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MAX8555AEUB+T

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17
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 (V
CS+
+ 5V).
During startup, the MAX8555/MAX8555A monitor the
voltage drop across the external MOSFETs. Once V
CS+
approaches or exceeds the bus voltage (V
CS-
), 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’ R
DS(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
Features
♦ Simple, Integrated, and Inexpensive MOSFET
Controllers
♦ ORing FET Drive for 0.5V to 3.3V
♦ Eliminate ORing Diode Power Dissipation
♦ Provide N+1 Redundant Supply Capability for
Highly Reliable Systems
♦ Isolate Failed Short-Circuit Supply from
Output BUS
♦ Respond to Reverse Short-Circuit Current
in 200ns
♦ Adjustable Blank Time
♦ Programmable Soft-Start
♦ Logic Enable Input
♦ Adjustable Overvoltage and Undervoltage
Trip Points
♦ Fault-Indicator Output
♦ Space-Saving Packages
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
13-3087; Rev 0; 1/04
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
PART
TEMP
RANGE
PIN-
PACKAGE
TOP
MARK
MAX8555ETB
-40°C to 85°C
10 TDFN
3mm x 3mm*
ACC
MAX8555EUB
-40°C to 85°C
10 µMAX
8555EUB
MAX8555AETB
-40°C to 85°C
10 TDFN
3mm x 3mm*
ADD
MAX8555AEUB
-40°C to 85°C
10 µMAX
8555AEUB
1
2
3
4
5
10
9
8
7
6
CS+
CS-
OVP
V
DD
VL
GND
GATE
MAX8555/
MAX8555A
µMAX
TOP VIEW
TIMERUVP
FAULT
1
2
3
4
5
10
9
8
7
6
CS+
CS-
OVP
V
DD
VL
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
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
DD
= 12V, V
CS-
= 1.4V, V
CS+
= 1.5V, R
TIMER
= 25kΩ, V
UVP
= 1V, V
OVP
= 0.25V, R
FAULT
= 50kΩ, C
VDD
= C
GATE
= C
VL
= 0.01µF,
T
A
= 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 +(V
VL
+ 0.3V)
V
DD
to GND..................................................(V
VL
- 0.3V) to +18V
Continuous Power Dissipation (T
A
= +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
PARAMETER CONDITIONS
MIN
TYP
MAX
V
DD
SUPPLY
VL unconnected
8.00 13.25
V
DD
Input Voltage V
TIMER
= 2.5V
VL = V
DD
3.0 5.5
V
VL unconnected, V
TIMER
= 2.5V, V
DD
= 13.25V 2.0 3.3
V
DD
Supply Current
V
DD
= V
VL
= 5V, V
TIMER
= 2.5V
0.04
0.2
V
DD
Shutdown Current V
TIMER
= 0V, V
DD
= 13.25V 3.0
Rising threshold
14.0 14.4
15.0
V
DD
Overvoltage Internal
Threshold
Falling threshold
13.3 13.8
14.5
V
VL SUPPLY
VL Input Voltage V
DD
= V
VL
3.0 5.5 V
VL Supply Current V
DD
= V
VL
= 5V, V
TIMER
= 2.5V 1.8 3.0
VL Current in Shutdown Mode TIMER = GND, V
DD
= V
VL
= 5V 1.6 3.0
VL Output Voltage V
DD
= 8V to 13.25V, I
VL
= 0A
3.80
4.1 4.45 V
VL = V
DD
, rising threshold
2.78 2.82
2.90
VL Undervoltage Lockout
VL = V
DD
, falling threshold
2.68 2.75
2.82
V
CS INPUTS
CS+, CS- Input Current V
TIMER
= 2.5V, V
CS
= 3.0V 5.2 µA
Offset Input Current (CS+, CS-) V
CS
= 3.0V, Figure 4
-250 +250
nA
CS+/CS- Input Range (Note 1) 0.5
V
VL
- 0.5
V
V
CS+
= +3V, V
CS-
= 0V, I
CS-
-0.5
CS Isolation
V
CS-
= +3V, V
CS+
= 0V, I
CS+
-0.5
µA
CHARGE-PUMP VOLTAGE
V
DD
= 8V to 13.25V
GATE Voltage, V
GATE
Measured from GATE to CS+
V
DD
= V
VL
= 5V
5.0
5.25
5.5 V
R
TIMER
= 20kΩ
187
R
TIMER
= 125kΩ
450
R
TIMER
= open
500
Charge-Pump Switching
Frequency
V
TIMER
= 1.5V
550
MAX8555/MAX8555A
Low-Cost, High-Reliability, 0.5V to 3.3V ORing
MOSFET Controllers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 12V, V
CS-
= 1.4V, V
CS+
= 1.5V, R
TIMER
= 25kΩ, V
UVP
= 1V, V
OVP
= 0.25V, R
FAULT
= 50kΩ, C
VDD
= C
GATE
= C
VL
= 0.01µF,
T
A
= 0°C to +85°C, unless otherwise noted.)
PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
TIMER
TIMER Voltage
1.22 1.25
1.28 V
TIMER Maximum Source Current
V
TIMER
= 1.0V 85
100
115 µA
TIMER High Input Current V
TIMER
= 1.5V 10 15 µA
TIMER Maximum Frequency
Select Voltage Input Range
(Note 1) 1.5 V
VL
V
TIMER Logic High, V
IH
Charge pump enabled 1.0 V
TIMER Logic Low, V
IL
Charge pump disabled 0.5 V
FAULT
Fault Output Low Voltage I
FAULT
= 10mA 0.2 V
Fault Sink Current V
FAULT
= 0.4V 15
mA
Fault Leakage Current V
FAULT
= 5.5V, T
A
= +25°C 1 µA
GATE
MAX8555 80
100
120
Gate-On Threshold Measured from CS- to CS+
MAX8555A 35 50 65
mV
R
TIMER
= open 17 25 33
V
GATE
= V
CS+
= 2.5V
R
TIMER
= 25kΩ 81216
R
TIMER
= open 15
V
GATE
= V
CS+
= 2.5V,
V
DD
= V
VL
= 3V
R
TIMER
= 25kΩ 7.5
R
TIMER
= open 30
Gate-Drive Current
V
GATE
= V
CS+
= 2.5V,
V
DD
= V
VL
= 5V
R
TIMER
= 25kΩ 15
µA
V
TIMER
falling
100
200
Gate Shutdown Delay (Note 2)
I
REV
fault 60 150
ns
Gate Discharge Current V
GATE
= V
CS+
= +5V
1000
mA
GATE Fall Time
Gate voltage fall from FAULT to V
GATE
= V
CS+
,
R1 = 2Ω, Figure 3 or Figure 4
0.2 µs
CURRENT SENSE
MAX8555 34 40 46
Reverse-Current Threshold Measured from CS- to CS+
MAX8555A 16 20 24
mV
Startup I
REV
Blank Time TIMER = unconnected 4.1 ms
Forward-Current Threshold Measured from CS+ to CS- 6 10 14
mV
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17

MAX8555AEUB+T

Mfr. #:
Buy MAX8555AEUB+T
Manufacturer:
Maxim Integrated
Description:
Gate Drivers .5-3.3V ORing MOSFET Controller
Lifecycle:
New from this manufacturer.
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