ADP3207 ANALOG DEVICES, ADP3207 Datasheet - Page 22

• Manufacturer Part Number: ADP3207
• Description: 7-Bit Programmable Multiphase Mobile CPU Synchronous Buck Controller
• Manufacturer: ANALOG DEVICES

ADP3207
The following procedure and equations yield values for
R
R
1.
2.
3.
4.
CS1
CS
where:
TC = 0.0039
T
T
value:
, R
Select an NTC to be used based on type and value. Because
there is no value yet, start with a thermistor with a value
close to R
of better than 5%.
Based on the type of NTC, find its relative resistance value
at two temperatures. Temperatures that work well are 50°C
and 90°C. These are called Resistance Value A (A is
R
R
is always 1 at 25°C.
Next, find the relative value of R
of these temperatures. This is based on the percentage of
change needed, which is initially 0.39%/°C. These are
called r
Compute the relative values for r
r
r
r
r
r
1
2
1
CS
CS
TH
2
TH
TH
= 50°C
= 90°C.
CS2
=
=
2
1
ADP3207
(50°C)/R
(90°C)/R
=
=
1
=
1
, and R
Figure 11. Temperature Compensation Circuit Values
+
+
CSCOMP
1
1
(
CSSUM
CSREF
TC
TC
A
1
−
−
1
and r
1
−
r
r
CS
A
CS
CS
×
×
B
PLACE AS CLOSE AS POSSIBLE
(
1
2
. The NTC should also have an initial tolerance
1
2
(
×
1
TH
(
1
T
T
)
18
17
16
TH
TH
−
−
(
−
×
1
2
1
TO NEAREST INDUCTOR
2.
OR LOW–SIDE MOSFET
(the thermistor value at 25°C) for a given
−
A
r
r
−
r
(25°C)) and Resistance Value B (B is
(25°C)). Note that the relative value of NTC
−
1
CS
1
25
1
)
25
×
B
−
1
A
r
)
)
r
C
)
2
CS
×
CS
−
2
r
1
A
R
−
R
CS1
×
TH
B
(
1
×
−
(
1
R
R
B
−
CS2
PH1
)
×
A
CS
CS1
r
)
2
×
that is required for each
+
R
, r
r
2
AS SHORT AS POSSIBLE
PH2
AND WELL AWAY FROM
B
SWITCH
−
NODES
CS2
SWITCH NODE LINES
×
TO
(
KEEP THIS PATH
(
, and r
A
1
R
−
−
PH3
A
B
)
)
×
TH
r
1
using
SENSE
V
TO
OUT
Rev. 0 | Page 22 of 32
(9)
(10)
5.
6.
This example starts with a thermistor value of 100 kΩ and uses
a Vishay NTHS0603N04 NTC thermistor (a 0603 size thermistor)
with A = 0.3359 and B = 0.0771. From this data, r
r
220 kΩ is chosen, making k = 0.914. Finally, R
72.3 kΩ and 166 kΩ. Choosing the closest 1% resistor values
yields a choice of 71.5 kΩ and 165 kΩ.
C
The required output decoupling for processors and platforms is
typically recommended by Intel. The following guidelines can
also be used if both bulk and ceramic capacitors in the system:
•
•
•
CS2
OUT
= 0.729 and r
Calculate R
thermistor that is available. Also, compute a scaling factor
k based on the ratio of the actual thermistor value relative
to the computed one
Finally, calculate values for R
Select the total amount of ceramic capacitance. This is based
on the number and type of capacitors to be used. The best
location for ceramics is inside the socket; 20 pieces of
Size 0805 being the physical limit. Additional capacitors
can be placed along the outer edge of the socket.
Select the number of ceramics and find the total ceramic
capacitance (C
300 µF are recommended and are usually made up of
multiple 10 µF or 22 µF capacitors.
Note that there is an upper limit imposed on the total
amount of bulk capacitance (C
VID on-the-fly output voltage stepping (voltage step V
time t
meeting the critical capacitance for load release at a given
maximum load step ΔI
current version of the IMVP-6 specification allows a
maximum V
the VID voltage. For example, if the VID is 1.150 V, then
the largest overshoot allowed is 27 mV.
C
C
k =
R
R
SELECTION
CS
CS
X
x
(
(
1
2
MIN
MAX
R
=
=
TH
R
V
)
R
R
)
TH
(
with error of V
≥
CALCULATED
CS
CS
≤
(
⎛
⎜
⎜
⎜
⎜
⎜
⎝
ACTUAL
×
nK
×
n
TH
k
(
×
(
TH
L
CORE
1
×
2
⎛
⎜
⎜
⎝
R
= R
−
r
Z
R
CS
O
)
= 1.094. Solving for R
2
). Combined ceramic values of 200 µF to
k
O
1
)
)
overshoot (V
×
TH
+
+
L
V
V
(
V
VID
×
k
×
V
OSMAX
∆
×
∆
R
ERR
I
O
r
I
O
×
CS
CS
. For a step-off load current, the
O
⎛
⎜
⎜
⎜
⎝
), and also a lower limit based on
, then select the closest value of
2
))
⎞
⎟
⎟
⎠
1
×
CS1
+
V
OSMAX
X
⎛
⎜
⎜
⎝
VID
and R
) when considering the
t
v
V
V
−
VID
) of 10 mV, plus 1.5% of
V
C
TH
CS2
z
×
⎞
⎟
⎟
⎟
⎟
⎟
⎠
yields 240 kΩ, so
using
nKR
CS1
www.DataSheet4U.com
L
and R
O
CS1
⎞
⎟
⎟
⎠
2
= 0.359,
−
CS2
1
⎞
⎟
⎟
⎟
⎠
are
−
V
C
(11)
(12)
z
in
(13)
(14)