ADP3208CJCPZ-RL View Datasheet(PDF) - ON Semiconductor
Part Name
Description
Manufacturer
ADP3208CJCPZ-RL
ON Semiconductor
ADP3208CJCPZ-RL Datasheet PDF : 41 Pages
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ADP3208C
capacitor bank is formed by eight pieces of 10 μF, 25 V MLC
capacitors, with a ripple current rating of about 1.5 A each.
Selecting Thermal Monitor Components
To monitor the temperature of a single-point hot spot, set
RTTSET1 equal to the NTC thermistor’s resistance at the alarm
temperature. For example, if the alarm temperature for VRTT is
100°C and a Vishey thermistor (NTHS-0603N011003J) with a
resistance of 100 kΩ at 25°C, or 6.8 kΩ at 100°C, is used, the
user can set RTTSET1 equal to 6.8 kΩ (the RTH1 at 100°C).
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 RTTSET1, RTTSET2, … RTTSETn.
TUNING PROCEDURE FOR ADP3208C
Set Up and Test the Circuit
1. Build a circuit based on the compensation values
computed from the design spreadsheet.
2. Connect a dc load to the circuit.
3. Turn on the ADP3208C and verify that it operates
properly.
4. Check for jitter with no load and full load conditions.
Set the DC Load Line
1. Measure the output voltage with no load (VNL) and verify
that this voltage is within the specified tolerance range.
2. Measure the output voltage with a full load when the
device is cold (VFLCOLD). Allow the board to run for ~10
minutes with a full load and then measure the output when
the device is hot (VFLHOT). If the difference between the two
measured voltages is more than a few millivolts, adjust RCS2
using Equation 35.
Figure 39. Single-Point Thermal Monitoring
To monitor the temperature of multiple-point hot spots, use the
configuration shown in Figure 40. If any of the monitored hot
spots reaches the alarm temperature, the VRTT signal is
asserted. The following calculation sets the alarm temperature:
1/ 2 + VFD
RTTSET1
=
VREF
1/ 2 − VFD
× RTH1AlarmTemperature
VREF
(34)
where VFD is the forward drop voltage of the parallel diode.
Because the forward current is very small, the forward drop
voltage is very low, that is, less than 100 mV. Assuming the same
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 RTTSET of 7.37 kΩ, and the closest standard resistor is
7.32 kΩ (1%).
RCS2(NEW)
=
RCS2(OLD)
×
VNL
VNL
− VFLCOLD
− VFLHOT
(35)
3. Repeat Step 2 until no adjustment of RCS2 is needed.
4. 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 (ROMEAS).
5. If the difference between ROMEAS and RO is more than 0.05 mΩ,
use the following equation to adjust the RPH values:
RPH(NEW )
=
R PH (OLD )
× ROMEAS
RO
(36)
6. Repeat Steps 4 and 5 until no adjustment of RPH is needed.
Once this is achieved, do not change RPH, RCS1, RCS2, or RTH
for the rest of the procedure.
7. Measure the output ripple with no load and with a full load
with scope, making sure both are within the specifications.
Set the AC Load Line
1. Remove the dc load from the circuit and connect a
dynamic load.
2. Connect the scope to the output voltage and set it to dc
coupling mode with a time scale of 100 μs/div.
3. Set the dynamic load for a transient step of about 40 A at
1 kHz with 50% duty cycle.
4. Measure the output waveform (note that use of a dc offset
on the scope may be necessary to see the waveform). Try to
Figure 40. Multiple-Point Thermal Monitoring
use a vertical scale of 100 mV/div or finer.
Rev. 1 | Page 38 of 41 | www.onsemi.com
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