ADP3211AMNR2G ON Semiconductor, ADP3211AMNR2G Datasheet - Page 22

• Manufacturer Part Number: ADP3211AMNR2G
• Description: IC CTLR BUCK 7BIT 2PHASE 32QFN
• Manufacturer: ON Semiconductor

Specifications of ADP3211AMNR2G

• Applications: Controller, Power Supplies for Next-Generation Intel Processors
• Voltage - Input: 3.3 ~ 22 V
• Number Of Outputs: 1
• Voltage - Output: 0.0125 ~ 1.5 V
• Operating Temperature: -10°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 32-TFQFN Exposed Pad
• Output Voltage: 1.1 V
• Output Current: 10 A
• Input Voltage: 19 V
• Supply Current: 6 mA
• Switching Frequency: 400 KHz
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 100 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application Information
the final design. The equations in the Application Information
section are used as a starting point for a new design.
compliant GPU core VR application are as follows:
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Setting the Clock Frequency for PWM
during startup, for 100 ms after a VID change, and in current
limit. In PWM operation,
fixed−frequency control architecture. The frequency is set by
an external timing resistor (R
determines the switching frequency, which relates directly to
the switching losses and the sizes of the inductors and input
and output capacitors. For example, a clock frequency of 400
kHz sets the switching frequency to 400 kHz. This selection
represents the trade−off between the switching losses and the
minimum sizes of the output filter components. To achieve a
400 kHz oscillator frequency at a VID voltage of 1.1 V, R
must be 274 kW. Alternatively, the value for R
calculated by using the following equation:
where:
9 pF and 16 kW are internal IC component values.
V
f
recommended to use a 1% resistor.
Ramp Resistor Selection
internal PWM ramp. The value of this resistor is chosen to
provide the best combination of thermal balance, stability,
and transient response. Use this equation to determine a
starting value:
SW
R
R
VID
The ADP3211 application circuit should be fine−tuned in
The design parameters for a typical IMVP−6.5−
The ADP3211 operates in fixed frequency PWM mode
For good initial accuracy and frequency stability, it is
The ramp resistor (R
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 10 A load (V
Static output voltage drop from no load to full load
(DV) = V
Maximum output current step (DI
Switching frequency (f
Duty cycle at maximum input voltage (D
Duty cycle at minimum input voltage (D
R
R
R
T
+
+
is the switching frequency in hertz.
is the VID voltage in volts.
+
3
3
2
V
A
5
VID
ONL
0.5
D
f
A
SW
) 1.0 V
R
5.2 mW
− V
R
560 nH
DS
9 pF
L
OFL
O
R
) = 8 mW
) is used for setting the size of the
* 16 kW
C
= 1.1 V − 1.02 V = 80 mV
SW
R
5 pF
) = 400 kHz
INMIN
INMAX
O
) = 10 A
+ 718 kW
T
the ADP3211 uses a
). The clock frequency
) = 8.0 V
VID
O
) = 19 V
) = 8 A
) = 1.1 V
OFL
MIN
MAX
) = 1.02 V
) = 0.054
) = 0.14
T
can be
http://onsemi.com
(eq. 1)
(eq. 2)
T
22
where:
A
A
R
C
Setting the Switching Frequency for
RPM Operation
pseudo−constant frequency if the load current is high
enough for continuous current mode. While in DCM, the
switching frequency is reduced with the load current in a
linear manner. To save power with light loads, lower
switching frequency is usually preferred during RPM
operation. However, the V
IMVP−6.5 sets a limitation for the lowest switching
frequency. Therefore, depending on the inductor and
output capacitors, the switching frequency in RPM can be
equal to, greater than, or less than its counterpart in PWM.
frequency as following:
R
where:
A
C
R
internal ramp magnitude.
400 kHz switching frequency in RPM operation.
R
Inductor Selection
of 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 buck
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.
RPM
DS
R
RPM
R
R
R
D
R
During the RPM operation, the ADP3211 runs in
A resistor from RPM to GND sets the pseudo constant
Because R
1.1 V ) 1.0 V
The choice of inductance determines the ripple current
2
is an external resistor on the RAMPADJ pin to set the
is the internal ramp amplifier gain.
is the internal ramp capacitor value.
is the internal ramp amplifier gain.
is the internal ramp capacitor value.
is the current balancing amplifier gain.
is the total low−side MOSFET on−resistance,
+
+
274 kW
V
VID
2
R
) 1.0 V
= 718 kW, the following resistance sets up
R
718 kW
0.5
T
(1 * 0.054)
A
5 pF
R
R
CCGFX
R
(1 * D)
400 kHz
C
ripple specification of
R
1.1 V
f
* 500 W + 93.1 kW
SW
V
VID
* 0.5 kW
(eq. 3)
(eq. 4)