IRAC5001-HS100A ORing Demo Board
INTRODUCTION
High-reliability DC power distribution system normally consists of several DC
power supplies with each output connected in parallel to the system load bus.
These power converters may come with current sharing and/or hot-swapping
circuit but each of them will have a common basic feature that is output fault
isolation. Passive solution using Schottky diodes becomes a popular choice
before, but due to ever increasing load current demand, the power loss due to
its forward voltage drop becomes significantly high which requires separate
thermal management and additional cost.
With the introduction of the active OR-ing as a more efficient scheme for fault
isolation, the use of low Rds-on mosfet(s) and discrete solution for gate drives
has become a more attractive solution.
GENERAL DESCRIPTION
This Active OR-ing demo board is an evaluation kit which aims to demonstrate
the functionality of the IR5001 OR-ing controller IC by driving 4 low-Rds-on 20V
N-channel mosfets ( IRF6609 DirectFETs as OR-FETs) connected in parallel. Its
basic circuit is intended for use as a simple and efficient means of providing the
OR-ing function by actively linking the positive side of individual 12-Volt power
converter to the system bus and output fault isolation during short circuit
condition of any of the power source.
The board is tested for 65 – 100 Amp max and requires a floating 12Volt dc
supply to power up the IR5001 IC. It is equipped with normally-open
microswitch for FETCHK function. This switch is intended to check manually the
output status of the IC controller as well as giving the user a quick way of
knowing if there is an abnormality on the board itself, such as bad mosfets
(please refer to Table1 ).
SPECIFICATION
1.
2.
3.
4.
Fast Reverse polarity sensing of IR5001 OR-ing Controller IC
IC’s gate drive capability of 3A
pk
Low dissipation of IRF6609 Low-Rds-on (2mOhm) DirectFET (OR-FETs)
Highside implementation (positive rail) of OR-ing function capable of
handling continuous 65-100Amp max in a 12Volt system
5. Less than 10A
pk
reverse current during short circuit.
6. With FETCHK feature ( for quick checking of IC output and OR-FETs
functionality )
MODEL : IRAC5001-HS100A ORing DEMO BOARD
DOCUMENT Name : IRAC5001-HS100A_USERGUIDE_Rev1.3
Documented by : Israel Serrano, IR Singapore Design Center
DATE : 8/3/2004
PN : 1950-1003_Rev_1.3
Page 1 of 12
WORLD HEADQUARTERS:
233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105
http://www.irf.com/
Data and specifications subject to change without notice.
IRAC5001-HS100A ORing Demo Board
Figure1A. Front side of the IRAC5001-HS100A Demo Board
IRAC5001-HS100A
ORING DEMO BOARD REV1.0
Figure1B. Back side of the IRAC5001-HS100A Demo Board
MODEL : IRAC5001-HS100A ORing DEMO BOARD
DOCUMENT Name : IRAC5001-HS100A_USERGUIDE_Rev1.3
Documented by : Israel Serrano, IR Singapore Design Center
DATE : 8/3/2004
PN : 1950-1003_Rev_1.3
Page 2 of 12
WORLD HEADQUARTERS:
233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105
http://www.irf.com/
Data and specifications subject to change without notice.
IRAC5001-HS100A ORing Demo Board
CIRCUIT OPERATION :
The diagram in Figure 2 shows the test setup to evaluate the functionality of this
demo board in each of 12Volt power supply output connected to the system bus
load.
The power load can be a single high power E-load (~1kW) or composed of
several medium power E-loads ( 3 x 300W ) connected in parallel. At least 2
units of high power converter - each capable of sourcing 100Amp is required to
check the OR-ing functionality. Each power supply should have an output
voltage setting of about 12V ( +/- 0.01 V ) to simulate a near balanced current
sharing condition, and each output is link to the bus by one demo board-
individually powered by a floating 12Volt DC supply ( bias voltage) through
connector CON5. This connector route the positive bias voltage to the IC’s pin 7
(Vcc : < 13.9Vmax) and the negative bias to the output rail connector (Con1) of
the power converter. This is necessary to drive the gates of 4 IRF6609 OR-FETs
in parallel linking the highside (or positive output rail) to the positive of the bus.
The negative rails of all power converters are all connected together to the
negative rail of the bus.
Since this is a high current test setup, extra care should be observed
in proper connections on the board to avoid unnecessary contact
resistance which may further add heat to the board itself.
As a general design practice in choosing the appropriate mosfets, they must
have low Rds
on
and the Vsd generated should be at least ~50mV when the OR-
FET is “ON”.
FETCHK FEATURE
Ensure the test setup is correct and both power converters and OR-ing boards
are in good condition before starting-up. For safe initial test, it is recommended
to power up the OR-ing boards first with system load preset to less than 10Amps
as startup load before doing the full load test. The thermal performance should
be acceptable at room temperature testing even if the OR-ing board has no
heatsink but do not press one or both FETSW for too long . This test will force
the circuit to conduct the total load current through the body diodes of the OR-
FET which will increase the heat dissipation at a very fast rate; thus extra
precaution must be observed during this FETCHK test.
MODEL : IRAC5001-HS100A ORing DEMO BOARD
DOCUMENT Name : IRAC5001-HS100A_USERGUIDE_Rev1.3
Documented by : Israel Serrano, IR Singapore Design Center
DATE : 8/3/2004
PN : 1950-1003_Rev_1.3
Page 3 of 12
WORLD HEADQUARTERS:
233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105
http://www.irf.com/
Data and specifications subject to change without notice.
IRAC5001-HS100A ORing Demo Board
The board takes advantage of a unique feature that comes with the IR5001 IC to
assess the redundancy status of the system as well as the functionality of the
OR-ing mosfets as a group (OR-FET1 or OR-FET2). Referring to Figure 6, the
FETCHK feature enables the system designer to manually switch OFF the IC’s
Vout pin ( gate drive) by pressing a normally-open microswitch “FETCHK SW1/
2”. This switch link the +12V_aux thru R7 to the clamping zener Z1 (5.1V) in
order to provide a logic voltage of ~5V (with reference to the IC’s GND ( pin (7))
to FETCHK/OFF pin 3. The desired outcome if FETCHK is initiated (while the OR-
FET is ON) is to toggle OFF the output of the IC, which will turn-off the OR-FET.
This will result in an increase of Vsd of more than 0.3V and a comparator inside
will compare it to a 0.3V reference voltage. The internal comparator will turn-ON
an open-drain mosfet to pull down pin 4 (FETSHORT pin), providing a ground
path for the LED to light up.
SHORT CIRCUIT TEST
During a fault condition such as short circuit of one of the converter, a finite
amount of reverse current in the form of short duration negative current spike
will occur just before the OR-FET completely turn-off. The peak of this reverse
current is dependent on how fast the controller circuit switches off the OR-FETs
during this fault condition. The IR5001 IC is capable of sourcing and sinking
3A
pk
to fast turn - ON or OFF of the OR-FETs.
If short circuit occur at the secondary side of any power converter unit before
the Active OR-ing circuit, this faulty unit will be isolated by turning-off the OR-
FET(s) as quickly as possible, preventing the faulty unit from further drawing
any current from the other remaining good power converter(s) connected in the
system bus.
It is recommended to set the E-load to 65Amp and set the current limit of the
converters to ~120Amp before the evaluation of the reverse current during
short circuit test.
Caution : Use appropriate size of shorting wire ( larger than
#10 AWG with thick insulation) when performing short circuit
test. Shorting V1 or V2 should be done very quickly. It is
recommended to use a DC high current probe with amplifier
initially set to >50A/V to avoid overloading the probe or the
amplifier on the first test trial.
MODEL : IRAC5001-HS100A ORing DEMO BOARD
DOCUMENT Name : IRAC5001-HS100A_USERGUIDE_Rev1.3
Documented by : Israel Serrano, IR Singapore Design Center
DATE : 8/3/2004
PN : 1950-1003_Rev_1.3
Page 4 of 12
WORLD HEADQUARTERS:
233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105
http://www.irf.com/
Data and specifications subject to change without notice.
IRAC5001-HS100A ORing Demo Board
INPUT / OUTPUT CONNECTION :
FIGURE 2. TEST APPLICATION SETUP OF IR5001_HS100A OR-ING DEMOBOARD
Digital
Oscilloscope
SYSTEM
LOAD
150AMP DC
CURRENT
PROBE
125 Amp
Current - limited
Power Supply 1
(V
1
)
12V aux
Gate drive (G
1
)
12Volt
Vbus
CON 3
I
1
CON 1
CON 2
IRAC5001
-HS100A
OR-ing
Demoboard 1
C
bus
CON 4
CON 5
FetchkSW1
125 Amp
Current - limited
Power Supply 2
(V
2
)
Gate drive (G
2
)
I
2
CON 1
CON 2
IRAC5001
-HS100A
OR-ing
Demoboard 2
CON 3
CON 4
12V aux
CON 5
FetchkSW2
125 Amp
Current - limited
Power Supply N
(V
n
)
12V aux
Gate drive (G
n
)
I
n
CON 1
CON 3
IR5001
OR-ing
Demoboard
N
CON 3
CON 4
CON 5
FetchkSW
n
DATE : 8/3/2004
PN : 1950-1003_Rev_1.3
MODEL : IRAC5001-HS100A ORing DEMO BOARD
DOCUMENT Name : IRAC5001-HS100A_USERGUIDE_Rev1.3
Documented by : Israel Serrano, IR Singapore Design Center
Page 5 of 12
WORLD HEADQUARTERS:
233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105
http://www.irf.com/
Data and specifications subject to change without notice.
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