SUMMIT
MICROELECTRONICS, Inc.
SMH4802
Preliminary Information
See Last Page
Programmable -48V Hot-Swap Controller with Forced Shut Down
FEATURES & APPLICATIONS
l
Soft Start Power Supply
l
Live Insertion into a -48V backplane
l
Programmable Control of a DC/DC Converter
w
I
2
C Power On/Off Control
l
Highly Programmable Circuit Breaker
w
Active In-rush Current Limiting
w
Over-current Filter Circuit Breaker Immunity
to Voltage Steps and Current Spikes
l
Programmable Forced Shutdown Timer
l
Internal Shunt Regulator Allows a Wide Supply
Range
l
14-pin SOIC and 16-pin SSOP packages
APPLICATIONS
l
-48V Power Distribution
w
w
w
w
Telecom Line Cards
Central Office Switching
High Availability Servers
Hot Board Insertion
INTRODUCTION
The SMH4802 is designed to control in-rush current
during hot swapping of plug-in cards operating in a
distributed power environment. The device drives an
external power MOSFET switch that connects the supply
to the load and protects against over-current conditions
that might disrupt the host supply. It also provides under-
voltage and over-voltage monitoring of the host power
supply. When the source and drain voltages of the
external MOSFETs are within specification it will provide
a Power Good logic output that can be used to enable a
DC/DC converter. Additional features of the device
include: temperature sense or master enable input, a 5V
reference output for expanding monitor functions, and
duty-cycle or latched over-current protection modes. An
internal Shunt regulator allows a wide supply range. The
SMH4802 -48V Hot-Swap Controller also features a
simple software I
2
C Power On/Off Interface for remote
power control applications.
Programming of configuration, control and calibration val-
ues by the user can be simplified with the SMX3200
interface adapter and a windows based GUI supplied by
Summit.
SIMPLIFIED APPLICATION DRAWING
–48V Ret
R
D
4
5
14
SDA
I
2
C
Header
SCL
V
DD
8
UV
PG#
12
V+
Out+
On/
DC/DC
Off
V–
Out–
9
OV
SMH4802
FS#
10
3
EN/TS
VSS
7
CBSENSE VGATE
6
2
DRAIN
SENSE 5VREF
1
11
–48V A
R
S
V
SS
2062 SAD
–48V B
Figure 1. The drawing illustrates the SMH4802 in a typical line-card application. It should be noted this is just an
example, and the specific component values are purposely not shown. Pin numbers reflect SOIC package.
©SUMMIT MICROELECTRONICS, Inc., 2003 • 1717 Fox Drive • San Jose, CA 95131 • Phone 408-436-9890 • FAX 408-436-9897 •
www.summitmicro.com
Characteristics subject to change without notice
2062 2.3 6/19/03
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
