ISL6144IRZA-T Intersil, ISL6144IRZA-T Datasheet - Page 18

• Manufacturer Part Number: ISL6144IRZA-T
• Description: IC CTRLR MOSFET HV ORING 20-QFN
• Manufacturer: Intersil

Specifications of ISL6144IRZA-T

• 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
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -

Gate Fast Turn-off Test
During normal operation, the ISL6144 provides gate drive
voltage for the ORing MOSFET when the Input voltage
exceeds the output voltage. The current flows in the forward
direction from the input to the output. Now, what happens if
the input voltage drops quickly below the output voltage as a
result of a failure on the input sourcing power supply while
the MOSFET remained on? The answer is: If the MOSFET is
kept on, current starts to flow in the reverse direction from
the output to the input. Of course this is not desired nor
acceptable. It will lead to effectively shorting the output and
causing an overall system failure. In order to block this
reverse current, the ISL6144 senses the voltage at both VIN
and COMP pins (this is V
programmable threshold (V
55mV on the EVAL board and could be adjusted by
changing R
COMP (V
off the gate of the ORing MOSFET very quickly, the gate pull
down current I
is prevented. The maximum turn-off time is less than 300ns
when using an ORing MOSFET(s) with an equivalent gate-
source capacitance of 39nF (equivalent to Q
V
On the ISL6144EVAL1Z board, FDB3632 has an equivalent
gate-source capacitance of 8.4nF, some of the tests are
performed while an external gate to source capacitance is
added to demonstrate gate current sink capability.
Worst-case turn-off time can be calculated as:
t
t
V
toff WC
toff WC
GS
FIGURE 21. FAST SPEED TURN-OFF
IN1
0.1µs/DIV
(
(
= 10V).
= V
2V/DIV
V
GS1
IN2
)
)
=
=
OUT
= 48V; RESISTIVE LOAD = 4A, C
1
t
50ns
DELAY HS
, R
(MOSFET WITH Q
PDH
- V
4
2A/DIV
I
IN1
+
values for both feeds. If V
TH(HS
⎛
⎝
(
is 2A. As a result the reverse current flow
39nF
)
+
), the High Speed Comparator turns
12V
---------- -
⎛
⎜
⎝
2A
OUT
C
TH(HS
GS
⎞
⎠
REVERSE CURRENT DISSAPPEARS
WHEN GATE IS COMPLETELY OFF
18
=
voltage reduced by a resistor
------------ -
I
TOT
V
PDH
284ns
GS
), it is programmed to
= 8.4nc)
⎞
⎟
⎠
GS(EXT)
IN
TOT
= 0nF
10V/DIV
drops below
V
OUT
10V/DIV
= 390nC at
V
G2
(EQ. 9)
ISL6144
t
case time delay. The setup in Figure 17 can be used to
perform the Input dead-short test; a pulse generator is
connected between Gate-Source of Q
mode single shot, set the frequency to <10Hz and pulse
width of approximately 10ms, t
through 5 in the two feed parallel operation section. Make
sure that both feeds operate in parallel current sharing
mode. Proceed with the short test by applying the single
pulse to the gate of Q
shorts V
Figures 21, 22 and 23 show the results for different
combinations of C
connect the V
possible to the V
board to minimize lead impedance and reduce parasitic
ringing.
DELAY(HS)
FIGURE 22. FAST SPEED TURN-OFF (MOSFET WITH
FIGURE 23. FAST SPEED TURN-OFF (MOSFET WITH
0.1µs/DIV
0.1µs/DIV
5V/DIV
REVERSE CURRENT
V
IN1
5V/DIV
GS1
V
2A/DIV
GS1
2A/DIV
I
I
is the High Speed Comparator internal worst-
IN1
IN1
causing it to fall quickly (in less than 10
10V/DIV
Q
Q
IN1
V
TOT
TOT
G2
IN
shorting-MOSFET terminals as close as
GS1
-GND (J4 to J6) terminals on the EVAL
= 8.4nc) AND 33nF EXTERNAL C
= 8.4nc) AND 33nF EXTERNAL C
SHORT1
and load current. Make sure to
RESISTIVE LOAD = 6A, C
RESISTIVE LOAD = 6A, C
. Once turned on, Q
RISE
= 1µs). Follow steps 1
SHORT1
10V/DIV
V
10V/DIV
V
IN1
OUT
V
V
IN1
IN1
(use pulse
gs(ext)
10V/DIV
= V
gs(ext)
= V
V
January 6, 2011
OUT
SHORT1
IN2
GS
gs
µ
IN2
s).
= 33nF
= 48V;
= 33nF
FN9131.6
= 48V;