Datasheet

High
Frequency
Current
Path
L1
R1
C3
C1
C2
PGND
SW
V
BAT
BAT
V
IN
CurrentDirection
ToSRP -SRNpinor ACP - ACNpin
R
SNS
CurrentSensingDirection
bq24630
www.ti.com SLUS894A –JANUARY 2010– REVISED OCTOBER 2011
7. Route the analog ground separately from the power ground and use a single ground connection to tie the
charger power ground to the charger analog ground. Just beneath the IC, use the copper pour for analog
ground, but avoid power pins to reduce inductive and capacitive noise coupling. Connect the analog ground
to GND. Connect the analog ground and power ground together using the power pad as the single ground
connection point. Or use a 0-Ω resistor to tie the analog ground to power ground (the thermal pad should tie
to analog ground in this case). A star-connection under the tharmal pad is highly recommended.
8. It is critical that the exposed thermal pad on the backside of the IC package be soldered to the PCB ground.
Ensure that there are sufficient thermal vias directly under the IC connecting to the ground plane on the other
layers.
9. Decoupling capacitors should be placed next to the IC pins; make the trace connections as short as possible.
10. All via sizes and numbers should be adequate for a given current path.
Figure 24. High Frequency Current Path
Figure 25. Sensing Resistor PCB Layout
See the EVM design (SLUU396) for recommended component placement of trace and via locations.
For QFN information, see SCBA017 and SLUA271.
SPACER
REVISION HISTORY
Changes from Revision Original (January 2010) to Revision A Page
• Changed descriptions for PH and BTST pins ..................................................................................................................... 12
• Changed Equation 1 From: R1/R2 To: R2/R1 .................................................................................................................... 15
• Changed Equation 1 ........................................................................................................................................................... 15
• Changed Equation 16 ......................................................................................................................................................... 26
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