ir3086mtr International Rectifier Corp., ir3086mtr Datasheet - Page 21

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

DESIGN EXAMPLE 1 - VRM 10 2U CONVERTER
SPECIFICATIONS
Input Voltage: V
DAC Voltage: V
No Load Output Voltage Offset: V
Output Current: I
Maximum Output Current: I
Output Impedance: R
VCC Ready to VCC Power Good Delay: t
Soft Start Time: t
Over Current Delay: t
Dynamic VID Down-Slope Slew Rate: SR
Over Temperature Threshold: T
POWER STAGE
Phase Number: n=6
Switching Frequency: f
Output Inductors: L=220 nH, R
Output Capacitors: AL-Polymer, C=560uF, R
IR3081 EXTERNAL COMPONENTS
Oscillator Resistor Rosc
Once the switching frequency is chosen, R
Sheet. For switching frequency of 400kHz per phase, choose R
Soft Start Capacitor C
Because faster over-current protection is required, the soft start capacitor C
R
Calculate the soft start resistor from the required over current delay time t
The soft start delay time is
The power good delay time is
C
t
t
R
VccPG
SSDEL
SS/DEL
SS
SS
/
/
DEL
DEL
=
=
C
Page 21 of 34
=
C
=
is used. Calculate the soft start capacitor from the required soft start time.
SS
SS
. 0
I
CHG
/
/
09
DEL
DEL
V
−
O
∗
DAC
( *
I
∗
t
=12 V
O
SS
t
OCDEL
I
1 (
I
SS
. 3
=105 ADC
DISCHG
CHG
3 .
=2 mS
=1.35 V
91
C
I
=
−
OCDEL
CHG
O
SS
−
∗
=0.91 mΩ
SW
70
R
SS/DEL
/
V
. 1
I
SS
DEL
O
DISCHG
*
=400 kHz
35
/
−
10
DEL
OMAX
=0.5mS
. 1
−
−
) 3
6
20
∗
and Resistor R
L
∗
PCB
=0.47 mΩ
I
=
=
=120 ADC
*
2
CHG
O_NLOFST
10
. 0
. 0
*
10
=115 ºC
09
* 1
−
)
3
−
=
10
−
3
. 0
0
−
=
VccPG
5 .
6
DOWN
* 1
0
6
( *
70
=20 mV
*
1 .
*
10
10
. 0
10
. 3
C
OSC
uF
*
= 7mΩ, Number Cn=10
* 1
−
91
10
SS/DEL
−
=0-10mS
−
6
=2.5mV/uS
3
6
∗
10
−
∗
−
6
can be determined from the curve in Figure 13 of IR3081 Data
1 (
6
. 1
−
3 .
*
6
33
70
10
−
−
*
10
−
10
6
1
) 3 .
*
=
−
10
6
10
=
3
k
1
*
Ω
8 .
70
OSC
ms
*
10
=30.1kΩ
−
6
)
=
OCDEL
. 0
86
mS
,
SS/DEL
in series with the resistor
9/30
IR3086
/04