max5938 Maxim Integrated Products, Inc., max5938 Datasheet - Page 7

• Manufacturer Part Number: max5938
• Description: Max5938 -48v Hot-swap Controller With Vin Step Immunity, No Rsense, And Overvoltage Protection
• Manufacturer: Maxim Integrated Products, Inc.

The MAX5938 hot-swap controller incorporates over-
current and overvoltage fault management and is
intended for negative-supply-rail applications. The
MAX5938 eliminates the need for an external R
and includes V
which prevents powering up into a shorted load. It is
intended for negative 48V telecom power systems
where low cost, flexibility, multifault management, and
compact size are required. The MAX5938 is ideal for
the widest range of systems from those requiring low
current with small MOSFETs to high-current systems
requiring large power MOSFETs and low on-resistance.
-48V Hot-Swap Controller with V
13, 15
2, 10,
PIN
11
12
14
16
1
3
4
5
6
7
8
9
STEP_MON
POL_SEL
CB_ADJ
PGOOD
NAME
GATE
V
GND
N.C.
OFF
V
ON
OV
LP
OUT
EE
IN
input step protection and load probe,
_______________________________________________________________________________________
Ground. The high supply connection for a negative rail hot-swap controller.
No Connection. Not internally connected. Leave open.
Off Control Input. Referenced to V
ON input low requirements are met and OFF falls below 1.25V (typ), the MAX5938 turns off.
On Control Input. Referenced to V
MAX5938. When the voltage at OFF falls below its 1.25V (typ) threshold and the voltage at ON falls below
1.125V for longer than the ON 1.5ms glitch rejection period, the MAX5938 turns off.
Overvoltage Control Input. Referenced to V
GATE pulls to V
than 1.5ms, fault management initiates and PGOOD deasserts (see the Detailed Description).
Input Voltage Step Monitor. Connect a resistor between STEP_MON and V
Connect a capacitor from GND to STEP_MON to adjust the step response relative to a negative step at V
eliminate false circuit-breaker and short-circuit faults. Connect to V
See the Selecting Resistor and Capacitor Values for Step Monitor section in the Applications Information.
PGOOD Output Polarity Select. Leave POL_SEL open for an active-low PGOOD assertion. Connect POL_SEL
to V
Negative Input Voltage
Load-Probe Detect. Connect a resistor from LP to V
test current to 1A. Connect to V
Gate-Drive Output. Connect to the gate of the external n-channel MOSFET.
Circuit-Breaker Adjust. Connect a resistor from CB_ADJ to V
CB_ADJ to V
breaker and short-circuit fault detection.
Output Voltage Sense. V
MOSFET.
Power-Good Open-Drain Output. Referenced to V
(POL_SEL open) when V
ON and OFF are cycled low.
Detailed Description
EE
No R
for an active-high open-drain PGOOD assertion.
EE
EE
for the default circuit-breaker 50mV (typ) threshold. Leave CB_ADJ open to disable circuit-
SENSE
until OV falls below the 1.125V falling threshold. If the overvoltage condition remains longer
OUT
OUT
is the negative rail of the load. Connect to the drain of the external n-channel
is within limits and there is no fault condition. PGOOD is deasserted when
EE
SENSE
EE
EE
, and Overvoltage Protection
to disable load-probe function.
. Drive OFF and ON above 1.25V (typ) to turn on the MAX5938. When the
. Drive ON and OFF above the 1.25V rising thresholds to turn on the
EE
. When the voltage at OV rises above the 1.25V rising threshold,
The MAX5938 controls an external n-channel power
MOSFET placed in the negative supply path of an
external load. When no power is applied, the GATE out-
put of the MAX5938 clamps the V
keeping the MOSFET turned off (Figure 2). When power
is applied to the MAX5938, the 2V clamp at the GATE
output is replaced by a strong pulldown device, which
pulls GATE to V
As shown in Figure 2, this transition enables the
MAX5938 to keep the power MOSFET continually off
during the board insertion phase when the circuit board
first makes contact with the backplane. Without this
clamp, the GATE output of a powered-down controller
would be floating and the MOSFET reverse transfer
FUNCTION
OUT
OUT
. PGOOD asserts high (POL_SEL = V
to set the load-probe test current. Limit load-probe
EE
to adjust the circuit-breaker threshold. Short
IN
EE
EE
to disable the step immunity function.
and the V
Step Immunity,
EE
to set the step sensitivity.
GS
Pin Description
GS
of the MOSFET to 0.
of the MOSFET to 2V
EE
) or low
EE
to
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