ADP3208DJCPZ-RL ON Semiconductor, ADP3208DJCPZ-RL Datasheet - Page 27

• Manufacturer Part Number: ADP3208DJCPZ-RL
• Description: IC CTLR BUCK 7BIT 2PHASE 48LFCSP
• Manufacturer: ON Semiconductor

Specifications of ADP3208DJCPZ-RL

• Applications: Controller, Power Supplies for Next-Generation Intel Processors
• Voltage - Input: 3.3 ~ 22 V
• Number Of Outputs: 1
• Voltage - Output: 0.01 ~ 1.5 V
• Operating Temperature: -10°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 48-LFCSP
• Output Voltage: 10 mV
• Output Current: 40 A
• Input Voltage: 19 V
• Supply Current: 6 mA
• Switching Frequency: 300 KHz
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 100 C
• Minimum Operating Temperature: - 10 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application Information
CPU core VR application are as follows:
•
•
•
•
•
•
•
•
•
•
•
•
Setting the Clock Frequency for PWM
fixed−frequency control architecture. The frequency is set
by an external timing resistor (RT). The clock frequency and
the number of phases determine the switching frequency per
phase, which relates directly to the switching losses and the
sizes of the inductors and input and output capacitors. For a
dual−phase design, a clock frequency of 600 kHz sets the
switching frequency to 300 kHz per phase. This selection
represents the trade−off between the switching losses and
the minimum sizes of the output filter components. To
achieve a 600 kHz oscillator frequency at a VID voltage of
1.2 V, RT must be 187 kW. Alternatively, the value for RT can
be calculated by using the following equation:
9 pF and 16 kW are internal IC component values.
V
n is the number of phases.
f
recommended to use a 1% resistor.
switching frequency does not change with VID. The value
for RT can be calculated by using the following equation.
recommended to use a 1% resistor.
Setting the Switching Frequency for RPM Operation of
Phase 1
ADP3208D runs in pseudo constant frequency, given that
the load current is high enough for continuous current mode.
While in discontinuous current mode, the switching
SW
VID
The design parameters for a typical IMVP−6+ compliant
In
where:
For good initial accuracy and frequency stability, it is
When VARFREQ pin is connected to ground, the
For good initial accuracy and frequency stability, it is
During the RPM mode operation of Phase 1, the
Maximum input voltage (V
Minimum input voltage (V
Output voltage by VID setting (V
Maximum output current (I
Droop resistance (R
Nominal output voltage at 40 A load (V
Static output voltage drop from no load to full load
(DV) = V
Maximum output current step (DI
Number of phases (n) = 2
Switching frequency per phase (f
Duty cycle at maximum input voltage (D
Duty cycle at minimum input voltage (D
is the switching frequency in hertz for each phase.
is the VID voltage in volts.
PWM
ONL
R
R
T
T
operation,
− V
+
+
2
n
OFL
O
V
) = 2.1 mW
n
f
= 1.4375 V − 1.3535 V = 84 mV
VID
1.0 V
SW
) 1.0 V
f
the
INMIN
SW
INMAX
O
9 pF
) = 40 A
ADP3208D
) = 8.0 V
9 pF
SW
VID
* 16 kW
O
) = 19 V
) = 27.9 A
) = 300 kHz
) = 1.4375 V
* 16 kW
OFL
MIN
MAX
) = 1.3535 V
) = 0.076 V
) = 0.18 V
uses
(eq. 1)
(eq. 2)
http://onsemi.com
a
27
frequency is reduced with the load current in a linear
manner. When considering power conversion efficiency in
light load, lower switching frequency is usually preferred
for RPM mode. However, the V
the IMVP−6 sets the limitation for lowest switching
frequency. Therefore, depending on the inductor and output
capacitors, the switching frequency in RPM mode can be
equal, larger, or smaller than its counterpart in PWM mode.
frequency as following:
A
C
R
internal ramp magnitude.
300 kHz switching frequency in RPM operation.
Inductor Selection
the inductor. Less inductance results in more ripple current,
which increases the output ripple voltage and the conduction
losses in the MOSFETs. However, this allows the use of
smaller−size inductors, and for a specified peak−to−peak
transient deviation, it allows less total output capacitance.
Conversely, a higher inductance results in lower ripple
current and reduced conduction losses, but it requires
larger−size inductors and more output capacitance for the
same peak−to−peak transient deviation. For a multiphase
converter, the practical value for peak−to−peak inductor
ripple current is less than 50% of the maximum dc current
of that inductor. Equation 5 shows the relationship between
the inductance, oscillator frequency, and peak−to−peak
ripple current. Equation 6 can be used to determine the
minimum inductance based on a given output ripple voltage.
ripple voltage yields
L w
selected value, the inductor can be changed to a smaller
value until the ripple value is met. This iteration allows
optimal transient response and minimum output decoupling.
the number of output capacitors. Choosing a 490 nH
inductor is a good choice for a starting point, and it provides
P
P
L w
I
S(MF)
S(MF)
R
R
R
R
A resistor from RPM to GND sets the pseudo constant
where:
Because R
The choice of inductance determines the ripple current of
Solving Equation 6 for a 16 mV peak−to−peak output
If the resultant ripple voltage is less than the initially
The smallest possible inductor should be used to minimize
is the internal ramp capacitor value.
is an external resistor on the RAMPADJ pin to set the
+
is the internal ramp amplifier gain.
1.4375 V
V
V
VID
+ 2
+ 2
VID
f
SW
f
R
R
SW
f
f
O
300 kHz
SW
SW
1 * D
= 280 kW, the following resistance sets up
2.1 mW
L
(1 * (n
V
MIN
V
V
RIPPLE
CC
CC
n
n
MF
MF
16 mV
(1 * (2
I
I
O
O
D
MIN))
CORE
R
R
G
G
0.076)
ripple specification in
n
n
MF
MF
n
n
+ 533 nH
C
C
ISS
ISS
(eq. 5)
(eq. 6)
(eq. 3)
(eq. 4)
(eq. 7)