MAX12930 Datasheet, PDF (16/20 Pages) Maxim Integrated Products – Two-Channel Digital Isolators

MAX12930/MAX12931
Two-Channel Digital Isolators
Detailed Description
The MAX12930/MAX12931 are a family of 2-channel
digital isolators. The MAX12930 transfers digital signals
between circuits with different power domain in one
direction, which is convenient for applications such as
digital I/O. The MAX12931 transfers digital signals in
opposite directions, which is necessary for isolated
RS-485 or other UART applications.
Devices available in the 8-pin narrow body SOIC package
are rated for up to 3.75kV_RMS isolation voltage for 60
seconds and the device in the 16-pin wide body SOIC
package is rated for up to 5kV_RMS. 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.
Devices are available with data rates from DC to 25Mbps
(B/E versions) or 150Mbps (C/F versions). Each device
can be ordered with default-high or default-low outputs.
The default is the state the output assumes when the
input is not powered, or if the input is open circuit.
The devices have two supply inputs (V_DDA and V_DDB)
that independently set the logic levels on either side of
device. V_DDA and V_DDB are referenced to GNDA and
GNDB, respectively. The MAX12930/MAX12931 family
also features a refresh circuit to ensure output accuracy
when an input remains in the same state indefinitely.
Digital Isolation
The device family provides galvanic isolation for digital
signals that are transmitted between two ground domains.
Up to 630V_PEAK of continuous isolation is supported
in the narrow SOIC package and up to 1200V_PEAK of
continuous isolation is supported in the wide SOIC
package. The devices withstand differences of up to
3.75kV_RMS in the 8-pin narrow SOIC package or 5kV_RMS
in the 16-pin wide SOIC package for up to 60 seconds.
Level-Shifting
The wide supply voltage range of both V_DDA and V_DDB
allows the MAX12930/MAX12931 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
corresponding side of the isolator.
Unidirectional Channels
Each channel of the MAX12930/MAX12931 is
unidirectional; it only passes data in one direction, as
indicated in the functional diagram. Each device features
two unidirectional channels that operate independently
with guaranteed data rates from DC up to 25Mbps (B/E
versions), or DC to 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
monitored for undervoltage conditions. Undervoltage
events can occur during power-up, power-down, or during
normal 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 state of
the inputs (Table 3). Figure 2 through Figure 5 show the
behavior of the outputs during power-up and power-down.
Table 3. Output Behavior During Undervoltage Conditions
V_{IN_}
1
0
X
X
V_VDDA
Powered
Powered
Undervoltage
Powered
V_VDDB
Powered
Powered
Powered
Undervoltage
V_{OUTA_}
1
0
Default
Default
V_{OUTB_}
1
0
Default
Default
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