LT1571_15 Datasheet, PDF (1/16 Pages) Linear Technology – Constant-Current/ Constant-Voltage Battery Chargers with Preset Voltage and Termination Flag

LT1571 Series
Constant-Current/
Constant-Voltage Battery Chargers
with Preset Voltage and Termination Flag
FEATURES
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 _{LT1571-1: 200kHz, Adjustable Voltage}
LT1571-2: 200kHz, Fixed 8.2V or 8.4V
LT1571-5: 500kHz, Fixed 4.1V or 4.2V
U
APPLICATIO S
s Cellular Phones, PDAs, Notebook Computers,
Portable Instruments
s _{Cradle Chargers for Li-Ion, NiCd, NiMH and}
Lead-Acid Rechargeable Batteries
DESCRIPTIO
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 APPLICATION
V_IN
8.2V TO 20V
(ADAPTER
OUTPUT)
D3
MBRM120T3
C_IN*
10µF
D1
MBRM120T3
V_CC
SW
LT1571-5
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)
1