ir3086a International Rectifier Corp., ir3086a Datasheet - Page 21

• Manufacturer Part Number: ir3086a
• 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
IR3081A 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
Determine the soft start capacitor from the required soft start time.
The soft start delay time is
The power good delay time is
Over current delay time is
C
t
t
t
VccPG
SSDEL
OCDEL
SS
/
DEL
C
Page 21 of 33
C
C
SS
SS
SS
I
I
/
CHG
/
I
OCDISCHG
DEL
/
DEL
CHG
DEL
V
O
DAC
( *
I
=12 V
*
O
SS
t
1
SS
. 3
. 0
I
=105 ADC
3 .
CHG
=2 mS
=1.35 V
735
115
OCDEL
O
70
=0.91 mŸ
SW
. 0

SS/DEL
. 1
* 1
V
70
*
35
=400 kHz
. 0
O
10
10
OMAX
* 1
< 0.5mS
*



10

. 1
40
6
20
10
6
L
) 3

*
PCB
=0.47 mŸ
6

*
2
1
=120 ADC
6
10
10
3 .
O_NLOFST
*
*
10

. 0
. 0
=115 ºC

6
3
* 1
115

. 1
3
86
10
VccPG
DOWN
mS
0

6
1 .
. 0
=20 mV
( *
uF
OSC
70
29
C
. 3
= 7mŸ, Number Cn=10
=0-10mS
ms
=2.5mV/uS
*
735
10
can be determined from the curve in Figure 13 of IR3081A Data


6
. 1
33

. 1
) 3
OSC
. 1
58
=30.1kŸ
ms
IR3086A
1/31
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