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MAX15068 Schematic ( PDF Datasheet ) - Maxim Integrated Products

Teilenummer MAX15068
Beschreibung Single Hot-Swap Controller
Hersteller Maxim Integrated Products
Logo Maxim Integrated Products Logo 




Gesamt 17 Seiten
MAX15068 Datasheet, Funktion
MAX15068
EVALUATION KIT AVAILABLE
Dual ORing, Single Hot-Swap Controller with
Accurate Current Monitoring
General Description
The MAX15068 offers ORing function and hot-swap
features for two input-supply-rail applications requiring the
safe insertion and removal of circuit line cards from a live
backplane. The device integrates dual ORing MOSFET
controllers, a single hot-swap controller, electronic circuit-
breaker protection, and power monitoring in a single
package. The device is designed to operate from 3.7V to
18V supply voltages.
The device regulates the forward voltage drop across the
ORing MOSFETs to ensure smooth current transfer from
one supply to the other without oscillation. The ORing
MOSFET turns on quickly to reduce the load voltage droop
during supply switchover. If the input supply fails or is short-
ed, a fast turn-off minimizes reverse-current transients.
The device implements a foldback current limit during hot-
swap startup in order to control inrush current, thereby
lowering di/dt and keeping the operation of the hot-swap
MOSFET under safe operating area (SOA). An internal
70ms timer starts counting when the device enters the
hot-swap startup phase. After the hot-swap startup cycle
is completed, on-chip comparators provide active current-
limit protection against short-circuit and overcurrent faults.
The load is disconnected from the input quickly in the
event of a fault condition.
The device provides current monitoring from 3A to 10A
(VIN = 12V, TA = +25°C with RSENSE = 3mΩ) with ±0.6%
accuracy. A voltage proportional to the input current
delivered to the system could be read directly at the
IPMON pin.
The device is factory-calibrated to deliver accurate
overcurrent protection with ±5% accuracy. During an
overcurrent-fault condition, the device enters an autoretry
mode. The device features an adjustable slew-rate control
during startup. Additional features include power-good
and fault-indicator outputs.
The MAX15068 is available in a 20-pin, (4mm x 5mm)
TQFN package and is specified from a -40°C to +125°C
operating temperature range.
Features and Benefits
● 3.7V to 18V Operating Voltage Range (ORing and
Hot Swap)
● 4.8V to 18V Operating Voltage Range (Current
Monitor)
● Seamless Power Transition of Redundant Supplies
● Controls N-Channel MOSFETs
● < 0.5µs Turn-On and Reverse Turn-Off Time
Current Monitoring (±0.6% Accuracy Typ)
● Programmable Slew-Rate Control
Adjustable Current-Limit Fault Delay
● Programmable Circuit-Breaker Current Threshold
● Inrush Current Regulated at Startup with
Programmable SOA Control
● Programmable Undervoltage Lockout
● Small (4mm x 5mm) TQFN Package
Applications
● Baseband Station
● Redundant Power Supplies
● Supply Holdup
● Computer Systems and Servers
● Telecom Networks
● Storage Bridge Bay
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part, refer
to www.maximintegrated.com/MAX15068.related.
19-6872; Rev 0; 12/13
Free Datasheet http://www.datasheet4u.com/






MAX15068 Datasheet, Funktion
MAX15068
Dual ORing, Single Hot-Swap Controller with
Accurate Current Monitoring
Typical Operating Characteristics
(VIN1 = VIN2 = 12V, CIN1 = CIN2 = CVS = 1µF, RSENSE = 3mΩ, unless otherwise noted.)
IN_ SUPPLY CURRENT vs. VOLTAGE
6 toc01
IIN2
4
2 IIN1
0
0 3 6 9 12 15 18
VIN_ (V)
VS LOAD REGULATION
6 toc02
VIN_ = 12V or 18V
5
4 VIN_ = 5V
3 VIN_ = 3.7V
2
1
0
0 2 4 6 8 10
ILOAD (mA)
CHARGE-PUMP VOLTAGE vs. CURRENT
12 toc03
10
VIN_ = 12V
8 VIN_ = 18V
6
4
VIN_ = 3.7V
2
0
0 20 40 60 80 100 120 140
IICP_ (µA)
CHARGE-PUMP VOLTAGE
vs. INPUT VOLTAGE
14 toc04
12
10
8
6
4
2
0
3 6 9 12 15 18
VIN_ (V)
ORing GATE VOLTAGE vs. CURRENT
12 toc05
VIN_ = 12V
10
8 VIN_ = 18V
6
4
VIN_ = 3.7V
2
0
0 20 40 60 80 100 120 140
IICP_ (µA)
HOT-SWAP MOSFET GATE VOLTAGE
vs. CURRENT
15 toc06
VOUT = VIN_
VIN_ = 12V or 18V
12
9 VIN_ = 5V
6 VIN_ = 3.7V
3
0
0 5 10 15
IGATE (µA)
CIRCUIT-BREAKER TRIP VOLTAGE
vs. TEMPERATURE
80 toc07
CB = VS
ACTIVE CURRENT-LIMIT SENSE VOLTAGE
vs. TEMPERATURE
100 toc08
CB = VS
60 CB = Hi-Z
CB = GND
40
80
CB = Hi-Z
60
CB = GND
20
-40 -15 10 35 60 85 110 125
TEMPERATURE (ºC)
40
-40 -15 10 35 60 85 110 125
TEMPERATURE (ºC)
www.maximintegrated.com
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MAX15068 pdf, datenblatt
MAX15068
Dual ORing, Single Hot-Swap Controller with
Accurate Current Monitoring
Detailed Description
Startup
When input voltage is applied to IN_, CSP comes up to
one diode below the higher of IN1 or IN2. The internal
LDO regulator powers VS from the higher of two inputs as
well. When both VS and CSP reach their respective UVLO
thresholds, the internal charge pumps (CP1 or CP2)
for the ORing controller start operating. An internal time
starts when both ON is above its threshold and EN is
below its threshold. After the timer counts 85ms, the
ORing control (OG1 or OG2) begins operating. After an-
other 15ms have elapsed, the hot-swap control (GATE)
also starts operating.
ORing Control
ORing Control in Startup
During a normal power-up, the ORing MOSFETs turn
on first. As soon as the internally generated supply, VS,
rises above its undervoltage lockout threshold, the inter-
nal charge pump is allowed to charge up the CP_ pins.
Because the ideal diode MOSFETs are connected in par-
allel as a diode-OR, the CSP pin voltage selects the high-
est of the supplies at the IN1 and IN2 pins. The MOSFET
associated with the lower input supply voltage is turned
off by the corresponding gate drive amplifier.
At power-up the CP_ and OG_ pin voltages are at the
IN_ voltage level. CP_ starts ramping up after VS clears
its undervoltage lockout level. Afterward, OG_ ramps up
with CP_.
The gate drive amplifier monitors the voltage between the
IN and CSP pins and drives the respective OG_ pin.
If the amplifier senses a forward voltage drop greater than
80mV between IN and CSP then the OG_ pin is pulled to
CP to quickly turn on the MOSFET. If the amplifier senses
a reverse voltage drop greater than 10mV between CSP
and IN_, then the OG_pin is pulled to IN_ to quickly turn
off the MOSFET. With the ideal diode MOSFETs acting as
an input supply diode-OR, the CSP pin voltage rises to the
highest of the supplies at the IN1 and IN2 pins. The stored
charge in an external capacitor connected between the
CP_ and IN_ pins provides the charge needed to quickly
turn on and off the ideal diode MOSFET. An internal charge
pump charges the external capacitors at the CP pins. The
OG_ pin sources current from the CP_ pin and sinks cur-
rent into the IN_ and GND pins.
ORing MOSFET Regulation Mode
When the ideal diode MOSFET is turned on, the gate
drive amplifier controls OG_ to servo the forward voltage
drop (VIN - VCSP) across the MOSFET to 10mV. If the
load current causes more than 10mV of voltage drop,
across the FET, then the OG voltage rises to enhance the
MOSFET. For large output currents, the MOSFET’s gate
is driven fully on and the voltage drop is equal to ILOAD x
RDS(ON) of the MOSFET.
Hot-Swap Control
Hot-Swap in Startup
Once the output is enabled, the device provides controlled
application of power to the load. The voltage at OUT
begins to rise until the internal selected final maximum
current limit is reached, which is programmed through the
CB pin (Table 1). The low limit is approximately 1/12th of
the upper limit as shown in Figure 1. Once the power-
good threshold is achieved, the normalized hot-swap
electronic circuit-breaker (ECB) threshold goes to its full
value.
An external capacitor connected to the GATE pin allows
the user to program the slew rate to a value lower than the
default. During startup, a foldback current limit is active to
protect the external hot-swap MOSFET to operate within
the SOA (Figure 1).
An internal timer is activated to count for 70ms, which is
the maximum time duration for the startup phase. The
startup phase is completed when the voltage at OUT rises
above the power-good threshold (0.9 x VCSP typical)
and hot-swap GATE to OUT voltage exceeds 4.2V even
though the 70ms timeout has not yet elapsed.
Programmable Speed Circuit-Breaker
Response on Hot-Swap MOSFET
The device features an adjustable current limit with
circuit-breaker function that protects the external
MOSFETs against short circuits or excessive load current.
The voltage across the external sense resistor (RSENSE)
is monitored by an electronic circuit breaker (ECB) and
FiguVrCeB N1ORMALIZE
THRESHOLD
0.6
0.5
0.4
0.3
0.2
0.1
2V
10V 12V
VCSN - VOUT
Figure 1. Inrush Current vs. Voltage Drop Across the Hot-Swap
Switch During Startup Period
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