IP1206TRPBF International Rectifier, IP1206TRPBF Datasheet - Page 12

• 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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Current Share Mode
This feature allows the connection of both outputs
together to increase current handling capability of
the converter to support a common load. In current
sharing mode, error amplifier 1 becomes the master
which regulates the common output voltage and the
error amplifier 2 performs the current sharing
function, Fig. 9 shows the configuration of error
amplifiers. See Fig 25a for a typical application.
In this mode iP1206 makes sure the master channel
starts first followed by slave channel to prevent any
glitch during start up. This is done by clamping the
output of slave’s error amplifier until the master
channel generates the first PWM signal.
At no load condition the slave channel may be kept
off depending on the offset of error amplifier.
Lossless Inductor Current Sensing
The iP1206 uses a lossless current sensing
technique for current share purposes. The inductor
current is sensed by connecting a series resistor
and a capacitor network in parallel with the inductor
and measuring the voltage across the capacitor,
this voltage is proportional to the inductor current.
As shown in Fig. 9 the voltage across the inductor’s
DCR can be expressed by:
The voltage across the C
Combining equations (1),(2) and (3) result in the
following expression for V
Usually the resistor R
the time constant of R
constant of the inductor which is the inductance L
over the inductor’s DCR (R
constants
proportional to the current through L
V
V
C
RL
1
1
V
(
(
s
C
s
)
1
)
(
=
s
V
=
)
(
RL
V
match,
(
=
V
1
in
(
in
I
s
−
L
1
−
)
V
*
V
=
out
1
out
I
R
L
+
the voltage
* )
1
* )
1
L
*
sR
1
and C
R
1
R
+
1
R
C1
1
1
L
can expressed by:
and C
sL
L
1
1
1
+
:
*
R
C
+
sC
1
L
1
L1
1
1
1
sL
sC
1
). If the two time
-
are chosen so that
1
1
- -
1
equals the time
1
-
across
, and
( -
- -
2
- -
-
( -
)
- -
- -
4
1 (
)
( -
C
3
2/26/2008
)
1
)
is
1
the sense circuit can be treated as if only a sense
resistor with the value R
The mismatch of the time constants does not
affect the measurements of inductor DC current,
but affects the AC component of the inductor
current.
Soft-Start
The iP1206 has a programmable soft-start to
control the output voltage rise and limit the inrush
current during start-up. It provides a separate
Soft-start function for each output. This enables
the user to sequence the outputs by controlling
the rise time of each output through the selection
of different value soft-start capacitors.
To
sequence initiates when the Vcc and Enable rise
above their threshold and generate the Power On
Reset (POR) signal. Soft-start function operates
by sourcing an internal current to charge an
external capacitor to about 3V. Initially, the soft-
start function clamps the error amplifier’s output
of the PWM converter.
Fig. 9: Loss Less inductor current sensing
ensure
V
V
in
in
Q3
Q2
Q4
correct
and current sharing
V
If
Master Phase
C
:
(
+
Slave Phase
s
R
R1
R2
L2
L1
IL1
)
1
V
VP2
FB2
≈
*
L1
L1
C
start-up,
iP1206PbF
I
(s) -
L
+ V
1
1
was used.
R
C2
R
*
C1
C1
=
L1
L2
(s)
R
R
L
-
L
1
1
L
1
V
OUT
the
soft-start
12