LINER LT1510IS8 Constant-voltage/ constant-current battery charger Datasheet

LT1510/LT1510-5
Constant-Voltage/
Constant-Current Battery Charger
FEATURES
■
■
■
■
■
■
■
■
■
Charges NiCd, NiMH and Lithium-Ion Batteries ––
Only One 1/10W 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
U
APPLICATIONS
■
■
Chargers for NiCd, NiMH and Lithium Batteries
Step-Down Switching Regulator with Precision
Adjustable Current Limit
U
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 rechargeable batteries including lithium-ion (Li-Ion), nickelmetal-hydride (NiMH)* and nickel-cadmium (NiCd)* that
require constant-current and/or constant-voltage charging. 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 charging 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 saturating switch running at 200kHz (500kHz for LT1510-5) gives
high charging efficiency and small inductor size. A blocking 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).
U
TYPICAL APPLICATIONS
C1
0.22µF
SW
VCC
BOOST
L1**
10µH
D2
MMBD914L
+
PROG
LT1510-5
GND
VC
0.1µF
SW
8.2V TO 20V
VCC
+
–+
CIN*
10µF
1µF
D3
1N5819
C1
D1
0.22µF 1N5819
D3
MBRM120T3
D1
MBRM120T3
BOOST
300Ω
L1**
33µH
6.19k
1k
D2
1N914
PROG
1µF
VC
–+
CIN*
10µF
LT1510
GND
11V TO 28V
0.1µF
300Ω
3.83k
1k
OVP
OVP
SENSE
SENSE
BAT
+
COUT***
22µF
BAT
+
+
4.2V
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
COUT
22µF
TANT
+
4.2V
Q3†
VN2222
+
4.2V
R3
70.6k
0.25%
R4
100k
0.25%
1510 F01
Figure 1. 500kHz Smallest Li-Ion Cell Phone Charger (0.8A)
NOTE: COMPLETE LITHIUM-ION CHARGER, NO TERMINATION REQUIRED
* TOKIN OR MARCON CERAMIC SURFACE MOUNT
** COILTRONICS CTX33-2
† OPTIONAL, SEE APPLICATIONS INFORMATION
R3
240k
0.25%
R4
100k
0.25%
1510 F02
Figure 2. Charging Lithium Batteries (Efficiency at 1.3A > 87%)
1
LT1510/LT1510-5
W W
U
W
ABSOLUTE MAXIMUM RATINGS
Operating Ambient Temperature Range
Commercial ............................................. 0°C to 70°C
Extended Commercial (Note 7) ........... – 40°C to 85°C
Industrial (Note 8) .............................. – 40°C to 85°C
Operating Junction Temperature Range
LT1510C (Note 7) ............................. – 40°C to 125°C
LT1510I ............................................ – 40°C to 125°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Supply Voltage (VMAX) ............................................ 30V
Switch Voltage with Respect to GND ...................... – 3V
Boost Pin Voltage with Respect to VCC ................... 30V
Boost Pin Voltage with Respect to GND ................. – 5V
VC, PROG, OVP Pin Voltage ...................................... 8V
IBAT (Average) ........................................................ 1.5A
Switch Current (Peak)............................................... 2A
Storage Temperature Range ................. – 65°C to 150°C
W
U
U
PACKAGE/ORDER INFORMATION
TOP VIEW
ORDER PART
NUMBER
TOP VIEW
SW 1
8
VCC
BOOST 2
7
PROG
GND 3
6
VC
SENSE 4
5
BAT
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 125°C, θJA = 125°C/ W
**GND
1
16 GND**
SW
2
15 VCC2
BOOST
3
14 VCC1
GND
4
13 PROG
OVP
5
12 VC
NC
6
11 NC
SENSE
7
10 BAT
**GND
8
9
ORDER PART
NUMBER
LT1510CS8
LT1510IS8
S8 PART MARKING
LT1510CGN
LT1510IGN
LT1510-5CGN
LT1510-5IGN
GND**
GN PACKAGE (0.015 IN)
16-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 75°C/ W
** FOUR CORNER PINS ARE FUSED TO
INTERNAL DIE ATTACH PADDLE FOR
HEAT SINKING. CONNECT THESE FOUR
PINS TO EXPANDED PC LANDS FOR
PROPER HEAT SINKING.
1510
1510I
GN PART
MARKING
1510
1510I
15105
15105I
ORDER PART
NUMBER
TOP VIEW
**GND
1
16 GND**
SW
2
15 VCC2
BOOST
3
14 VCC1
GND
4
13 PROG
OVP
5
12 VC
SENSE
6
11 BAT
GND
7
10 GND
**GND
8
9
N PACKAGE
16-LEAD PDIP
LT1510CN
LT1510CS
LT1510IN
LT1510IS
GND**
S PACKAGE*
16-LEAD PLASTIC SO
TJMAX = 125°C, θJA = 75°C/ W (N)
TJMAX = 125°C, θJA = 50°C/ W (S)*
* VCC1 AND VCC2 SHOULD BE CONNECTED
TOGETHER CLOSE TO THE PINS.
** FOUR CORNER PINS ARE FUSED TO
INTERNAL DIE ATTACH PADDLE FOR
HEAT SINKING. CONNECT THESE FOUR
PINS TO EXPANDED PC LANDS FOR
PROPER HEAT SINKING.
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
VCC = 16V, VBAT = 8V, VMAX (maximum operating VCC) = 28V, no load on any outputs, unless otherwise noted. (Notes 7, 8)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
2.90
2.91
4.3
4.5
mA
mA
Overall
Supply Current
VPROG = 2.7V, VCC ≤ 20V
VPROG = 2.7V, 20V < VCC ≤ VMAX
●
●
DC Battery Current, IBAT (Note 1)
8V ≤ VCC ≤ 25V, 0V ≤ VBAT ≤ 20V, TJ < 0°C
RPROG = 4.93k
RPROG = 3.28k (Note 4)
RPROG = 49.3k
TJ < 0°C
●
●
●
●
●
0.91
0.93
1.35
75
70
1.0
1.5
100
1.09
1.07
1.65
125
130
A
A
A
mA
mA
VCC = 28V, VBAT = 20V
RPROG = 4.93k
RPROG = 49.3k
●
●
0.93
75
1.0
100
1.07
125
A
mA
2
LT1510/LT1510-5
ELECTRICAL CHARACTERISTICS
VCC = 16V, VBAT = 8V, VMAX (maximum operating VCC) = 28V, no load on any outputs, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Overall
Minimum Input Operating Voltage
Undervoltage Lockout
●
7
7.8
V
Reverse Current from Battery (When VCC Is Not
Connected, VSW Is Floating)
VBAT ≤ 20V, 0°C ≤ TJ ≤ 70°C
●
6.2
3
15
µA
Boost Pin Current
VCC – VBOOST ≤ 20V
20V < VCC – VBOOST ≤ 28V
2V ≤ VBOOST – VCC ≤ 8V (Switch ON)
8V < VBOOST – VCC ≤ 25V (Switch ON)
●
●
●
●
0.10
0.25
6
8
20
30
11
14
µA
µA
mA
mA
VCC = 10V
ISW = 1.5A, VBOOST – VSW ≥ 2V (Note 4)
ISW = 1A, VBOOST – VSW < 2V (Unboosted)
●
●
0.3
0.5
2.0
Ω
Ω
20
35
mA/A
2
4
100
200
µA
µA
Switch
Switch ON Resistance
∆IBOOST/∆ISW During Switch ON
VBOOST = 24V, ISW ≤ 1A
Switch OFF Leakage Current
VSW = 0V, VCC ≤ 20V
20V < VCC ≤ 28V
Maximum VBAT with Switch ON
●
●
●
Minimum IPROG for Switch ON
Minimum IPROG for Switch OFF at VPROG ≤ 1V
●
2
4
1
2.4
VCC – 2
V
20
µA
mA
Current Sense Amplifier Inputs (SENSE, BAT)
Sense Resistance (RS1)
0.08
0.12
Ω
Total Resistance from SENSE to BAT (Note 3)
0.2
0.25
Ω
– 200
700
– 375
1300
µA
µA
VCC – 2
V
BAT Bias Current (Note 5)
VC < 0.3V
VC > 0.6V
Input Common Mode Limit (Low)
●
Input Common Mode Limit (High)
●
– 0.25
V
Reference
Reference Voltage (Note 1) S8 Package
RPROG = 4.93k, Measured at PROG Pin
Reference Voltage (Note 2) 16-Pin
RPROG = 3.28k, Measured at OVP with
VA Supplying IPROG and Switch OFF
Reference Voltage Tolerance, 16-Pin Only
8V ≤ VCC ≤ 28V, 0°C ≤ TJ ≤ 70°C
8V ≤ VCC ≤ 28V, 0°C ≤ TJ ≤ 125°C
8V ≤ VCC ≤ 28V, TJ < 0°C
●
●
●
●
2.415
2.465
2.515
V
2.453
2.465
2.477
V
2.446
2.441
2.430
2.465
2.480
2.489
2.489
V
V
V
180
440
200
500
220
550
kHz
kHz
200
230
230
575
575
kHz
kHz
kHz
kHz
Oscillator
Switching Frequency
LT1510
LT1510-5
Switching Frequency Tolerance
All Conditions of VCC, Temperature, LT1510
LT1510, TJ < 0°C
LT1510-5
LT1510-5, TJ < 0°C
●
●
●
●
170
160
425
400
LT1510
LT1510, TA = 25°C (Note 8)
LT1510-5 (Note 9)
●
87
90
77
Maximum Duty Cycle
●
500
93
81
%
%
%
3
LT1510/LT1510-5
ELECTRICAL CHARACTERISTICS
VCC = 16V, VBAT = 8V, VMAX (maximum operating VCC) = 28V, no load on any outputs, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VC = 1V, IVC = ±1µA
150
250
550
µmho
Current Amplifier (CA2)
Transconductance
Maximum VC for Switch OFF
●
VC ≥ 0.6V
VC < 0.45V
IVC Current (Out of Pin)
0.6
V
100
3
µA
mA
2.5
mho
Voltage Amplifier (VA), 16-Pin Only
Transconductance (Note 2)
Output Current from 100µA to 500µA
0.5
Output Source Current, VCC = 10V
VPROG = VOVP = VREF + 10mV
1.3
OVP Input Bias Current
At 0.75mA VA Output Current
The ● denotes specifications which apply over the specified
temperature range.
Note 1: Tested with Test Circuit 1.
Note 2: Tested with Test Circuit 2.
Note 3: Sense resistor RS1 and package bond wires.
Note 4: Applies to 16-pin only. 8-pin packages are guaranteed but not
tested at – 40°C.
Note 5: Current (≈ 700µA) flows into the pins during normal operation and
also when an external shutdown signal on the VC pin is greater than 0.3V.
Current decreases to ≈ 200µA and flows out of the pins when external
shutdown holds the VC pin below 0.3V. Current drops to near zero when
input voltage collapses. See external Shutdown in Applications Information
section.
Note 6: A linear interpolation can be used for reference voltage
specification between 0°C and – 40°C.
1.2
mA
50
●
150
nA
Note 7: Commercial grade device specifications are guaranteed over the
0°C to 70°C temperature range. In addition, commercial grade device
specifications are assured over the –40°C to 85°C temperature range by
design or correlation, but are not production tested.
Maximum allowable ambient temperature may be limited by power
dissipation. Parts may not necessarily be operated simultaneously at
maximum power dissipation and maximum ambient temperature.
Temperature rise calculations must be done as shown in the Applications
Information section to ensure that maximum junction temperature does
not exceed the 125°C limit. With high power dissipation, maximum
ambient temperature may be less than 70°C.
Note 8: Industrial grade device specifications are guaranteed over the
– 40°C to 85°C temperature range.
Note 9: 91% maximum duty cycle is guaranteed by design if VBAT or VX
(see Figure 8 in Application Information) is kept between 3V and 5V.
Note 10: VBAT = 4.2V.
U W
TYPICAL PERFORMANCE CHARACTERISTICS
Thermally Limited Maximum
Charging Current, 8-Pin SO
Thermally Limited Maximum
Charging Current, 16-Pin SO
1.5
1.1
4V BATTERY
0.9
8V BATTERY
0.7
12V BATTERY
0.5
16V BATTERY
1.5
4V BATTERY
8V BATTERY
1.3
MAXIMUM CHARGING CURRENT (A)
(θJA =125°C/W)
TAMAX = 60°C
TJMAX =125°C
MAXIMUM CHARGING CURRENT (A)
MAXIMUM CHARGING CURRENT (A)
1.3
12V BATTERY
1.1
16V BATTERY
0.9
(θJA =50°C/W)
TAMAX =60°C
TJMAX =125°C
0.7
0.5
0.3
0
5
15
10
INPUT VOLTAGE (V)
20
25
1510 G12
4
Thermally Limited Maximum
Charging Current, 16-Pin GN
0
5
15
10
INPUT VOLTAGE (V)
20
25
1510 G13
1.3
4V BATTERY
1.1
8V BATTERY
0.9
θJA = 80°C/W
TAMAX = 60°C
TJMAX = 125°C
0.7
12V BATTERY
16V BATTERY
0.5
0
5
15
10
INPUT VOLTAGE (V)
20
25
LT1510 • TPC14
LT1510/LT1510-5
U W
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency of Figure 2 Circuit
100
8
7
205
6
94
ICC (mA)
92
90
88
FREQUENCY (kHz)
96
210
VCC = 16V
VCC = 15V (EXCLUDING DISSIPATION
ON INPUT DIODE D3)
VBAT = 8.4V
98
EFFICIENCY (%)
Switching Frequency vs
Temperature
ICC vs Duty Cycle
5
0°C
125°C
4
25°C
3
86
200
195
190
2
84
185
1
82
80
0
0.1
0.3
0.5
0.7 0.9
IBAT (A)
1.1
1.3
1.5
0
10
20
30 40 50 60
DUTY CYCLE (%)
70
180
–20
80
0
20
40 60 80 100 120 140
TEMPERATURE (°C)
1510 G04
1510 G01
ICC vs VCC
1510 G05
IVA vs ∆VOVP (Voltage Amplifier)
VREF Line Regulation
7.0
4
0.003
MAXIMUM DUTY CYCLE
0.002
0°C
6.5
3
0.001
125°C
5.5
ALL TEMPERATURES
∆VOVP (mV)
6.0
∆VREF (V)
ICC (mA)
25°C
0
2
125°C
–0.001
1
5.0
–0.002
4.5
0
5
10
15
VCC (V)
20
25
30
–0.003
25°C
0
5
10
15
VCC (V)
1510 G03
20
25
0
30
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
IVA (mA)
1510 G02
Maximum Duty Cycle
1510 G08
VC Pin Characteristic
PROG Pin Characteristic
–1.20
98
6
–1.08
97
–0.72
94
125°C
IPROG (mA)
–0.84
95
IVC (mA)
DUTY CYCLE (%)
–0.96
96
–0.60
–0.48
93
–0.36
92
–0.24
25°C
0
–0.12
91
0
90
0
20
40
60
80
100
120
140
TEMPERATURE (°C)
1510 G09
0.12
–6
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
0
1
2
3
VPROG (V)
4
5
1510 G11
5
LT1510/LT1510-5
U W
TYPICAL PERFORMANCE CHARACTERISTICS
Switch Current vs Boost Current
vs Boost Voltage
Reference Voltage vs
Temperature
2.470
50
95
35
30
25
20
15
10
MAXIMUM DUTY CYCLE (%)
2.468
VBOOST = 38V
28V
18V
40
BOOST CURRENT (mA)
96
VCC = 16V
REFERENCE VOLTAGE (V)
45
VBOOST vs
Maximum Duty Cycle
2.466
2.464
2.462
2.460
5
0
94
93
92
91
90
89
88
87
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
SWITCH CURRENT (A)
2.458
0
25
1510 G07
50
75
100
TEMPERATURE (°C)
125
150
86
2
4
6
1510 G14
8
10 12 14 16 18 20 22
VBOOST (V)
LT1510 • TPC15
U
U
U
PIN FUNCTIONS
GND: Ground Pin.
BAT: Current Amplifier CA1 Input.
SW: Switch Output. The Schottky catch diode must be
placed with very short lead length in close proximity to SW
pin and GND.
PROG: This pin is for programming the charging current
and for system loop compensation. During normal operation, VPROG stays close to 2.465V. If it is shorted to GND
the switching will stop. When a microprocessor-controlled
DAC is used to program charging current, it must be
capable of sinking current at a compliance up to 2.465V.
VCC: Supply for the Chip. For good bypass, a low ESR
capacitor of 10µF or higher is required, with the lead length
kept to a minimum. VCC should be between 8V and 28V
and at least 2V higher than VBAT for VBAT less than 10V, and
2.5V higher than VBAT for VBAT greater than 10V. Undervoltage lockout starts and switching stops when VCC goes
below 7V. Note that there is a parasitic diode inside from
SW pin to VCC pin. Do not force VCC below SW by more
than 0.7V with battery present. All VCC pins should be
shorted together close to the pins.
BOOST: This pin is used to bootstrap and drive the switch
power NPN transistor to a low on-voltage for low power
dissipation. In normal operation, VBOOST = VCC + VBAT
when switch is on. Maximum allowable VBOOST is 55V.
SENSE: Current Amplifier CA1 Input. Sensing can be at
either terminal of the battery. Note that current sense
resistor RS1 (0.08Ω) is between Sense and BAT pins.
6
VC: This is the control signal of the inner loop of the current
mode PWM. Switching starts at 0.7V and higher VC
corresponds to higher charging current in normal operation. A capacitor of at least 0.1µF to GND filters out noise
and controls the rate of soft start. To shut down switching,
pull this pin low. Typical output current is 30µA.
OVP: This is the input to the amplifier VA with a threshold
of 2.465V. Typical input current is about 50nA into pin. For
charging lithium-ion batteries, VA monitors the battery
voltage and reduces charging current when battery voltage reaches the preset value. If it is not used, the OVP pin
should be grounded.
LT1510/LT1510-5
W
BLOCK DIAGRAM
200kHz
OSCILLATOR
+
VCC
SHUTDOWN
0.7V
+
–
VSW
BOOST
S
–
VCC
QSW
R
R
+
SW
+
–
1.5V
SLOPE
COMPENSATION
PWM
VBAT
C1
B1
R2
+
–
+
IPROG
+
GND
R1 IPROG = 500µA/A
1k IBAT
R3
RS1
–
BAT
+
–
VC
SENSE
IBAT
CA1
CA2
+
60k
0VP
VA
gm = 0.64
VREF
PROG
RPROG
CPROG
IPROG
Ω
–
VREF
2.465V
CHARGING CURRENT IBAT
= (IPROG)(2000)
1510 BD
( )
= 2.465V (2000)
RPROG
TEST CIRCUITS
Test Circuit 1
LT1510
SENSE
+
–
VC
60k
RS1
–
1k
+
0.047µF
CA1
CA2
IBAT
BAT
+
+
56µF
VBAT
VREF
PROG
0.22µF
3.3k
RPROG
+
LT1006
1k
+
LT1010
–
2N3055
1k
≈ 0.65V
20k
1510 TC01
7
LT1510/LT1510-5
TEST CIRCUITS
Test Circuit 2
LT1510
OVP
+
VA
–
VREF
PROG
10k
IPROG
10k
0.47µF
RPROG
–
+
+
LT1013
2.465V
1510 TC02
U
OPERATIO
The LT1510 is a current mode PWM step-down (buck)
switcher. The battery DC charging current is programmed
by a resistor RPROG (or a DAC output current) at the PROG
pin (see Block Diagram). Amplifier CA1 converts the
charging current through RS1 to a much lower current
IPROG (500µA/A) fed into the PROG pin. Amplifier CA2
compares the output of CA1 with the programmed current
and drives the PWM loop to force them to be equal. High
DC accuracy is achieved with averaging capacitor CPROG.
Note that IPROG has both AC and DC components. IPROG
goes through R1 and generates a ramp signal that is fed to
the PWM control comparator C1 through buffer B1 and
level shift resistors R2 and R3, forming the current mode
inner loop. The Boost pin drives the switch NPN QSW into
saturation and reduces power loss. For batteries like
lithium-ion that require both constant-current and constant-voltage charging, the 0.5%, 2.465V reference and
the amplifier VA reduce the charging current when battery
voltage reaches the preset level. For NiMH and NiCd, VA
can be used for overvoltage protection. When input voltage is not present, the charger goes into low current (3µA
typically) sleep mode as input drops down to 0.7V below
battery voltage. To shut down the charger, simply pull the
VC pin low with a transistor.
U
W
U
U
APPLICATIONS INFORMATION
Application Note 68, the LT1510 design manual, contains
more in depth appications examples.
Input and Output Capacitors
In the chargers in Figures 1 and 2 on the first page of this
data sheet, the input capacitor CIN is assumed to absorb all
input switching ripple current in the converter, so it must
have adequate ripple current rating. Worst-case RMS
ripple current will be equal to one half of output charging
current. Actual capacitance value is not critical. Solid
8
tantalum capacitors such as the AVX TPS and Sprague
593D series have high ripple current rating in a relatively
small surface mount package, but caution must be used
when tantalum capacitors are used for input bypass. High
input surge currents can be created when the adapter is
hot-plugged to the charger and solid tantalum capacitors
have a known failure mechanism when subjected to very
high turn-on surge currents. Highest possible voltage
rating on the capacitor will minimize problems. Consult with
the manufacturer before use. Alternatives include new high
LT1510/LT1510-5
U
W
U
U
APPLICATIONS INFORMATION
capacity ceramic capacitor (5µF to 10µF) from Tokin or
United Chemi-Con/MARCON, et al., and the old standby,
aluminum electrolytic, which will require more microfarads
to achieve adequate ripple rating. OS-CON can also be used.
The output capacitor COUT is also assumed to absorb
output switching current ripple. The general formula for
capacitor current is:
IRMS =
 V 
0.29 VBAT  1 − BAT 
VCC 

( )
(L1)(f)
For example, with VCC = 16V, VBAT = 8.4V, L1 = 30µH and
f = 200kHz, IRMS = 0.2A.
EMI considerations usually make it desirable to minimize
ripple current in the battery leads, and beads or inductors
may be added to increase battery impedance at the 200kHz
switching frequency. Switching ripple current splits between the battery and the output capacitor depending on
the ESR of the output capacitor and the battery impedance.
If the ESR of COUT is 0.2Ω and the battery impedance is
raised to 4Ω with a bead of inductor, only 5% of the current
ripple will flow in the battery.
deliver full power to the load when the input voltage is still
well below its final value. If the adapter is current limited,
it cannot deliver full power at reduced output voltages and
the possibility exists for a quasi “latch” state where the
adapter output stays in a current limited state at reduced
output voltage. For instance, if maximum charger plus
computer load power is 20W, a 24V adapter might be
current limited at 1A. If adapter voltage is less than (20W/1A
= 20V) when full power is drawn, the adapter voltage will be
sucked down by the constant 20W load until it reaches a
lower stable state where the switching regulators can no
longer supply full load. This situation can be prevented by
utilizing undevoltage lockout, set higher than the minimum
adapter voltage where full power can be achieved.
A fixed undervoltage lockout of 7V is built into the VCC pin.
Internal lockout is performed by clamping the VC pin low.
The VC pin is released from its clamped state when the VCC
pin rises above 7V. The charger will start delivering current
about 2ms after VC is released, as set by the 0.1µF at VC
pin. Higher lockout voltage can be implemented with a
Zener diode (see Figure 3 circuit).
VIN
VZ
Soft Start
The LT1510 is soft started by the 0.1µF capacitor on VC
pin. On start-up, VC pin voltage will rise quickly to 0.5V,
then ramp at a rate set by the internal 45µA pull-up current
and the external capacitor. Battery charging current starts
ramping up when VC voltage reaches 0.7V and full current
is achieved with VC at 1.1V. With a 0.1µF capacitor, time to
reach full charge current is about 3ms and it is assumed
that input voltage to the charger will reach full value in less
than 3ms. Capacitance can be increased up to 0.47µF if
longer input start-up times are needed.
In any switching regulator, conventional timer-based soft
starting can be defeated if the input voltage rises much
slower than the time-out period. This happens because the
switching regulators in the battery charger and the computer power supply are typically supplying a fixed amount
of power to the load. If input voltage comes up slowly
compared to the soft start time, the regulators will try to
D1
1N4001
VCC
VC
2k
LT1510
GND
1510 F03
Figure 3. Undervoltage Lockout
The lockout voltage will be VIN = VZ + 1V.
For example, for a 24V adapter to start charging at 22VIN,
choose VZ = 21V. When VIN is less than 22V, D1 keeps VC
low and charger off.
Charging Current Programming
The basic formula for charging current is (see Block
Diagram):
 2.465V 
IBAT = IPROG 2000 = 
 2000
 RPROG 
( )(
)
(
)
9
LT1510/LT1510-5
U
U
W
U
APPLICATIONS INFORMATION
where RPROG is the total resistance from PROG pin to
ground.
For example, 1A charging current is needed.
RPROG =
even this low current drain. A 47k resistor from adapter
output to ground should be added if Q3 is used to ensure
that the gate is pulled to ground.
With divider current set at 25µA, R4 = 2.465/25µA = 100k
and,
(2.465V)(2000) = 4.93k
1A
Charging current can also be programmed by pulse width
modulating IPROG with a switch Q1 to RPROG at a frequency
higher than a few kHz (Figure 4). Charging current will be
proportional to the duty cycle of the switch with full current
at 100% duty cycle.
When a microprocessor DAC output is used to control
charging current, it must be capable of sinking current
at a compliance up to 2.5V if connected directly to the
PROG pin.
LT1510
PROG
R3 =
(R4)(V
) = 100k (8.4 − 2.465)
2.465 + R4(0.05µA) 2.465 + 100k (0.05µA)
BAT − 2.465
= 240k
Lithium-ion batteries typically require float voltage accuracy of 1% to 2%. Accuracy of the LT1510 OVP voltage is
±0.5% at 25°C and ±1% over full temperature. This leads
to the possibility that very accurate (0.1%) resistors might
be needed for R3 and R4. Actually, the temperature of the
LT1510 will rarely exceed 50°C in float mode because
charging currents have tapered off to a low level, so 0.25%
resistors will normally provide the required level of overall
accuracy.
300Ω
External Shutdown
RPROG
4.64k
CPROG
1µF
Lithium-Ion Charging
The LT1510 can be externally shut down by pulling the VC
pin low with an open drain MOSFET, such as VN2222. The
VC pin should be pulled below 0.8V at room temperature
to ensure shutdown. This threshold decreases at about
2mV/°C. A diode connected between the MOSFET drain
and the VC pin will still ensure the shutdown state over all
temperatures, but it results in slightly different conditions
as outlined below.
The circuit in Figure 2 uses the 16-pin LT1510 to charge
lithium-ion batteries at a constant 1.3A until battery voltage reaches a limit set by R3 and R4. The charger will then
automatically go into a constant-voltage mode with current decreasing to zero over time as the battery reaches full
charge. This is the normal regimen for lithium-ion charging, with the charger holding the battery at “float” voltage
indefinitely. In this case no external sensing of full charge
is needed.
If the VC pin is held below threshold, but above ≈ 0.4V, the
current flowing into the BAT pin will remain at about
700µA. Pulling the VC pin below 0.4V will cause the current
to drop to ≈ 200µA and reverse, flowing out of the BAT pin.
Although these currents are low, the long term effect may
need to be considered if the charger is held in a shutdown
state for very long periods of time, with the charger input
voltage remaining. Removing the charger input voltage
causes all currents to drop to near zero.
Current through the R3/R4 divider is set at a compromise
value of 25µA to minimize battery drain when the charger
is off and to avoid large errors due to the 50nA bias current
of the OVP pin. Q3 can be added if it is desired to eliminate
If it is acceptable to have 200µA flowing into the battery
while the charger is in shutdown, simply pull the VC pin
directly to ground with the external MOSFET. The resistor
divider used to sense battery voltage will pull current out
5V
0V
Q1
VN2222
PWM
IBAT = (DC)(1A)
1510 F04
Figure 4. PWM Current Programming
10
LT1510/LT1510-5
U
U
W
U
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.
R3
12k
LT1510
Q3
VN2222
–
+
R5
220k
VIN
OVP
VBAT
+
–
4.2V
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.
D3
1N5819
C1
D1
0.22µF 1N5819
SW
VCC
+
BOOST PROG
L1**
33µH
D2
1N914
WALL
ADAPTER
1µF
R1
100k
300Ω
LT1510
GND
CIN*
10µF
0.1µF
VC
R2
11k
1k
Q1
VN2222
IBAT
SENSE
BAT
* TOKIN OR MARCON CERAMIC
SURFACE MOUNT
** COILTRONICS CTX33-2
+
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%)
4.2V
R4
4.99k
0.25%
For a 2-level charger, R1 and R2 are found from:
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
IBAT =
R1 =
(2000)(2.465)
RPROG
(2.465)(2000)
ILOW
R2 =
(2.465)(2000 )
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
LT1510/LT1510-5
U
U
W
U
APPLICATIONS INFORMATION
BAT
0.18Ω
INTERNAL
SENSE
RESISTOR
LT1510
ADAPTER
OUTPUT
SENSE
R1*
1.6k
D1
1N4148
C1
0.1µF
3
2
R2
D2
560k 1N4148
R4
470k
8
–
7
LT1011
GND
3.3V OR 5V
+
NEGATIVE EDGE
TO TIMER
4
1
R3
430k
* TRIP CURRENT =
R1(VBAT)
(R2 + R3)(0.18Ω)
1510 F06
Figure 7. Current Comparator for Initiating Float Time-Out
voltage decrease is detected as an indication of near full
charge. The charging current is then reduced to a much
lower value and maintained as a constant trickle charge.
An intermediate “top off” current may be used for a fixed
time period to reduce 100% charge time.
NiMH batteries are similar in chemistry to NiCd but have
two differences related to charging. First, the inflection
characteristic in battery voltage as full charge is approached is not nearly as pronounced. This makes it more
difficult to use dV/dt as an indicator of full charge, and
change of temperature is more often used with a temperature sensor in the battery pack. Secondly, constant trickle
charge may not be recommended. Instead, a moderate
level of current is used on a pulse basis (≈ 1% to 5% duty
cycle) with the time-averaged value substituting for a
constant low trickle.
battery and 1.1A for a 4.2V battery. This assumes a 60°C
maximum ambient temperature. The 16-pin SO, with a
thermal resistance of 50°C/W, can provide a full 1.5A
charging current in many situations. The 16-pin PDIP falls
between these extremes. Graphs are shown in the Typical
Performance Characteristics section.
( )( )
( )
(V ) 7.5mA + (0.012)(I )
+
PBIAS = 3.5mA VIN + 1.5mA VBAT
2
BAT
VIN
[
BAT
2
]

(I )(V ) 1+ V30 
=
55(V )
(I ) (R )(V ) + (t )(V )(I )(f)
=
V
= (0.18Ω)(I )
BAT
BAT
BAT
PDRIVER
IN
2
Thermal Calculations
If the LT1510 is used for charging currents above 0.4A, a
thermal calculation should be done to ensure that junction
temperature will not exceed 125°C. Power dissipation in
the IC is caused by bias and driver current, switch resistance, switch transition losses and the current sense
resistor. The following equations show that maximum
practical charging current for the 8-pin SO package
(125° C/W thermal resistance) is about 0.8A for an 8.4V
12
PSW
BAT
SW
BAT
OL
IN
IN
PSENSE
2
BAT
RSW = Switch ON resistance ≈ 0.35Ω
tOL = Effective switch overlap time ≈ 10ns
f = 200kHz (500kHz for LT1510-5)
BAT
LT1510/LT1510-5
U
U
W
U
APPLICATIONS INFORMATION
Example: VIN = 15V, VBAT = 8.4V, IBAT = 1.2A;
(
)( )
( )
PDRIVER 0.045W
=
= 14mA
VX
3.3V
Total board area becomes an important factor when the
area of the board drops below about 20 square inches. The
graph in Figure 9 shows thermal resistance vs board area
for 2-layer and 4-layer boards. Note that 4-layer boards
have significantly lower thermal resistance, but both types
show a rapid increase for reduced board areas. Figure 10
shows actual measured lead temperature for chargers
operating at full current. Battery voltage and input voltage
will affect device power dissipation, so the data sheet
power calculations must be used to extrapolate these
readings to other situations.
PBIAS = 3.5mA 15 + 1.5mA 8.4
(8.4)
+
2
15
[7.5mA + (0.012)(1.2)] = 0.17W
2

(1.2)(8.4) 1+ 830.4
=
= 0.13W
55(15)
2
1.2) (0.35)(8.4)
(
=
+
PDRIVER
PSW
15
( )( )(
 10 • 10 −9  15 1. 2 200kHz


= 0.28 + 0.04 = 0.32W
( )( )
PSENSE = 0.18 1.2
2
The average IVX required is:
)
Vias should be used to connect board layers together.
Planes under the charger area can be cut away from the
rest of the board and connected with vias to form both a
= 0.26W
Total power in the IC is:
SW
0.17 + 0.13 + 0.32+ 0.26 = 0.88W
D2
SENSE
VX
( )( )( )
=
55(V )
IN
For example, VX = 3.3V,
PDRIVER
 3.3V 
1.2A 8.4V 3.3V  1 +
30 

( )( )( )
=
55 (15V)
10µF
Figure 8
60
THERMAL RESISTANCE (°C/W)
PDRIVER
 V 
VX  1 + X 
 30 
1510 F07
+
IVX
The PDRIVER term can be reduced by connecting the boost
diode D2 (see Figures 2 and 6 circuits) to a lower system
voltage (lower than VBAT) instead of VBAT (see Figure 8).
Then,
BOOST
L1
Temperature rise will be (0.88W)(50°C/W) = 44°C. This
assumes that the LT1510 is properly heat sunk by connecting the four fused ground pins to the expanded traces
and that the PC board has a backside or internal plane for
heat spreading.
IBAT VBAT
LT1510
C1
55
50
2-LAYER BOARD
45
4-LAYER BOARD
40
35
S16, MEASURED FROM AIR AMBIENT
TO DIE USING COPPER LANDS AS
SHOWN ON DATA SHEET
30
25
0
= 0.045W
5
20
15
25
10
BOARD AREA (IN2)
30
35
1510 F08
Figure 9. LT1510 Thermal Resistance
13
LT1510/LT1510-5
U
W
U
U
APPLICATIONS INFORMATION
90
LEAD TEMPERATURE (°C)
event of an input short. The body diode of Q2 creates the
necessary pumping action to keep the gate of Q1 low
during normal operation (see Figure 11).
NOTE: PEAK DIE TEMPERATURE WILL BE
ABOUT 10°C HIGHER THAN LEAD TEMPERATURE AT 1.3A CHARGING CURRENT
80
70
2-LAYER BOARD
Q1
60
VIN
+
4-LAYER BOARD
50
VCC
ICHRG = 1.3A
VIN = 16V
VBAT = 8.4V
VBOOST = VBAT
TA = 25°C
40
30
20
0
5
20
15
25
10
BOARD AREA (IN2)
SW
Q2
D1
BOOST
L1
D2
30
35
SENSE
VX
3V TO 6V
1510 F09
Figure 10. LT1510 Lead temperature
Q1: Si4435DY
Q2: TP0610L
low thermal resistance system and to act as a ground
plane for reduced EMI.
Maximum duty cycle for the LT1510 is typically 90% but
this may be too low for some applications. For example, if
an 18V ±3% adapter is used to charge ten NiMH cells, the
charger must put out 15V maximum. A total of 1.6V is lost
in the input diode, switch resistance, inductor resistance
and parasitics so the required duty cycle is 15/16.4 =
91.4%. As it turns out, duty cycle can be extended to 93%
by restricting boost voltage to 5V instead of using VBAT as
is normally done. This lower boost voltage VX (see Figure
8) also reduces power dissipation in the LT1510, so it is a
win-win decision.
Even Lower Dropout
For even lower dropout and/or reducing heat on the board,
the input diode D3 (Figures 2 and 6) should be replaced
with a FET. It is pretty straightforward to connect a
P-channel FET across the input diode and connect its gate
to the battery so that the FET commutates off when the
input goes low. The problem is that the gate must be
pumped low so that the FET is fully turned on even when
the input is only a volt or two above the battery voltage.
Also there is a turn off speed issue. The FET should turn off
instantly when the input is dead shorted to avoid large
current surges form the battery back through the charger
into the FET. Gate capacitance slows turn off, so a small
P-FET (Q2) discharges the gate capacitance quickly in the
BAT
CX
10µF
VBAT
+
HIGH DUTY CYCLE
CONNECTION
1510 F10
Figure 11. Replacing the Input Diode
Higher Duty Cycle for the LT1510 Battery Charger
14
LT1510
C3
RX
50k
Layout Considerations
Switch rise and fall times are under 10ns for maximum
efficiency. To prevent radiation, the catch diode, SW pin
and input bypass capacitor leads should be kept as short
as possible. A ground plane should be used under the
switching circuitry to prevent interplane coupling and to
act as a thermal spreading path. All ground pins should be
connected to expand traces for low thermal resistance.
The fast-switching high current ground path including the
switch, catch diode and input capacitor should be kept
very short. Catch diode and input capacitor should be
close to the chip and terminated to the same point. This
path contains nanosecond rise and fall times with several
amps of current. The other paths contain only DC and /or
200kHz triwave and are less critical. Figure 13 shows
critical path layout. Figure 12 indicates the high speed,
high current switching path.
SWITCH NODE
L1
VBAT
VIN
CIN
HIGH
FREQUENCY
CIRCULATING
PATH
COUT
BAT
1510 F12
Figure 12. High Speed Switching Path
LT1510/LT1510-5
U
U
W
U
APPLICATIONS INFORMATION
GND
LT1510
D1
GND
GND
SW
VCC2
BOOST
VCC1
GND
PROG
OVP
L1
CIN
VC
SENSE
BAT
GND
GND
GND
GND
1510 F11
Figure 13. Critical Electrical and Thermal Path Layer
U
PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
GN Package
16-Lead Plastic SSOP (Narrow 0.150)
(LTC DWG # 05-08-1641)
0.015 ± 0.004
× 45°
(0.38 ± 0.10)
0.0075 – 0.0098
(0.191 – 0.249)
0.053 – 0.069
(1.351 – 1.748)
0.004 – 0.009
(0.102 – 0.249)
0° – 8° TYP
0.016 – 0.050
(0.406 – 1.270)
16 15 14 13 12 11 10 9
0.229 – 0.244
(5.817 – 6.198)
0.025
(0.635)
BSC
0.008 – 0.012
(0.203 – 0.305)
0.189 – 0.196*
(4.801 – 4.978)
0.150 – 0.157**
(3.810 – 3.988)
1
2 3
4
5 6
8
7
* DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
GN16 (SSOP) 0895
N Package
16-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.130 ± 0.005
(3.302 ± 0.127)
0.300 – 0.325
(7.620 – 8.255)
0.015
(0.381)
MIN
0.009 – 0.015
(0.229 – 0.381)
(
+0.025
0.325 –0.015
+0.635
8.255
–0.381
)
0.770*
(19.558)
MAX
0.045 – 0.065
(1.143 – 1.651)
0.065
(1.651)
TYP
0.125
(3.175)
MIN
0.005
(0.127)
MIN
0.100 ± 0.010
(2.540 ± 0.254)
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
0.255 ± 0.015*
(6.477 ± 0.381)
0.018 ± 0.003
(0.457 ± 0.076)
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
0.014 – 0.019
(0.355 – 0.483)
N16 0695
0.189 – 0.197*
(4.801 – 5.004)
8
7
6
5
0.228 – 0.244
(5.791 – 6.197)
0.150 – 0.157**
(3.810 – 3.988)
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270) BSC
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
1
2
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.
3
4
SO8 0695
15
LT1510/LT1510-5
U
TYPICAL APPLICATION
Adjustable Voltage Regulator with Precision Adjustable Current Limit
0.22µF
LT1510
1N5819
SW
VCC2
VIN
18V TO 25V
+
100µF
VCC1
PROG
BOOST
RPROG
4.93k
1k
30µH
0.01µF
VC
GND
1N914
0.1µF
OVP
SENSE
BAT
POT
5k
CURRENT LIMIT LEVEL =
( )
2.465V
(2000)
RPROG
+
500µF
POT
100k
VOUT
2.5V TO 15V
CURRENT LIMIT LEVEL
50mA TO 1A
1µF
1k
1510 TA01
U
PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
S Package
16-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.386 – 0.394*
(9.804 – 10.008)
16
0.008 – 0.010
(0.203 – 0.254)
0.014 – 0.019
(0.355 – 0.483)
13
12
11
10
9
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
0° – 8° TYP
0.016 – 0.050
0.406 – 1.270
14
0.004 – 0.010
(0.101 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
0.010 – 0.020
× 45°
(0.254 – 0.508)
15
0.050
(1.270)
TYP
1
2
3
4
5
6
7
8
S16 0695
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC 1325
Microprocessor-Controlled Battery Management
System
Can Charge, Discharge and Gas Gauge NiCd, NiMH and Pb-Acid
Batteries with Software Charging Profiles
LT1372/LT1377
500kHz/1MHz Step-Up Switching Regulators
High Frequency, Small Inductor, High Efficiency Switchers, 1.5A Switch
LT1373
250kHz Step-Up Switching Regulator
High Efficiency, Low Quiescent Current, 1.5A Switch
LT1376
500kHz Step-Down Switching Regulator
High Frequency, Small Inductor, High Efficiency Switcher, 1.5A Switch
LT1511
3A Constant-Voltage/Constant-Current Battery Charger
High Efficiency, Minimal External Components to Fast Charge Lithium,
NiMH and NiCd Batteries
LT1512
SEPIC Battery Charger
VIN Can Be Higher or Lower Than Battery Voltage
®
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417 ● (408) 432-1900
FAX: (408) 434-0507● TELEX: 499-3977 ● www.linear-tech.com
1510fc LT/GP 1197 REV C 4K • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 1995