IR3084AMPBF International Rectifier, IR3084AMPBF Datasheet - Page 34

• Manufacturer Part Number: IR3084AMPBF
• Description: IC XPHASE CONTROL 28-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase™r

Specifications of IR3084AMPBF

• Applications: Processor
• Current - Supply: 14mA
• Voltage - Supply: 9.5 V ~ 16 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 28-MLPQ
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

DESIGN EXAMPLE: VRM 11 7−PHASE CONVERTER
SPECIFICATIONS
Input Voltage: V
DAC Voltage: V
No Load Output Voltage Offset: V
Output Current: I
Maximum Output Current: I
Load Line Slope: R
VRM11 Startup Boot Voltage = 1.100V
Soft Start Time: TD2 = 1.1ms
VCC Ready to VCC Power Good Delay: TD5 = 1.0ms
Over Current Delay: T
Dynamic VID Negative Slew Rate: SR
Over Temperature Threshold: T
POWER STAGE
Phase Number: n = 7
Switching Frequency: f
Output Inductors: L = 220 nH, R
Output Capacitors: C = 560uF, R
IR3084A EXTERNAL COMPONENTS
Oscillator Resistor Rosc
The switching frequency sets the value of R
the switching frequency of 400kHz per phase requires R
VDAC Slew Rate Programming Capacitor C
From Figure 17 on page 23, the sink current of the VDAC pin at 400kHz (R
VDAC slew-rate programming capacitor from the specified negative slew rate using Equation (1).
Calculate the VDAC compensation resistor from Equation (2);
From Figure 17 on page 23, the source current of the VDAC pin is 90uA at R
slew rate is can be calculated using Equation (3);
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C
R
SR
VDAC
VDAC
UP



DAC
I
O
= 12V
I
0.5
C
SR
SOURCE
= 130 ADC
O
I
VDAC
= 1.3V
SINK
= 1.20 mΩ
DOWN

OCDEL
SW
3.2*10
=400 kHz
C

VDAC
OMAX

90*10
33*10
= 250µs
2
5 .

2
PCB
L
15
= 150 ADC
C
80
*
= 0.60 mΩ
O_NLOFST
= 7mΩ, Number Cn = 10
10



= 115 ºC
*
6
9
0.5
10

DOWN

3
/

2.7mV/uS
10

6
(33*10
= 15mV

= 2.5mV/us
OSC
3.2*10
6
VDAC

as shown by the curve in Figure 13 on page 23. In this design,
32

0 .
and Resistor R

9
15
nF
)
2
OSC

,
3.5Ω
to be 30.1kΩ.
Choose C
VDAC
VDAC
OSC
OSC
= 33nF
= 30.1KΩ. The VDAC positive
=30.1kΩ) is 80uA. Calculate the
IR3084A
3/3/2009