Texas Instruments bq24725, User Manual

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PCB Layout Guideline
Figure 4. Test Setup for HPA-542
4. Type in "7905" in the Charge Option, and click the Write button. This enables charging.
Measure → Ibat = 500 mA ± 100 mA
5. Type in "2944" (mA) in the Charge Current DAC, and click the Write button. This sets the battery
charge current regulation threshold to 2.944 A.
Measure
→ Ibat = 3000 mA ± 300 mA
Measure → V(TP(IOUT)) = 340 mV ± 40 mV
6. Enable the output of the Load #1.
Measure → Isys = 3000 mA ± 300 mA, Ibat = 1600 mA ± 200 mA, Iin = 4100 mA ± 400 mA
Measure → V(TP(IOUT)) = 820 mV ± 100 mV
7. Turn off the Load #1.
Measure
→
Isys = 0 A
±
100 mA, Ibat = 3000 mA
±
300 mA.
8.
2.4.4 Power Path Selection
1. Type in "7905" in the Charge Option, and click the Write button. This disables charging.
2. Replace Load #2 and current meter with PS#3. Make sure a voltage meter is connected across J2
(BAT, GND). Enable the output of the PS #3. Ensure that the output voltage is 10 V ± 500 mV.
Measure → Measure ± V(J2(SYS)) = 19.5 V ± 1 V (adapter connected to system)
3. Turn off PS#1.
Measure → V(J2(SYS)) = 10 V ± 1 V (battery connected to system)
Measure → V(J2(BAT)) = 10 V ± 1 V (battery connected to system)
3 PCB Layout Guideline
The switching node rise and fall times must be minimized for minimum switching loss. Proper layout of the
components to minimize high-frequency current path loop is important to prevent electrical and magnetic
field radiation and high-frequency resonant problems. The following is a printed-circuit board (PCB) layout
priority list for proper layout. Laying out a PCB according to this specific order is essential.
7 SLUU439A – August 2010 – Revised May 2011 bq24725EVM Evaluation Module
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