MAX5903 MAXIM [Maxim Integrated Products], MAX5903 Datasheet - Page 8

• Manufacturer Part Number: MAX5903
• Description: +72V SOT23 Simple Swapper Hot-Swap Controllers
• Manufacturer: MAXIM [Maxim Integrated Products]

After power is applied, or ON/OFF is released, there is
a 150ms 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 4µs. An undervoltage condition must exist for at
least 10ms (t
off the external MOSFET. ON/OFF must be held low for
at least 10ms (t
turns off the external MOSFET. Turn-off delay minimizes
spurious shutdowns due to noisy signals or momentary
voltage spikes, as well as preventing accidental reset-
ting of the circuit breaker latch (MAX5902L/MAX5903L).
A thermal shutdown feature helps protect the external
MOSFET. If the die temperature of the MAX5902/
MAX5903 exceeds +125°C, the MOSFET is turned off.
For accurate performance the MAX5902/MAX5903
must be in close thermal contact with the external MOS-
FET. See Layout Guidelines for information. Due to the
low power dissipation of the MAX5902/MAX5903, its
junction temperature will typically be within a few
degrees of the MOSFET. All versions of the MAX5902/
MAX5903 automatically restart from a temperature fault
when the junction temperature drops below +110°C.
The MAX5902/MAX5903 turns off the external MOSFET
if the magnitude of the input voltage is below the level
set by ON/OFF for longer than 10ms (t
is left unconnected, the lockout voltage (V
defaults to 31.5V. V
within the power-supply range by using external resis-
+72V SOT23 Simple Swapper Hot-Swap
Controllers
8
Figure 5. Logic Control
_______________________________________________________________________________________
5V LOGIC
LOGIC CONTROL OF 3.3V OR LESS MAY BE CONNECTED
DIRECTLY TO THE MAX5902/MAX5903. FOR 5V LOGIC
CONTROL INSERT A SERIES 47kΩ RESISTOR AS SHOWN.
GND
OFF
47kΩ
) before the MAX5902/MAX5903 turns
OFF
ON
Turn-On and Turn-Off Delays
UVLO
) before the gate ramp is started.
) before the MAX5902/MAX5903
HOT-SWAP CONTROLLER
ON/OFF
GND
may also be set to any value
Undervoltage Lockout
MAX5902
MAX5903
Thermal Shutdown
OFF
). If ON/OFF
UVLO
)
tors. To set the lockout voltage to a value between +9V
and +72V use a resistor divider connected between V
and GND, with the center node of the divider connect-
ed to ON/OFF. For example, use a 3kΩ resistor (R1 in
Figure 3) from ON/OFF to GND and calculate the other
resistor, R2, using:
where V
V
the Electrical Characteristics table (typically 1.26V).
Figure 3 shows an example circuit with V
+18V. To defeat the UVLO simply connect a single
100kΩ resistor between ON/OFF and V
Figure 6.
The power good output, PGOOD (PGOOD), is open-
drain and asserts when the external MOSFET is fully
enhanced and V
threshold (V
function (MAX5902N/MAX5903N), PGOOD (PGOOD)
asserts when the external MOSFET is fully enhanced.
PGOOD (PGOOD) deasserts within 4µs when a circuit
breaker event occurs or if the die temperature exceeds
+125°C. PGOOD (PGOOD) deasserts if V
longer than 10ms or ON/OFF is held low for longer than
10ms.
The MAX5902 PGOOD is active-low and the MAX5903
PGOOD is active-high. Both are open-drain N-channel
MOSFETs with their sources connected to GND, and
can withstand up to +72V.
Figure 6. Defeating Undervoltage Lockout
ON/OFF
+9V TO +72V
UVLO
is the ON/OFF reference threshold specified in
R
CB
2
GND
). For versions without the circuit breaker
=
is the desired lockout voltage, and
R
SD
1
×
is less than the circuit breaker
100kΩ



V
The Power Good Output
ON OFF
V
UVLO
/
HOT-SWAP CONTROLLER
ON/OFF
GND
V
S
MAX5902
−
1



S
, as shown in
S
UVLO
< V
UVLO
set for
for
S