10. EVB Test Points and LEDs
10.1 Test Points
The Si5xxUC-EVB has many test points that are useful for probing various nodes and/or making connections to external test equip-
ment.
Please refer to the schematic for functions of the various test points.
One set of test points in particular provides oscillator current sense capability and is shown in the drawing below. These two test points
allow an external voltage measurement to be taken across the two test points to determine the current being used by the oscillator.
Since the resistor value is 1 Ω, the voltage measured across these 2 test points corresponds to the current through the resistor. For
example, if the measured voltage is 75 mV, the current flow is 75 mA. Each oscillator site has this current sense circuit.
Figure 10.1. Current Sense Test Points
10.2 LEDs
The Si5xxUC-EVB has 5 status LEDs as shown in table below. The board silkscreen identifies each LED.
Table 10.1. Status LEDs
LED name
Color
Location
Description
+5V_EXT
Green
D1
Ex5V source is present (independent of +5V_SELECT (SW5) switch
setting)
VBUS_5V
Green
D5
USB +5V is present (independent of +5V_SELECT (SW5) switch setting)
VDD_3.3
Green
D4
On-board MCU 3.3V is present
USB_ACT
Red
D3
USB port activity
Aux
Red
D2
TBD (spare)
UG298: Si5xxUC-EVB
EVB Test Points and LEDs
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