ADP3212 ON Semiconductor, ADP3212 Datasheet - Page 36

• Manufacturer Part Number: ADP3212
• Description: 7-bit Programmable, 3-phase,mobile Cpu Synchronous Buck Controller
• Manufacturer: ON Semiconductor

ADP3212/NCP3218
conditions used for the single-point thermal monitoring
example—that is, an alarm temperature of 100°C and use of an
NTHS-0603N011003J Vishay thermistor—solving Equation 42
gives a R
7.32 kΩ (1%).
The number of hot spots monitored is not limited. The alarm
temperature of each hot spot can be individually set by using
different values for R
TUNING PROCEDURE FOR ADP3212/NCP3218
Set Up and Test the Circuit
1.
2.
3.
4.
Set the DC Load Line
1.
2.
3.
4.
5.
Build a circuit based on the compensation values
computed from the design spreadsheet.
Connect a dc load to the circuit.
Turn on the ADP3212/NCP3218 and verify that it operates
properly.
Check for jitter with no load and full load conditions.
Measure the output voltage with no load (V
that this voltage is within the specified tolerance range.
Measure the output voltage with a full load when the
device is cold (V
minutes with a full load and then measure the output when
the device is hot (V
measured voltages is more than a few millivolts, adjust R
using Equation 39.
Repeat Step 2 until no adjustment of R
Compare the output voltage with no load to that with a full
load using 5 A steps. Compute the load line slope for each
change and then find the average to determine the overall
load line slope (R
If the difference between R
use the following equation to adjust the R
TTSET
R
R
CS2(NEW)
PH
Figure 26. Multiple-Point Thermal Monitoring
of 7.37 kΩ, and the closest standard resistor is
(
NEW
)
=
=
TTSET1
FLCOLD
R
R
OMEAS
CS2(OLD)
PH
FLHOT
(
, R
OLD
). Allow the board to run for ~10
).
TTSET2
). If the difference between the two
)
OMEAS
×
×
V
V
R
, … R
NL
OMEAS
NL
R
and R
O
−
−
V
V
TTSETn
FLCOLD
FLHOT
O
is more than 0.05 mΩ,
CS2
.
is needed.
PH
NL
values:
) and verify
Rev. SpA | Page 36 of 43
(39)
(40)
CS2
6.
7.
Set the AC Load Line
1.
2.
3.
4.
5.
6.
7.
8.
9.
Repeat Steps 4 and 5 until no adjustment of R
Once this is achieved, do not change R
for the rest of the procedure.
Measure the output ripple with no load and with a full load
with scope, making sure both are within the specifications.
Remove the dc load from the circuit and connect a
dynamic load.
Connect the scope to the output voltage and set it to dc
coupling mode with a time scale of 100 μs/div.
Set the dynamic load for a transient step of about 40 A at
1 kHz with 50% duty cycle.
Measure the output waveform (note that use of a dc offset
on the scope may be necessary to see the waveform). Try to
use a vertical scale of 100 mV/div or finer.
The resulting waveform will be similar to that shown in
Figure 27. Use the horizontal cursors to measure V
V
shoot or overshoot that occurs immediately after the step.
If the difference between V
couple of millivolts, use Equation 46 to adjust C
be necessary to try several parallel values to obtain an
adequate one because there are limited standard capacitor
values available (it is a good idea to have locations for two
capacitors in the layout for this reason).
Repeat Steps 5 and 6 until no adjustment of C
Once this is achieved, do not change C
procedure.
Set the dynamic load step to its maximum step size (but do
not use a step size that is larger than needed) and verify
that the output waveform is square, meaning V
V
Ensure that the load step slew rate and the power-up slew
rate are set to ~150 A/μs to 250 A/μs (for example, a load
DCDRP
DCDRP
C
, as shown in Figure 27. Do not measure the under-
CS
are equal.
(
NEW
Figure 27. AC Load Line Waveform
)
=
C
CS
(
OLD
)
×
V
V
ACDRP
ACDRP
DCDRP
V
ACDRP
and V
DCDRP
PH
CS
, R
V
for the rest of the
DCDRP
CS1
is more than a
PH
, R
CS
ACDRP
CS
is needed.
is needed.
CS2
ACDRP
. It may
, or R
and
and
(41)
TH