IR3843AMTR1PBF International Rectifier, IR3843AMTR1PBF Datasheet - Page 23

• Manufacturer Part Number: IR3843AMTR1PBF
• Description: IC REG SYNC BUCK 3A 15-QFN
• Manufacturer: International Rectifier
• Series: SupIRBuck™r
• Type: Step-Down (Buck)r

Specifications of IR3843AMTR1PBF

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 0.7 ~ 18.9 V
• Current - Output: 3A
• Frequency - Switching: 225kHz ~ 1.32MHz
• Voltage - Input: 1.5 ~ 21 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 15-PowerVQFN
• Power - Output: 682mW
• Part Status: Active
• Package: PQFN / 5 x 6
• Circuit: Single Output
• Iout (a): 3
• Switch Freq (khz): 250 - 1200
• Input Range (v): 1.5 - 21
• Output Range (v): 0.7 - 0.9*Vin
• Ocp Otp Uvlo Pre-bias Soft Start And: PGOOD + EN + SEQ
• Digital Home Media: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: IR3843AMTR1PBFTR

Detailed calculation of compensation TypeIII
Rev 13.0
Desired
F
F
Select
F
Select
Calculate
R
Select
C
C
Calculate
R
R
Select
R
P
P
Z
3
10
3
4
8
9
2
2
3
=
=
=
=
=
=
=
=
=
2
V
2
2
2
F
0.5
F
2
π
π
π
π
:
:
:
:
o
π
o
o
V
C
R
F
R
*
*
*
*
-
ref
7
*
Z
8
*
V
F
C
F
3
F
1
1
Phase
1
1
1
1
C
F
1
P
ref
=
o
Z
1
=
R
=
R
−
+
7
+
−
1
=
s
1
3
7
C
*
10
2.2
3
*
4.99
sin
sin
sin
sin
. 2
*
*
*
0
,
=
*
L
7
F
,
.
R
R
74
F
C
R
o
5
Z
300
*
R
P
nF
3
2
Θ
Θ
V
Θ
Θ
3
3
8
*
*
2
8
;
;
C
;
k
F
in
k
-
R
C
;
Margin
and
C
Ω
Ω
=
=
Z
R
and
o
9
3
2
4
kHz
R
14.11
10
453.7
*
=
=
=
=
10
V
;
193.62
3.18
C
osc
. 8
R
7.05
R
=
4
8
24
9
160
:
;
Θ
=
kHz
kHz
R
:
k
nF,
5
3
=
kHz
Ω
Ω
=
pF
70
k
Ω
,
2.71
Select
,
o
Select
,
Select
and
Select
k
Ω
:
:
R
:
C
:
R
9
C
4
10
=
3
=
3.16
=
=
8
180
158
2 .
nF
k
Ω
pF
Ω
Setting the Power Good Threshold
A window comparator internally sets a lower
Power Good threshold at 0.6V and an upper
Power Good threshold at 0.8V. When the voltage
at the FB pin is within the window set by these
thresholds, PGood is asserted.
The PGood is an open drain output. Hence, it is
necessary to use a pull up resistor R
PGood pin to Vcc.
resistor must be chosen such as to limit the
current flowing into the PGood pin, when the
output voltage is not in regulation, to less than 5
mA. A typical value used is 10kΩ.
Programming the Current-Limit
The Current-Limit threshold can be set by
connecting a resistor (R
to the OCSet pin. The resistor can be calculated
by using equation (4). This resistor R
be placed close to the IC.
The
coefficient and it should be considered for the
worst case operation.
I
SET
I
R
I
(50%
R
OCSet
SET
DS
OCSet
=
R
(
I
on
≅
DS(on)
L
(
)
=
critical
I
over
=
o
=
59.07
(
LIM
2.33
24.5
)
)
=
nominal
has
=
R
μA
k
m
3A
Ω
OCSet
Ω
IR3843AMPbF
R
*
*
(at
Select
DS
1.5
a
1.25
The value of the pull-up
∗
(
on
F
OCSET
I
OCSet
=
output
s
)
positive
=
4
=
5 .
30.625
R
600
) from the SW pin
A
7
..........
=
current
kHz)
2.26
PD-97509
m
temperature
..........
Ω
OCSET
k
Ω
)
PG
...
must
(32)
23
from