MAX14826 Datasheet, PDF (29/32 Pages) Maxim Integrated Products – IO-Link Device Transceiver

MAX14826
IO-Link Device Transceiver
Applications Information
Transient Protection
Inductive load-switching, surges, and bursts create high
transient voltages. C/Q, DO, and DI should be protected
against high overvoltage and undervoltage transients.
Positive voltage transients on C/Q, DO, and DI must be
limited to +55V relative to GND and negative voltage
transients must be limited to -55V (relative to V_CC) on DO
and C/Q and to -55V (relative to GND) on DI. Figure 14
shows suitable protection using TVS diodes to meet both
the IEC 61000-4-2 ESD and IEC 61000-4-4 burst testing.
Other protection schemes may also be suitable.
The V_CC and LDOIN must be protected against transients
that occur during hot-plugging of the L+ sensor supply
(V_CC). To protect the device, place a 10W resistor and
1µF capacitor before LDOIN and connect an RC between
the sensor supply into and V_CC, as shown in Figure 8.
Ensure that the RC time constant of the filter on V_CC is
at least 0.8µs.
Optional External Powering
The MAX14826 is powered by V_CC and V₅. V_L is a
reference voltage input to set the logic levels of the
microcontroller interface. The logic and SPI interface are
operational when V₅ and V_L are present even if V_CC is
not present.
The V_P output provides a reverse-polarity-protected
voltage one diode drop below V_CC and can be used
for supplying external circuitry, like power supplies. The
current drawn from V_P cannot exceed 50mA. Be aware
that capacitance on V_P can cause transient currents at
power-up equal to C x dV_CC/dt.
V₅ is typically powered by the internal 5V regulator, but
can alternatively be powered by an external 5V regula-
tor. When powering V₅ externally, connect LDOIN to V₅.
(Figure 15). This configuration disables operation of the
internal 5V regulator and reduces power consumption.
1uF
10Ω
LDOIN
VP
VCC
DO
MAX14826
C/Q
DI
GND
SDC36
0.8Ω
1µF
SDC36
Figure 14. MAX14826 Operating Circuit with TVS Protection
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