic iso-
lation for digital signals that are transmitted between two
ground domains. Up to 1200V_PEAK of continuous isola-
tion is supported, as well as transient differences of up to
5kV_RMS for up to 60 seconds.
Level Shifting
The wide supply voltage range of both V_DDA and V_DDB
allows the MAX14934–MAX14936 family to be used for
level translation in addition to isolation. V_DDA and V_DDB
can be independently set to any voltage from 1.71V to
5.5V. The supply voltage sets the logic level on the cor-
responding side of the isolator.
Unidirectional Channels
Each channel of the MAX14934–MAX14936 is unidirec-
tional; it only passes data in one direction, as indicated in
the functional diagram. Each device features four unidi-
rectional channels that operate independently with guar-
anteed data rates from DC up to 1Mbps (A/D versions),
25Mbps (B/E versions), or 150Mbps (C/F versions). The
output driver of each channel is push-pull, eliminating the
need for pullup resistors. The outputs are able to drive
both TTL and CMOS logic inputs.
Startup and Undervoltage Lockout
The V_DDA and V_DDB supplies are both internally moni-
tored for undervoltage conditions. Undervoltage events
can occur during power-up, power-down, or during nor-
mal operation due to a sagging supply voltage. When an
undervoltage condition is detected on either supply, all
outputs go to their default states regardless of the status
of the inputs (Table 1). Figures 2–5 show the behavior of
the outputs during power-up and power-down.
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