IR3080 International Rectifier, IR3080 Datasheet - Page 23

• Manufacturer Part Number: IR3080
• Description: XPHASE VRD10 CONTROL IC WITH VCCVID & OVERTEMP DETECT
• Manufacturer: International Rectifier

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
Over Temperature Setting Resistors R
The threshold voltage of VRHOT comparator is proportional to the die temperature T
the relationship between the die temperature of phase IC and the temperature of the power converter according to
the power loss, PCB layout and airflow etc, and then calculate HOTSET threshold voltage corresponding to the
allowed maximum temperature from Equation (23).
There are two ways to set the over temperature threshold, central setting and local setting. In the central setting,
only one resistor divider is used, and the setting voltage is connected to HOTSET pins of all the phase ICs. To
reduce the influence of noise on the accuracy of over temperature setting, a 0.1uF capacitor should be placed next
to HOTSET pin of each phase IC. In the local setting, a resistor divider per phase is needed, and the setting voltage
is connected to HOTSET pin of each phase. The 0.1uF decoupling capacitor is not necessary. Use VBIAS as the
reference voltage. If R
Phase Delay Timing Resistors R
The phase delay of the interleaved multiphase converter is programmed by the resistor divider connected at
RMPIN+ or RMPIN- depending on which slope of the oscillator ramp is used for the phase delay programming of
phase IC, as shown in Figure 3.
If the upslope is used, RMPIN+ pin of the phase IC should be connected to RMPOUT pin of the control IC and
RMPIN- pin should be connected to the resistor divider. When RMPOUT voltage is above the trip voltage at
RMPIN- pin, the PWM latch is set. GATEL becomes low, and GATEH becomes high after the non-overlap time.
If down slope is used, RMPIN- pin of the phase IC should be connected to RMPOUT pin of the control IC and
RMPIN+ pin should be connected to the resistor divider. When RMPOUT voltage is below the trip voltage at
RMPIN- pin, the PWM latch is set. GATEL becomes low, and GATEH becomes high after the non-overlap time.
Use VBIAS voltage as the reference for the resistor divider since the oscillator ramp magnitude from control IC
tracks VBIAS voltage. Try to avoid both edges of the oscillator ramp for better noise immunity. Determine the ratio
of the programming resistors corresponding to the desired switching frequencies and phase numbers. If the resistor
R
CS+,
PHASEx1
CS-
Page 23 of 41
which is equivalent to an input offset voltage of the current sense amplifier. The offset affects the accuracy of
is not used, R
is pre-selected, the resistor R
V
R
R
R
R
CS
HOTSET
HOTSET
CS
CS+
PHASEx
HOTSET1
−
+
=
=
should be chosen so that the offset voltage is small enough. Usually R
I
I
2
L
C
2
CSIN
CSIN
=
=
CS
=
R
. 4
.
RA
L
+
R
The resistor R
is pre-selected, R
+
−
73
HOTSET
V
∗
PHASEx
BIAS
1
*
CS+
R
PHASE1
10
−
CS
RA
−
−
+
1
3
value is needed.
V
∗
PHASEx2
∗
*
PHASEx
HOTSET
V
HOTSET1
T
R
HOTSET
and R
J
PHASEx
+
CS-
. 1
241
1
is determined as:
PHASE2
HOTSET2
is determined by the ratio of the bias current from the non-inverting
and R
HOTSET2
can be calculated as follows.
L
. Pre-select the capacitor C
CS-
should be added between the amplifier inverting
J
(ºC) of phase IC. Determine
CS+
(21)
(22)
(23)
(24)
(25)
and calculate R
CS+
9
/30/04
IR3080
should be less
CS+
as