Texas Instruments bq24295EVM-549, User Manual

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Test Summary
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2.4.3 Verify Scope Measurements (see Figure 6 through Figure 8 – 500 ns/div):
Connect scope probe ground lead to Ground J1-GND (make sure lead is short), probe and verify the
following waveforms, as shown in
Figure 6 through Figure 8 .
Figure 6 ) Buck Mode Switch Node Waveform - (2 VDC/div): TP left of inductor L1
Figure 7 ) Buck Mode Input PMID Ripple - (AC coupled 20 mV/div): Right side of C2 Cap
Figure 8 ) Buck Mode Output System Ripple – (AC coupled 50 mV/div): top side of C12 cap
Measure
→
Figure 6 – SW node Frequency between 1.25 MHz and 1.6 MHz,
Measure → Figure 6 – SW node Duty cycle between 71 and 81%.
Measure → Figure 7 - PMID AC Ripple < 15 mV excluding high frequency spikes
Measure → Figure 8 - SYS AC Ripple < 10 mV excluding high frequency spikes
Figure 6. Buck Mode Switch Node Waveform, VBUS = 5 Figure 7. Buck Mode Input PMID Ripple, VBUS = 5 V,
V, VBAT = 3.7 V VBAT = 3.7 V
Figure 8. Buck Mode Output Ripple, VBUS = 5 V, VBAT = 3.7 V
8 bq24295EVM-549 (PWR549) User’s Guide SLUUAO5B – August 2013 – Revised April 2014
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