4
Measurements/waveforms/test data
4.1
STWBC2-HP startup waveform
Once the board is supplied, you can check each voltage during the startup as described below:
1.
the board is supplied by the USB PD adapter and the voltage is ready and stable at about 5 V
2.
the internal DC-DC buck converter and LDOs are starting
3.
the internal 1.8 V LDO is ready and the output is stable at 1.8 V
4.
the internal 3.3V LDO is ready and the output is stable at 3.3 V
5.
the internal DC-DC buck converter is ready and the output is stable at 3.6 V
Figure 4.
Typical startup waveform: power-on sequence
4.2
Presence detection waveform
power-up is ready, you can check the presence detection waveform at RING_NODE1
triggered by TANK1_SEL and RING_NODE2 triggered by TANK2_SEL as described below:
1.
the RING_NODE1 starts oscillating about 75 ms in the end of TANK1_SEL active high and the
RING_NODE2 is off
2.
the RING_NODE2 starts oscillating about 75ms in the end of TANK2_SEL active high and the
RING_NODE1 is off
3.
the RING_NODE1 starts oscillating again in the end of TANK1_SEL active high and the RING_NODE2 is off
4.
the RING_NODE1 and RING_NODE2 repeat the above process in a period of about 900 ms
TN1399
Measurements/waveforms/test data
TN1399
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Rev 1
page 6/26