IP1206TRPBF International Rectifier, IP1206TRPBF Datasheet - Page 20

• Manufacturer Part Number: IP1206TRPBF
• Description: IC PWR BLOCK MULTIPHASE 30A LGA
• Manufacturer: International Rectifier
• Series: iPOWIR™r
• Type: Step-Down (Buck), PWM - Voltage Moder

Specifications of IP1206TRPBF

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1 or 2
• Voltage - Output: 0.8 V ~ 5.5 V
• Current - Output: 30A, 15A
• Frequency - Switching: 200kHz ~ 600kHz
• Voltage - Input: 7.5 V ~ 14.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: *
• Package / Case: *
• Package: LGA - 15.5 x 9.25
• Circuit: Single Output or Dual Ch
• Iout (a): 30
• Switch Freq (khz): 200 - 600
• Input Range (v): 7.5 - 14.5
• Output Range (v): 0.8 - 5.5
• Ocp Otp Uvlo Pre-bias Soft Start And: Pre-Bias + SEQ + SYNC + Tracking
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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Feedback Compensation
The iP1206 is a voltage mode controller; the control
loop is a single voltage feedback path including
error amplifier and error comparator. To achieve
fast
regulation, a compensation circuit is necessary. The
goal of the compensation network is to provide a
closed loop transfer function with the highest 0dB
crossing frequency and adequate phase margin
(greater than 45
The output LC filter introduces a double pole, –
40dB/decade gain slope above its corner resonant
frequency, and a total phase lag of 180
20). The resonant frequency of the LC filter
expressed as follows:
Since we already have 180
the output filter, the system risks being unstable.
The iP1206’s error amplifier is a differential-input
transconductance amplifier. The output is available
for DC gain control or AC phase compensation.
The E/A can be compensated either in type II or
type III compensation. When it is used in type II
compensation the transconductance properties of
the E/A become evident and can be used to cancel
one of the output filter poles. This will be
accomplished with a series RC circuit from Comp
pin to ground as shown in Fig. 21.
This method requires that the output capacitor
should have enough ESR to satisfy stability
requirements. In general the output capacitor’s ESR
generates a zero typically at 5kHz to 50kHz which is
essential for an acceptable phase margin. The ESR
zero of the output capacitor expressed as follows:
0dB
Gain
transient
F
Fig. 20: Gain and Phase of LC filter
LC
=
F
LC
2
o
∗
Frequency
-40dB/decade
).
response
π
1
L
o
∗
C
-180
o
0
Phase
and accurate
o
phase shift just from
-
- -
-(12)
F
LC
o
Frequency
(see Fig.
output
2/26/2008
The transfer function (Ve/Vo) is given by:
The (s) indicates that the transfer function varies as
a
introduces a gain and zero, expressed by:
The gain is determined by the voltage divider and
E/A’s transconductance gain.
First select the desired zero-crossover frequency
(Fo):
Use the following equation to calculate R
Where:
function
V
H
V
V
F
F
F
Fig. 21: TypeII compensation network
OUT
g
H(s) dB
(
R
o
LC
in
osc
ESR
s
m
R
4
= Crossover Frequency
R
)
= Maximum Input Voltage
= Resonant Frequency of the Output Filter
= Error Amplifier Transconductance
F
F
=
= Oscillator Ramp Voltage
6
=
5
= Zero Frequency of the Output Capacitor
ESR
o
[
F
⎛
⎜ ⎜
⎝
V
V
and its asymptotic gain plot
H
z
>
g
osc
REF
Fb
Gain(dB)
( )
=
=
m
F
s
of
V
*
ESR
*
2
2
]
in
π
F
=
R
∗
o
*
*
5
⎛
⎜ ⎜
⎝
and
π
*
R
F
+
g
R
frequency.
1
*
5
F
LC
m
4
2
R
E/A
ESR
ESR
*
*
1
6
*
F
F
C
⎞
⎟ ⎟
⎠
R
o
R
Z
9
( *
*
5
≤
5
R
iP1206PbF
+
*
1
*
5
R
+
(
C
Frequency
R
1/5
5
g
Comp
sC
6
-
o
sR
+
m
⎞
⎟ ⎟
⎠
- -
9
*
R
4
~
C
R
-(16)
R
6
C
1/10
9
)
4
4
-
This
9
- -
Ve
-(13)
)
-
-
-
*
- -
- -
- -
F
s
C
-(14)
configuratio n
-(15)
-(17)
POLE
4
:
20