MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
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changes in currents flowing through the power-supply
traces. This can cause inductive voltage spikes that
could exceed 85V. Use wider traces or heavier trace
plating and connect a 0.1µF capacitor between V
CC
and
GND to minimize these inductive spikes. Use a transient
voltage suppressor (TVS) at the input to prevent damage
from voltage surges. An SMBJ54A is recommended.
Power-Up Sequence
At power-up, transistor Q1 (see the Typical Application
Circuit) is off until these three conditions are met:
•V
ON
exceeds the turn-on threshold voltage
•V
CC
exceeds the UVLO threshold
•V
TIMER
stays below 1.233V
The voltage at GATE increases with a slope of 10µA/C1
(where C1 is shown in the Typical Application Circuit)
and I
INRUSH
= C
L
x 10µA / C1. When the voltage across
R
SENSE
goes too high, the inrush current is limited by
the internal current-limit circuitry that adjusts the GATE
voltage to keep a constant voltage across R
SENSE
.
Thermal Shutdown
If the MAX5934/MAX5934A die temperature reaches
+150°C, an overtemperature fault is generated. As a
result, GATE goes low and turns the external MOSFET
off. The MAX5934/MAX5934A die temperature must
cool down below +120°C before the overtemperature
fault condition is removed.
Board Layout and Bypassing
Kelvin connections are recommended for accurate cur-
rent sensing. Make sure the minimum trace width for
2oz copper is 1.5mm per amp. A width of 4mm per amp
is recommended.
Connect a resistive divider from V
CC
to ON as close as
possible to ON and have short traces from V
CC
and
GND. To decrease induced noise connect a 0.1µF
capacitor between ON and GND (see Figure 10).
The external MOSFET must be thermally coupled to the
MAX5934/MAX5934A to ensure proper thermal shut-
down operation.
