LT1571 Datasheet, PDF (1/16 Pages) Linear Technology – Constant-Current/ Constant-Voltage Battery Charger with Preset Voltage and Termination Flag

Final Electrical Specifications
LT1571 Series
Constant-Current/
Constant-Voltage Battery Charger
with Preset Voltage and Termination Flag
FEATURES
DESCRIPTIO
April 2000
s _{Fast Charging of Li-Ion, NiMH and NiCd Batteries}
s _{Simple Charge Current Programming Requires Only}
One Low Cost, 1/32W Resistor
s _{High Efficiency Charger with Up to}
1.5A Charge Current
s _{Precision 0.6% Internal Voltage Reference}
s _{Preset Battery Voltages: 4.1V, 4.2V, 8.2V, 8.4V}
s _{500kHz or 200kHz Switching Frequency}
Minimizes Charger Size
s _{Low Reverse Battery Drain Current: 5µA}
s _{Flag Indicates Li-Ion Charge Completion}
s _{5% Typical Charge Current Accuracy}
s _{Low Shutdown Current}
s _{LT1571-5: 500kHz, Fixed 4.1V or 4.2V}
LT1571-1: 200kHz, Adjustable Voltage
LT1571-2: 200kHz, Fixed 8.2V or 8.4V
U
APPLICATIO S
s _{Cellular Phones, PDAs, Notebook Computers,}
Portable Instruments
s _{Cradle Chargers for Li-Ion, NiCd, NiMH and}
Lead-Acid Rechargeable Batteries
The LT^®1571 PWM battery charger is a simple, efficient
solution to fast-charge rechargeable batteries including
lithium-ion (Li-Ion), nickel-metal-hydride (NiMH) and
nickel-cadmium (NiCd) using constant-current and/or
constant-voltage control. The internal switch is capable
of delivering 1.5A DC current (2A peak current). The
onboard current sense resistor (0.1Ω) allows simple
charge current programming to within 5% accuracy
using a low cost external resistor. The constant-voltage
output can be selected for 4.1V or 4.2V per cell with 0.6%
accuracy.
LT1571 can charge batteries ranging from 1V to 20V. A
saturating switch operating at 200kHz (LT1571-1,
LT1571-2) or 500kHz (LT1571-5) gives high efficiency
and small charger size. A logic output (flag) indicates
Li-Ion near full charge when the charge current drops to
20% of the programmed value. The LT1571-1 and
LT1571-2 are in a 28-pin fused lead narrow SSOP power
package. The LT1571-5 is in a 16-pin fused lead narrow
SSOP power package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
V_IN
8.2V
TO 20V
D3
MBRM120T3
C_IN*
10µF
D1
MBRM120T3
V_CC
SW
LT1571-5
V_DD
100k 6.19k
CHARGE
COMPLETE
4.2V
Li-Ion
BATTERY
1µF
300Ω
PROG
0.33µF
V_C
1k
+ _COUT***
22µF
FLAG
BAT
BAT2
BOOST
SENSE
CAP
SELECT
GND
C1
0.22µF
D2
MMBD914L
L1**
10µH
0.1µF
*TOKIN OR MARCON CERAMIC SURFACE MOUNT
**COILTRONICS TP3-100, 10µH, 2.2mm HEIGHT (0.8A CHARGING CURRENT)
COILTRONICS TP1 SERIES, 10µH, 1.8mm HEIGHT (<0.5A CHARGING CURRENT)
***PANASONIC EEFCD1B220
1571 F01
Figure 1. Compact Li-Ion Cellular Phone Charger (0.8A)
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
1