MAX5900 Maxim, MAX5900 Datasheet - Page 7

• Manufacturer Part Number: MAX5900
• Description: -100V SOT23 Simple Swapper Hot-Swap Controllers
• Manufacturer: Maxim

After power is applied, or ON/OFF is released, there is
a 300ms delay (t
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 (t
off the external MOSFET. ON/OFF must be held low for
at least 20ms (t
off the external MOSFET. Turn-off delay minimizes spu-
rious shutdowns due to noisy signals or momentary
voltage spikes, as well as preventing accidental
Figure 2. Programmed -20V Lockout With Optional
Optocoupler On/Off Control
Figure 3. Power-Supply Sequencing
OPTIONAL
ON/OFF
DGND
-48V
GND
GND
V
EE
OFF
OFF
) before the MAX5900/MAX5901 turn
ON
_______________________________________________________________________________________
Turn-On and Turn-Off Delays
) before the MAX5900/MAX5901 turn
-100V SOT23 Simple Swapper Hot-Swap
) before the gate ramp is started.
C
2C
R2
47kΩ
HOT-SWAP CONTROLLER #1
HOT-SWAP CONTROLLER #2
R1
3kΩ
GND
ON/OFF
GND
ON/OFF
V
V
EE
EE
MAX5900
MAX5900
MAX5901
MAX5901
HOT-SWAP CONTROLLER
GND
ON/OFF
V
EE
MAX5901
MAX5900
resetting of the circuit breaker latch (MAX5900L/
MAX5901L).
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 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.
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 (t
left unconnected, the lockout voltage (V
to -31.5V. V
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 V
to ON/OFF. For example, use a 3kΩ resistor (R1 in
Figure 2) from ON/OFF to V
resistor, R2, using:
where V
V
the Electrical Characteristics table (typically 1.26V).
Figure 2 shows an example circuit with V
-20V. To defeat the UVLO, simply connect a single 100kΩ
resistor between ON/OFF and GND, as shown in Figure 4.
Figure 4. Defeating Undervoltage Lockout
ON/OFF
EE
, with the center node of the divider connected
UVLO
is the ON/OFF reference threshold specified in
-48V
GND
UVLO
R
2
is the desired lockout voltage, and
=
may also be set to any value within
R
100kΩ
1
×



Undervoltage Lockout
V
HOT-SWAP CONTROLLER
EE
Controllers
1 26
UVLO
.
GND
ON/OFF
V
EE
Thermal Shutdown
and calculate the other
MAX5901
MAX5900
−
OFF
1



). If ON/OFF is
UVLO
UVLO
) defaults
set for
7