ADP1043A Analog Devices, ADP1043A Datasheet - Page 28

• Manufacturer Part Number: ADP1043A
• Description: Digital Controller for Isolated Power Supply Applications
• Manufacturer: Analog Devices

ADP1043A
OUTPUT VOLTAGE SETTING (VS3+, VS3− TRIM)
The VS3 input requires a gain trim. Enable the power supply with
no-load current. The power supply output voltage is divided down
by the VS3 resistor divider to give 1 V at the VS3+ and VS3−
input pins. The VS3 trim register (Register 0x3A) is altered until
the VS3 value in Register 0x17 reads 2643 decimal (0xA53).
This step should be done before any other trim routines.
VS1 TRIM
The VS1 input requires a gain trim. Enable the power supply with
no-load current. The VS1 voltage is divided down by the VS1
resistor divider to give 1 V at the VS1 pin. The VS1 trim register
(Register 0x38) is altered until the VS1 value in Register 0x15
reads 2643 decimal (0xA53).
VS2 TRIM
The VS2 input requires a gain trim. Enable the power supply with
no-load current. The VS2 voltage is divided down by the VS2
resistor divider to give 1 V at the VS2 pin. The VS2 trim register
(Register 0x39) is altered until the VS2 value in Register 0x16
reads 2643 decimal (0xA53).
RTD/OTP TRIM
A 100 kΩ NTC thermistor should be used with the ADP1043A.
In a PSU trim, the following procedure should be used:
1.
2.
3.
This procedure achieves the most accurate OTP, because it takes
into account the part-to-part variations of the ADP1043A and
the thermistor being used.
LAYOUT GUIDELINES
This section explains best practices that should be followed to
ensure optimal performance of the ADP1043A. In general, all
components should be placed as close to the ADP1043A as
possible.
Several inputs to the ADP1043A are sensitive. Therefore, take
extra care when handling and soldering the part. Along with
correct cleaning of the IC after soldering, a short curing process
(1 hour at 150°C) is recommended. Analog Devices also recom-
mends encapsulating the IC in protective resin after this curing
to ensure that any impurities cannot contaminate the IC.
Heat the thermistor or PSU to a known temperature that
will result in an OTP threshold.
Adjust the temperature gain trim register (Register 0x2B)
to give the correct temperature reading (Register 0x1A) at
this temperature.
Adjust the OTP threshold register (Register 0x2F) until the
OTP flag is set.
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CS2 + and CS2−
The routing of the traces from the sense resistor to the ADP1043A
should be laid out in parallel to each other. The traces should
also be kept close together and as far from the switch nodes as
possible.
VS3+ and VS3−
The routing of the traces from the remote voltage sense point
to the ADP1043A should be laid out in parallel to each other.
The traces should also be kept close together and as far from
the switch nodes as possible.
VDD
Place decoupling capacitors as close to the part as possible.
A 100 nF capacitor from VDD to AGND is recommended.
SDA and SCL
The routing of the traces should be laid out in parallel to each
other. The traces should also be kept close together and as far
from the switch nodes as possible.
CS1
Run the traces from the current sense transformer to the
ADP1043A in parallel to each other. The traces should also be
kept close together and as far from the switch nodes as possible.
Exposed Pad
The exposed pad underneath the ADP1043A should be
soldered to the PCB ground plane.
VCORE
Place the 100 nF capacitor as close to the part as possible.
RES
Place the 49.9 kΩ resistor as close to the part as possible.
RTD
Route a single trace to the ADP1043A from the thermistor.
Place the thermistor close to the hottest part of the power supply.
AGND
Create an AGND ground plane and make a single point (star)
connection to the power supply system ground.