1
LT1510/LT1510-5
Constant-Voltage/
Constant-Current Battery Charger
Figure 2. Charging Lithium Batteries (Efficiency at 1.3A > 87%)
* NiCd and NiMH batteries require charge termination circuitry (not shown in Figure 1).
TYPICAL APPLICATIONS
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
plest, most efficient solution to fast-charge modern re-
chargeable 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 1.5A DC
current (2A peak current). The 0.1Ω onboard current
sense resistor makes the charging current programming
very simple. One resistor (or a programming current from
a DAC) is required to set the full charging current (1.5A) to
within 5% accuracy. The LT1510 with 0.5% reference
voltage accuracy meets the critical constant-voltage charg-
ing requirement for lithium cells.
The LT1510 can charge batteries ranging from 2V 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 (500kHz for LT1510-5) gives
high charging efficiency and small inductor size. A block-
ing diode is not required between the chip and the battery
because the chip goes into sleep mode and drains only 3µA
when the wall adaptor is unplugged. Soft start and shutdown
features are also provided. The LT1510 is available in a 16-pin
fused lead power SO package with a thermal resistance of
50°C/W, an 8-pin SO and a 16-pin PDIP.
FEATURES
■
Charges NiCd, NiMH and Lithium-Ion Batteries ––
Only One
1
/
10
W Resistor Is Needed to Program
Charging Current
■
High Efficiency Current Mode PWM with 1.5A
Internal Switch and Sense Resistor
■
3% Typical Charging Current Accuracy
■
Precision 0.5% Voltage Reference for Voltage
Mode Charging or Overvoltage Protection
■
Current Sensing Can Be at Either Terminal of
the Battery
■
Low Reverse Battery Drain Current: 3µA
■
Charging Current Soft Start
■
Shutdown Control
■
500kHz Version Uses Small Inductor
With switching frequency as high as 500kHz, The LT
®
1510
current mode PWM battery charger is the smallest, sim-
APPLICATIONS
U
DESCRIPTION
U
■
Chargers for NiCd, NiMH and Lithium Batteries
■
Step-Down Switching Regulator with Precision
Adjustable Current Limit
Figure 1. 500kHz Smallest Li-Ion Cell Phone Charger (0.8A)
SW
BOOST
GND
SENSE
V
CC
PROG
V
C
BAT
6.19k
8.2V TO 20V
+
R3
70.6k
0.25%
R4
100k
0.25%
Q3
†
2N7002
NOTE: COMPLETE LITHIUM-ION CHARGER, NO TERMINATION REQUIRED
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
OPTIONAL, SEE APPLICATIONS INFORMATION
1510 F01
C1
0.22µF
C
IN
*
10µF
L1**
10µH
LT1510-5
D1
MBRM120T3
D3
MBRM120T3
D2
MMBD914L
OVP
+
C
OUT
***
22µF
4.2V
+
+
–
0.1µF
1k
1µF
300Ω
*
**
***
†
SW
BOOST
GND
SENSE
V
CC
PROG
V
C
BAT
3.83k
11V TO 28V
+
+
R3
240k
0.25%
R4
100k
0.25%
Q3
†
VN2222
NOTE: COMPLETE LITHIUM-ION CHARGER, NO TERMINATION REQUIRED
* TOKIN OR MARCON CERAMIC SURFACE MOUNT
** COILTRONICS CTX33-2
†
OPTIONAL, SEE APPLICATIONS INFORMATION
1510 F02
C1
0.22µF
C
IN
*
10µF
L1**
33µH
LT1510
D1
1N5819
D3
1N5819
D2
1N914
OVP
+
C
OUT
22µF
TANT
4.2V
4.2V
+
+
–
0.1µF
1k
1µF
300Ω
