MAX5901 查看數據表（PDF） - Maxim Integrated
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MAX5901 Datasheet PDF : 14 Pages
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-100V, SOT23/TDFN, Simple Swapper
Hot-Swap Controllers
GND
OPTIONAL
ON/OFF
DGND
-48V
HOT-SWAP CONTROLLER
R2
47kΩ
R1
3kΩ
MAX5900
MAX5901
GND
ON/OFF
VEE
Figure 2. Programmed -20V Lockout With Optional
Optocoupler On/Off Control
HOT-SWAP CONTROLLER #1
GND
MAX5900
MAX5901
GND
ON/OFF
C
VEE
HOT-SWAP CONTROLLER #2
MAX5900
MAX5901
GND
ON/OFF
2C
VEE
VEE
Figure 3. Power-Supply Sequencing
Turn-On and Turn-Off Delays
After power is applied, or ON/OFF is released, there is
a 300ms delay (tON) before the gate ramp is started.
This delay is also the automatic restart time delay.
In the event of a circuit-breaker condition or an over-
temperature fault condition, the turn-off delay is less
than 2µs. An undervoltage condition must exist for at
least 20ms (tOFF) before the MAX5900/MAX5901 turn
off the external MOSFET. ON/OFF must be held low for
at least 20ms (tOFF) before the MAX5900/MAX5901 turn
off the external MOSFET. Turn-off delay minimizes spu-
rious shutdowns due to noisy signals or momentary
voltage spikes, as well as preventing accidental
resetting of the circuit-breaker latch (MAX5900L/
MAX5901L).
Thermal Shutdown
A thermal shutdown feature helps protect the external
MOSFET. If the die temperature of the MAX5900/
MAX5901 exceeds +125°C, the MOSFET is turned off.
For accurate performance, the MAX5900/MAX5901
must be in close thermal contact with the external
MOSFET (see the Layout Guidelines section). Due to
the low power dissipation of the MAX5900/MAX5901, its
junction temperature will typically be within a few
degrees of the MOSFET. All versions of the MAX5900/
MAX5901 automatically restart from a temperature fault
when the junction temperature drops below +110°C.
Undervoltage Lockout
The MAX5900/MAX5901 turn off the external MOSFET if
the magnitude of the input voltage is below the level set
by ON/OFF for longer than 20ms (tOFF). If ON/OFF is
left unconnected, the lockout voltage (VUVLO) defaults
to -31.5V. VUVLO may also be set to any value within
the power-supply range by using external resistors. To
set the lockout voltage to a value between -9V and
-100V, use a resistor-divider connected between GND
and VEE, with the center node of the divider connected
to ON/OFF. For example, use a 3kΩ resistor (R1 in
Figure 2) from ON/OFF to VEE and calculate the other
resistor, R2, using:
R2
=
R1 ×
⎛
⎝⎜
VUVLO
1.26
− 1⎞⎠⎟
where VUVLO is the desired lockout voltage, and
VON/OFF is the ON/OFF reference threshold specified in
the Electrical Characteristics table (typically 1.26V).
Figure 2 shows an example circuit with VUVLO set for
-20V. To defeat the UVLO, simply connect a single 100kΩ
resistor between ON/OFF and GND, as shown in Figure 4.
HOT-SWAP CONTROLLER
GND
100kΩ
MAX5900
MAX5901
GND
ON/OFF
VEE
-48V
Figure 4. Defeating Undervoltage Lockout
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