MAX5920BESA ,-48V Hot-Swap Controller with External RSENSEFeaturesThe MAX5920A/MAX5920B are hot-swap controllers that Allows Safe Board Insertion and Remova ..
MAX5921AESA+T ,-48V Hot-Swap Controllers with External RSENSE and High Gate Pulldown CurrentELECTRICAL CHARACTERISTICS(V = 0V, V = 48V, T = -40°C to +85°C, unless otherwise noted. Typical val ..
MAX5921BESA ,-48V Hot-Swap Controllers with External RSENSE and High Gate Pulldown CurrentApplicationsMAX5921AESA -40°C to +85°C 8 SOTelecom Line CardsMAX5921BESA -40°C to +85°C 8 SONetwork ..
MAX5921BESA+ ,-48V Hot-Swap Controllers with External RSENSE and High Gate Pulldown Currentfeatures over these devices.and Current SpikesThe MAX5921/MAX5939 provide a controlled turn-on to♦ ..
MAX5921BESA+ ,-48V Hot-Swap Controllers with External RSENSE and High Gate Pulldown CurrentFeaturesThe MAX5921/MAX5939 hot-swap controllers allow a cir-♦ Allows Safe Board Insertion and Remo ..
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MAZ8091-H ,Silicon planar typeElectrical Characteristics T = 25°CaParameter Symbol Conditions Min Typ Max UnitForward voltage V ..
MAZ8091-L ,Silicon planar typeelectrical characteristicsZ Zwithin part numbersReverse current I V ··············· Specified value ..
MAZ8091M ,Silicon planar typeFeatures•Extremely low noise voltage caused from the diode (2.4V to 39V,1/3 to 1/10 of our conventi ..
MAZ8091-M ,Silicon planar typeelectrical characteristicsZ Zwithin part numbersReverse current I V ··············· Specified value ..
MAZ8100-H ,Silicon planar typeZener DiodesMAZ8000 SeriesSilicon planar typeUnit : mmFor stabilization of power supplyKA
MAZ8100-L ,Silicon planar typeElectrical characteristics within part numbers T = 25°CaTemperaturecoefficient ofZener voltage Rev ..
MAX5920AESA-MAX5920BESA
-48V Hot-Swap Controller with External RSENSE
General DescriptionThe MAX5920A/MAX5920B are hot-swap controllers that
allow a circuit card to be safely hot plugged into a live
backplane. The MAX5920A/MAX5920B operate from
-20V to -80V and are well-suited for -48V power systems.
These devices are pin and function compatible with the
LT4250 and pin compatible with the LT1640.
The MAX5920A/MAX5920B provide a controlled turn-on
to circuit cards preventing glitches on the power-supply
rail and damage to board connectors and components.
The MAX5920A/MAX5920B provide undervoltage, over-
voltage, and overcurrent protection. These devices
ensure the input voltage is stable and within tolerance
before applying power to the load.
Both the MAX5920A and MAX5920B protect a system
against overcurrent and short-circuit conditions by turn-
ing off the external MOSFET in the event of a fault con-
dition. The MAX5920A/MAX5920B also provide
protection against input voltage steps. During an input
voltage step, the MAX5920A/MAX5920B limit the cur-
rent drawn by the load to a safe level without turning off
power to the load.
Both devices feature an open-drain power-good status
output (PWRGDfor the MAX5920A or PWRGD for the
MAX5920B) that can be used to enable downstream
converters. A built-in thermal-shutdown feature is also
included to protect the external MOSFET in case of
overheating.
The MAX5920A/MAX5920B are available in an 8-pin SO
package. Both devices are specified for the extended
-40°C to +85°C temperature range.
ApplicationsTelecom Line Cards
Network Switches/Routers
Central-Office Line Cards
Server Line Cards
Base-Station Line Cards
FeaturesAllows Safe Board Insertion and Removal
from a Live -48V BackplanePin- and Function-Compatible with LT4250L
(MAX5920A)Pin-Compatible with LT1640L (MAX5920A)Pin- and Function-Compatible with LT4250H
(MAX5920B)Pin-Compatible with LT1640H (MAX5920B)Circuit-Breaker Immunity to Input Voltage Steps
and Current SpikesWithstands -100V Input Transients with No
External ComponentsProgrammable Inrush and Short-Circuit Current
LimitsOperates from -20V to -80VProgrammable Overvoltage ProtectionProgrammable Undervoltage LockoutPowers Up into a Shorted LoadPower-Good Control OutputThermal Shutdown Protects External MOSFET
MAX5920
-48V Hot-Swap Controller
with External RSENSE
Pin Configuration
Ordering Information19-2931; Rev 0; 8/03
Typical Operating Circuit and Selector Guide appear at end
of data sheet.
MAX5920
-48V Hot-Swap Controller
with External RSENSE
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VEE= 0V, VDD= 48V, TA= -40°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.) (Notes 1, 4)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
All Voltages are Referenced to VEE, Unless Otherwise Noted.
Supply Voltage (VDD- VEE).................................-0.3V to +100V
DRAIN, PWRGD, PWRGD....................................-0.3V to +100V
PWRGD to DRAIN .............................................… -0.3V to +95V
PWRGD to VDD........................................................-95V to +85V
SENSE (Internally Clamped).................................-0.3V to +1.0V
GATE (Internally Clamped)....................................-0.3V to +18V
UV and OV..............................................................-0.3V to +60V
Current Through SENSE...................................................±40mA
Current into GATE...........................................................±300mA
Current into Any Other Pin................................................±20mA
Continuous Power Dissipation (TA= +70°C)
8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature .....................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
MAX5920
-48V Hot-Swap Controller
with External RSENSE
ELECTRICAL CHARACTERISTICS (continued)
Note 1:All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to VEE,
unless otherwise specified.
Note 2:Current into VDDwith UV = 3V, OV, DRAIN, PWRGD, SENSE = VEE, GATE = floating.
Note 3:Minimum duration of GATE pulldown following a circuit-breaker fault. The circuit breaker can be reset during this time by
toggling UV low, but the GATE pulldown does not release until tOFFhas elapsed.
Note 4:Limits are 100% tested at TA= +25°C and +85°C. Limits at -40°C are guaranteed by design.
MAX5920
-48V Hot-Swap Controller
with External RSENSE
Typical Operating Characteristics(VDD= 48V, VEE= 0V, TA = +25°C, unless otherwise noted.)
MAX5920
-48V Hot-Swap Controller
with External RSENSEFigure 1a. Test Circuit 1
Figure 1b. Test Circuit 2
MAX5920
-48V Hot-Swap Controller
with External RSENSE
Timing DiagramsFigure 2. OV to GATE Timing
Figure 3. UV to GATE Timing
Figure 4a. SENSE to GATE Timing
Figure 4b. Active Current-Limit Threshold
MAX5920
-48V Hot-Swap Controller
with External RSENSE
Timing Diagrams (continued)Figure 5a. DRAIN to PWRGD/PWRGD Timing
Figure 5b. GATE to PWRGD/PWRGD Timing
Block Diagram
MAX5920
Detailed DescriptionThe MAX5920A/MAX5920B are integrated hot-swap
controllers for -48V power systems. They allow circuit
boards to be safely hot plugged into a live backplane
without causing a glitch on the power-supply rail. When
circuit boards are inserted into a live backplane, the
bypass capacitors at the input of the board’s power
module or switching power supply can draw large
inrush currents as they charge. The inrush currents can
cause glitches on the system power-supply rail and
damage components on the board.
The MAX5920A/MAX5920B provide a controlled turn-on
to circuit cards preventing glitches on the power-supply
rail and damage to board connectors and components.
Both the MAX5920A and MAX5920B provide undervolt-
age, overvoltage, and overcurrent protection. The
MAX5920A/MAX5920B ensure the input voltage is sta-
ble and within tolerance before applying power to the
load. The devices also provide protection against input
voltage steps. During an input voltage step, the
MAX5920A/MAX5920B limit the current drawn by the
load to a safe level without turning off power to the load.
-48V Hot-Swap Controller
with External RSENSE
Board InsertionFigure6a shows a typical hot-swap circuit for -48V sys-
tems. When the circuit board first makes contact with
the backplane, the DRAIN to GATE capacitance (Cgd)
of Q1 pulls up the GATE voltage to roughly IVEE x Cgd /
Cgd + CgsI. The MAX5920_ features an internal dynam-
ic clamp between GATE and VEEto keep the gate-to-
source voltage of Q1 low during hot insertion,
preventing Q1 from passing an uncontrolled current to
the load. For most applications, the internal clamp
between GATE and VEEof the MAX5920A/MAX5920B
eliminates the need for an external gate-to-source
capacitor. Resistor R3 limits the current into the clamp
circuitry during card insertion.
Power-Supply RampingThe MAX5920A/MAX5920B can reside either on the
backplane or the removable circuit board (Figure6a).
Power is delivered to the load by placing an external
N-channel MOSFET pass transistor in the power-supply
path.
After the circuit board is inserted into the backplane
and the supply voltage at VEEis stable and within the
undervoltage and overvoltage tolerance, the
MAX5920A/MAX5920B turn on Q1. The MAX5920A/
MAX5920B gradually turn on the external MOSFET by
charging the gate of Q1 with a 45µA current source.
Capacitor C2 provides a feedback signal to accurately
limit the inrush current. The inrush current can be
calculated:
IINRUSH= IPU x CL / C2
where CLis the total load capacitance, C3 + C4, and
IPUis the MAX5920_ gate pullup current.
Figure6b shows the inrush current waveform. The cur-
rent through C2 controls the GATE voltage. At the end
of the DRAIN ramp, the GATE voltage is charged to its
final value. The GATE-to-SENSE clamp limits the maxi-
mum VGSto about 18V under any condition.
Board RemovalIf the circuit card is removed from the backplane, the volt-
age at the UV pin falls below the UVLO detect threshold,
and the MAX5920_ turns off the external MOSFET.
Current Limit and Electronic
Circuit BreakerThe MAX5920_ provides current-limiting and circuit-
breaker features that protect against excessive load cur-
rent and short-circuit conditions. The load current is
monitored by sensing the voltage across an external
sense resistor connected between VEEand SENSE.
MAX5920
-48V Hot-Swap Controller
with External RSENSE
