MCP18480_13 Datasheet, PDF (1/64 Pages) Microchip Technology – -48V Hot Swap Controller

MCP18480
-48V Hot Swap Controller
Features
• Allows safe board removal and insertion from a
live backplane
• Accurate (<1.5%) internal voltage reference for
fault detection and precision timing
• Programmable foldback current limiting
• Programmable circuit breaker current limiting
• Auto restart option for all faults
• Adjustable Undervoltage lockout thresholds
• Adjustable Overvoltage protection threshold
• Adjustable Power Good delay
• Configurable Power Good output polarity
• Low-side drive of an external N-channel FET
CMOS Technology
• High-Voltage Operation
• Temperature range: Industrial (I): -40°C to +85°C
Packaging
• 20-lead SSOP
Package Type
SSOP
V_POS
OV_TH
UV_TH
UV_HYS
UV_D
V_REFOUT
V_REFIN
CL
I_SET
TIMER
1
20
2
19
3
18
4
17
5
16
6
15
7
14
8
13
9
12
10
11
RESTART
ENABLE
PWRGOOD
OVO
DRAIN_TH
V_FB
GATE
SENSE
R_DISCH
V_NEG
Description
The MCP18480 is a Hot Swap controller that allows
boards to be safely removed or inserted from an active
backplane using -48V.
When PCBs are inserted into a live backplane, high-
peak or transient currents from the source are gener-
ated due to the charging of the bypass capacitors on
the supply. The high transient currents can destroy
connectors and capacitors. The high inrush current can
pull the input voltage BUS down and reset the system.
The MCP18480 solves this problem by controlling the
slew rate of the backplane voltage to the board so that
these transients are eliminated. This allows boards to
be removed and inserted without causing damage to
connector pins and input bulk capacitors, in addition to
preventing false resets to the other boards on the
backplane.
The MCP18480 can be used in applications in several
areas including:
• Telecom Line Cards
• Network Switches
• Network Routers and Servers
• Base Station Line Cards
• Power-Over-LAN
• Power-Over-MDI
• IP Phone Switches/Routers
• Mid-Span, Power-Over-MDI
Two forms of current limit are provided in the
MCP18480. These are:
• Foldback
• Circuit breaker
The foldback current-limiting circuit uses an external
sense resistor and a voltage that is proportional to the
external MOSFET’s drain voltage. These are used to
keep the MOSFET in its Safe Operating Area (SOA).
If the device remains in current limit for a programmed
time period, the external N-channel FET is turned off.
The option exists to configure the device to automati-
cally restart after a programmed time delay. A program-
mable catastrophic current limit threshold shuts down
the switch (circuit breaker) if excessive current is
sensed due to a short-circuit condition.
 2002-2012 Microchip Technology Inc.
DS20091C-page 1