78M6610+PSU/EK#1 Maxim Integrated, 78M6610+PSU/EK#1 Datasheet - Page 14

• Manufacturer Part Number: 78M6610+PSU/EK#1
• Description: Development Boards & Kits - Other Processors 78M6610 EVAL KIT
• Manufacturer: Maxim Integrated

Specifications of 78M6610+PSU/EK#1

• Rohs: yes
• Part # Aliases: 90-X6610#KK1

reset them. Similarly, a value of 0x7FFFFF should be written to the Vlo and Ilo registers in order to reset
them.
2.8.2 Voltage and Current Peak Tracking
78M6610+PSU Data Sheet
2.8 Voltage and Current Min/Max and Peak Tracking
2.8.1 Voltage and Current Min/Max Tracking
The 78M6610+PSU allows recording the lowest and highest voltage and current rms values. These
values are stored in the registers Vhi, Vlo, Ihi, and Ilo. To reset these values it is necessary to write to
these registers. For example, a value of 0x000000 should be written in the Vhi or Ihi register in order to
The 78M6610+PSU allows recording the highest voltage and current measured during an accumulation
interval. These values are updated at each accumulation interval and available on the output registers
Vpeak and Ipeak, for voltage and current, respectively.
2.9 X+Y Capacitor Current and I/R Voltage Drop Compensation
The 78M6610+PSU location in the power supply AC input stage can be different from design to design. In
order to achieve high accuracy, the components preceding the measurement point should be accounted
for. For example, current flowing in filter capacitors or the voltage drop across PCB traces (I, Vdrop)
should be considered in the measurement as shown in Figure 9.
2.9.1 X+Y Capacitor Compensation
The 78M6610+PSU, and therefore the measurement point, is usually located between the inlet and the
diode bridge. This stage is where the EMI filters are usually located as shown in Figure 9.
In this case the current flowing through the filter (X+Y) capacitors preceding the measurement cannot be
measured and is compensated for by the 78M6610+PSU. The current in flowing into these capacitors is
at 90° phase respect to the voltage; therefore it has no effect on the power measurement. The effect is
prominent in the current reading, in particular at light loads. Compensation is required in order to achieve
higher accuracy.
A fixed coefficient value can be set for compensation, however due to the tolerance of the filter capacitors
(in the +/-20% range) a calibration routine is included in the firmware. Calibration of the X+Y capacitor
coefficient facilitates higher accuracy in the measurement of the current
14
AC INLET
I
I
I
I
Figure 9: Typical Measurement Location in Power Supplies
Vdrop
Vdrop
Current (Measured)
78M6610+PSU
SHUNT
TO PFC
Rev 1