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PDF MAX4273 Data sheet ( Hoja de datos )
| Número de pieza | MAX4273 | |
| Descripción | 3V to 12V Current-Limiting Hot-Swap Controllers | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-1694; Rev 2; 12/07
EVAALVUAAILTAIOBNLEKIT
3V to 12V Current-Limiting Hot-Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
General Description
The MAX4271/MAX4272/MAX4273 comprise a com-
plete family of integrated 3V to 12V hot-swap con-
trollers. They allow the safe insertion and removal of
circuit cards into live backplanes.
The discharged filter capacitors of the circuit card pro-
vide a low impedance to the live backplane. High in-
rush currents from the backplane to the circuit card can
burn up connectors and components, or momentarily
collapse the backplane power supply leading to a sys-
tem reset. This family of hot-swap controllers prevents
such problems by regulating the current to a preset
limit when the board is plugged in, allowing the system
to stabilize safely. After the startup cycle is completed,
two on-chip comparators provide DualSpeed/BiLevel™
protection against short circuits, load glitches, and
overcurrent conditions. In the event of a fault condition,
the load is disconnected. Fault recovery is handled by
unlatching (MAX4271), autoretry (MAX4272), or pro-
grammed (MAX4273) methods.
The MAX4271 family includes many integrated features
that reduce component count and design time. An on-
board charge pump provides the gate drive for a low-
cost, external n-FET. Integrated features like startup
current regulation and current glitch protection eliminate
external timing resistors and capacitors. Also featured
are an open-drain status output to indicate a fault condi-
tion, and an adjustable overcurrent response time.
The MAX4271 (latched fault protection) and MAX4272
(autoretry fault protection) come in 8-pin SO packages.
The MAX4273 (full function) comes in the space-saving
16-pin QSOP package and 16-pin SO package. All
parts are specified across the extended temperature
range, and have an absolute maximum rating of 15V to
provide extra protection against inductive kickback dur-
ing board removal.
DualSpeed/BiLevel is a trademark of Maxim Integrated
Products.
Features
♦ Provide Safe Hot Swap for +3V to +12V Power
Supplies with Few External Components
♦ Unique Current Regulation Architecture
Minimizes n-FET Linear Mode Duration
♦ Autoretry Feature (MAX4272/MAX4273)
♦ DualSpeed/BiLevel Current Limit Protects Against
Current Glitches and Short Circuits
♦ Power-On RESET (MAX4273)
♦ 15V Absolute Maximum Rating Protects Against
Inductive Kickbacks During Board Removal
♦ Internal Charge Pump Generates Gate Drive for
External n-MOSFET
♦ Status Output Pin Indicates Fault/Safe Condition
♦ Space-Saving 8-Pin SO, 16-Pin QSOP Packages
________________________Applications
Base Stations
RAID
Remote-Access Servers
Network Routers and
Switches
ISDN
PART
MAX4271ESA
MAX4272ESA
MAX4273EEE
MAX4273ESE
Ordering Information
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
8 SO
8 SO
16 QSOP
16 SO
PKG
CODE
S8-1
S8-1
E16-1
E16-1
Pin Configurations appear at end of data sheet.
Typical Operating Circuit
BACKPLANE
VCC
REMOVABLE CARD
2.7V TO 13.2V
RSENSE
M1
N
STAT
GND
ON
IN
STAT
ON
SENSE
GATE
MAX4271
MAX4272
GND
CSPD
CTIM
VOUT
CBOARD
CTIM
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1 page  
3V to 12V Current-Limiting Hot-Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
Typical Operating Characteristics
(VIN = 5V, RSENSE = 100mΩ, CBOARD = 47µF, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. INPUT VOLTAGE
1.0
0.9
0.8 ON = VIN
0.7 IGATE = 10μA
0.6
0.5
0.4
0.3 ON = GND
0.2
0.1
0
0 2 4 6 8 10 12 14
VIN (V)
SUPPLY CURRENT vs. TEMPERATURE
1.0
ON = VIN
0.9
0.8 VIN = 12V
0.7 VIN = 5V
0.6
0.5
0.4
0.3 VIN = 3V
0.2
0.1
0
-40 -15 10 35 60
TEMPERATURE (°C)
85
SLOW COMPARATOR
RESPONSE TIME vs. INPUT VOLTAGE
MAX4271/3-03
240 24
230 23
CSPD = 110nF
TIME IN ms
220 22
210 21
200 20
CSPD = 0
TIME IN μs
190 19
180 18
0 2 4 6 8 10 12 14
VIN (V)
SLOW COMPARATOR THRESHOLD
vs. INPUT VOLTAGE
51.0
50.8 TA = +25°C
50.6 TA = -40°C
50.4
50.2
50.0
49.8
49.6 TA = +85°C
49.4
49.2
49.0
0 2 4 6 8 10 12 14
VIN (V)
FAST COMPARATOR THRESHOLD
vs. INPUT VOLTAGE
210
208
206
204 TA = -40°C
202 TA = +25°C
200
198
196 TA = +85°C
194
192
190
0 2 4 6 8 10 12 14
VIN (V)
FAST COMPARATOR RESPONSE TIME
vs. OVERDRIVE VOLTAGE
450
400 VIN = 12V
350
300
VIN = 3V
250
VIN = 5V
200
1
10 100
OVERDRIVE VOLTAGE (mV)
1000
TIME TO FAST DISCHARGE GATE
vs. CGATE
100k
NO EXTERNAL MOSFET
10k DISCHARGE TO VGATE = 0.1V
1k
VIN = 12V
100
VIN = 5V
10
1 VIN = 3V
0.1
0.01
0.1
1 10
CGATE (nF)
100 1000
FAST COMPARATOR RESPONSE TIME
vs. TEMPERATURE
500
450
400 VIN = 12V
350
300 VIN = 5V
250 VIN = 3V
200
-40
-15 10 35 60
TEMPERATURE (°C)
85
STARTUP PERIOD
vs. INPUT VOLTAGE
350 35MAX4271/3-09
CTIM = 100nF
330 TIME IN ms 33
310 31
290
CTIM = 1nF
TIME IN μs
29
270 27
250 25
0 2 4 6 8 10 12 14
VIN (V)
_______________________________________________________________________________________ 5
5 Page 
3V to 12V Current-Limiting Hot-Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
CSPD
CSPD
VIN
IN
STAT
CTIM
CTIM
MAX4271
2.45V MAX4272
SLOW COMPARATOR
INPUT
UVLO
150ms
DELAY
ON
VIN RISING
FAST COMPARATOR
VIN
4μA
LOGIC
CONTROL
6μA
VSC,TH
6μA 50mV
VSC,TH
200mV
DISCHARGE
ENABLE
GATE
DRIVE
CHARGE
PUMP
(1MHz)
0.1V
GATE
OVLO
ON COMPARATOR
0.6V
GND
RSENSE
SENSE
GATE
M1
N
ON
VOUT
Figure 1. MAX4271/MAX4272 Functional Diagram
Unlike other circuit breaker ICs, the MAX4271/
MAX4272/MAX4273 regulate the current to a preset
level instead of completely turning off the external
N-FET if an overcurrent condition occurs during startup.
In startup mode, the gate drive current is limited to
100µA and decreases with the increase of the gate
voltage (see Gate Charge Current vs. Gate Voltage in
the Typical Operating Characteristics). This allows the
controller to slowly enhance the MOSFET. If the fast
comparator detects an overcurrent, the gate voltage is
momentarily discharged with a fixed 70µA current until
the load current through the sense resistor (RSENSE)
decreases below its threshold point. This effectively
regulates the inrush current during startup. Figure 3
shows the startup waveforms. STAT goes high at the
end of the startup period if no fault condition is present.
Normal Operation (DualSpeed/BiLevel)
In normal operation (after the startup timer has
expired), protection is provided by turning off the exter-
nal MOSFET when a fault condition is encountered.
DualSpeed/BiLevel fault protection incorporates two
comparators with different thresholds and response
times to monitor the current:
1) Slow comparator. This comparator has an externally
set response time (from 20µs to seconds) and a fixed
50mV threshold voltage. The slow comparator
ignores low-amplitude momentary current glitches.
After an extended overcurrent condition, a fault is
generated and the MOSFET gate is slowly dis-
charged.
2) Fast comparator. This comparator has a fixed 350ns
response time and a 200mV threshold voltage
(adjustable from 50mV to 750mV in MAX4273). The
fast comparator turns off the MOSFET immediately
after it detects a large amplitude event such as a
short circuit.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 26 Páginas | |
| PDF Descargar | [ Datasheet MAX4273.PDF ] | |
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