MAX14827 Datasheet, PDF (26/41 Pages) Maxim Integrated Products – Integrated LED Driver

MAX14827
IO-Link Device Transceiver
where P_C/Q is the power generated in the C/Q driver,
P_DO is the power dissipated by the DO driver, P_V5 and
P_V33 are the power generated by the LDOs, P₂₄ is the
quiescent power generated by the device, and P_PU and
P_PD are the power generated in the C/Q and DO weak
pullup/pulldown current sources/sinks, respectively.
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(max)]² × R_O
where RO driver on-resistance.
Calculate the internal power dissipation of the DO driver
using the following equation:
P_DO = [I_DO(max)]² x R_O
where RO driver on-resistance.
Calculate the power dissipation in the 5V LDO, V₅, using
the following equation:
P₅ = (V₂₄ - V₅) × I₅
where I₅ includes the I₃₃ current sourced from V33.
Calculate the power dissipated in the 3.3V LDO, V33,
using the following equation:
P₃₃ = 1.7V × I_LOAD33
Calculate the quiescent power dissipation in the device
using the following equation:
P₂₄ = I₂₄(max) × V₂₄(max)
If the weak current sinks/sources are enabled, calculate
their associated power dissipation as:
P_PD = I_PD(max) × V_C/Q (max)
P_PU = I_PU(max) × [V₂₄ - V_C/Q](max)
Overtemperature Warning
In SPI mode, the device generates interrupts when the
junction temperature of any of the drivers (C/Q or DO)
exceeds +140°C (typ) warning threshold. The TempW bit
in the STATUS register is set and the TempWInt in the
INTERRUPT register is set and IRQ/OC asserts under
these conditions.
The TempW bit is cleared when the die temperature falls
to +125°C. The INTERRUPT register must be read to
clear the TempWInt bit and deassert IRQ/OC.
The device continues to operate normally unless the
die temperature reaches the +165°C thermal shutdown
threshold, when the device enters thermal shutdown.
The device does not generate overtemperature warnings
when operating in pin-mode.
Thermal Shutdown
The C/Q and DO drivers, and the V5 and V33 regulators are
automatically switched off when the junction temperature
exceeds the +165°C (typ) thermal shutdown threshold.
SPI communication and and the internal regulators are
not disabled during thermal shutdown. In SPI mode, the
ThShut bit in the STATUS register and the ThShutInt in the
INTERRUPT register are set.
Regulators are automatically switched on when the
internal die temperature falls below the thermal shutdown
threshold plus hysteresis. If the internal V5 regulator is
used, the internal registers return to their default state
when the V5 regulator is switched back on.
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