MAX14824 Datasheet, PDF (17/28 Pages) Maxim Integrated Products – IO-Link Master Transceiver

MAX14824
IO-Link Master Transceiver
Wake-Up Generation
The MAX14824 features automatic wake-up polarity gen-
eration functionality that can be initiated through hard-
ware or software. The following conditions must be met
prior to automatic wake-up polarity generation to ensure
proper functionality:
• WUEN is low
• TXEN is low and C/QDEn = 0
• Q=0
• TXC and TXQ are both high
Drive WUEN high to enable the automatic wake-up
polarity generation circuitry in the device. When WUEN
is high, apply an external pulse to TXC or TXQ from
high-to-low for 80Fs (typ) to generate a valid wake-up
pulse. The applied pulse is independent of the logic
state that the IO-Link sensor was forcing on the C/Q level
(Figure 5). Drive WuEN low after the wake-up has been
generated.
The C/Q driver is automatically enabled while TXC/TXQ
is low and C/Q is pulled either from high-to-low or from
low-to-high, depending on the previous state. The C/Q
driver is automatically disabled when the TXC/TXQ inputs
are pulled high again.
Wake-up polarity generation can also be enabled through
software by setting the WuEnBit bit in the Mode register
to 1. See the Mode Register [R1, R0] = [1,1] section for
more information.
Thermal Protection and Considerations
The internal LDOs and C/Q driver can generate more
power than the package for the device can safely dis-
sipate. Ensure that the driver LDO loading is less than
the package can dissipate. Total power dissipation for
the device is calculated using the following equation:
P_TOTAL = P_C/Q + P₅ + P_LDO33 + P_Q + P_CLCQ + P_CLDI
where P_C/Q is the power generated in the C/Q driver,
P₅ and P_LDO33 are the power generated by the LDOs,
P_Q is the quiescent power generated by the device, and
P_CLCQ and P_CLDI are the power generated in the C/Q
and DI current sinks.
Ensure that the total power dissipation is less than the
limits listed in the Absolute Maximum Ratings section.
Use the following to calculate the power dissipation (in
mW) due to the C/Q driver:
P_C/Q = [I_C/Q]² x [R_O]
Calculate the power dissipation in the 5V LDO, V5, using
the following equation:
P₅ = (V_LDOIN - V₅) × I₅
where I5 includes the ILDO33 current sourced from
LDO33.
Calculate the power dissipated in the 3.3V LDO, LDO33,
using the following equation:
P_LDO33 = 1.7V × I_LDO33
Calculate the quiescent power dissipation in the device
using the following equation:
P_Q = I_CC × V_CC
If the current sinks are enabled, calculate their associ-
ated power dissipation as:
P_CLCQ = I_{LLM_C/Q} × V_C/Q
P_CLDI = I_{LLM_DI} × V_DI
Overtemperature Warning
Two bits in the Status and Mode registers are set when
the temperature of the device exceeds +115NC (typ). The
OTempInt bit in the Status register is set and IRQ asserts
when the OTemp bit in the Mode register is set. Read the
Status register to clear the OTempInt bit and IRQ.
The OTemp bit is cleared when the die temperature falls
below +95NC.
The device continues to operate normally unless the
die temperature reaches the +150NC thermal shutdown
threshold, when the device enters thermal shutdown.
Thermal Shutdown
When the die temperature rises above +150NC (typ) ther-
mal shutdown threshold, the C/Q drivers and the C/Q and
DI current loads are automatically turned off. The internal
3.3V and 5V LDOs remain on during thermal shutdown, if
enabled. If the internal or external V5 supply remains on
during thermal shutdown (which is always true in case of
the internal V5 regulator), the register contents are main-
tained and SPI communication available.
When the die temperature falls below the thermal shut-
down threshold plus hysteresis, the C/Q driver and C/Q
and DI current sinks turn on automatically.
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