ISL6144IRZA Intersil, ISL6144IRZA Datasheet - Page 8

• Manufacturer Part Number: ISL6144IRZA
• Description: IC CTRLR O-RING MOSFET HV 20-QFN
• Manufacturer: Intersil

Specifications of ISL6144IRZA

• Applications: Telecom/Datacom Systems
• Fet Type: N-Channel
• Number Of Outputs: 1
• Internal Switch(s): No
• Delay Time - On: 1ms
• Delay Time - Off: 250ns
• Voltage - Supply: 10 V ~ 75 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 20-VQFN Exposed Pad, 20-HVQFN, 20-SQFN, 20-DHVQFN
• Rohs Compliant: Yes
• Package: 20QFN EP
• Output Voltage: -0.3 to 100 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -

High Voltage Pass and Clamp
A high voltage pass and clamping circuit prevents the high
output voltage from damaging the comparators in case of
quick drop in V
supply between HVREF and V
for 5V and will be damaged if V
(as the output is powered from other parallel supplies), and
does not fall when V
30V, V
between the “-” and “+” terminals of the comparator would be
18V, exceeding the rating of the devices and causing
permanent damage to the IC.
Fault Detection Block
The fault detection block has two monitoring circuits (refer to
Figure 2):
These two outputs are ORed, inverted, level shifted, and
delayed using an internal filter (
The following failures can be detected by the fault detection
circuitry:
The FAULT pin is not latched off and the pull down will shut
off as soon as the fault is removed and the pin becomes high
impedance. Typically, an external pull-up resistor is
connected to an external voltage source (for example 5V,
3.3V) to pull the pin high, an LED can be used to indicate the
presence of a fault.
FAULT
1. Gate monitoring detects when the GATE < V
2. V
1. ORing FET off due to dead short in the sourcing supply,
2. Shorted terminals of the ORing FET
3. Blown fuse in the power path of the sourcing supply
4. Open Gate terminal
5. HVREF UV
leading to V
OUT
OUT
monitoring detects when V
remains at 48V and the differential Voltage
FIGURE 2. FAULT DETECTION BLOCK
DELAY
IN
120µs
IN
. The comparators are running from the 5V
< V
IN
OUT
is falling. For example, if V
LEVEL SHIFT
8
IN
OUT
T
. These devices are rated
FLT
)
is allowed to be present
IN
- 0.41V > V
+
+
0.37V
-
0.41V
-
IN
IN
+
+
OUT
-
-
+ 0.37V
falls to
GATE
VOUT
VIN
ISL6144
100µF
100µF
Application Considerations
ORing MOSFET Selection
Using an ORing MOSFET instead of an ORing diode results
in increased overall power system efficiency as losses
across the ORing elements are reduced. The use of ORing
MOSFETs becomes more important at higher current levels,
as power loss across the traditionally used ORing diode is
very high. The high power dissipation across these diodes
requires special thermal design precautions such as heat
sinks and forced airflow.
For example, in a 48V, 40A (1+1) redundant system with
current sharing, using a Schottky diode as the ORing
(auctioneering) device (see Figure 3), the forward voltage
drop is in the 0.4V to 0.7V range. Let us assume it is 0.5V,
power loss across each diode is as shown in Equation 4:
Total power loss across the two ORing diodes is 20W.
36VDC TO 75 VDC
If a 5mΩ single MOSFET per feed is used, the power loss
across each MOSFET is as shown in Equation 5:
Total power loss across the two ORing MOSFETs is 4W.
In case of failure of current sharing scheme, or failure of
DC/DC #1, the full load will be supplied by DC/DC #2. ORing
MOSFET M2 or ORing Diode D
P loss D1
INPUT BUS 2
CIN1
P loss
P loss
C
INPUT BUS 1
36VDC TO 75 VDC
FIGURE 3. 1 + 1 REDUNDANT SYSTEM WITH DIODE ORing
IN2
(
(
(
M
M
1
1
220nF
)
C
C
220nF
PRIMARY GROUND
)
)
d2
d1
=
C
=
=
1nF
cs2
P loss D2
P loss
(
20A
C
1nF
cs1
)
(
2
(
M
⋅
+IN
PC
PR
-IN
+IN
PC
PR
-IN
5mΩ
2
)
)
DC/DC
DC/DC
=
=
#2
#1
+OUT
+OUT
-OUT
-OUT
I OUT
-------------- - V
⎛
⎝
=
I OUT
-------------- -
SC
SC
+S
+S
-S
-S
2
2W
2
SECONDARY
2
⋅
+OUT2 = 48V
⎞
⎠
+OUT1 = 48V
GROUND
will be conducting the full
2
(Note 11)
Figure 14
F
R
10
R
10
(Note 11)
Figure 14
⋅
pb1
pb2
r
=
DS ON
20A 0.5V
(
⋅
)
0.5V@ 20A
January 6, 2011
=
0.5V@ 20A
10W
D
1
(EQ. 4)
FN9131.6
(EQ. 5)
D
VOUT
(40A)
2