LTC4060 Linear Integrated, LTC4060 Datasheet - Page 17

• Manufacturer Part Number: LTC4060
• Description: Standalone Linear NiMH/NiCd Fast Battery Charger
• Manufacturer: Linear Integrated

Trickle Charge
The trickle charge function is normally not required due to
the automatic recharge feature. However, the LTC4060
does provide a modest pull-up current (I
battery removal detection method. If additional current is
required for trickle charge or to support battery removal
detection with current loads greater than I
simple circuit of Figure 4 will facilitate that. The diode
insures no reverse discharge current when V
and the resistor sets the trickle current.
Extending Charge Current
Extending the charge current beyond 2A can be accom-
plished by paralleling an external current sense resistor,
R
Figure 5. Bond wire, lead frame and PCB interconnect
TYPICAL APPLICATIO S
ISET,
with the internal current sense resistor as shown in
U
Figure 5. Extended Charge Current Operation
BRD
BRD
) as part of its
IN
Figure 4. Adding Trickle Charge
is removed
, then the
LTC4060
V
LTC4060
14
CC
V
V
IN
CC
V
14
SENSE
DRIVE
IN
SENSE
DRIVE
0.08Ω
BAT
BAT
3
1
2
1
2
1N4001
3
R
0.16Ω
resistance and mismatches in the two sense resistor’s
value will cause charge current variability to increase in
proportion to the extension in current. Resistor R
should be connected directly to the LTC4060 to reduce
errors. The total current sense resistor, bond wire and lead
frame resistance is approximately 0.08Ω (T.C. ≅ 3500ppm/
°C). The formula for extended fast charge current is:
for R
Adequate PNP beta is required to meet the DRIVE pin
capability and the increased PNP power dissipation will
require additional heat sinking.
ISET
+
4060 F05
I
MAX EXT
2-CELL
NiMH
BATTERY
ISET
+
4060 F04
3.3k
2-CELL
NiMH
BATTERY
(
= 0.16Ω and R
)
=
=
2
I
MAX
A
• .
1 5 3
•
⎛
⎜
⎝
1
=
+
PROG
R
A
0 08
ISET
.
= 698Ω.
⎞
⎟
⎠
LTC4060
17
ISET
4060f