Input Voltage - Analog Devices MAX77857 Manual

Evaluates: MAX77857 (WLP)
Critical Node Measurement (OUT and LX)
The EV kit comes with probe points for measuring critical nodes OUT1, LX1, and LX2. See
the EV kit. Use these probe points to eliminate as much noise as possible when measuring the critical nodes. To ensure
the best results, use a very short ground wire from the ground sleeve of the scope probe to the GND side of the probe
point, and use the bare tip of the probe directly to the signal side of the probe point
gives the most accurate results when measuring parameters such as output voltage ripple, switching waveforms, and
load transient response.
Figure 6. Probing Critical Nodes
Efficiency Measurement (INS and OUTS)
The EV kit also comes with sense pins for accurately measuring input voltage (INS, PGND1S) and output voltage (OUTS,
PGND2S). See Figure 2
measurements, use these sense pins to measure input and output voltages.
Warning: These sense pins are only for measuring voltages. Do not connect input supply to input sense pins and do not
connect an electronic load to output sense pins, as these sense pins are not designed to have current running through
them. Doing so damages the EV kit. Use input supply terminals for connecting to input supply and use output terminals
for connecting to electronic load as shown in
Table 4. Usage of Critical Test Points
LOAD TRANSIENT,
OUTPUT RIPPLE
V
OUT
(OUT1)
EV Kit Software
The graphical user interface (GUI) software allows for a quick, easy, and thorough evaluation of the MAX77857. The GUI
along with the MAXUSB_INTERFACE# drives I
directly to a register within the MAX77857. Refer to the Register Map section of the MAX77857 IC data sheet for a
complete description of the registers. See
www.analog.com
for their locations on the EV kit. For most accurate efficiency, load regulation, and line regulation
Figure
LOAD REGULATION,
LINE REGULATION,
V ACCURACY
OUT
V
OUT
(OUTS, PGND2S)
2
Figure 7
2.
EFFICIENCY
OUTPUT VOLTAGE
V
OUT
(OUTS, PGND2S)
C communication with the EV kit. Every control in the GUI corresponds
for a screenshot of the GUI upon first opening.
MAX77857 Evaluation Kit
Figure 2
(Figure 6). Following these guidelines
SWITCHING NODE

INPUT VOLTAGE

V
IN
(INS, PGND1S)
for their locations on
LX1 LX2
LX1 LX2
(LX1) (LX2)
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