Terasic CY8CKIT-035, User Manual

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Figure 4-21 LCD Display - Currents
The
0.1mA
reading in the top left corner indicates the units of the 4+1 power supply current
measurements. The next 2 numbers on the 1st line of the display indicate the measured 12 V
primary input load current value and the measured 5 V rail load current value. The 2
nd
line of the
display indicates the measured 3.3 V, 2.5 V and 1.8 V rail load current values. Loads can be
adjusted on PME EBK using the potentiometers. The load currents measured by PSoC’s ADC
converter can be compared with a digital multimeter (DMM) by removing the appropriate jumper
and connecting the DMM configured to measure current.
When currents are displayed on the LCD, pressing and holding the SW1 on the CY8CKIT-001
PSoC DVK (SW2 on the CY8CKIT-030 PSoC 3 DVK) for a longer period will enable manual
trimming control. The example below shows the manual trimming display for rail 1 (+5V nominal).
(See
Figure 4-22
)
Figure 4-22 LCD Display - Trimming
The top line of the display shows the actual voltage of the rail currently measured by PSoC. The left
side of the second line shows the deviation from the nominal 5V as a percentage. The right side of
the second line shows the current PWM duty cycle used by the trimming hardware to achieve the
currently selected voltage. In this mode, pressing and releasing SW1 on the CY8CKIT-001 PSoC
DVK (SW2 on the CY8CKIT-030 PSoC 3 DVK) will trim the rail down in steps of approximately
2%. Pressing and releasing the SW2 on the CY8CKIT-001 PSoC DVK (SW3 on the CY8CKIT-030
PSoC 3 DVK) will trim the rail up in steps of approximately 2%. The actual voltages and PWM
duty cycles will update in response to switch presses.
Trimming below or above the nominal voltage by more than 7.5% will cause the under/over voltage
window comparator fault detection circuit to trip which will cause all regulators to be turned off by
the
Voltage Sequencer
component. The green LEDs on the Power Management EBK will all be
turned off in that case and the LCD will report that a “Rail Failure” has occurred. To re-start the
voltage sequencer, press and hold SW2 on the CY8CKIT-001 PSoC DVK (SW3 on the
CY8CKIT-030 PSoC 3 DVK) until the regulators power up again, indicated by the green LEDs on
PME EBK turning on in sequence.
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