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 ..
MAX5921EESA+ ,-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 ..
MAX5922AEUI ,+48V, Single-Port Network Power Switch For Power-Over-LANfeatures a programmable undervoltagelockout (UVLO) that keeps the device in shutdown until Current ..
MAX5922AEUI+ ,+48V, Single-Port Network Power Switch For Power-Over-LANApplicationspare pairs. In midspan mode, a detection collision♦ Input Logic Signals Compatible with ..
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 ..
MAX5921BESA
-48V Hot-Swap Controllers with External RSENSE and High Gate Pulldown Current
General DescriptionThe MAX5921/MAX5939 hot-swap controllers allow a cir-
cuit card to be safely hot plugged into a live backplane.
The MAX5921/MAX5939 operate from -20V to -80V and
are well suited for -48V power systems. These devices
are pin compatible with both the LT1640 and LT4250 and
provide improved features over these devices.
The MAX5921/MAX5939 provide a controlled turn-on to
circuit cards preventing damage to board connectors,
board components, and preventing glitches on the
power-supply rail. The MAX5921/MAX5939 provide
undervoltage, overvoltage, and overcurrent protection.
These devices ensure that the input voltage is stable
and within tolerance before applying power to the load.
Both the MAX5921 and MAX5939 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 MAX5921/MAX5939 protect against input
voltage steps by limiting the load current to a safe level
without turning off power to the load.
The device features an open-drain power-good status
output, PWRGDor PWRGD for enabling downstream
converters (see Selector Guide). A built-in thermal shut-
down feature is also included to protect the external
MOSFET in case of overheating. The MAX5939 features
a latched fault output. The MAX5921 contains built-in
autoretry circuitry after a fault condition.
The MAX5921/MAX5939 are available in an 8-pin SO
package and operate in 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-Compatible with LT1640 and LT4250Circuit Breaker Immunity to Input Voltage Steps
and Current Spikes450mA GATE Pulldown Current During Short-
Circuit ConditionExponential GATE Pulldown CurrentWithstands -100V Input Transients with No
External ComponentsProgrammable Inrush and Short-Circuit Current
LimitsOperates from -20V to -80VProgrammable Overvoltage ProtectionProgrammable Undervoltage Lockout
with Built-In Glitch FilterOvercurrent Fault IntegratorPowers Up into a Shorted LoadPower-Good Control OutputThermal Shutdown Protects External MOSFET
MAX5921/MAX5939
-48V Hot-Swap Controllers with External
RSENSEand High Gate Pulldown Current
Pin Configuration
Ordering Information19-2946; Rev 0; 9/03
Typical Operating Circuit and Selector Guide appear at end
of data sheet.
Ordering Information continued at end of data sheet.
MAX5921/MAX5939
-48V Hot-Swap Controllers with External
RSENSEand High Gate Pulldown Current
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICSStresses 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 into 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
MAX5921/MAX5939
-48V Hot-Swap Controllers with External
RSENSEand High Gate Pulldown Current
ELECTRICAL CHARACTERISTICS (continued)(VEE= 0V, VDD= 48V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C, unless otherwise noted.) (Notes 1, 4)
unless otherwise specified.
Note 2:Gate pulldown current after the current limit to GATE low (tPHLCL) time has elapsed.
Note 3:Minimum duration of GATE pulldown following a circuit breaker fault. The MAX5921_ automatically restarts after a circuit
breaker fault. The MAX5939_ is latched off and can be reset by toggling UV low. The GATE pulldown does not release until
tOFFhas elapsed.
Note 4:The min/max limits are 100% production tested at +25°C and +85°C and guaranteed by design at -40°C.
MAX5921/MAX5939
-48V Hot-Swap Controllers with External
RSENSEand High Gate Pulldown Current
Typical Operating Characteristics(VDD= +48V, VEE= 0V, TA = +25°C, unless otherwise noted.)
MAX5921/MAX5939
-48V Hot-Swap Controllers with External
RSENSEand High Gate Pulldown CurrentFigure 1a. Test Circuit 1
Figure 1b. Test Circuit 2
MAX5921/MAX5939
-48V Hot-Swap Controllers with External
RSENSEand High Gate Pulldown Current
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
MAX5921/MAX5939
-48V Hot-Swap Controllers with External
RSENSEand High Gate Pulldown Current
Timing Diagrams (continued)Figure 5a. DRAIN to PWRGD/PWRGD Timing
Figure 5b. GATE to PWRGD/PWRGD Timing
Block Diagram
MAX5921/MAX5939
-48V Hot-Swap Controllers with External
RSENSEand High Gate Pulldown Current
Detailed DescriptionThe MAX5921/MAX5939 integrated hot-swap controllers
for -48V power systems 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. Uncontrolled inrush currents can cause glitches
on the system power supply and damage components
on the board.
The MAX5921/MAX5939 provide a controlled turn-on to
circuit cards preventing damage to connectors, board
components, and prevent glitches on the power-supply
rail. Both the MAX5921/MAX5939 provide undervolt-
age, overvoltage, and overcurrent protection. The
MAX5921/MAX5939 ensure that the input voltage is sta-
ble and within tolerance before applying power to the
load. The device also provides protection against input
voltage steps by limiting the load current to a safe level
without turning off power to the load.
MAX5921/MAX5939
-48V Hot-Swap Controllers with External
RSENSEand High Gate Pulldown Current
Board InsertionFigure 6a 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 IVEEx
(Cgd/Cgd + Cgs)I. The MAX5921/MAX5939 feature an
internal dynamic 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 MAX5921/
MAX5939 eliminates the need for an external gate-to-
source capacitor. The resistor R3 limits the current into
the clamp circuitry during card insertion.
Power-Supply RampingThe MAX5921/MAX5939 can reside either on the back-
plane or the removable circuit board (Figure 6a). Power
is delivered to the load by placing an external N-chan-
nel 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
MAX5921/MAX5939 gradually turn on the external
MOSFET by charging the gate of Q1 with a 45µA cur-
rent 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 gate pullup current.
Figure 6b 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 ∆VGATEto 18V.
Board RemovalIf the circuit card is removed from the backplane, the volt-
age at the UV falls below the UVLO detect threshold, and
the MAX5921/MAX5939 turn off the external MOSFET.
Current Limit and Electronic Circuit
BreakerThe MAX5921/MAX5939 provide current-limiting and cir-
cuit-breaker features that protect against excessive load
current and short-circuit conditions. The load current is
monitored by sensing the voltage across an external
sense resistor connected between VEEand SENSE.
