LTC4006 Datasheet, PDF (15/16 Pages) Linear Technology – 4A, High Efficiency, Standalone Li-Ion Battery Charger

LTC4006
APPLICATIO S I FOR ATIO
current sense feedback traces going to resistor are not
long. The feedback traces need to be routed together
as a single pair on the same layer at any given time with
smallest trace spacing possible. Locate any filter
component on these traces next to the IC and not at the
sense resistor location.
5. Place output capacitors next to the sense resistor
output and ground.
6. Output capacitor ground connections need to feed
into same copper that connects to the input capacitor
ground before tying back into system ground.
General Rules
7. Connection of switching ground to system ground or
internal ground plane should be single point. If the
system has an internal system ground plane, a good
way to do this is to cluster vias into a single star point
to make the connection.
8. Route analog ground as a trace tied back to IC ground
(analog ground pin if present) before connecting to
SWITCH NODE
L1
V_BAT
HIGH
V_IN
C2
FREQUENCY
CIRCULATING
PATH
D1
C3
BAT
any other ground. Avoid using the system ground
plane. CAD trick: make analog ground a separate
ground net and use a 0Ω resistor to tie analog ground
to system ground.
9. A good rule of thumb for via count for a given high
current path is to use 0.5A per via. Be consistent.
10. If possible, place all the parts listed above on the same
PCB layer.
11. Copper fills or pours are good for all power connec-
tions except as noted above in Rule 3. You can also use
copper planes on multiple layers in parallel too—this
helps with thermal management and lower trace in-
ductance improving EMI performance further.
12. For best current programming accuracy provide a
Kelvin connection from R_SENSE to CSP and BAT. See
Figure 12 as an example.
It is important to keep the parasitic capacitance on the R_T,
CSP and BAT pins to a minimum. The traces connecting
these pins to their respective resistors should be as short
as possible.
DIRECTION OF CHARGING CURRENT
R_SNS
4006 F13
4006 F12
Figure 12. High Speed Switching Path
CSP
BAT
Figure 13. Kelvin Sensing of Charging Current
PACKAGE DESCRIPTION
GN Package
16-Lead Plastic SSOP (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1641)
.015 ± .004
(0.38 ± 0.10)
× 45°
.007 – .0098
(0.178 – 0.249)
.053 – .068
(1.351 – 1.727)
0° – 8° TYP
.004 – .0098
(0.102 – 0.249)
.189 – .196*
(4.801 – 4.978)
16 15 14 13 12 11 10 9
.009
(0.229)
REF
.045 ±.005
.016 – .050
(0.406 – 1.270)
.008 – .012
(0.203 – 0.305)
.0250
(0.635)
.229 – .244
(5.817 – 6.198)
.150 – .157** _{.254 MIN}
(3.810 – 3.988)
NOTE:
BSC
1. CONTROLLING DIMENSION: INCHES *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
2.
DIMENSIONS
ARE
IN
INCHES
(MILLIMETERS)
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
GN16 (SSOP) 0502
3. DRAWING NOT TO SCALE
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
1 234 5678
.0165 ± .0015
.150 – .165
.0250 TYP
RECOMMENDED SOLDER PAD LAYOUT
sn4006 4006is
15