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Número de pieza | LT1510I | |
Descripción | Constant-Voltage/ Constant-Current Battery Charger | |
Fabricantes | Linear Technology | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de LT1510I (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
No Preview Available ! LT1510/LT1510-5
Constant-Voltage/
Constant-Current Battery Charger
FEATURES
s Charges NiCd, NiMH and Lithium-Ion Batteries ––
Only One 1/10W Resistor Is Needed to Program
Charging Current
s High Efficiency Current Mode PWM with 1.5A
Internal Switch and Sense Resistor
s 3% Typical Charging Current Accuracy
s Precision 0.5% Voltage Reference for Voltage
Mode Charging or Overvoltage Protection
s Current Sensing Can Be at Either Terminal of
the Battery
s Low Reverse Battery Drain Current: 3µA
s Charging Current Soft Start
s Shutdown Control
s 500kHz Version Uses Small Inductor
U
APPLICATIONS
s Chargers for NiCd, NiMH and Lithium Batteries
s Step-Down Switching Regulator with Precision
Adjustable Current Limit
DESCRIPTION
With switching frequency as high as 500kHz, The LT®1510
current mode PWM battery charger is the smallest, sim-
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
* NiCd and NiMH batteries require charge termination circuitry (not shown in Figure 1).
TYPICAL APPLICATIONS
C1 D1
0.22µF MBRM120T3
SW
VCC +
D3
MBRM120T3
CIN*
10µF
8.2V TO 20V
–+
L1**
10µH
D2
MMBD914L
BOOST PROG
LT1510-5
GND VC
OVP
1µF
300Ω
0.1µF
1k
6.19k
SENSE
BAT
+
+
COUT***
22µF
4.2V
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
Q3†
2N7002
R3
70.6k
0.25%
R4
100k
0.25%
1510 F01
Figure 1. 500kHz Smallest Li-Ion Cell Phone Charger (0.8A)
C1 D1
0.22µF 1N5819
SW
VCC +
CIN*
10µF
D3
1N5819
11V TO 28V
–+
L1**
33µH
D2
1N914
BOOST PROG
LT1510
GND VC
OVP
1µF
300Ω
0.1µF
1k
3.83k
SENSE
BAT
+
+
COUT
4.2V
22µF
TANT +
4.2V
NOTE: COMPLETE LITHIUM-ION CHARGER, NO TERMINATION REQUIRED
* TOKIN OR MARCON CERAMIC SURFACE MOUNT
** COILTRONICS CTX33-2
† OPTIONAL, SEE APPLICATIONS INFORMATION
Q3†
VN2222
R3
240k
0.25%
R4
100k
0.25%
1510 F02
Figure 2. Charging Lithium Batteries (Efficiency at 1.3A > 87%)
1
1 page TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency of Figure 2 Circuit
100
98 VCC = 15V (EXCLUDING DISSIPATION
ON INPUT DIODE D3)
96 VBAT = 8.4V
94
92
90
88
86
84
82
80
0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5
IBAT (A)
1510 G01
ICC vs VCC
7.0
MAXIMUM DUTY CYCLE
6.5 0°C
25°C
6.0
125°C
5.5
5.0
4.5
0
5 10 15 20 25 30
VCC (V)
1510 G03
Maximum Duty Cycle
98
97
96
95
94
93
92
91
90
0 20 40 60 80 100 120 140
TEMPERATURE (°C)
1510 G09
ICC vs Duty Cycle
8
VCC = 16V
7
6
5
0°C
4
3 25°C
125°C
2
1
0
0 10 20 30 40 50 60 70 80
DUTY CYCLE (%)
1510 G04
VREF Line Regulation
0.003
0.002
0.001
0
ALL TEMPERATURES
–0.001
–0.002
–0.003
0
5 10 15 20 25 30
VCC (V)
1510 G02
VC Pin Characteristic
–1.20
–1.08
–0.96
–0.84
–0.72
–0.60
–0.48
–0.36
–0.24
–0.12
0
0.12
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
VC (V)
1510 G10
LT1510/LT1510-5
Switching Frequency vs
Temperature
210
205
200
195
190
185
180
–20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
1510 G05
IVA vs ∆VOVP (Voltage Amplifier)
4
3
2
125°C
1
25°C
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
IVA (mA)
1510 G08
PROG Pin Characteristic
6
125°C
0 25°C
–6
0 1234 5
VPROG (V)
1510 G11
5
5 Page LT1510/LT1510-5
APPLICATIONS INFORMATION
of the battery, canceling part or all of the 200µA. Note that
if net current is into the battery and the battery is removed,
the charger output voltage will float high, to near input
voltage. This could be a problem when reinserting the
battery, if the resulting output capacitor/battery surge
current is high enough to damage either the battery or the
capacitor.
If net current into the battery must be less than zero in
shutdown, there are several options. Increasing divider
current to 300µA - 400µA will ensure that net battery
current is less than zero. For long term storage conditions
however, the divider may need to be disconnected with a
MOSFET switch as shown in Figures 2 and 5. A second
option is to connect a 1N914 diode in series with the
MOSFET drain. This will limit how far the VC pin will be pulled
down, and current (≈ 700µA) will flow into the BAT pin, and
therefore out of the battery. This is not usually a problem
unless the charger will remain in the shutdown state with
input power applied for very long periods of time.
Removing input power to the charger will cause the BAT
pin current to drop to near zero, with only the divider
current remaining as a small drain on the battery. Even
that current can be eliminated with a switch as shown in
Figures 2 and 5.
LT1510
OVP
R3
12k
Q3
VN2222
R5
220k
R4
4.99k
0.25%
VIN
+
4.2V
–
+
4.2V
–
VBAT
1510 F05
Figure 5. Disconnecting Voltage Divider
Some battery manufacturers recommend termination of
constant-voltage float mode after charging current has
dropped below a specified level (typically 50mA to 100mA)
and a further time-out period of 30 minutes to 90 minutes
has elapsed. This may extend the life of the battery, so
check with manufacturers for details. The circuit in Figure
7 will detect when charging current has dropped below
75mA. This logic signal is used to initiate a time-out
period, after which the LT1510 can be shut down by
pulling the VC pin low with an open collector or drain.
Some external means must be used to detect the need for
additional charging if needed, or the charger may be
turned on periodically to complete a short float-voltage
cycle.
Current trip level is determined by the battery voltage, R1
through R3, and the internal LT1510 sense resistor
(≈ 0.18Ω pin-to-pin). D2 generates hysteresis in the trip
level to avoid multiple comparator transitions.
Nickel-Cadmium and Nickel-Metal-Hydride Charging
The circuit in Figure 6 uses the 8-pin LT1510 to charge
NiCd or NiMH batteries up to 12V with charging currents
of 0.5A when Q1 is on and 50mA when Q1 is off.
C1 D1
0.22µF 1N5819
SW
VCC +
D3
1N5819
CIN*
10µF
WALL
ADAPTER
L1**
33µH
D2
1N914
BOOST PROG
LT1510
1µF
300Ω
R1
100k
GND
VC
0.1µF
1k
IBAT
R2
11k
Q1
VN2222
SENSE
* TOKIN OR MARCON CERAMIC
SURFACE MOUNT
** COILTRONICS CTX33-2
BAT
+
COUT
22µF
TANT
+
2V TO
20V
ON: IBAT = 0.5A
OFF: IBAT = 0.05A
1510 F05.5
Figure 6. Charging NiMH or NiCd Batteries
(Efficiency at 0.5A ≈ 90%)
For a 2-level charger, R1 and R2 are found from:
( )( )2000 2.465
IBAT =
RPROG
( )( )2.465 2000
R1 =
ILOW
( )( )2.465 2000
R2 =
IHI − ILOW
All battery chargers with fast-charge rates require some
means to detect full charge state in the battery to terminate
the high charging current. NiCd batteries are typically
charged at high current until temperature rise or battery
11
11 Page |
Páginas | Total 16 Páginas | |
PDF Descargar | [ Datasheet LT1510I.PDF ] |
Número de pieza | Descripción | Fabricantes |
LT1510 | Constant-Voltage/ Constant-Current Battery Charger | Linear Technology |
LT1510-5 | Constant-Voltage/ Constant-Current Battery Charger | Linear Technology |
LT1510-5CGN | Constant-Voltage/ Constant-Current Battery Charger | Linear Technology |
LT1510-5IGN | Constant-Voltage/ Constant-Current Battery Charger | Linear Technology |
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