MAX8555AEUB+ Fast Delivery |IC PHOENIX CO.,LIMITED

MAX8555AEUB+ ,Low-Cost, High-Reliability, 0.5V to 3.3V ORing MOSFET ControllersFeaturesCritical loads often employ parallel-connected power♦ Simple, Integrated, and Inexpensive M ..
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MAX8555AEUB+
Low-Cost, High-Reliability, 0.5V to 3.3V ORing MOSFET Controllers
General Description
Critical loads often employ parallel-connected power
supplies with redundancy to enhance system reliability.
The MAX8555/MAX8555A are highly integrated, inex-
pensive MOSFET controllers that provide isolation and
redundant power capability in high-reliability systems.
The MAX8555/MAX8555A are used in 0.5V to 3.3V sys-
tems, and have an internal charge pump to drive the
gates of the N-channel pass elements to (VCS++ 5V).
During startup, the MAX8555/MAX8555A monitor the
voltage drop across the external MOSFETs. Once VCS+
approaches or exceeds the bus voltage (VCS-), the
MOSFETs are turned on. The MAX8555/MAX8555A fea-
ture a dual-purpose TIMER input. A single external
resistor from TIMER to ground sets the turn-on speed of
the external MOSFETs. Optionally, the TIMER input can
be used as a logic enable input. Once the external
MOSFET is turned on, these controllers monitor the
load, protecting the bus against overvoltage, undervolt-
age, and reverse-current fault conditions. The
MAX8555 is available with a 40mV reverse-current
threshold, while the MAX8555A is available with a 20mV
reverse-current threshold.
Overvoltage and undervoltage fault thresholds are
adjustable and can be disabled. The current-limit trip
points are set by the external MOSFETs’ RDS(ON),
reducing component count. An open-drain, logic-low
fault output indicates if an overvoltage, undervoltage, or
reverse-current fault occurs. The MAX8555 and the
MAX8555A can shut down in response to a reverse-
current fault condition as quickly as 200ns.
Both devices come in space-saving 10-pin µMAX or
TDFN packages and are specified over the extended
-40°C to +85°C temperature range.
Applications
Point-of-Load Supplies
Power-Supply Modules
Servers
Telecom Power Supplies
Rectifiers
Redundant Power Supplies in High-Availability
Systems
FeaturesSimple, Integrated, and Inexpensive MOSFET
ControllersORing FET Drive for 0.5V to 3.3VEliminate ORing Diode Power DissipationProvide N+1 Redundant Supply Capability for
Highly Reliable SystemsIsolate Failed Short-Circuit Supply from
Output BUSRespond to Reverse Short-Circuit Current
in 200nsAdjustable Blank TimeProgrammable Soft-StartLogic Enable InputAdjustable Overvoltage and Undervoltage
Trip PointsFault-Indicator OutputSpace-Saving Packages
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
Ordering Information
13-3087; Rev 0; 1/04
EVALUATION KIT
AVAILABLE
PARTTEMP
RANGE
PIN-
PACKAGE
TOP
MARK
MAX8555ETB-40°C to 85°C10 TDFN
3mm x 3mm*ACC
MAX8555EUB-40°C to 85°C10 µMAX8555EUB
MAX8555AETB-40°C to 85°C10 TDFN
3mm x 3mm*ADD
MAX8555AEUB-40°C to 85°C10 µMAX8555AEUB
CS+
CS-
OVP
VDD
GND
GATE
MAX8555/
MAX8555A
µMAX
TOP VIEW
TIMERUVP
FAULT
CS+
CS-
OVP
VDD
GND
GATE
MAX8555/MAX8555A
TDFN
TIMERUVP
FAULT
Pin Configurations
*Exposed paddle
Typical Operating Circuit appears at end of data sheet.
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD = 12V, VCS-= 1.4V, VCS+ = 1.5V, RTIMER = 25kΩ, VUVP= 1V, VOVP= 0.25V, RFAULT = 50kΩ, CVDD = CGATE= CVL = 0.01µF,
TA = 0°C to +85°C, unless otherwise noted.)
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.
GATE to GND.........................................................-0.3V to +12V
FAULT, VL to GND...................................................-0.3V to +6V
OVP, UVP, TIMER, CS+, CS- to GND.......-0.3V to +(VVL+ 0.3V)
VDDto GND..................................................(VVL- 0.3V) to +18V
Continuous Power Dissipation (TA= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C)...........444mW
10-Pin TDFN (derate 24.4mW/°C above +70°C).......1951mW
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
PARAMETERCONDITIONSMINTYPMAXUNITS
VDD SUPPLY
VL unconnected8.0013.25VDD Input VoltageVTIMER = 2.5VVL = VDD3.05.5V
VL unconnected, VTIMER = 2.5V, VDD = 13.25V2.03.3VDD Supply CurrentVDD = VVL = 5V, VTIMER = 2.5V0.040.2mA
VDD Shutdown CurrentVTIMER = 0V, VDD = 13.25V3.0mA
Rising threshold14.014.415.0VDD Overvoltage Internal
ThresholdFalling threshold13.313.814.5V
VL SUPPLY
VL Input VoltageVDD = VVL3.05.5V
VL Supply CurrentVDD = VVL = 5V, VTIMER = 2.5V1.83.0mA
VL Current in Shutdown ModeTIMER = GND, VDD = VVL = 5V1.63.0mA
VL Output VoltageVDD = 8V to 13.25V, IVL = 0A3.804.14.45V
VL = VDD, rising threshold2.782.822.90VL Undervoltage LockoutVL = VDD, falling threshold2.682.752.82V
CS INPUTS
CS+, CS- Input CurrentVTIMER = 2.5V, VCS = 3.0V5.2µA
Offset Input Current (CS+, CS-)VCS = 3.0V, Figure 4-250+250nA
CS+/CS- Input Range(Note 1)0.5VVL - 0.5V
VCS+ = +3V, VCS- = 0V, ICS--0.5CS IsolationVCS- = +3V, VCS+ = 0V, ICS+-0.5µA
CHARGE-PUMP VOLTAGE
VDD = 8V to 13.25VGATE Voltage, VGATEMeasured from GATE to CS+VDD = VVL = 5V5.05.255.5V
RTIMER = 20kΩ187
RTIMER = 125kΩ450
RTIMER = open500
Charge-Pump Switching
Frequency
VTIMER = 1.5V550
kHz
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 12V, VCS-= 1.4V, VCS+ = 1.5V, RTIMER = 25kΩ, VUVP= 1V, VOVP= 0.25V, RFAULT = 50kΩ, CVDD = CGATE= CVL = 0.01µF,
TA = 0°C to +85°C, unless otherwise noted.)
PARAMETERCONDITIONSMINTYPMAXUNITS
TIMER
TIMER Voltage1.221.251.28V
TIMER Maximum Source CurrentVTIMER = 1.0V85100115µA
TIMER High Input CurrentVTIMER = 1.5V1015µA
TIMER Maximum Frequency
Select Voltage Input Range(Note 1)1.5VVLV
TIMER Logic High, VIHCharge pump enabled1.0V
TIMER Logic Low, VILCharge pump disabled0.5V
FAULT
Fault Output Low VoltageIFAULT = 10mA0.2V
Fault Sink CurrentV FAULT = 0.4V15mA
Fault Leakage CurrentV FAULT = 5.5V, TA = +25°C1µA
GATE
MAX855580100120Gate-On ThresholdMeasured from CS- to CS+MAX8555A355065mV
RTIMER = open172533VGATE = VCS+ = 2.5VRTIMER = 25kΩ81216
RTIMER = open15VGATE = VCS+ = 2.5V,
VDD = VVL = 3VRTIMER = 25kΩ7.5
RTIMER = open30
Gate-Drive Current
VGATE = VCS+ = 2.5V,
VDD = VVL = 5VRTIMER = 25kΩ15
VTIMER falling100200Gate Shutdown Delay(Note 2)IREV fault60150ns
Gate Discharge CurrentVGATE = VCS+= +5V1000mA
GATE Fall TimeGate voltage fall from FAULT to VGATE = VCS+,
R1 = 2Ω, Figure 3 or Figure 40.2µs
CURRENT SENSE
MAX8555344046Reverse-Current ThresholdMeasured from CS- to CS+MAX8555A162024mV
Startup IREV Blank TimeTIMER = unconnected4.1ms
Forward-Current ThresholdMeasured from CS+ to CS-61014mV
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 12V, VCS-= 1.4V, VCS+ = 1.5V, RTIMER = 25kΩ, VUVP= 1V, VOVP= 0.25V, RFAULT = 50kΩ, CVDD = CGATE= CVL = 0.01µF,
TA = 0°C to +85°C, unless otherwise noted.)
PARAMETERCONDITIONSMINTYPMAXUNITS
OVERVOLTAGE PROTECTION
OVP rising0.49 0.50.51OVP Fault Threshold, VOVPOVP falling0.4V
TA = +25°C0.1OVP Bias CurrentTA = +85°C0.021µA
UNDERVOLTAGE PROTECTION
UVP rising0.488 0.50.512UVP Fault Threshold, VUVPUVP falling0.4V
TA = +25°C0.1UVP Bias CurrentTA = +85°C0.003µA
ELECTRICAL CHARACTERISTICS
(VDD = 12V, VCS-= 1.4V, VCS+ = 1.5V, RTIMER = 25kΩ, VUVP= 1V, VOVP= 0.25V, RFAULT = 50kΩ, CVDD = CGATE= CVL = 0.01µF,
TA = -40°C to +85°C, unless otherwise noted.) (Note 3)
PARAMETERCONDITIONSMINTYPMAXUNITS
VDD SUPPLY
VL unconnected8.0013.25VDD Input VoltageVTIMER = 2.5VVL = VDD3.05.5V
VL unconnected, VTIMER = 2.5V, VDD = 13.25V3.3VDD Supply CurrentVDD = VVL = 5V, VTIMER = 2.5V0.2mA
VDD Shutdown CurrentVTIMER = 0V, VDD = 13.25V3.0mA
Rising threshold14.015.0VDD Overvoltage Internal
ThresholdFalling threshold13.314.5V
VL SUPPLY
VL Input VoltageVDD = VVL3.05.5V
VL Supply CurrentVDD = VVL = 5V, VTIMER = 2.5V3.0mA
VL Current in Shutdown ModeTIMER = GND, VDD = VVL= 5V3.0mA
VL Output VoltageVDD = 8V to 13.25V, IVL = 0A3.804.45V
VL = VDD, rising threshold2.782.90VL Undervoltage LockoutVL = VDD, falling threshold2.682.82V
CS INPUTS
Offset Input Current (CS+, CS-)VCS = 3.0V, Figure 4-250+250nA
CS+/CS- Input Range(Note 1)0.5VVL - 0.5V
CHARGE-PUMP VOLTAGE
VDD = 8V to 13.25VGATE Voltage, VGATEMeasured from GATE to CS+VDD = VVL = 5V5.05.5V
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
Note 1:Guaranteed by design. Not production tested.
Note 2:Gate shutdown delay is measured from reverse-current fault to the start of gate-voltage falling or from TIMER to the start of
gate-voltage falling.
Note 3:Specifications to -40°C are guaranteed by design and not production tested.
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 12V, VCS-= 1.4V, VCS+ = 1.5V, RTIMER = 25kΩ, VUVP= 1V, VOVP= 0.25V, RFAULT = 50kΩ, CVDD = CGATE= CVL = 0.01µF,
TA = -40°C to +85°C, unless otherwise noted.) (Note 3)
PARAMETERCONDITIONSMINTYPMAXUNITS
TIMER
TIMER Voltage1.221.28V
TIMER Maximum Source CurrentVTIMER = 1.0V85115µA
TIMER High Input CurrentVTIMER = 1.5V15µA
TIMER Maximum Frequency
Select Voltage Input Range(Note 1)1.5VVLV
TIMER Logic High, VIHCharge pump enabled1.1V
TIMER Logic Low, VILCharge pump disabled0.5V
FAULT
Fault Output Low VoltageIFAULT = 10mA0.2V
Fault Sink CurrentV FAULT = 0.4V15mA
GATE
MAX855580120Gate-On ThresholdMeasured from CS- to CS+MAX8555A3565mV
RTIMER = open1733Gate-Drive CurrentVGATE = VCS+ = 2.5VRTIMER = 25kΩ816µA
VTIMER falling200Gate Shutdown DelayIREV fault150ns
CURRENT SENSE
MAX85553446Reverse-Current ThresholdMeasured from CS- to CS+MAX8555A1624mV
Forward-Current ThresholdMeasured from CS+ to CS-614mV
OVERVOLTAGE PROTECTION
OVP Fault Threshold, VOVPOVP rising0.490.51V
UNDERVOLTAGE PROTECTION
UVP Fault Threshold, VUVPUVP rising0.4880.512V
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
Typical Operating Characteristics
(VDD = 12V, VCS+= 1.5V, RTIMER = 25kΩ, VUVP= 1V, VOVP= 0.4V, RFAULT = 50kΩto output bus, CVDD = CGATE= CVL= 0.01µF, TA =
+25°C, R1 = 2Ωin Figure 3, MAX8555A, unless otherwise noted.)
GATE-CHARGE CURRENT
vs. TIMER RESISTOR (VDD = 12V)
MAX8555/55A toc01
TIMER RESISTOR (kΩ)
GATE CURRENT (
TA = +85°C
TA = +25°C
TA = -40°C
GATE-CHARGE CURRENT vs.
TIMER RESISTOR (VDD = VVL = 3V)
MAX8555/55A toc02
TIMER RESISTOR (kΩ)
GATE-CHARGE CURRENT (
TA = +85°C
TA = +25°CTA = -40°C
VDD CURRENT vs. TEMPERATURE
MAX8555/55A toc03
TEMPERATURE (°C)
CURRENT (mA)40200-20
TIMER = OPEN
TIMER = GND
VDD = 13.25V
REVERSE-CURRENT THRESHOLD vs.
TEMPERATURE
MAX8555/55A toc04
TEMPERATURE (°C)
REVERSE-CURRENT THRESHOLD (mV)40200-20
OVP AND UVP LEAKAGE CURRENT vs.
TEMPERATURE
MAX8555/55A toc05
TEMPERATURE (°C)
LEAKAGE CURRENT (nA)40200-20
OVP
UVP
POWER-UP WAVEFORMS BUS
VOLTAGE HIGH IMPEDANCE
MAX8555/55A toc06
1ms/div
VCS+
VGATE
VCS-
IMOSFET
1V/div
5V/div
1V/div
1A/div
POWER-UP WAVEFORMS
BUS VOLTAGE IS LIVE
MAX8555/55A toc07
2ms/div
VCS+
VGATE
VCS-
IMOSFET
1V/div
5V/div
1V/div
500mA/div
POWER-UP AND DOWN WAVEFORMS
USING TIMER
MAX8555/55A toc08
5ms/div
VGATE
VTIMER
IMOSFET1A/div
2V/div
5V/div
REVERSE-CURRENT
SHUTDOWN WAVEFORMS
MAX8555/55A toc09
200ns/div
VGATE
VCS-
VFAULT
IMOSFET0A
-2A
5V/div
1V/div
100mV/div
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
UVP SHUTDOWN WAVEFORMS
MAX8555/55A toc10
200ns/div
VGATE
VUVP
VCS-
AC-COUPLED
VFAULT
2V/div
2V/div
5V/div
100mV/div
OVP SHUTDOWN WAVEFORMS
MAX8555/55A toc11
200ns/div
VGATE
VOVP
VCS-
AC-COUPLED
VFAULT1V/div
2V/div
5V/div
100mV/div
POWER-SUPPLY OUTPUT
SHORT-CIRCUIT SHUTDOWN WAVEFORMS
MAX8555/55A toc12
200ns/div
VGATE1
IMOSFET2
VCS+
VCS-
AC-COUPLED
1V/div
5V/div
200mA/div
100mV/div
VDD FAULT SHUTDOWN WAVEFORMS
MAX8555/55A toc13
1µs/div
VGATE
VFAULT
VDD
VCS-1V/div
5V/div
1V/div
10V/divypical Operating Characteristics (continued)
(VDD = 12V, VCS+= 1.5V, RTIMER = 25kΩ, VUVP= 1V, VOVP= 0.4V, RFAULT = 50kΩto output bus, CVDD = CGATE= CVL= 0.01µF, TA =
+25°C, R1 = 2Ωin Figure 3, MAX8555A, unless otherwise noted.)
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
PINNAMEFUNCTIONGATEGate-Drive Output. Nominal GATE load is a 0.01µF capacitor to ground. Gate is discharged to GND in
shutdown.GNDGround
3VLLow-Voltage Optional Input Power. Leave disconnected when VDD = 8V to 13.25V, or connect VDD to VL
when VDD = 3V to 5.5V. Bypass VL to GND with a 0.01µF capacitor.
4VDDPower-Supply Input. Connect to an 8V to 13.25V supply or connect to VL when using a 3V to 5.5V supply.
Bypass VDD with a 0.01µF capacitor to ground.UVPUndervoltage-Protection Input. Connect UVP to the center of a resistor-divider from CS+ to GND. Connect
UVP to VL to disable the undervoltage protection.TIMER
Timer Input. Connect a resistor from TIMER to GND to select the charge-pump operating frequency. Drive
TIMER low (< 0.5V) to disable the gate drive. Drive TIMER high (above 1.5V) for charge-pump operation
at 550kHz.FAULT
Open-Drain Fault Output. FAULT is high impedance during normal operation and is pulled to GND when a
fault condition occurs. Connect a pullup resistor of 10kΩ or higher value (50kΩ typ) to a voltage rail of 5.5V
or lower.OVPOvervoltage-Protection Input. Connect OVP to the center of a resistor-divider from the output bus to GND.
Connect OVP to GND to disable the overvoltage protection.CS-Current-Sensing Input. Connect CS- to the positive side of the system bus. Bypass with a 1000pF capacitor
to GND.CS+Current-Sensing Input. Connect CS+ to the positive side of the input power. Bypass with a 1000pF capacitor
to GND.
Pin Description
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
MAX8555/
(MAX8555A)
CS+
CLK
CHARGE
PUMP
CONTROL
LOGIC
SHUTDOWN
GATECS-
REVERSE CURRENT
FORWARD CURRENT
100mV
(50mV)10mV
OVP
UVP
OVERVOLTAGE EXTERNAL
UNDERVOLTAGE
TIMER
IOSC
0.5V
0.4V
1.25V REF
ENABLE
14.5V
OVERVOLTAGE INTERNAL
40mV
(20mV)
VOLTAGE SHARE
VDD
REGULATORGND
FAULT
Figure 1. MAX8555/MAX8555A Functional Diagram

Partno	Mfg	Dc	Qty	Available	Descript
MAX8555AEUB+ \|MAX8555AEUB	MAXIM	N/a	250	avai	Low-Cost, High-Reliability, 0.5V to 3.3V ORing MOSFET Controllers