ir3500a International Rectifier Corp., ir3500a Datasheet - Page 38

• Manufacturer Part Number: ir3500a
• Description: Xphase3 Vr11.0 & Amd Pvid Control Ic
• Manufacturer: International Rectifier Corp.

Choose CCP1=47pF to reduce high frequency noise.
DESIGN EXAMPLE 2 – VR11 HIGH FREQUENCY ALL-CERAMIC CONVERTER (FIG. 21)
SPECIFICATIONS
Input Voltage: V
DAC Voltage: V
No Load Output Voltage Offset: V
Output Current: I
Maximum Output Current: I
Output Impedance: R
Soft Start Delay Time: TD1=1-5mS
Soft Start Time: TD2=0-3mS
VID Sample Delay Time: TD3=0.05-3mS
VID Rise Time: TD4=0-2.5mS
VR Ready Delay Time: TD5=0-3mS
Maximum Over Current Delay Time: 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
IR3500A EXTERNAL COMPONENTS
Oscillator Resistor Rosc
Once the switching frequency is chosen, R
switching frequency of 800kHz per phase, choose R
Soft Start Capacitor C
Determine the soft start capacitor to meet the specifications of the delay time.
Choose C
C
TD
R
R
CP
CP
DRP
1
=
=
=
2 (
=
10
V
C
I
π
Page 38 of 47
R
∗
*
SS
∗
SS/DEL
FB
R
f
1
/
L
I
C
CP
DEL
+
E
CHG
∗
)
2
2 (
∗
R
∗
n
DAC
C
I
π
1 *
=12 V
=0.1uF. The soft start delay time is
O
L
L
∗
E
*
_
E
=105 ADC
4 .
MAX
R
=1.3 V
∗
f
=
C
C
O
O
10
*
=
E
SW
=0.91 m
C
SS/DEL
*
∗
∗
0
*
G
R
1 .
52
= 800 kHz
R
FB
(
CS
OMAX
C
470
*
5 .
)
∗
10
2
5
=
L
*
∗
MAX
=0.5 m
=
−
=120 ADC
10
10
2000
6
O_NLOFST
2 (
1 *
21
−
−
=115 ºC
π
9
6
5 .
/
4 .
OCDEL
∗
3
) 3
*
∗
25
*
12
10
. 1
C
=
∗
0
∗
DOWN
= 2m , Number Cn=62
(
29
*
3
7 .
10
560
. 2
=20 mV
OSC
<2.5mS
67
3
1
*
*
)
+
∗
10
2
10
10
=2.5mV/uS
mS
∗
2 (
can be determined from the curve in Figure 23 data sheet. For a
(
−
π
−
−
470
3
3
6
*
*
*
OSC
25
12
∗
34
10
*
)
10
−
= 15.0 k . The reference current is given by 40uA.
=
=
9
3
15
/
*
41
) 3
560
nF
∗
8 .
(
560
*
k
10
Ω
∗
−
, choose R
10
6
*
−
7
6
*
∗
10
12
−
)
3
∗
)
2
2000
DRP
=42.2k
∗
5
=
21
5 .
k
Ω
July 3, 2008
,
IR3500A