MAX5903 MAXIM [Maxim Integrated Products], MAX5903 Datasheet - Page 5

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

The MAX5902/MAX5903 are integrated hot-swap con-
troller ICs contained in 6-pin SOT23 packages. They
allow a board to be safely hot-plugged into a live back-
plane without causing a glitch on the power-supply rail.
They are well suited for +48V power systems allowing
cost-effective, simple, and compact design. The
MAX5902/MAX5903 operate from +9V to +72V to cover
a wide range of end equipment hot-swap needs. They
require only an external P-channel power MOSFET to
provide hot-swap control. Figure 1 shows a functional
block diagram of the MAX5902/MAX5903.
The MAX5902/MAX5903 controls an external P-channel
power MOSFET placed in the positive power-supply
pathway. When power is first applied, the MAX5902/
MAX5903 keep the MOSFET turned off. The
MAX5902/MAX5903 hold the MOSFET off indefinitely if
ON/OFF is held low, if the supply voltage is below the
undervoltage lockout level, or if the die temperature
exceeds +125°C. If none of these conditions exist for
150ms (typ), the MAX5902/MAX5903 begin to gradually
turn on the MOSFET. During this turn-on phase, the
MAX5902/MAX5903 slowly enhance the MOSFET,
allowing the voltage on the load, i.e. the drain of the
MOSFET, to rise at a rate of 9V/ms (typ). The inrush cur-
rent to the load is thus limited to a level proportional to
the load capacitance, and the constant slew rate. After
the MOSFET is fully enhanced, and the load voltage is
MAX5902
—
1
2
3
4
5
6
PIN
MAX5903
—
1
2
3
4
5
6
_______________________________________________________________________________________
+72V SOT23 Simple Swapper Hot-Swap
Detailed Description
PGOOD
PGOOD
ON/OFF
DRAIN
NAME
GATE
GND
V
S
Positive Supply Voltage Input and External P-Channel MOSFET Source Connection
Drain Sense Input for External P-Channel MOSFET. Connect DRAIN as close as
possible to the MOSFET’s drain and use wide circuit traces to assure good thermal
coupling between the MAX5902/MAX5903 and the MOSFET. See Layout Guidelines.
Gate Drive Output for External P-Channel MOSFET
Ground Connection
Power Good Output. PGOOD is an N-channel, open-drain, active-low output,
referenced to GND.
Power Good Output. PGOOD is an N-channel, open-drain, active-high output,
referenced to GND.
ON/OFF Control Input. ON/OFF is referenced to GND. Drive ON/OFF above 1.38V or
leave unconnected to enable the device. Drive ON/OFF below 1V to disable the device.
ON/OFF is also used to adjust the UVLO threshold. Internally clamped to nominally 3V
through a 1kΩ resistor. (See Figure 1.) (See Undervoltage Lockout in the Applications
section of this data sheet.)
settled to its final value, the MAX5902A/ MAX5903A and
MAX5902L/MAX5903L monitor the voltage drop across
the MOSFET. If the voltage drop exceeds the circuit
breaker threshold the MAX5902A/MAX5903A and
MAX5902L/MAX5903L turn off the MOSFET, discon-
Figure 1. Functional Block Diagram
ON/OFF
GND
V
S
( ) ARE FOR THE MAX5903 ONLY
* RELATIVE TOLERANCE ±1%, ABSOLUTE TOLERANCE ±50% (TYP)
FUNCTION
*
828kΩ
*
34.5kΩ
GND
1kΩ
3V
*900kΩ
*650kΩ
MAX5902
MAX5903
DRAIN
Controllers
CONTROL
LOGIC
Pin Description
GATE
GND
PGOOD
(PGOOD)
5