DC086A - Demo Manual

DEMO MANUAL DC086
BATTERY CHARGER
DESCRIPTIO
LT1510 Constant-Voltage/
Constant-Current Lithium-Ion
Battery Charger
U
Demonstration board DC086 is a complete lithium-ion
battery charger designed for 1-, 2- or 3-cell applications
(other rechargeable battery types can also be charged, see
page three). The LT ®1510 is used in a high efficiency
current mode step-down switching topology, capable of
providing up to 1.5A of charging current. This demo board
uses all surface mount components, resulting in a circuit
occupying approximately 1 square inch of board area with
less than 0.3 in. (7.6mm) height.
Jumpers J1 and J2, located on the demo board, are used
to select the correct charging voltage for the number of
cells being charged (4.2V, 8.4V or 12.6V). Charging current is programmed for 1.3A by resistor R1.
The DC input voltage must be at least 3V greater than the
output voltage. When the input voltage is removed, an
external low current MOSFET (Q1) provides a disconnect
for the output voltage divider resistors and the chip goes
into a sleep mode, draining approximately 3µA from the
battery.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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PERFOR A CE SU
ARY
PARAMETER
CONDITIONS
LIMITS
VOUT + 3V ≤ VIN ≤ 28V*
VIN
Battery Voltage (VBAT)
When Charging Terminates
4.2 ±0.7%
8.4V ±0.7%
12.6V ±0.7%
VIN = 10V
VIN = 15V
VIN = 20V
1.3A ±5%
Maximum Battery Charging Current
Note: Good thermal PC board layout techniques are required when operating near maximum power levels to prevent excessive junction temperatures.
Note: For 0.5% battery-voltage accuracy, replace R3 to R8 with 0.1% resistors.
*For VIN > 25V, C1 should be replaced with a higher voltage rating capacitor.
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TYPICAL PERFOR A CE CHARACTERISTICS A D BOARD PHOTO
Component Side Demo Board
Charging Efficiency
96
94
VCC = 15V
VBAT = 8.4V
EFFICIENCY (%)
92
90
88
86
84
82
80
0.1
0.3
0.5
0.7 0.9 1.1 1.3
BATTERY CHARGING CURRENT (A)
1.5
DM086 • TPC01
1
DEMO MANUAL DC086
BATTERY CHARGER
U
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PACKAGE A D SCHE ATIC DIAGRA S
J3
GND
J4
VIN
D1
MBRS140L
1
2
1, 4
L1
CTX33-2
33µH
2, 3
C2
0.22µF
3
4
D3
MMBD914
5
6
7
8
GND
GND
SW
VCC
BOOST
VCC
GND
PROG
LT1510
OVP
VC
SENSE
BAT
GND
GND
GND
GND
J1
R3
4.99k
0.25%
16
TOP VIEW
D2
MBRS140L
GND 1
16 GND
SW 2
15 VCC2
BOOST 3
14 VCC1
15
14
C1
10µF
13
12
R9
1k
C5
0.1µF
11
10
9
Q1
2N7002
J2
R4
R5
R6
R7
R8
3.52k 4.99k 3.52k 4.99k 3.52k
0.25% 0.25% 0.25% 0.25% 0.25%
R2
300Ω
R1
3.83k
0.25%
C3
1µF
16V
IBAT
VBAT
+ C4
J6
VIN
GND 4
13 PROG
OVP 5
12 VC
SENSE 6
11 BAT
GND 7
10 GND
GND 8
9
S PACKAGE
16-LEAD PLASTIC SO
+ Li-Ion
22µF
GND
BATTERY
LT1510CS
J5
FOUR CORNER PINS ARE FUSED TO
INTERNAL DIE ATTACH PADDLE FOR
HEAT SINKING TO PC BOARD
PROGRAM OUTPUT VOLTAGE
BATTERY
J1
J2
VOLTAGE
CLOSED CLOSED
4.2V
CLOSED OPEN
8.4V
OPEN
OPEN
12.6V
USE GENEROUS AMOUNTS OF PC BOARD
COPPER AROUND LEADS (SEE LT1510
DATA SHEET AND DESIGN NOTE 124)
DM086 • SCHEMATIC
Figure 1. Demo Board Schematic
PARTS LIST
REFERENCE
DESIGNATOR
QUANTITY
PART NUMBER
DESCRIPTION
VENDOR
TELEPHONE
C1
1
1E106ZY5U-C304F-T
THCS50EIE106Z
10µF 25V 20% Y5U Ceramic Capacitor
Tokin
United Chemicon/Marcon
(408) 432-8020
(708) 696-2000
C2
1
12063C224MAT2A
0.22µF 25V 20% X7R Ceramic Capacitor
AVX
(207) 282-5111
C3
1
1206YG105ZAT2A
1µF 16V Y5V Ceramic Capacitor
AVX
(207) 282-5111
C4
1
TPSD226M025R0200
22µF 25V 20% Tantalum Capacitor
AVX
(207) 282-5111
C5
1
12065C104MAT2A
0.1µF 50V 20% X7R Ceramic Capacitor
AVX
(207) 282-5111
D1, D2
2
MBRS140LT3
1A 40V Schottky Diode
Motorola
(602) 244-3550
D3
1
MMBD914LT1
100V Silicon Diode
Motorola
(602) 244-3550
J1, J2
2
TSW-102-07-G-S
0.1"cc, 0.025"sq. 2-Pin Jumper
Samtech
(800) 726-8329
J3 to J6
4
1502-2
0.090" Turret Terminal
Keystone
(718) 956-8900
L1
1
CTX33-2
33µH 2A SMT Inductor
Coiltronics
(407) 241-7876
Q1
1
2N7002
N-Channel MOSFET Transistor
Siliconix
(800) 554-5565
R1
1
CR1206F3K83CT
3.83k 1/4W 0.25% Chip Resistor
IRC
(512) 992-7900
R2
1
CR32-301J-T
300Ω 1/8W 5% Chip Resistor
AVX
(207) 282-5111
R3, R5, R7
3
CR1206F4K99CT
4.99k 1/4W 0.25% Chip Resistor
IRC
(512) 992-7900
R4, R6, R8
3
CR1206F3K52CT
3.52k 1/4W 0.25% Chip Resistor
IRC
(512) 992-7900
R9
1
CR32-102J-T
1k 1/8W 5% Chip Resistor
AVX
(207) 282-5111
U1
1
LT1510CS
SO-16 Battery Charger IC
LTC
(408) 432-1900
2
DEMO MANUAL DC086
BATTERY CHARGER
U
OPERATIO
The DC086 demonstration board is intended for evaluating the LT1510 switching regulator battery charger IC.
Solder terminals are provided for easy hookup to a power
supply and to a lithium-ion battery to be charged. The
correct charging voltage for either 1, 2 or 3 cells is
selectable by a combination of jumpers (J1 and J2) on the
board. See the schematic diagram for jumper information.
Current limit is set for 1.29A by resistor R1.
With a suitable input power supply and a discharged
battery connected to the demo board, the battery will
begin charging at the programmed current limit of 1.29A.
As the battery charges, the voltage rises and approaches
the program voltage of either 4.2V, 8.4V or 12.6V. The
charger will then maintain a constant voltage across the
battery, with the charging current decreasing to zero over
time as the battery reaches a fully charged condition.
The IC goes into a sleep mode when the input voltage is
removed. In the sleep mode, the drain from the battery due
to the LT1510 is approximately 3µA. An additional source
of battery drain is due to the leakage current of Schottky
diode D1. Selecting a low leakage Schottky diode such as
a Motorola MBRD340 or a low leakage 3A silicon diode
can minimize this current drain.
Some lithium-ion battery manufacturers recommend terminating the constant-voltage float mode after the charge
current has dropped below a specific level (typically 50mA
to 100mA) and a specific amount of time has elapsed
(typically from 30 to 90 minutes). This may extend the life
of the battery, but check with the manufacturer of the
battery you are using for details. Included on the board is
an area for breadboarding a timing circuit.
Other Battery Types
Although the demo board was designed for charging
Li-Ion batteries, simple modifications will allow other
battery types to be charged.
Sealed lead-acid batteries are charged using a currentlimited constant voltage. Over a 0°C to 40°C temperature
range, a charge voltage of 2.35V/cell can be used with no
charge termination needed. The maximum charge current
is determined by the battery manufacturer and is typically
0.25C or less. To use the demo board for charging sealed
Note: C is the capacity rating of the battery in Ampere-Hours.
lead-acid batteries, reprogram the OVP (overvoltage protection) feedback resistor divider for the correct battery
charging voltage using the following formula:
V

RF = R3  OUT – 1
 VREF 
where RF = total resistance between OVP pin and BAT pin,
VREF = 2.465V, select R3 = 4.99k, 1% or less.
Maximum charging current (up to 1.5A) is programmed
by R1 using the following formula:
R1 =
(2000)(2.465)
ICHARGE
where 2.465V = reference voltage present at PROG pin.
The maximum charging current (or current limit) is 2000
times the current out of the PROG pin. This current has both
AC and DC components present; therefore, to provide high
DC accuracy, averaging components R2 and C3 are required.
For nickel-cadmium and nickel-metal-hydride batteries,
the normal charging method is constant current. Fast
charging requires some method to detect full charge and
terminate the high charge current. Some methods often
used to indicate full charge include battery temperature
rise and observing battery voltage profile during charging.
LT1510 Step-Down Switching Regulator
The LT1510 is designed for constant-voltage and/or constant-current operation with a 0.5% voltage accuracy and
a 5% current accuracy. An external resistor voltage divider
programs the output voltage, while a single resistor (or a
programming current from a DAC) sets the maximum
charging current .
An internal 2A NPN switch operating at 200kHz provides
high efficiency with low inductor values using a minimum
number of external components. The charging current
sense resistor is included on the die and can be wired for
sensing charging current at either the positive or negative
side of the battery.
Refer to the LT1510 data sheet for complete product
specifications and design notes DN111 and DN124 for
additional application information.
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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DEMO MANUAL DC086
BATTERY CHARGER
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PCB LAYOUT AUD FILW
Component Side Silkscreen
Component Side
Component Side Solder Mask
Solder Side
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PC FAB DRAWI G
3.000
4
SYMBOL
DIAMETER
NUMBER
OF HOLES
NONE
0.010
10
B
0.015
17
C
0.035
80
D
0.040
4
E
0.095
4
F
0.070
2
TOTAL HOLES
117
F
E
C
B
E
2.000
E
0.150
Linear Technology Corporation
F
DD DD
0.150
E
NOTES:
1. BOARD MATERIAL IS FR-4, 0.062" THICK,
2 0Z COPPER
2. PCB WILL BE DOUBLE-SIDED
WITH PLATED THROUGH HOLES
3. SOLDER MASK BOTH SIDES WITH PC4014.
SILKSCREEN COMPONENT SIDE. USE
WHITE NONCONDUCTIVE INK
4. ALL DIMENSIONS IN INCHES ±0.005"
DC086 • PC DWG
LT/GP 0696 500 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1996
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