ir3500a International Rectifier Corp., ir3500a Datasheet - Page 35

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

DESIGN EXAMPLE 1 – AMD OPTERON CONVERTER (FIGURE 20)
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=2 mS
VR Ready Delay Time: TD3=0-10mS
Maximum Over Current Delay: t
Dynamic VID Down-Slope Slew Rate: SR
Over Temperature Threshold: T
POWER STAGE
Phase Number: n=3
Switching Frequency: f
Output Inductors: L=470 nH, R
Output Capacitors: Polymer, C=560uF, R
IR3500A EXTERNAL COMPONENTS
Oscillator Resistor Rosc
Once the switching frequency is chosen, R
frequency of 250kHz per phase, choose R
11.9 uA.
Soft Start Capacitor C
Determine the soft start capacitor from the required soft start time.
C
SS
/
DEL
Page 35 of 47
=
TD
2
V
*
O
DAC
I
I
=12 V
O
CHG
=120 ADC
C
C
C
R
R
=1.3 V
CP
CP
CP
FB
FB
=
O
1
1
SW
=0.7 m
=
=
=
2
SS/DEL
=
=
*
R
2
2
2
2
=250 kHz
10
π
π
FB
π
π
OMAX
∗
∗
−
∗
∗
∗
3
f
f
*
2 (
K
K
C
f
C
f
L
1
C
C
52
OCDEL<
MAX
= 1m
3 .
π
∗
∗
=135 ADC
∗
1
∗
1
R
R
O_NLOFST
5 .
∗
K
K
CP
FB
=115 ºC
*
∗
∗
10
L
R
C
E
V
CP
2.5mS
−
∗
FB
6
I
C
∗
C
DOWN
=
= 7m , Number Cn=12
E
K
OSC
=10 mV
0
OSC
∗
1 .
uF
f
=50k . The reference current for VSETPT and OCSET is given by
C
=2.5mV/uS
)
can be determined from the curve in Figure 23. For a switching
2
∗
5
(36)
(37)
(38)
(39)
(40)
July 3, 2008
IR3500A