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  Microchip Technology Semiconductor Electronic Components Datasheet  

MCP18480 Datasheet

Hot Swap Controller

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MCP18480 pdf
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M
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
VPOS
OVTH
UVTH
UVHYS
UVD
VREFOUT
VREFIN
CL
ISET
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
DRAINTH
VFB
GATE
SENSE
RDISCH
VNEG
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.
2003 Microchip Technology Inc.
DS20091B-page 1



  Microchip Technology Semiconductor Electronic Components Datasheet  

MCP18480 Datasheet

Hot Swap Controller

No Preview Available !

MCP18480 pdf
MCP18480
Internal comparators are incorporated to add hystere-
sis for adjusting the Undervoltage Lockout (UVLO)
threshold. The external N-channel MOSFET is turned
on when the input is below the user-programmable,
Overvoltage threshold and above the user-
programmable, Undervoltage threshold.
MCP18480 Block Diagram
VPOS
The PWRGOOD pin indicates the status of the
MCP18480 and is active when the device has com-
pleted power-up and the system is not in an Undervolt-
age, Overvoltage or current-limit condition.
PWRGOOD can be externally configured to either
active-high or active-low to accommodate external cir-
cuitry (power supplies) that have either enabling logic.
A block diagram of the MCP18480 is shown below.
DRAINTH
VNEG
VREFOUT
VREFIN
ISET
BIAS (Section 6.8.8)
12V
Regulator
12VOUT
5V
Reg.
5VOUT
Internal
Bias
Generation
FET Good
(Section 6.8.3)
VPOS
PWRGOOD
Output Block
(Section 6.8.9)
GATE
Drive
(Section 6.8.7)
SENSE
PWRGOOD (1)
GATE
OVTH
OVO
Overvoltage
(Section 6.8.2)
5VOUT
ENABLE
UVTH
UVHYS
UVD
Undervoltage
(Section 6.8.1)
Latch
(Section
6.8.6)
RESTART
VNEG
VFB
SENSE
CL
Current Limit
(Section 6.8.4)
Current Limit Timer
Circuit Breaker
Timer
(Section 6.8.5)
TIMER
RDISCH
MCP18480
Note 1:
The PWRGOOD output pin can be either active-high or active-low. This polarity is determined by the
voltage (either the level on the VREFIN pin or level on the VNEG pin) on the ISET pin:
- Connecting the external RISET resistor to VREFIN configures the PWRGOOD pin as active-low
- Connecting the external RISET resistor to VNEG configures the PWRGOOD pin as active-high
DS20091B-page 2
2003 Microchip Technology Inc.



  Microchip Technology Semiconductor Electronic Components Datasheet  

MCP18480 Datasheet

Hot Swap Controller

No Preview Available !

MCP18480 pdf
MCP18480
1.0 ELECTRICAL
CHARACTERISTICS
Absolute Maximum Ratings†
Ambient Temperature under bias ........ –40°C to +85°C
Storage Temperature ........................ –65°C to +150°C
Voltage on VPOS with respect to VNEG -0.3V to +15.0V
Voltage on DVTH, UVTH, VFB, OVO and UVHYS pins
with respect to VNEG ..... VNEG – 0.3V to (VPOS + 0.3V)
Voltage on VREFIN, CL, SENSE, DRAINTH, ENABLE
and RESTART pins with respect to VNEG
........................................................ VNEG - 0.3V to 6V.
Total Power Dissipation (Note 1) .................... 800 mW
Max. Current out of VNEG pin............................. 80 mA
Max. Current into VPOS pin ................................ 50 mA
Max. Output Current sunk by Gate pin............... 80 mA
Max. Output Current sunk by VREFOUT pin .......... 5 mA
Max. Output Current sunk by any other
Output pin......................................................... 25 mA
Max. Output Current sourced by Gate pin ........ 200 µA
DC CHARACTERISTICS
Max. Output Current sourced by VREFOUT pin .....5 mA
Max. Output Current sourced by any other
Output pin...........................................................25 mA
Junction to Ambient, ΘJA
(20 pin SSOP Package) Derating ............... 108.1°C/W
Junction to Case, ΘJC
(20 pin SSOP Package) Derating ................. 32.2°C/W
Lead Temperature, Soldering, 10 seconds ........ 300°C
† Notice: Stresses above those listed under "Maximum
Ratings" may cause permanent damage to the device. This is
a stress rating only and functional operation of the device at
those or any other conditions above those indicated in the
operation listings of this specification is not implied. Exposure
to maximum rating conditions for extended periods may affect
device reliability.
Note 1: Power Dissipation is calculated as follows:
PDIS = VDD x {IDD - Σ IOH} + Σ{(VDD-VOH) x IOH} + Σ(VOL x IOL)
Electrical Specifications: Unless otherwise specified, operating temperature: –40°C TA +85°C (Industrial),
Supply Current: 5 mA IPOS 25 mA, RISET = 125 k, CBYP = 2 µF.
Param.
No.
Parameter
Sym
Min Typ (1) Max Units
Conditions
MD001 Current into shunt regulator
IPOS1
5
25 mA ENABLE pin = 5V
that produces VPOS output volt-
age that meets MD001A speci-
5 — 25
ENABLE pin = VNEG
fication
MD001A
MD002
MD010
MD011
Regulated Output Voltage
Differential of VPOS to VNEG
VREFOUT pin output voltage
VGATE pin output voltage
Voltage on ISET pin
VPOS
10.4
12.0
13.4
VREFOUT
VGATE
VISET
2.463
VPOS - 2
(VREFIN/2) -
0.02
2.5
VPOS -1
VREFIN/2
2.538
VPOS
(VREFIN/2)
+0.02
V See MD001
V Load = 50 µA
V
V
MD012A
MD012B
MD012C
MD013
Voltage on SENSE pin to
trigger current-limiting
Undervoltage Threshold
VSENSE
UVTH
40
25
7
VREFIN
- 0.03
50
31.0
12
VREFIN
60
40
17
VREFIN
+ 0.03
mV VFB = VNEG
mV VFB = VNEG + 0.25V
mV VFB = VNEG + 0.5V
V
MD014A Overvoltage
Threshold
rising
OVTH
VREFIN
- 0.05
VREFIN
VREFIN
+ 0.05
V VREFIN = 2.5V
MD014B
falling
OVTH
VREFIN
- 0.035
VREFIN
- 0.02
VREFIN
- 0.005
V VREFIN = 2.5V
MD015 DRAIN Pin Input Threshold
VDTH
90
100
130 mV
Voltage
Note 1: Data in the Typical (“Typ”) column is based on characterization results at +25°C. This data is for design guidance only
and is not tested.
2: Negative current is defined as current sourced by the pin.
3: All voltages are with respect to the VNEG pin voltage.
2003 Microchip Technology Inc.
DS20091B-page 3




Part Number MCP18480
Description Hot Swap Controller
Maker Microchip Technology
Total Page 30 Pages
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