IP1837TRPBF International Rectifier, IP1837TRPBF Datasheet - Page 23

• Manufacturer Part Number: IP1837TRPBF
• Description: IC DC-DC REG SYNC BUCK LGA
• Manufacturer: International Rectifier
• Series: iPOWIR™r
• Type: Step-Down (Buck), PWM - Voltage Moder

Specifications of IP1837TRPBF

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 0.6 V ~ 12 V
• Current - Output: 35A
• Frequency - Switching: 250kHz ~ 1.5MHz
• Voltage - Input: 1.5 V ~ 16 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: *
• Package / Case: *
• Package: LGA - 7.7 x 7.7
• Circuit: Single Output
• Iout (a): 35
• Switch Freq (khz): 250 - 1500
• Input Range (v): 1.5 - 16
• Output Range (v): 0.6 - 0.75*Vin
• Internal Bias Ldo: Yes
• Ocp Otp Uvlo Pre-bias Soft Start And: Remote Sense + Body Tracking + Temp Comp OCP
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The transfer function (V
The (s) indicates that the transfer function varies as a
function of frequency. This configuration introduces a gain
and zero, expressed by:
First select the desired zero‐crossover frequency (F
Use the following equation to calculate R
H(s) dB
V
V
oso
e
R

3
Z
F
F
Figure 18: Type II compensation network
H

H
o
IN
z
23
Gain(dB)
(

V
 

s
s
in
)
F
F
2
and its asymptotic gain plot


*
o
ESR

F

*
*
F
March 3, 2011 | V1.24
V
Z
R
R
OSO
m
Z
R
F
Z
1
and
3
8
3
ESR
R
IN
R
*
f
e
*
/V
8

9
C

*
oso
F
*
4
V

o
R
Fb
REF
) is given by:
F
1

8
LC
2

sR

1/5
sR
8
R
C
3
E/A
C
3
4
~
4
1/10
3
C
F
:
POLE
POLE
(19)
(20)

*
Highly Integrated 35A Single‐input Voltage,
(21)
C
F
Comp
4
s
(18)
Frequency
o
):
Z
Ve
f
Synchronous Buck Regulator
Where:
To cancel one of the LC filter poles, place the zero before
the LC filter resonant frequency pole:
Use equations (20), (21) and (22) to calculate C
One more capacitor is sometimes added in parallel with C
and R
to suppress the switching noise.
The additional pole is given by:
For a general solution for unconditional stability for any
type of output capacitors, and a wide range of ESR values,
we should implement local feedback with a type III
compensation network. The typically used compensation
network for voltage‐mode controller is shown in Figure 19.
Again, the transfer function is given by:
The pole sets to one half of the switching frequency which
V
F
F
F
R
β = V
F
3
C
o
ESR
LC
m
. This introduces one more pole which is mainly used
8
F
in
= Crossover Frequency
F
F
= Feedback Resistor
=Modulator gain
= Maximum Input Voltage
= Resonant Frequency of the Output Filter
POLE
P
= Zero Frequency of the Output Capacitor
z
z



ref
75
. 0
2

/V

75

%
results in the capacitor C
o
*
*R
*
R
F
2
V
3
3
V

LC
*F
oso
*
e
1
C
1
C
s
L

1
4

4
o
H
*

*
C
C
1
C
(
C
4
s
o
POLE
POLE
)




*R
Z
Z
1
3
IN
*F
f
POLE:
iP1837
s
4
(22)
.
(23)
(24)
97600
4