ir3088a International Rectifier Corp., ir3088a Datasheet - Page 25

• Manufacturer Part Number: ir3088a
• Description: Xphase Ic With Fault And Overtemp Detect
• Manufacturer: International Rectifier Corp.

DESIGN EXAMPLE 2 - EVRD 10 HIGH FREQUENCY ALL-CERAMIC 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=100 nH, R
Output Capacitors: Ceramic, C=22uF, R
IR3081A EXTERNAL COMPONENTS
Oscillator Resistor Rosc
Once the switching frequency is chosen, R
Sheet. For switching frequency of 800kHz 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
VDAC Slew Rate Programming Capacitor C
From Figure 15 of IR3081A Data Sheet, the sink current of VDAC pin corresponding to 800kHz (R
170uA. Calculate the VDAC down-slope slew-rate programming capacitor from the required down-slope slew rate.
C
t
t
t
VccPG
SSDEL
OCDEL
SS
/
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DEL
=
=
=
C
=
C
C
SS
SS
SS
I
CHG
I
/
/
I
OCDISCHG
DEL
/
DEL
CHG
DEL
V
O
∗
DAC
( *
I
∗
=12 V
t
*
O
SS
SS
1
. 3
. 0
I
=105 ADC
3 .
CHG
=2.9mS
=1.3 V
735
115
=
=
OCDEL
O
70
=0.91 mΩ
SW
. 0
−
SS/DEL
1
=
*
15
3 .
V
10
70
=800 kHz
. 0
O
−
*
OMAX
15
=2.1mS
−
−
10
*
20
6
. 1
10
40
∗
*
−
L
*
) 3
10
3
6
−
PCB
=0.5 mΩ
10
*
∗
6
=120 ADC
*
−
=
10
O_NLOFST
1
10
−
6
3 .
3
. 0
*
=115 ºC
−
−
. 0
6
3
15
=
115
=
2
*
C
8 .
. 0
10
VccPG
DOWN
= 2mΩ, Number Cn=62
mS
16
=
−
=20 mV
6
uF
. 0
OSC
( *
70
43
VDAC
=0-10mS
=2.5mV/uS
. 3
, choose C
*
ms
735
10
can be determined from the curve in Figure 13 of IR3081A Data
−
6
and Resistor R
−
. 1
33
SS/DEL
−
. 1
) 3
OSC
=
=0.15uF
2
4 .
=13.3kΩ
VDAC
ms
IR3088A
1/15
OSC
/05
=13.3kΩ) is