ir3086mtr International Rectifier Corp., ir3086mtr Datasheet - Page 16

• Manufacturer Part Number: ir3086mtr
• Description: Xphasetm Phase Ic With Ovp, Fault And Overtemp Detect
• Manufacturer: International Rectifier Corp.

Body Braking
The body braking
enabled, Resistors R
Dynamic VID step down. Usually R
IR3086 EXTERNAL COMPONENTS
PWM Ramp Resistor R
PWM ramp is generated by connecting the resistor R
as the capacitor C
the capacitor C
(17). To achieve feed-forward voltage mode control, the resistor R
converter.
Inductor Current Sensing Capacitor C
The DC resistance of the inductor is utilized to sense the inductor current. Usually the resistor R
C
across the capacitor C
component of the capacitor voltage is different from that of the real inductor current. The time constant mismatch
does not affect the average current sharing among the multiple phases, but affect the current signal ISHARE as well
as the output voltage during the load current transient if adaptive voltage positioning is adopted.
Measure the inductance L and the inductor DC resistance R
follows.
The bias current flowing out of the non-inverting input of the current sense amplifier creates a voltage drop across
R
converter current signal ISHARE as well as the accuracy of the converter output voltage if adaptive voltage
positioning is adopted. To reduce the offset voltage, a resistor R
input and the converter output
input and the bias current from the inverting input.
If R
than 2 kΩ and therefore a larger C
CS+
CS+,
CS-
in parallel with the inductor are chosen to match the time constant of the inductor, and therefore the voltage
which is equivalent to an input offset voltage of the current sense amplifier. The offset affects the accuracy of
is not used, R
Page 16 of 34
TM
PWMRMP
Related Resistors R
TM
PWMRMP
R
R
R
R
R
CS
PWMRMP
FB
DRP
during Dynamic VID can be disabled by connecting BBFB pin to ground. If the feature is
CS
CS+
BBFB
−
+
CS+
=
PWMRMP
in the range of 100pF and 470pF, and then calculate the resistor R
=
=
=
should be chosen so that the offset voltage is small enough. Usually R
R
I
I
R
L
C
L
and R
between PWMRMP and LGND. Choose the desired PWM ramp magnitude V
CSIN
CSIN
represents the inductor current. If the two time constants are not the same, the AC
FB
_
=
CS
R
MAX
.
V
L
+
The resistor R
∗
+
−
IN
R
∗
and Capacitor C
∗
*
BBDRP
CS+
L
R
BBFB
V
_
CS
n
f
O
MAX
SW
∗
+
_
value is needed.
BBFB
R
I
NLOFST
*
FB
and R
CS+
O
C
∗
are needed to restore the feedback voltage of the error amplifier after
G
PWMRMP
∗
CS
and R
R
and Resistors R
CS-
−
L
_
BBDRP
_
MIN
V
MAX
is determined by the ratio of the bias current from the non-inverting
CS
*
BBDRP
PWMRMP
[ln(
_
TOFST
are chosen to match R
PWMRMP
V
IN
−
∗
V
V
n
O
DAC
L
∗
. Pre-select the capacitor C
CS+
R
between a voltage source and PWMRMP pin as well
O
)
CS-
−
and R
ln(
should be added between the amplifier inverting
RAMP
V
IN
CS-
−
V
should be connected to the input of the
DAC
FB
and R
−
V
PWMRMP
DRP
)]
respectively
CS+
PWMRMP
(15)
(16)
(17)
(18)
(19)
and calculate R
CS+
CS+
9/30
IR3086
.
should be less
from Equation
and capacitor
/04
RAMP
CS+
and
as