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MAX5948AESA+ |MAX5948AESAMAXIMN/a53avai-48V Hot-Swap Controllers with External RSENSE
MAX5948BESA+ |MAX5948BESAMAXIMN/a17avai-48V Hot-Swap Controllers with External RSENSE


MAX5948AESA+ ,-48V Hot-Swap Controllers with External RSENSEApplicationsSelector GuideCentral-Office SwitchingNetwork Switches/Routers PART PWRGD POLARITYMAX59 ..
MAX5948BESA ,-48V Hot-Swap Controllers with External RSENSEELECTRICAL CHARACTERISTICS(V = 0V, V = 48V, T = -40°C to +85°C. Typical values are at T = +25°C, un ..
MAX5948BESA+ ,-48V Hot-Swap Controllers with External RSENSEFeaturesThe MAX5948A/MAX5948B are hot-swap controllers♦ Allow Safe Board Insertion and Removal from ..
MAX5949AESA ,-48V Hot-Swap Controllers with External RSENSEFeaturesThe MAX5949A/MAX5949B are hot-swap controllers that♦ Allow Safe Board Insertion and Removal ..
MAX5949AESA ,-48V Hot-Swap Controllers with External RSENSEApplicationsTelecom Line CardsPART TEMP RANGE PIN-PACKAGENetwork Switches/RoutersMAX5949AESA -40°C ..
MAX5949AESA+ ,-48V Hot-Swap Controllers with External RSENSEELECTRICAL CHARACTERISTICS(V = 0V, V = 48V, T = -40°C to +85°C. Typical values are at T = +25°C, un ..
MAZ8150-H ,Silicon planar typeZener DiodesMAZ8000 SeriesSilicon planar typeUnit : mmFor stabilization of power supplyKA
MAZ8150-L ,Silicon planar typeFeatures•Extremely low noise voltage caused from the diode (2.4V to 39V,1/3 to 1/10 of our conventi ..
MAZ8150-M ,Silicon planar typeAbsolute Maximum Ratings T = 25°CaMarking SymbolParameter Symbol Rating UnitRefer to the list of t ..
MAZ8160-H ,Silicon planar typeElectrical Characteristics T = 25°CaParameter Symbol Conditions Min Typ Max UnitForward voltage V ..
MAZ8160-L ,Silicon planar typeZener DiodesMAZ8000 SeriesSilicon planar typeUnit : mmFor stabilization of power supplyKA
MAZ8160-M ,Silicon planar typeelectrical characteristicsZ Zwithin part numbersReverse current I V ··············· Specified value ..


MAX5948AESA+-MAX5948BESA+
-48V Hot-Swap Controllers with External RSENSE
General Description
The MAX5948A/MAX5948B are hot-swap controllers
that allow a circuit card to be safely hot plugged into a
live backplane. The MAX5948A/MAX5948B operate
from -20V to -80V and are well-suited for -48V power
systems. The MAX5948A is pin- and function-compati-
ble with both the LT1640AL and LT1640L. The
MAX5948B is pin- and function-compatible with both
the LT1640AH and LT1640H.
The MAX5948A/MAX5948B provide a controlled turn-on
to circuit cards preventing glitches on the power-supply
rail and damage to board connectors and components.
The MAX5948A/MAX5948B 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 MAX5948A and MAX5948B protect a system
against overcurrent and short-circuit conditions by turning
off the external MOSFET in the event of a fault condition.
Both devices feature an open-drain power-good status
output, PWRGDfor MAX5948A or PWRGD for
MAX5948B, that can be used to enable downstream
converters.
The MAX5948A/MAX5948B are available in an 8-pin SO
package. Both devices are specified for the extended
-40°C to +85°C temperature range.
Applications

Central-Office Switching
Network Switches/Routers
Server Line Cards
Base-Station Line Cards
Features
Allow Safe Board Insertion and Removal from a
Live -48V Backplane
Pin- and Function-Compatible with
LT1640AL/LT1640L (MAX5948A)
Pin- and Function-Compatible with
LT1640AH/LT1640H (MAX5948B)
Withstand -100V Input Transients with No
External Components
Operate from -20V to -80VProgrammable Inrush and Short-Circuit Current
Limits
Programmable Overvoltage ProtectionProgrammable Undervoltage LockoutPower Up into a Shorted LoadPower-Good Control Output
MAX5948A/MAX5948B
-48V Hot-Swap Controllers
with External RSENSE

GATE
SENSEVEE
VDD
DRAINOV
PWRGD
(PWRGD)
TOP VIEW
MAX5948A
MAX5948B
( ) FOR MAX5948B.
Pin Configuration

19-3473; Rev 1; 8/11
Selector Guide
PARTPWRGD POLARITY

MAX5948AESAActive Low (PWRGD)
MAX5948BESAActive High (PWRGD)
Ordering Information
PARTTEMP RANGEPIN-PACKAGE

MAX5948AESA+-40°C to +85°C8 SO
MAX5948BESA+-40°C to +85°C8 SO
+Denotes a lead(Pb)-free/RoHS-compliant package.
MAX5948A/MAX5948B
-48V Hot-Swap Controllers
with External RSENSE
ABSOLUTE MAXIMUM RATINGS

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
PWRGD, PWRGD.................................................-0.3V to +100V
DRAIN (Note 1)........................................................-2V to +100V
SENSE....................................................................-0.3V to +20V
GATE (internally clamped).....................................-0.3V to +18V
UV and OV..............................................................-0.3V to +60V
Current through SENSE....................................................±20mA
Current into GATE...........................................................±300mA
Current into Any Other Pin................................................±20mA
Current into Drain............................................-100mA to +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
Soldering Temperature (reflow).......................................+260°C
ELECTRICAL CHARACTERISTICS

(VEE= 0V, VDD= 48V, TA= -40°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.) (Notes 2, 3)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
POWER SUPPLIES

Operating Input Voltage RangeVDD2080V
Supply CurrentIDDVUV = 3V, OV = VEE, SENSE = VEE0.72mA
GATE DRIVER AND CLAMPING CIRCUITS

Gate Pin Pullup CurrentIPUGATE drive on, VGATE = VEE-30-45-60µA
Gate Pin Pulldown CurrentIPDAny fault condition, VGATE = 2V245070mA
External Gate Drive∆VGATEVGATE - VEE, 20V ≤ VDD ≤ 80V1013.518V
GATE to VEE Clamp VoltageVGSCLMPVGATE - VEE, current into GATE = 30mA1516.418V
CIRCUIT BREAKER

Current-Limit Trip VoltageVCBVCB = VSENSE - VEE405060mV
SENSE Input Bias CurrentISENSEVSENSE = 50mV0-0.03-1µA
UV PIN

UV High ThresholdVUVHUV low to high transition1.2131.2431.272V
UV Low ThresholdVUVLUV high to low transition1.1981.2231.247V
UV HysteresisVUVHY20mV
UV Input Bias CurrentIINUVVUV = VEE0-0.5µA
OV PIN

OV High ThresholdVOVHOV low to high transition1.1981.2231.247V
OV Low ThresholdVOVLOV high to low transition1.1651.2031.232V
OV HysteresisVOVHY20mV
OV Input Bias CurrentIINOVVOV = VEE0-0.5µA
PWRGD OUTPUT SIGNAL REFERENCED TO DRAIN

DRAIN Input Bias CurrentIDRAINVDRAIN = 48V1080250µAow er - G ood Thr eshol d VPGVDRAIN - VEE, high to low transition1.11.42.0Vow er - G ood Thr eshol d H yster esi sVPGHY0.4V
Note 1:
Test condition per Figure 1. DRAIN current must be limited to the specified 100mA maximum.
MAX5948A/MAX5948B
-48V Hot-Swap Controllers
with External RSENSE
ELECTRICAL CHARACTERISTICS (continued)

(VEE= 0V, VDD= 48V, TA= -40°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.) (Notes 2, 3)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS

PWRGD, PWRGD Output
LeakageIOHVPWRGD (MAX5948A) = 80V, VDRAIN = 48V,
VPWRGD (MAX5948B) = 80V, VDRAIN = 0V10µA
Power-Good Output Impedance
(PWRGD to DRAIN)ROUTVPWRGD (MAX5948B) (VDRAIN - VEE) < VPG500 x
103MΩ
PWRGD Output Low VoltageVOLVPWRGD - VEE; VDRAIN - VEE < VPG,
IOUT = 1mA (MAX5948A)0.110.4V
PWRGD Output Low VoltageVOLVPWRGD - VDRAIN; VDRAIN = 5V,
IOUT = 1mA (MAX5948B)0.110.4V
AC PARAMETERS

OV High to GATE LowtPHLOVFigures 2, 30.5µs
UV Low to GATE LowtPHLUVFigures 2, 40.4µs
OV Low to GATE HightPLHOVFigures 2, 33.3µs
UV High to GATE HightPLHVLFigures 2, 43.4µs
SENSE High to GATE LowtPHLSENSEFigures 2, 5234µs
MAX5948A, Figures 2, 60.5DRAIN Low to PWRGD Low
DRAIN Low to (PWRGD - DRAIN)
High
tPHLPG
MAX5948B, Figures 2, 60.5
MAX5948A, Figures 2, 60.5DRAIN High to PWRGD High
DRAIN High to (PWRGD -
DRAIN) Low
tPLHPG
MAX5948B, Figures 2, 60.5
Note 2:
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 3:
Limits are 100% tested at TA= +25°C and +85°C. Limits at -40°C are guaranteed by design.
100mA MAX
MAX5948
PWRGD/PWRGD
VEE
VDD
DRAINGATE
TEST VOLTAGE
SENSE
Figure 1. -2V DRAIN Voltage Test Circuit
MAX5948A/MAX5948B
-48V Hot-Swap Controllers
with External RSENSE
Typical Operating Characteristics

(VDD= 48V, VEE= 0V, TA= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE

MAX5948 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (9060402070503010
SUPPLY CURRENT vs. TEMPERATURE
MAX5948 toc02
TEMPERATURE (°C)
SUPPLY CURRENT (mA)50250-25
GATE VOLTAGE vs. SUPPLY VOLTAGE
MAX5948 toc03
SUPPLY VOLTAGE (V)
GATE VOLTAGE (V)8010203050604070
GATE VOLTAGE vs. TEMPERATURE
MAX5948 toc04
TEMPERATURE (°C)
GATE VOLTAGE (V)50250-25
CIRCUIT-BREAKER TRIP VOLTAGE
vs. TEMPERATURE
MAX5948 toc05
TRIP VOLTAGE (mV)50250-25
GATE PULLUP CURRENT vs. TEMPERATURE
MAX5948 toc06
GATE PULLUP CURRENT (50-25025
VGATE = 0V
MAX5948A/MAX5948B
-48V Hot-Swap Controllers
with External RSENSE

5kΩ
VOV
VUV
VSENSE
VDRAIN
48V
MAX5948A
MAX5948B
PWRGD/PWRGD
VEE
VDD
DRAIN
GATE
SENSE
Figure 2. Test Circuit 1
Typical Operating Characteristics (continued)

(VDD= 48V, VEE= 0V, TA= +25°C, unless otherwise noted.)
GATE PULLDOWN CURRENT
vs. TEMPERATURE

MAX5948 toc07
TEMPERATURE (°C)
GATE PULLDOWN CURRENT (mA)50250-25
VGATE = 2V
PWRGD OUTPUT LOW VOLTAGE
vs. TEMPERATURE (MAX5948A)

MAX5948 toc08
TEMPERATURE (°C)
PWRGD OUTPUT LOW VOLTAGE (mV)50-25025
IOUT = 1mA
10,000
PWRGD OUTPUT IMPEDANCE
vs. TEMPERATURE (MAX5948B)
TEMPERATURE (°C)
OUTPUT IMPEDANCE (G
MAX5948A/MAX5948B
-48V Hot-Swap Controllers
with External RSENSE
Timing Diagrams

1.223V
tPHLOV0V
1.203V
tPLHOV
GATE
Figure 3. OV to GATE Timing
tPHLUV
1.223V1V
1.243V
tPLHUV
GATE
Figure 4. UV to GATE Timing
50mV
100mV
GATE
SENSE
VEE
tPHLSENSE
Figure 5. SENSE to GATE Timing
DRAIN
PWRGD
VPWRGD - VDRAIN = 0V
1.8V
VEE
DRAIN
VEE
1.8V
tPLHPG
1.4V
tPHLPG
1.4V
tPHLPGPWRGD
DRAIN
Figure 6. DRAIN to PWRGD/PWRGD Timing
MAX5948A/MAX5948B
-48V Hot-Swap Controllers
with External RSENSE
Detailed Description

The MAX5948A/MAX5948B 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 MAX5948A/MAX5948B provide a controlled turn-on
to circuit cards preventing glitches on the power-sup-
ply rail and damage to board connectors and compo-
nents. Both the MAX5948A and MAX5948B provide
undervoltage, overvoltage, and overcurrent protection.
The MAX5948A/MAX5948B ensure the input voltage is
stable and within tolerance before applying power to
Board Insertion

Figure 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 I(VEEx Cgd) /
(Cgd+ Cgs)I. The MAX5948_ features 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 MAX5948A/MAX5948B
eliminates the need for an external gate-to-source
capacitor. Resistor R3 limits the current into the clamp
circuitry during card insertion.
Pin Description
PIN
MAX5948AMAX5948BNAMEFUNCTION
PWRGD
Power-Good Signal Output. PWRGD is an active-low open-drain status output referenced
to VEE. PWRGD is low when VDRAIN - VEE ≤ VPG, indicating a power-good condition.
PWRGD is open drain otherwise.1PWRGD
Power-Good Signal Output. PWRGD is an active-high open-drain status output referenced
to DRAIN. PWRGD is in a high-impedance state when VDRAIN - VEE ≤ VPG, indicating a
power-good condition. PWRGD is pulled low to DRAIN otherwise.OV
Input Pin for Overvoltage Detection. OV is referenced to VEE. When OV is pulled above
VOVH voltage, the GATE pin is immediately pulled low. The GATE pin remains low until the
OV pin voltage reduces to VOVL.UV
Input Pin for Undervoltage Detection. UV is referenced to VEE. When UV is pulled above
VUVH voltage, the GATE is enabled. When UV is pulled below VUVL, GATE is pulled low.
UV is also used to reset the circuit breaker after a fault condition. To reset the circuit
breaker, pull UV below VUVL.VEEDevice Negative Power-Supply Input. Connect to the negative power-supply rail.5SENSE
Current-Sense Voltage Input. Connect to an external sense resistor and the external
MOSFET source. The voltage drop across the external sense resistor is monitored to detect
overcurrent or short-circuit fault conditions. Connect SENSE to VEE to disable the circuit-
breaker feature.6GATEGate-Drive Output. Connect to gate of the external n-channel MOSFET.7DRAINOutput-Voltage Sense Input. Connect to the output-voltage node (drain of external
n-channel MOSFET).VDDPositive Power-Supply Rail Input. This is the power ground in the negative-supply voltage
system. Connect to the most positive potential of the power-supply inputs.
MAX5948A/MAX5948B
-48V Hot-Swap Controllers
with External RSENSE
Power-Supply Ramping

The MAX5948A/MAX5948B can reside either on the
backplane or the removable circuit board (Figure 6a).
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 under-
voltage and overvoltage tolerance, the MAX5948A/
MAX5948B turn on Q1. The MAX5948A/MAX5948B grad-
ually 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= (IPUx CL)/C2
where CLis the total load capacitance, C3 + C4, and
IPUis the MAX5948_ 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 VGSto about 18V under any condition.
Board Removal

If the card is removed from a live backplane, the output
capacitor on the card may not be immediately discharged.
While the output capacitor is discharging, the MAX5948_
continues to operate as if the input supply were still con-
nected because the output capacitor temporarily supplies
operating current to the IC. If the circuit is connected as in
Figure 7a, the voltage at the UV pin falls below the UVLO
detect threshold, and the MAX5948_ turns off the external
MOSFET. If R4 in the circuit is connected directly to the -
48V return, the external MOSFET remains on until the
capacitor is discharged sufficiently to drop the UV pin volt-
age to the UVLO detect threshold.
In either case, when the MOSFET is turned off, the output
capacitor continues to discharge by the IC supply current
IDD. The IDDflows into the IC at the VDDterminal, out at the
VEEterminal, and back to the capacitor through the sub-
strate diode of the external MOSFET. There is also a paral-
lel current path between the VEEand DRAIN terminals
through multiple internal ESD-protection diodes. The pro-
tection circuit built into the IC allows the DRAIN terminal
voltage to drop below that of the VEEterminal so long as
the absolute maximum allowed DRAIN terminal current
(-100mA) is not exceeded. As IDDis only 2mA maximum,
LOGIC
AND
GATE DRIVE
VCC AND
REFERENCE
GENERATOR
REF
VCC
REF
VPG
VEE
50mV
VDD
VEESENSEGATEDRAIN
PWRGD
PWRGD
MAX5948A
MAX5948B
OUTPUT
DRIVE
Block Diagram
MAX5948A/MAX5948B
-48V Hot-Swap Controllers
with External RSENSE
Electronic Circuit Breaker

The MAX5948 provides a circuit-breaker feature that
protects against excessive load current and short-cir-
cuit conditions. The load current is monitored by sens-
ing the voltage across an external sense resistor
connected between VEEand SENSE.
If the voltage between VEEand SENSE exceeds the
current-limit trip voltage (VCB) for a period of
tPHLSENSE, the electronic circuit breaker will trip, caus-
ing the MAX5948A/MAX5948B to turn off the external
MOSFET as shown in Figure 8.
After an overcurrent fault condition, the circuit breaker
can be reset by pulling the UV pin low and then pulling
UV high or by cycling power to the MAX5948A/
MAX5948B.
VEESENSEGATEDRAIN
VDD
PWRGD
MAX5948B
-48V RTN
-48V
562kΩ
9.09kΩ
10kΩ
0.02Ω
18kΩ
10Ω
150nF
25V
IRF530
3.3nF
100V
GATE IN
VICOR
VI-J3D-CY
VIN+
VIN-
100μF
100V
0.1μF
100V
-48V RTN
(SHORT PIN)
*DIODES INC. SMAT70A.
Figure 7a. Inrush Control Circuitry
GATE - VEE
10V/div
VEE
50V/div
DRAIN
50V/div
INRUSH
CURRENT
1A/div
4ms/div
CONTACT
BOUNCE
Figure 7b. Input Inrush Current
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