LT1511 Datasheet, PDF (1/16 Pages) Linear Technology – Constant-Current/ Constant-Voltage 3A Battery Charger with Input Current Limiting

LT1511
Constant-Current/
Constant-Voltage 3A Battery
Charger with Input Current Limiting
FEATURES
s _{Simple Design to Charge NiCd, NiMH and Lithium}
Rechargeable Batteries—Charging Current
Programmed by Resistors or DAC
s _{Adapter Current Loop Allows Maximum Possible}
Charging Current During Computer Use
s _{Precision 0.5% Accuracy for Voltage Mode Charging}
s _{High Efficiency Current Mode PWM with 4A Internal}
Switch
s _{5% Charging Current Accuracy}
s _{Adjustable Undervoltage Lockout}
s _{Automatic Shutdown When AC Adapter is Removed}
s _{Low Reverse Battery Drain Current: 3µA}
s _{Current Sensing Can Be at Either Terminal of the Battery}
s _{Charging Current Soft-Start}
s _{Shutdown Control}
U
APPLICATIO S
s _{Chargers for NiCd, NiMH, Lead-Acid, Lithium}
Rechargeable Batteries
s _{Switching Regulators with Precision Current Limit}
, LTC and LT are registered trademarks of Linear Technology Corporation.
*See LT1510 for 1.5A Charger
DESCRIPTIO
The LT^®1511 current mode PWM battery charger is the
simplest, most efficient solution to fast charge modern
rechargeable batteries including lithium-ion (Li-Ion), nickel-
metal-hydride (NiMH) and nickel-cadmium (NiCd) that
require constant-current and/or constant-voltage charg-
ing. The internal switch is capable of delivering 3A* DC
current (4A peak current). Full-charging current can be
programmed by resistors or a DAC to within 5%. With 0.5%
reference voltage accuracy, the LT1511 meets the critical
constant-voltage charging requirement for Li-Ion cells.
A third control loop is provided to regulate the current
drawn from the AC adapter. This allows simultaneous
operation of the equipment and battery charging without
overloading the adapter. Charging current is reduced to
keep the adapter current within specified levels.
The LT1511 can charge batteries ranging from 1V to 20V.
Ground sensing of current is not required and the battery’s
negative terminal can be tied directly to ground. A saturat-
ing switch running at 200kHz gives high charging effi-
ciency and small inductor size. A blocking diode is not
required between the chip and the battery because the
chip goes into sleep mode and drains only 3µA when the
wall adapter is unplugged.
TYPICAL APPLICATIO
GND
CLP
D1
MBRD340
L1**
20µH
D2
MBR0540T
C2
0.47µF
200pF
SW
CLN
V_CC
BOOST
LT1511
COMP1
UV
PROG
SPIN
V_C
OVP SENSE BAT
NOTE: COMPLETE LITHIUM-ION CHARGER,
NO TERMINATION REQUIRED. R_S4, R7
AND C1 ARE OPTIONAL FOR I_IN LIMITING
*TOKIN OR UNITED CHEMI-CON/MARCON
CERAMIC SURFACE MOUNT
**20µH COILTRONICS CTX20-4
†_{SEE APPLICATIONS INFORMATION FOR}
INPUT CURRENT LIMIT AND UNDERVOLTAGE LOCKOUT
R_S3
200Ω
1%
R_S2
200Ω
1%
R_S1
0.033Ω
BATTERY CURRENT
SENSE
50pF
R7^†
500Ω
C1
1µF
+
+
10µF
C_IN*
10µF
D3
MBRD340
R_S4^†
ADAPTER
CURRENT SENSE
V_IN (ADAPTER INPUT)
11V TO 28V
TO MAIN
R5^{† SYSTEM POWER}
UNDERVOLTAGE
LOCKOUT
1k
0.33µF
R6
5k
300Ω
C_PROG
1µF
R_PROG
4.93k
1%
R3
+
390k
0.25%
BATTERY
VOLTAGE SENSE
R4
162k
0.25%
C_OUT
22µF
TANT
4.2V
4.2V
V_BAT
2 Li-Ion
1511 • F01
Figure 1. 3A Lithium-Ion Battery Charger
1