MAX5903LBETT 查看數據表（PDF） - Maxim Integrated
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MAX5903LBETT Datasheet PDF : 14 Pages
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+72V, SOT23/TDFN, Simple Swapper Hot-Swap
Controllers
+24V
OPTIONAL
ON/OFF
DGND
GND
HOT-SWAP CONTROLLER
R2
40.2kΩ
R1
3.01kΩ
MAX5902
MAX5903
VS
ON/OFF
GND
Figure 3. Programmed +18V Lockout, with Optional Optocoupler
On/Off Control.
A thermal shutdown feature protects the external MOS-
FET by turning it off if the die temperature of the
MAX5902/MAX5903 exceeds +125°C. The MAX5902/
MAX5903 must be in good thermal contact with the
external MOSFET. See Layout Guidelines in the Appli-
cations section of the data sheet.
A circuit-breaker function monitors the voltage across
the external MOSFET, VSD, and turns off the MOSFET if
VSD exceeds the circuit-breaker threshold, VCB. The
circuit-breaker function is enabled after the MOSFET is
fully enhanced. Three threshold voltage options are
available—300mV, 400mV, and 500mV. One version is
available with no circuit-breaker function. Fault man-
agement for the MAX5902/MAX5903 is offered with two
different configurations; latched and automatic retry.
Latched Circuit Breaker
After a circuit-breaker trip event, the latched
versions (MAX5902L/MAX5903L) drive GATE to
VS, turning off the external MOSFET, and PGOOD
(PGOOD) is deasserted. A latched off condition
needs to be reset by toggling ON/OFF low for at
least 10ms, or by cycling the power supply, VS.
Automatic Retry Circuit Breaker
After a circuit-breaker trip event, the automatic retry
versions (MAX5902A/MAX5903A) drive GATE to VS,
turning off the external MOSFET, and PGOOD
(PGOOD) is deasserted. If the start conditions are met
for a full 150ms (tRS) the start sequence is re-initiated.
The start conditions are: the device is not in UVLO;
ON/OFF is not driven low; and the device is not in ther-
mal shutdown.
No Circuit Breaker
For the versions without a circuit breaker, MAX5902N
(MAX5903N), PGOOD (PGOOD) are asserted when the
MOSFET is fully enhanced. Once powered up the
MAX5902N/MAX5903N ignore the MOSFET drain-to-
source voltage for applications where a circuit-breaker
function is not desired.
Applications Information
ON/OFF Control Input
The ON/OFF control input provides three functions:
external ON/OFF control; setting of the UVLO level; and
resetting after a circuit-breaker event has caused the
MAX5902L/MAX5903L to turn off the external MOSFET.
Pulling ON/OFF to GND for at least 10ms (tOFF) forces
the MAX5902/MAX5903 to turn off the external MOSFET
(see Figure 3 for a circuit example). To reset the
MAX5902L/MAX5903L after a circuit-breaker event,
toggle ON/OFF to GND for at least 10ms (tOFF).
ON/OFF can be used to sequence power supplies.
Connecting a capacitor from ON/OFF to GND will delay
the rise of ON/OFF proportional to the capacitance and
input impedance of ON/OFF, typically 33kΩ (Figure 4).
The MAX5902/MAX5903 can be controlled by logic-
level signals. Logic-level signals of 3.3V or 1.8V may be
directly connected to ON/OFF. For 5V logic level control,
insert a series 47kΩ resistor as shown in Figure 5.
HOT-SWAP CONTROLLER #1
VS
MAX5902
MAX5903
VS
ON/OFF
C
GND
HOT-SWAP CONTROLLER #2
MAX5902
VS MAX5903
ON/OFF
2C
GND
GND
Figure 4. Power-Supply Sequencing
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