SMH4812
Preliminary
DESCRIPTION
The SMH4812 is designed to control hot swapping of plug-
in cards operating from a single supply, which can have an
output range from 20V to 500V. The SMH4812 hot-swap
controller provides under-voltage and over-voltage moni-
toring of the host power supply, it drives an external power
MOSFET switch that connects the supply to the load, and
it protects against over-current conditions that might dis-
rupt the host supply. When the input and output voltages
to the SMH4812 controller are within specification it pro-
vides a Power Good logic output that may be used to
enable a DC-DC converter. Additional features of the
device include: temperature sense or master enable
input, 2.5V and 5V reference outputs for expanding moni-
tor functions, two Pin-Detect enable inputs for fault protec-
tion, and duty-cycle or latched over-current protection
modes. All of these features can be programmed by the
factory according to the user's requirements.
FUNCTIONAL BLOCK DIAGRAM
ENPG
14
VDD
16
12VREF
PROGRAMM-
ABLE
SHUTDOWN
TIMER
+
13
FS#
12
2.5VREF
DRAIN
1
SENSE
50kΩ
50kΩ
50kΩ
–
11
5.0VREF
EN/TS
3
PD1#
4
PD2#
5
+
–
PROGRAMM-
ABLE
DELAY
15
PG#
UV
9
+
–
FILTER
+
OV
10
5V
12V
2.5V
2
VGATE
VSS
8
PROGRAMM-
ABLE
DELAY
50mV
CBSENSE
7
Programmable
Quick Response
Ref. Voltage
2
–
50kΩ
VGATE
SENSE
+
–
+
–
6
FAULT#
DUTY
CYCLE
TIMER
2055 BD 3.0
2055 4.1 03/27/09
SUMMIT MICROELECTRONICS, Inc.
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
