max5939eesat Maxim Integrated Products, Inc., max5939eesat Datasheet - Page 8

• Manufacturer Part Number: max5939eesat
• Description: -48v Hot-swap Controllers With External Rsense And High Gate Pulldown Current
• Manufacturer: Maxim Integrated Products, Inc.

The MAX5921/MAX5939 integrated hot-swap controllers
for -48V power systems allow circuit boards to be safely
hot plugged into a live backplane without causing a
glitch on the power-supply rail. When circuit boards are
inserted into a live backplane, the bypass capacitors at
the input of the board’s power module or switching
power supply can draw large inrush currents as they
charge. Uncontrolled inrush currents can cause glitches
on the system power supply and damage components
on the board.
-48V Hot-Swap Controllers with External
R
8
MAX5921A/
MAX5939A/
MAX5921E
MAX5939E
SENSE
_______________________________________________________________________________________
—
1
2
3
4
5
6
7
8
PIN
MAX5921B/
MAX5939B/
MAX5921F
MAX5939F
—
1
2
3
4
5
6
7
8
and High Gate Pulldown Current
Detailed Description
PWRGD
PWRGD
SENSE
DRAIN
NAME
GATE
V
V
OV
UV
DD
EE
Power-Good Signal Output. PWRGD is an active-low open-drain status output referenced
to V
power-good condition. PWRGD is open drain otherwise.
Power-Good Signal Output. PWRGD is an active-high open-drain status output refer-
enced to DRAIN. PWRGD latches in a high-impedance state when V
and V
DRAIN otherwise.
Overvoltage Detection Input. OV is referenced to V
voltage, GATE pulls low. GATE remains low until the OV voltage reduces to V
V
Undervoltage Detection Input. UV is referenced to V
voltage, the GATE is enabled. When UV is pulled below V
UV is also used to reset the circuit breaker after a fault condition. To reset the circuit
breaker, pull UV below V
condition; however, the device will not restart until a t
fault condition is removed.
Negative Power-Supply Input. Connect to the negative power-supply rail.
Current-Sense Input. Connect to the external sense resistor and the source of the external
MOSFET. The voltage drop across the external sense resistor is monitored to detect
overcurrent or short-circuit fault conditions. Connect SENSE to V
limiting feature.
Gate Drive Output. Connect to the gate of the external N-channel MOSFET.
Output Voltage Sense Input. Connect to the output voltage node (drain of external N-
channel MOSFET). Place the MAX5921/MAX5939 such that DRAIN is close to the drain of
the external MOSFET for the best thermal protection.
Positive Power-Supply Input. This is the power ground in the negative supply voltage
system. Connect to the higher potential of the power-supply inputs.
OVHY
EE
GATE
. PWRGD latches low when V
.
> ∆V
GATE
- V
GH
UVL
The MAX5921/MAX5939 provide a controlled turn-on to
circuit cards preventing damage to connectors, board
components, and prevent glitches on the power-supply
rail. Both the MAX5921/MAX5939 provide undervolt-
age, overvoltage, and overcurrent protection. The
MAX5921/MAX5939 ensure that the input voltage is sta-
ble and within tolerance before applying power to the
load. The device also provides protection against input
voltage steps by limiting the load current to a safe level
without turning off power to the load.
indicating a power-good condition. PWRGD is pulled low to
. The reset command can be issued immediately after a fault
DRAIN
FUNCTION
- V
EE
≤ V
EE
DL
EE
OFF
. When OV is pulled above V
and V
. When UV is pulled above V
delay time has elapsed after the
UVL
GATE
, GATE pulls low.
Pin Description
EE
> ∆V
to disable the current-
DRAIN
GATE
- V
indicating a
OVH
EE
≤ V
-
OVH
UVH
DL